WorldWideScience

Sample records for next-to-leading-order qcd corrections

  1. Next-to-leading order QCD corrections to five jet production at the LHC

    DEFF Research Database (Denmark)

    David Badger, Simon; Biedermann, Benedikt; Uwer, Peter;

    2014-01-01

    We present theoretical predictions for five-jet production in proton-proton collisions at next-to-leading-order accuracy in QCD. Inclusive as well as differential observables are studied for collision energies of 7 and 8 TeV. In general the next-to-leading-order corrections stabilize the theoreti...

  2. Next-to-leading order QCD corrections to paired Bc production in e+e- annihilation

    Science.gov (United States)

    Berezhnoy, A. V.; Likhoded, A. K.; Onishchenko, A. I.; Poslavsky, S. V.

    2017-02-01

    We present theoretical analysis of paired Bc mesons production in e+e- annihilation at different energy scales taking into account full next-to-leading order QCD corrections. Both possible electroweak channels are considered: production via virtual photon and via virtual Z-boson. We study in detail the role of radiative QCD corrections, which were found to be significant especially at low energies. It is shown that the contribution from Z-boson is significant at high energies (√{ s} >MZ / 2) especially in the case of paired production of pseudo-scalar and vector (Bc +Bc*) mesons. Azimuthal asymmetry induced by a P-violating weak interaction with Z-boson is also analyzed.

  3. Next-to-leading order QCD corrections to the production of two bottom-antibottom pairs at the LHC.

    Science.gov (United States)

    Greiner, Nicolas; Guffanti, Alberto; Reiter, Thomas; Reuter, Jürgen

    2011-09-02

    We report the results of a computation of the full next-to-leading order QCD corrections to the production of two bb pairs at the LHC. This calculation at the parton level provides predictions for well separated b jets. The results show that the next-to-leading order corrections lead to an enhancement of the cross section for the central scale choice by roughly 50% with respect to the leading order result. The theoretical uncertainty estimated by variation of the renormalization and factorization scales is strongly reduced by the inclusion of next-to-leading order corrections.

  4. Next-to-leading order QCD corrections to Higgs boson decay to quarkonium plus a photon

    CERN Document Server

    Chao, Zhou; Gang, Li; Ya-Jin, Zhou; Jian-You, Guo

    2016-01-01

    In this paper, we investigate the decay of Higgs boson to $J/\\psi(\\Upsilon)$ plus a photon based on NRQCD factorization. For the direct process, we calculate the decay width up to QCD NLO. We find that the decay width for process $H \\to J/\\psi(\\Upsilon)+ \\gamma$ direct production at the LO is significantly reduced by the NLO QCD corrections. For the indirect process, we calculate the $H \\to \\gamma^\\ast\\gamma$ with virtual $\\gamma$ substantially decaying to $J/\\psi(\\Upsilon)$, including all the SM Feynman diagrams. The decay width of indirect production is much larger than the direct decay width. Since it is very clean in experiment, the $H \\to J/\\psi(\\Upsilon)+ \\gamma$ decay could be observable at a 14 TeV LHC and it also offers a new way to probe the Yukawa coupling and New Physics at the LHC.

  5. Next-to-leading order QCD corrections to Higgs boson decay to quarkonium plus a photon

    Science.gov (United States)

    Zhou, Chao; Song, Mao; Li, Gang; Zhou, Ya-Jin; Guo, Jian-You

    2016-12-01

    In this paper, we investigate the decay of the Higgs boson to J/ψ(ϒ) plus a photon based on NRQCD factorization. For the direct process, we calculate the decay width up to QCD NLO. We find that the decay width for process H → J/ψ(ϒ) + γ direct production at the LO is significantly reduced by the NLO QCD corrections. For the indirect process, we calculate the H → γ*γ with virtual γ substantially decaying to J/ψ(ϒ), including all the SM Feynman diagrams. The decay width of indirect production is much larger than the direct decay width. Since it is very clean in experiment, the H → J/ψ(ϒ) + γ decay could be observable at a 14 TeV LHC and it also offers a new way to probe the Yukawa coupling and New Physics at the LHC. Supported by National Natural Science Foundation of China (11305001, 11105083, 11205003)

  6. Next-to-leading order QCD corrections to paired $B_c$ production in $e^+e^-$ annihilation

    CERN Document Server

    Berezhnoy, A V; Onishchenko, A I; Poslavsky, S V

    2016-01-01

    We present theoretical analysis of paired $B_c$ mesons production in $e^+e^-$ annihilation at different energy scales taking into account full next-to-leading order QCD corrections. Both possible electroweak channels are considered: production via virtual photon and via virtual $Z$-boson. We study in detail the role of radiative QCD corrections, which were found to be significant especially at low energies. It is shown that the contribution from $Z$-boson is significant at high energies ($\\sqrt{s} > M_Z/2$) especially in the case of paired production of pseudo-scalar and vector ($B_c + B_c^*$) mesons. Azimuthal asymmetry induced by a $P$-violating weak interaction with $Z$-boson is also analyzed.

  7. Next-to-leading-order QCD corrections to Higgs boson production in association with a top quark pair and a jet.

    Science.gov (United States)

    van Deurzen, H; Luisoni, G; Mastrolia, P; Mirabella, E; Ossola, G; Peraro, T

    2013-10-25

    We present the calculation of the cross section for Higgs boson production in association with a top quark pair plus one jet, at next-to-leading-order accuracy in QCD. All mass dependence is retained without recurring to any approximation. After including the complete next-to-leading-order QCD corrections, we observe a strong reduction in the scale dependence of the result. We also show distributions for the invariant mass of the top quark pair, with and without the additional jet, and for the transverse momentum and the pseudorapidity of the Higgs boson. Results for the virtual contributions are obtained with a novel reduction approach based on integrand decomposition via the Laurent expansion, as implemented in the library, NINJA. Cross sections and differential distributions are obtained with an automated setup which combines the GOSAM and SHERPA frameworks.

  8. Short-distance QCD corrections to {K}^0{overline{K}}^0 mixing at next-to-leading order in Left-Right models

    Science.gov (United States)

    Bernard, Véronique; Descotes-Genon, Sébastien; Silva, Luiz Vale

    2016-08-01

    Left-Right (LR) models are extensions of the Standard Model where left-right symmetry is restored at high energies, and which are strongly constrained by kaon mixing described in the framework of the |Δ S| = 2 effective Hamiltonian. We consider the short-distance QCD corrections to this Hamiltonian both in the Standard Model (SM) and in LR models. The leading logarithms occurring in these short-distance corrections can be resummed within a rigourous Effective Field Theory (EFT) approach integrating out heavy degrees of freedom progressively, or using an approximate simpler method of regions identifying the ranges of loop momentum generating large logarithms in the relevant two-loop diagrams. We compare the two approaches in the SM at next-to-leading order, finding a very good agreement when one scale dominates the problem, but only a fair agreement in the presence of a large logarithm at leading order. We compute the short-distance QCD corrections for LR models at next-to-leading order using the method of regions, and we compare the results with the EFT approach for the W W ' box with two charm quarks (together with additional diagrams forming a gauge-invariant combination), where a large logarithm occurs already at leading order. We conclude by providing next-to-leading-order estimates for cc, ct and tt boxes in LR models.

  9. Short-distance QCD corrections to K{sup 0}K̄{sup 0} mixingat next-to-leading order in Left-Right models

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Véronique [Groupe de Physique Théorique, Institut de Physique Nucléaire, UMR 8608, CNRS,University Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex (France); Descotes-Genon, Sébastien [Laboratoire de Physique Théorique, UMR 8627, CNRS, University Paris-Sud, Université Paris-Saclay,91405 Orsay Cedex (France); Silva, Luiz Vale [Groupe de Physique Théorique, Institut de Physique Nucléaire, UMR 8608, CNRS,University Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex (France); Laboratoire de Physique Théorique, UMR 8627, CNRS, University Paris-Sud, Université Paris-Saclay,91405 Orsay Cedex (France)

    2016-08-23

    Left-Right (LR) models are extensions of the Standard Model where left-right symmetry is restored at high energies, and which are strongly constrained by kaon mixing described in the framework of the |ΔS|=2 effective Hamiltonian. We consider the short-distance QCD corrections to this Hamiltonian both in the Standard Model (SM) and in LR models. The leading logarithms occurring in these short-distance corrections can be resummed within a rigourous Effective Field Theory (EFT) approach integrating out heavy degrees of freedom progressively, or using an approximate simpler method of regions identifying the ranges of loop momentum generating large logarithms in the relevant two-loop diagrams. We compare the two approaches in the SM at next-to-leading order, finding a very good agreement when one scale dominates the problem, but only a fair agreement in the presence of a large logarithm at leading order. We compute the short-distance QCD corrections for LR models at next-to-leading order using the method of regions, and we compare the results with the EFT approach for the WW{sup ′} box with two charm quarks (together with additional diagrams forming a gauge-invariant combination), where a large logarithm occurs already at leading order. We conclude by providing next-to-leading-order estimates for cc, ct and tt boxes in LR models.

  10. On the next-to-next-to leading order QCD corrections to heavy-quark production in deep-inelastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, H. [KEK Theory Center, Tsukuba (Japan); Lo Presti, N.A.; Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2012-05-15

    The contribution of quarks with masses m >> {lambda}{sub QCD} is the only part of the structure functions in deep-inelastic scattering (DIS) which is not yet known at the next-to-next-to-leading order (NNLO) of perturbative QCD. We present improved partial NNLO results for the most important structure function F{sub 2}(x,Q{sup 2}) near the partonic threshold, in the high-energy (small-x) limit and at high scales Q{sup 2} >> m{sup 2}; and employ these results to construct approximations for the gluon and quark coefficient functions which cover the full kinematic plane. The approximation uncertainties are carefully investigated, and found to be large only at very small values, x

  11. Next-to-leading order corrections in exclusive meson production

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, M.; Kugler, W.

    2007-08-15

    We analyze in detail the size of next-to-leading order corrections to hard exclusive meson production within the collinear factorization approach. Corrections to the cross section are found to be huge at small x{sub B} and substantial in typical fixed-target kinematics. With the models we take for nucleon helicity-flip distributions, the transverse target polarization asymmetry in vector meson production is strongly affected by radiative corrections, except at large x{sub B}. Its overall size is very small for {rho} production but can be large in the {omega} channel. (orig.)

  12. Next-to-leading order corrections to the valon model

    Indian Academy of Sciences (India)

    G R Bouroun; E Esfandyari

    2016-01-01

    A seminumerical solution to the valon model at next-to-leading order (NLO) in the Laguerre polynomials is presented. We used the valon model to generate the structure of proton with respect to the Laguerre polynomials method. The results are compared with H1 data and other parametrizations.

  13. Top-quark decay at next-to-next-to-leading order in QCD.

    Science.gov (United States)

    Gao, Jun; Li, Chong Sheng; Zhu, Hua Xing

    2013-01-25

    We present the complete calculation of the top-quark decay width at next-to-next-to-leading order in QCD, including next-to-leading electroweak corrections as well as finite bottom quark mass and W boson width effects. In particular, we also show the first results of the fully differential decay rates for the top-quark semileptonic decay t → W(+)(l(+)ν)b at next-to-next-to-leading order in QCD. Our method is based on the understanding of the invariant mass distribution of the final-state jet in the singular limit from effective field theory. Our result can be used to study arbitrary infrared-safe observables of top-quark decay with the highest perturbative accuracy.

  14. Matching next-to-leading order predictions to parton showers in supersymmetric QCD

    CERN Document Server

    Degrande, Celine; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng

    2016-01-01

    We present a fully automated framework based on the FeynRules and MadGraph5 aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.

  15. Matching next-to-leading order predictions to parton showers in supersymmetric QCD

    Directory of Open Access Journals (Sweden)

    Céline Degrande

    2016-04-01

    Full Text Available We present a fully automated framework based on the FeynRules and MadGraph5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.

  16. QCD event generators with next-to-leading order matrix-elements and parton showers

    CERN Document Server

    Kurihara, Y; Ishikawa, T; Kato, K; Kawabata, S; Munehisa, T; Tanaka, H

    2003-01-01

    A new method to construct event-generators based on next-to-leading order QCD matrix-elements and leading-logarithmic parton showers is proposed. Matrix elements of loop diagram as well as those of a tree level can be generated using an automatic system. A soft/collinear singularity is treated using a leading-log subtraction method. Higher order re-summation of the soft/collinear correction by the parton shower method is combined with the NLO matrix-element without any double-counting in this method. An example of the event generator for Drell-Yan process is given for demonstrating a validity of this method.

  17. Differential Higgs boson pair production at next-to-next-to-leading order in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Florian, Daniel de; Mazzitelli, Javier [UNSAM, Campus Miguelete, Buenos Aires (Argentina). International Center for Advanced Studies (ICAS); Grazzini, Massimiliano; Hanga, Catalin; Lindert, Jonas M. [Zuerich Univ. (Switzerland). Physik-Inst.; Kallweit, Stefan [Mainz Univ. (Germany). PRISMA Cluster of Excellence; Maierhoefer, Philipp [Freiburg Univ. (Germany). Physikalisches Inst.; Rathlev, Dirk [Deutsches Elektronen-Synchrotron, Hamburg (Germany). Theory Group

    2016-06-15

    We report on the first fully differential calculation for double Higgs boson production through gluon fusion in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation is performed in the heavy-top limit of the Standard Model, and in the phenomenological results we focus on pp collisions at √(s)=14 TeV. We present differential distributions through NNLO for various observables including the transverse-momentum and rapidity distributions of the two Higgs bosons. NNLO corrections are at the level of 10%-25% with respect to the next-to-leading order (NLO) prediction with a residual scale uncertainty of 5%-15% and an overall mild phase-space dependence. Only at NNLO the perturbative expansion starts to converge yielding overlapping scale uncertainty bands between NNLO and NLO in most of the phase-space. The calculation includes NLO predictions for pp→HH+jet+X. Corrections to the corresponding distributions exceed 50% with a residual scale dependence of 20%-30%.

  18. Differential Higgs Boson Pair Production at Next-to-Next-to-Leading Order in QCD

    CERN Document Server

    de Florian, Daniel; Hanga, Catalin; Kallweit, Stefan; Lindert, Jonas M; Maierhöfer, Philipp; Mazzitelli, Javier; Rathlev, Dirk

    2016-01-01

    We report on the first fully differential calculation for double Higgs boson production through gluon fusion in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation is performed in the heavy-top limit of the Standard Model, and in the phenomenological results we focus on pp collisions at 14 TeV. We present differential distributions through NNLO for various observables including the transverse-momentum and rapidity distributions of the two Higgs bosons. NNLO corrections are at the level of 10%-25% with respect to the next-to-leading order (NLO) prediction with a residual scale uncertainty of 5%-15% and an overall mild phase-space dependence. Only at NNLO the perturbative expansion starts to converge yielding overlapping scale uncertainty bands between NNLO and NLO in most of the phase-space. The calculation includes NLO predictions for pp -> HH+jet+X. Corrections to the corresponding distributions exceed 50% with a residual scale dependence of 20%-30%.

  19. Differential Higgs boson pair production at next-to-next-to-leading order in QCD

    Science.gov (United States)

    de Florian, Daniel; Grazzini, Massimiliano; Hanga, Catalin; Kallweit, Stefan; Lindert, Jonas M.; Maierhöfer, Philipp; Mazzitelli, Javier; Rathlev, Dirk

    2016-09-01

    We report on the first fully differential calculation for double Higgs boson production through gluon fusion in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation is performed in the heavy-top limit of the Standard Model, and in the phenomenological results we focus on pp collisions at √{s}=14 TeV. We present differential distributions through NNLO for various observables including the transverse-momentum and rapidity distributions of the two Higgs bosons. NNLO corrections are at the level of 10%-25% with respect to the next-to-leading order (NLO) prediction with a residual scale uncertainty of 5%-15% and an overall mild phase-space dependence. Only at NNLO the perturbative expansion starts to converge yielding overlapping scale uncertainty bands between NNLO and NLO in most of the phase-space. The calculation includes NLO predictions for pp → HH + jet + X. Corrections to the corresponding distributions exceed 50% with a residual scale dependence of 20%-30%.

  20. Next-to-Leading Order Corrections to Higgs Boson Pair Production in Gluon Fusion

    CERN Document Server

    Kerner, Matthias

    2016-01-01

    We present a calculation of the next-to-leading order QCD corrections to the production of Higgs boson pairs in gluon fusion keeping the full dependence on the mass of the top quark. The virtual corrections, involving two-loop integrals with up to four mass scales, have been calculated numerically and we present an efficient algorithm to obtain accurate results of the virtual amplitude using numerical integrations. Taking the top quark mass into account we obtain significant differences compared to results obtained in the heavy top limit.

  1. Next-to-leading order SUSY-QCD calculation of associated production of gauginos and gluinos

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Edmond L.; Tait, T.M.P. [Argonne National Laboratory, High Energy Physics Division, Argonne, IL (United States); Klasen, M. [Universitaet Hamburg, II. Institut fuer Theoretische Physik, Hamburg (Germany)

    2001-07-01

    Results are presented of a next-to-leading order calculation in perturbative QCD of the production of charginos and neutralinos in association with gluinos at hadron colliders. Predictions for cross sections are shown at the energies of the Fermilab Tevatron and CERN Large Hadron Collider for a typical supergravity (SUGRA) model of the sparticle mass spectrum and for a light gluino model. (author)

  2. Topics in Perturbative Quantum Field Theory: Eighth Order QED Contribution to the Anomalous Magnetic Moment of the Muon and Next to Leading Order QCD Correction to Photon Photon ---> Positive M, Negative M

    Science.gov (United States)

    Nizic, Bene

    1985-12-01

    This thesis consists of two unrelated topics in perturbative quantum field theory: eighth order QED contribution to the anomalous magnetic moment of the muon and next to leading order perturbative QCD correction to (gamma)(gamma) ( --->) M('+)M('-)(M = (pi),K). In Part I we present the evaluation of the complete eighth order QED contribution to the difference of the anomalous magnetic moments of the muon and the electron, (a(,(mu)) - a(,e))('(8)), arising from 469 Feynman diagrams. Our result is 140.7(4.5)((alpha)/(pi))('4). The theoretical error represents the estimated accuracy of the required numerical integration. We have also improved the light -by-light QED contribution to (a(,(mu)) - a(,e))('(6)). With these results the difference a(,(mu)) - a(,e) through eighth order in QED is (a(,(mu)) - a(,e))('QED) = 619 551(21) x 10('-11). Adding to the present theoretical value of the electron anomaly a(,e)('QED) = 115 965 246(5) x 10(' -11), we find that the pure QED contribution to the muon anomaly is given by a(,(mu))('QED) = 116 584 797(22) x 10('-11). In Part II we present the results of our calculation of the next to leading order perturbative QCD correction to the two-photon exclusive channels (gamma)(gamma)(-- ->)M('+)M('-)(M = (pi),K) at large momentum transfer. Calculation is performed in the Feynman gauge. Dimensional regularization is used to treat both UV and (//R) divergences. The meson distribution amplitude is taken to be (PHI)(,M)(PROPORTIONAL)('(delta))(x - 1/2). In order to reduce the dependence on the particular choice of (PHI)(,M), similarity of (gamma)(gamma)(--->)M('+)M(' -) and meson electromagnetic form-factor is employed. One loop correction to the (gamma)(gamma)(--->)M('+)M('-) cross section is obtained. In the MS renormalization scheme this correction is found not to be large.

  3. W+ W- production at hadron colliders in next to next to leading order QCD.

    Science.gov (United States)

    Gehrmann, T; Grazzini, M; Kallweit, S; Maierhöfer, P; von Manteuffel, A; Pozzorini, S; Rathlev, D; Tancredi, L

    2014-11-21

    Charged gauge boson pair production at the Large Hadron Collider allows detailed probes of the fundamental structure of electroweak interactions. We present precise theoretical predictions for on-shell W+ W- production that include, for the first time, QCD effects up to next to next to leading order in perturbation theory. As compared to next to leading order, the inclusive W+ W- cross section is enhanced by 9% at 7 TeV and 12% at 14 TeV. The residual perturbative uncertainty is at the 3% level. The severe contamination of the W+ W- cross section due to top-quark resonances is discussed in detail. Comparing different definitions of top-free W+ W- production in the four and five flavor number schemes, we demonstrate that top-quark resonances can be separated from the inclusive W+ W- cross section without a significant loss of theoretical precision.

  4. Production of Heavy neutrino in next-to-leading order QCD at the LHC and beyond

    CERN Document Server

    Das, Arindam; Majhi, Swapan

    2016-01-01

    Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw models, respectively, in explaining the naturally small neutrino mass. TeV scale heavy neutrinos can also be accommodated to have a sizable mixing with the Standard Model light neutrinos, through which they can be produced and detected at the high energy colliders. In this paper we consider the Next-to-Leading Order QCD corrections to the heavy neutrino production, and study the scale variation in cross-sections as well as the kinematic distributions with different final states at $14$ TeV LHC and also in the context of $100$ TeV hadron collider. The repertoire of the Majorana neutrino is realized through the characteristic signature of the same-sign dilepton pair, whereas, due to a small lepton number violation, the pseudo-Dirac heavy neutrino can manifest the trileptons associated with missing energy in the final state. Using the $\\sqrt{s}=8$ TeV, $20.3$ fb$^{-1}$ and $19.7$ fb$^{-1}$ data at the ATLAS and CMS respec...

  5. Topics in perturbative quantum field theory: eighth order QED contribution to the anomalous magnetic moment of the muon and next to leading order QCD correction to. gamma gamma -->. M/sup +/M/sup -/(M =. pi. , K)

    Energy Technology Data Exchange (ETDEWEB)

    Nizic, B.

    1985-01-01

    In Part I the evaluation of the complete eighth order QED contribution to the difference of the anomalous magnetic moments of the muon and the electron, (a/sub ..mu../ - a/sub e/, arising from 469 Feynman diagrams is presented. The result is 140.7(4.5)(..cap alpha../..pi..). The theoretical error represents the estimated accuracy of the required numerical integration. The light-by-light QED contribution to (a/sub ..mu../ - a/sub e/) has also been improved. With these results the difference a/sub ..mu../ - a/sub e/ through eighth order in QED is (a/sub ..mu../ - a/sub e/)/sup QED/ = 619,551(21) x 10/sup -11/. Adding to the present theoretical value of the electron anomaly a/sub e//sup QED/ = 115,965,246(5) x 10/sup -11/, it was found that the pure QED contribution to the muon anomaly is given by a/sub ..mu..//sup QED/ = 116,584,797(22) x 10/sup -11/. In Part II the results of the calculation of the next to leading order perturbative QCD correction to the two-photon exclusive channels ..gamma gamma -->..M/sup +/M/sup -/(M = ..pi..,K) at large momentum transfer is presented. Calculation is performed in the Feynman gauge. Dimensional regularization is used to treat both UV and the set of reals divergences. One loop correction to the ..gamma gamma -->..M/sup +/M/sup -/ cross section is obtained. In the mean MS renormalization scheme this correction is found not to be large.

  6. Minijet initial state of heavy-ion collisions from next-to-leading order perturbative QCD

    CERN Document Server

    Paatelainen, Risto

    2014-01-01

    The aim of this thesis is to calculate field-theoretically as rigorously as possible the initial state of partonic matter produced in ultrarelativistic heavy-ion collisions at CERN-LHC and BNL-RHIC colliders. The computed minijet initial conditions are then used in the initialization of the relativistic hydrodynamical modeling of these collisions. In the theoretical introduction part the computation of parton production cross section at next-to-leading order (NLO) perturbative QCD (pQCD) is discussed. Furthermore, the full analytical calculation for the squared quark-quark scattering matrix element including the systematic ultraviolet renormalization is presented. Finally, the subtraction method allowing for the cancellation of the infrared and collinear singularities in the partonic QCD cross section at NLO is discussed. In the more phenomenological part of the thesis the original EKRT model, which combines collinearly factorized leading-order pQCD minijet production with gluon saturation, is introduced. Nex...

  7. Next-to-leading order QCD analysis of polarized deep inelastic scattering data

    OpenAIRE

    Abe, K.; Akagi, Takami; Anderson, B. D.; Anthony, P.L.; Arnold, Raymond G.; Averett, T.; Brand, H.R.; Berisso, C. M.; Bogorad, P.; Borel, H.; Bosted, P.E.; Breton, V.; Buenerd, Michel J.; Cates, Gordon D.; Chupp, Timothy E.

    1997-01-01

    We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions $g_1^p, g_1^n$, and $g_1^d$, including the new experimental information on the $Q^2$ dependence of $g_1^n$. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to de...

  8. Dark matter pair associated with a $W$ boson production at the LHC in next-to-leading order QCD

    CERN Document Server

    Mao, Song; Wen-Gan, Ma; Ren-You, Zhang; Jian-You, Guo

    2014-01-01

    We investigate the QCD next-to-leading order (NLO) corrections to the production of a pair of fermionic dark matter particles associated with a W boson production through a mediator which couples to standard model particles via either a vector or axial-vector coupling at the LHC. We find that the QCD NLO corrections reduce the dependence of the total cross sections on the factorization and renormalization scales, and the $K$-factors increase with the increment of the dark matter mass. We also provide the LO and QCD NLO corrected distributions of the transverse momenta $p_T^\\mu$ of final muon and transverse mass $M_T$. We find that the LO cross section is significantly changed by the QCD NLO corrections.

  9. Polarized Di-hadron production in lepton-nucleon collisions at the next-to-leading order of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Hendlmeier, Christof

    2008-05-15

    We compute the next-to-leading order QCD corrections to the spin-dependent cross section for hadron-pair photoproduction. In the first part of the Thesis the calculation is performed using largely analytical methods. We present a detailed phenomenological study of our results focussing on the K-factors and scale dependence of the next-to-leading order cross sections. The second part is dedicated to an alternative approach using Monte-Carlo integration techniques. We present a detailed description how this method works in practice and give phenomenological studies for the photoproduction of two hadrons. This process is relevant for the extraction of the gluon polarization in present and future spin-dependent lepton-nucleon scattering experiments. (orig.)

  10. Next-to-Leading Order {QCD} Predictions for $Z, \\gamma^*$ + 3-Jet Distributions at the Tevatron

    CERN Document Server

    Berger, C.F.; Dixon, Lance J.; Febres Cordero, F.; Forde, D.; Gleisberg, T.; Ita, H.; Kosower, D.A.; Maitre, D.

    2010-01-01

    Using BlackHat in conjunction with SHERPA, we have computed next-to-leading order QCD predictions for a variety of distributions in Z,gamma*+1,2,3-jet production at the Tevatron, where the Z boson or off-shell photon decays into an electron-positron pair. We find good agreement between the NLO results for jet p_T distributions and measurements by CDF and D0. We also present jet-production ratios, or probabilities of finding one additional jet. As a function of vector-boson p_T, the ratios have distinctive features which we describe in terms of a simple model capturing leading logarithms and phase-space and parton-distribution-function suppression.

  11. Dijet photoproduction of massless charm jets at next-to-leading order of QCD

    CERN Document Server

    Klasen, M

    2011-01-01

    We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree well with the data, in particular for large momentum fractions of the the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favour parameterizations with a substantial charm quark density such as the one proposed by Cornet et al.

  12. Dijet photoproduction of massless charm jets at next-to-leading order of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, Michael [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Theoretische Physik, Muenster (Germany); Kramer, Gustav [Universitaet Hamburg, II. Institut fuer Theoretische Physik, Hamburg (Germany)

    2011-10-15

    We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree with the data, in particular for large momentum fractions of the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favour parameterizations with a substantial charm-quark density such as the one proposed by Cornet et al. (orig.)

  13. Dijet photoproduction of massless charm jets at next-to-leading order of QCD

    Science.gov (United States)

    Klasen, Michael; Kramer, Gustav

    2011-10-01

    We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree with the data, in particular for large momentum fractions of the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favour parameterizations with a substantial charm-quark density such as the one proposed by Cornet et al.

  14. Dijet photoproduction of massless charm jets at next-to-leading order of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, Michael [Muenster Univ. (Germany). Inst. fuer Theoretische Physik; Kramer, Gustav [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2011-04-15

    We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree well with the data, in particular for large momentum fractions of the the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favour parameterizations with a substantial charm quark density such as the one proposed by Cornet et al. (orig.)

  15. A ZEUS next-to-leading-order QCD analysis of data on deep inelastic scattering

    CERN Document Server

    Chekanov, S; Adamczyk, L; Adamus, M; Adler, V; Aghuzumtsyan, G; Allfrey, P D; Antonioli, P; Antonov, A; Arneodo, M; Bailey, D S; Bamberger, A; Barakbaev, A N; Barbagli, G; Barbi, M; Bari, G; Barreiro, F; Bartsch, D; Basile, M; Behrens, U; Bell, M A; Bellagamba, L; Bellan, P M; Benen, A; Bertolin, A; Bhadra, S; Bloch, I; Bold, T; Boos, E G; Borras, K; Boscherini, D; Brock, I; Brook, N H; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Bussey, P J; Butterworth, J M; Büttner, C; Bylsma, B; Caldwell, A; Capua, M; Cara Romeo, G; Carli, T; Carlin, R; Cassel, D G; Catterall, C D; Chwastowski, J; Abramowicz, H; Ciborowski, J; Ciesielski, R; Cifarelli, Luisa; Cindolo, F; Cole, J E; Collins-Tooth, C; Contin, A; Cooper-Sarkar, A M; Coppola, N; Corradi, M; Corriveau, F; Costa, M; Cottrell, A; Cui, Y; D'Agostini, G; Dal Corso, F; Danilov, P; De Pasquale, S; Dementiev, R K; Derrick, M; Devenish, R C E; Dhawan, S; Dobur, D; Dolgoshein, B A; Doyle, A T; Drews, G; Durkin, L S; Dusini, S; Eisenberg, Y; Ermolov, P F; Eskreys, Andrzej; Everett, A; Ferrando, J; Ferrero, M I; Figiel, J; Foster, B; Foudas, C; Fourletov, S; Fourletova, J; Fry, C; Gabareen, A; Galas, A; Gallo, E; Garfagnini, A; Geiser, A; Genta, C; Gialas, I; Giusti, P; Gladilin, L K; Gladkov, D; Glasman, C; Göbel, F; Goers, S; Goncalo, R; González, O; Gosau, T; Göttlicher, P; Grabowska-Bold, I; Graciani-Díaz, R; Grigorescu, G; Grijpink, S; Groys, M; Grzelak, G; Gutsche, O; Gwenlan, C; Haas, T; Hain, W; Hall-Wilton, R; Hamatsu, R; Hamilton, J; Hanlon, S; Hart, C; Hartmann, H; Hartner, G; Heaphy, E A; Heath, G P; Helbich, M; Hilger, E; Hochman, D; Holm, U; Horn, C; Iacobucci, G; Iga, Y; Irrgang, P; Jakob, H P; Jiménez, M; Jones, T W; Kagawa, S; Kahle, B; Kaji, H; Kananov, S; Karshon, U; Karstens, F; Kasemann, M; Kataoka, M; Katkov, I I; Kcira, D; Keramidas, A; Khein, L A; Kim, J Y; Kind, O; Kisielewska, D; Kitamura, S; Koffeman, E; Kohno, T; Kooijman, P; Koop, T; Korzhavina, I A; Kotanski, A; Kötz, U; Kowal, A M; Kowalski, H; Kramberger, G; Kreisel, A; Krumnack, N; Kulinski, P; Kuze, M; Kuzmin, V A; Labarga, L; Lammers, S; Lelas, D; Levchenko, B B; Levy, A; Li, L; Lightwood, M S; Lim, H; Limentani, S; Ling, T Y; Liu, C; Liu, X; Löhr, B; Lohrmann, E; Loizides, J H; Long, K R; Longhin, A; Lukasik, J; Lukina, O Yu; Luzniak, P; Ma, K J; Maddox, E; Magill, S; Malka, J; Mankel, R; Margotti, A; Marini, G; Martin, J F; Martínez, M; Mastroberardino, A; Matsuzawa, K; Mattingly, M C K; Melzer-Pellmann, I A; Menary, S R; Metlica, F; Meyer, U; Miglioranzi, S; Milite, M; Mirea, A; Monaco, V; Montanari, A; Musgrave, B; Nagano, K; Namsoo, T; Nania, R; Nguyen, C N; Nigro, A; Ning, Y; Noor, U; Notz, D; Nowak, R J; Nuncio-Quiroz, A E; Oh, B Y; Olkiewicz, K; Ota, O; Padhi, S; Palmonari, F; Patel, S; Paul, E; Pavel, Usan; Pawlak, J M; Pelfer, P G; Pellegrino, A; Pesci, A; Piotrzkowski, K; Plamondon, M; Plucinsky, P P; Pokrovskiy, N S; Polini, A; Proskuryakov, A S; Przybycien, M B; Rautenberg, J; Raval, A; Reeder, D D; Ren, Z; Renner, R; Repond, J; Ri, Y D; Rinaldi, L; Robins, S; Rosin, M; Ruspa, M; Ryan, P; Sacchi, R; Salehi, H; Santamarta, R; Sartorelli, G; Savin, A A; Saxon, D H; Schagen, S; Schioppa, M; Schlenstedt, S; Schleper, P; Schmidke, W B; Schneekloth, U; Schörner-Sadenius, T; Sciulli, F; Shcheglova, L M; Skillicorn, I O; Slominski, W; Smith, W H; Soares, M; Solano, A; Son, D; Sosnovtsev, V V; Stairs, D G; Stanco, L; Standage, J; Stifutkin, A; Stonjek, S; Stopa, P; Stösslein, U; Straub, P B; Suchkov, S; Susinno, G; Suszycki, L; Sutiak, J; Sutton, M R; Sztuk, J; Szuba, D; Szuba, J; Tapper, A D; Targett-Adams, C; Tassi, E; Tawara, T; Terron, J; Tiecke, H G; Tokushuku, K; Tsurugai, T; Turcato, M; Tymieniecka, T; Tyszkiewicz, A; Ukleja, A; Ukleja, J; Vázquez, M; Vlasov, N N; Voss, K C; Walczak, R; Walsh, R; Wang, M; Whitmore, J J; Whyte, J; Wichmann, K; Wick, K; Wiggers, L; Wills, H H; Wing, M; Wlasenko, M; Wolf, G; Yagues-Molina, A G; Yamada, S; Yamazaki, Y; Yoshida, R; Youngman, C; Zambrana, M; Zawiejski, L; Zeuner, W; Zhautykov, B O; Zhou, C; Zichichi, A; Ziegler, A; Zotkin, D S; Zotkin, S A; De Favereau, J; De Wolf, E; Del Peso, J

    2003-01-01

    Next-to-leading order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been perfomed, from which the gluon and the quark densities of the proton and the value of the strong coupling constant, alpha_s(M_Z), were extracted. The study includes a full treatment of the experimental systematic uncertainties including point-to-point correlations. The resulting uncertainties in the parton density functions are presented. A combined fit for alpha_s(M_Z) and the gluon and qurak densities yields a value of alpha_s(M_Z) in agreement with the world average. The parton density functions derived from ZEUS data alone indicate the importance of HERA data in determining sea quark and gluon distributions at low x. The limits of applicability of the theoretical formalism have been explored by comparing the fit predictions to ZEUS data at very low Q^2.

  16. Next-to-Leading Order QCD Predictions for Z, gamma^* 3-Jet Distributions at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, L.J.; /SLAC; Cordero, F.Febres; /Simon Bolivar U.; Forde, D.; /CERN /NIKHEF, Amsterdam; Gleisberg, T.; /SLAC; Ita, H.; /UCLA; Kosower, D.A.; /DAPNIA, Saclay; Maitre, D.; /Durham U.

    2010-06-02

    Using BlackHat in conjunction with SHERPA, we have computed next-to-leading order QCD predictions for a variety of distributions in Z, {gamma}{sup {asterisk}}+ 1, 2, 3-jet production at the Tevatron, where the Z boson or off-shell photon decays into an electron-positron pair. We find good agreement between the NLO results for jet {sub pT} distributions and measurements by CDF and D0. We also present jetproduction ratios, or probabilities of finding one additional jet. As a function of vector-boson {sub pT} , the ratios have distinctive features which we describe in terms of a simple model capturing leading logarithms and phase-space and parton-distribution-function suppression.

  17. Towards next-to-leading order corrections to the heavy quark potential in the effective string theory

    Science.gov (United States)

    Hwang, Sungmin

    2017-03-01

    We present our calculation of the non-relativistic corrections to the heavy quark-antiquark potential up to leading and next-to-leading order (NLO) via the effective string theory (EST). Full systematics of effective field theory (EFT) are discussed in order for including the NLO contribution that arises in the EST. We also show how the number of dimensionful parameters arising from the EST are reduced by the constraints between the Wilson coeffcients from non-relativistic EFTs for QCD.

  18. Diphoton production at hadron colliders: a fully differential QCD calculation at next-to-next-to-leading order.

    Science.gov (United States)

    Catani, Stefano; Cieri, Leandro; de Florian, Daniel; Ferrera, Giancarlo; Grazzini, Massimiliano

    2012-02-17

    We consider direct diphoton production in hadron collisions, and we compute the next-to-next-to-leading order QCD radiative corrections at the fully differential level. Our calculation uses the q(T) subtraction formalism, and it is implemented in a parton-level Monte Carlo program. The program allows the user to apply arbitrary kinematical cuts on the final-state photons and the associated jet activity and to compute the corresponding distributions in the form of bin histograms. We present selected numerical results related to Higgs boson searches at the LHC and corresponding results at the Tevatron.

  19. Four-Jet Production at the Large Hadron Collider at Next-to-Leading Order in QCD

    CERN Document Server

    Bern, Z; Dixon, L J; Cordero, F Febres; Hoeche, S; Kosower, D A; Ita, H; Maitre, D; Ozeren, K

    2012-01-01

    We present the cross sections for production of up to four jets at the Large Hadron Collider, at next-to-leading order in the QCD coupling. We use the BlackHat library in conjunction with SHERPA and a recently developed algorithm for assembling primitive amplitudes into color-dressed amplitudes. We adopt the cuts used by ATLAS in their study of multi-jet events in pp collisions at \\sqrt{s} = 7 TeV. We include estimates of nonperturbative corrections and compare to ATLAS data. We store intermediate results in a framework that allows the inexpensive computation of additional results for different choices of scale or parton distributions.

  20. Next-to-Next-to Leading Order QCD Predictions for Single Jet Inclusive Production at the LHC

    Science.gov (United States)

    Currie, J.; Glover, E. W. N.; Pires, J.

    2017-02-01

    We report the first calculation of fully differential jet production at leading color in all partonic channels at next-to-next-to leading order in perturbative QCD and compare to the available ATLAS 7 TeV data. We discuss the size and shape of the perturbative corrections along with their associated scale variation across a wide range in jet transverse momentum, pT, and rapidity, y . We find significant effects, especially at low pT, and discuss the possible implications for parton distribution function fits.

  1. Charm-Quark Production in Deep-Inelastic Neutrino Scattering at Next-to-Next-to-Leading Order in QCD.

    Science.gov (United States)

    Berger, Edmond L; Gao, Jun; Li, Chong Sheng; Liu, Ze Long; Zhu, Hua Xing

    2016-05-27

    We present a fully differential next-to-next-to-leading order calculation of charm-quark production in charged-current deep-inelastic scattering, with full charm-quark mass dependence. The next-to-next-to-leading order corrections in perturbative quantum chromodynamics are found to be comparable in size to the next-to-leading order corrections in certain kinematic regions. We compare our predictions with data on dimuon production in (anti)neutrino scattering from a heavy nucleus. Our results can be used to improve the extraction of the parton distribution function of a strange quark in the nucleon.

  2. Charm-Quark Production in Deep-Inelastic Neutrino Scattering at Next-to-Next-to-Leading Order in QCD

    Science.gov (United States)

    Berger, Edmond L.; Gao, Jun; Li, Chong Sheng; Liu, Ze Long; Zhu, Hua Xing

    2016-05-01

    We present a fully differential next-to-next-to-leading order calculation of charm-quark production in charged-current deep-inelastic scattering, with full charm-quark mass dependence. The next-to-next-to-leading order corrections in perturbative quantum chromodynamics are found to be comparable in size to the next-to-leading order corrections in certain kinematic regions. We compare our predictions with data on dimuon production in (anti)neutrino scattering from a heavy nucleus. Our results can be used to improve the extraction of the parton distribution function of a strange quark in the nucleon.

  3. Next-to-leading order mass effects in QCD Compton process of polarized DIS

    CERN Document Server

    Akushevich, I V; Shumeiko, N M

    2001-01-01

    The method originally developed for the exact calculations in QED theory is applied for the calculation NLO effects in QCD Compton processes. QCD corrections to the structure functions and sum rules are obtained. Different interpretations of the NLO effects due to finite quark mass are discussed.

  4. Towards next-to-leading order corrections to the heavy quark potential in the effective string theory

    Directory of Open Access Journals (Sweden)

    Hwang Sungmin

    2017-01-01

    Full Text Available We present our calculation of the non-relativistic corrections to the heavy quark-antiquark potential up to leading and next-to-leading order (NLO via the effective string theory (EST. Full systematics of effective field theory (EFT are discussed in order for including the NLO contribution that arises in the EST. We also show how the number of dimensionful parameters arising from the EST are reduced by the constraints between the Wilson coeffcients from non-relativistic EFTs for QCD.

  5. Complete next-to-leading-order corrections to J/{psi} photoproduction in nonrelativistic quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Butenschoen, Mathias; Kniehl, Bernd A. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2009-09-15

    We calculate the cross section of inclusive direct J/{psi} photoproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics, for the first time including the full relativistic corrections due to the intermediate {sup 1}S{sub 0}{sup [8]}, {sup 3}S{sub 1}{sup [8]}, and {sup 3}P{sub J}{sup [8]} color-octet states. A comparison of our results to recent H1 data suggests that the color octet mechanism is indeed realized in J/{psi} photoproduction, although the predictivity of our results still suffers from uncertainties in the color-octet long-distance matrix elements. (orig.)

  6. Extra dimension searches at hadron colliders to next-to-leading order-QCD

    Indian Academy of Sciences (India)

    M C Kumar; Prakash Mathewes; V Ravindran

    2007-11-01

    The quantitative impact of NLO-QCD corrections for searches of large and warped extra dimensions at hadron colliders are investigated for the Drell-Yan process. The K-factor for various observables at hadron colliders are presented. Factorisation, renormalisation scale dependence and uncertainties due to various parton distribution functions are studied. Uncertainties arising from the error on experimental data are estimated using the MRST parton distribution functions.

  7. $ZZW$ production at the LHC within large extra dimensions model in next-to-leading order QCD

    CERN Document Server

    Chong, Chen; Wen-Gan, Ma; Ren-You, Zhang; Xiao-Zhou, Li; Yu, Zhang

    2014-01-01

    We investigate the large extra dimensions (LED) effects induced by the Kaluza-Klein gravitons up to the QCD next-to-leading order (NLO) on the $ZZW$ production at the large hardron collider (LHC). The integrated cross sections and some kinematic distributions are presented in both the standard model (SM) and the LED model. Our results show that the leading order (LO) relative deviations between the predictions in the LED model and the SM are significant, especially in the large $M_{ZZ}$ region, large $p_T$ and the central rapidity regions of the final products separately, while the NLO QCD corrections remarkably reduce the relative LED deviations. We find that if we take $M_S=4.8~{\\rm TeV}$, $d=3$, and adopt the event selection scheme with $M_{ZZ}>500~{\\rm GeV}$, $p_T^{Z}>100~{\\rm GeV}$ and $p_T^{W}>20~{\\rm GeV}$, the LO (NLO) relative deviations at the $14~{\\rm TeV}$ LHC increase to $19.8 \\%$ ($8.05\\%$) and $12.30\\%$ ($5.63\\%$) for the $ZZW^+$ and $ZZW^-$ productions, respectively. We also see that with the ...

  8. Top quark forward-backward asymmetry in e+ e- annihilation at next-to-next-to-leading order in QCD.

    Science.gov (United States)

    Gao, Jun; Zhu, Hua Xing

    2014-12-31

    We report on a complete calculation of electroweak production of top-quark pairs in e+ e- annihilation at next-to-next-to-leading order in quantum chromodynamics. Our setup is fully differential in phase space and can be used to calculate any infrared-safe observable. Especially we calculated the next-to-next-to-leading-order corrections to the top-quark forward-backward asymmetry and found sizable effects. Our results show a large reduction of the theoretical uncertainties in predictions of the forward-backward asymmetry, and allow for a precision determination of the top-quark electroweak couplings at future e+ e- colliders.

  9. Next-to-leading order correction to inclusive particle spectra in the color glass condensate framework

    Science.gov (United States)

    Gelis, François; Laidet, Julien

    2013-02-01

    In F. Gelis et al. [Phys. Rev. D 78, 054019 (2008).PRVDAQ1550-7998], we have analyzed the leading logarithms of energy that appear in the inclusive spectrum of gluons produced in heavy ion collisions, calculated in the color glass condensate framework. The main result of this paper was that these logarithms are intrinsic properties of the colliding projectiles, and that they can be resummed by letting the distributions of color sources in the nuclei evolve according to the Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner equation. An essential step in the proof of this factorization result is the calculation of the gluon spectrum at next-to-leading order (NLO), and in particular a functional relationship that expresses the NLO correction as the action of a certain operator on the leading order spectrum. In this paper, we show that this type of relation between spectra at leading order and NLO is not specific to the production of gluons, but that it is in fact generic for inclusive spectra in heavy ion collisions. To illustrate this, we compute up to NLO the inclusive spectrum of some hypothetical scalar fields, either color neutral or colored, that couple to gluons.

  10. Next-to-Leading Order correction to inclusive particle spectra in the Color Glass Condensate framework

    CERN Document Server

    Gelis, F

    2012-01-01

    In [arXiv:0804.2630], we have analyzed the leading logarithms of energy that appear in the inclusive spectrum of gluons produced in heavy ion collisions, calculated in the Color Glass Condensate framework. The main result of this paper was that these logarithms are intrinsic properties of the colliding projectiles, and that they can be resummed by letting the distributions of color sources in the nuclei evolve according to the JIMWLK equation. An essential step in the proof of this factorization result is the calculation of the gluon spectrum at Next-to-Leading order, and in particular a functional relationship that expresses the NLO correction as the action of a certain operator on the LO spectrum. In this paper, we show that this type of relation between spectra at LO and NLO is not specific to the production of gluons, but that it is in fact generic for inclusive spectra in heavy ion collisions. To illustrate this, we compute up to NLO the inclusive spectrum of some hypothetical scalar fields, either color...

  11. Diffractive dijet photoproduction in ultraperipheral collisions at the LHC in next-to-leading order QCD

    CERN Document Server

    Guzey, V

    2016-01-01

    We make predictions for the cross sections of diffractive dijet photoproduction in $pp$, $pA$ and $AA$ ultraperipheral collisions (UPCs) at the LHC during Runs 1 and 2 using next-to-leading perturbative QCD. We find that the resulting cross sections are sufficiently large and, compared to lepton-proton scattering at HERA, have an enhanced sensitivity to small observed momentum fractions in the diffractive exchange, commonly denoted $z_{P}^{\\rm jets}$, and an unprecedented reach in the invariant mass of the photon-nucleon system $W$. We examine two competing schemes of diffractive QCD factorization breaking, which assume either a global suppression factor or a suppression for resolved photons only and demonstrate that the two scenarios can be distinguished by the nuclear dependence of the distributions in the observed parton momentum fraction in the photon $x_{\\gamma}^{\\rm jets}$.

  12. Diffractive dijet photoproduction in ultraperipheral collisions at the LHC in next-to-leading order QCD

    Science.gov (United States)

    Guzey, V.; Klasen, M.

    2016-04-01

    We make predictions for the cross sections of diffractive dijet photoproduction in pp, pA and AA ultraperipheral collisions (UPCs) at the LHC during Runs 1 and 2 using next-to-leading perturbative QCD. We find that the resulting cross sections are sufficiently large and, compared to lepton-proton scattering at HERA, have an enhanced sensitivity to small observed momentum fractions in the diffractive exchange, commonly denoted {z}_{{P}}^{jets} , and an unprecedented reach in the invariant mass of the photon-nucleon system W. We examine two competing schemes of diffractive QCD factorization breaking, which assume either a global suppression factor or a suppression for resolved photons only and demonstrate that the two scenarios can be distinguished by the nuclear dependence of the distributions in the observed parton momentum fraction in the photon x γ jets.

  13. Higgs production in heavy-quark annihilation through next-to-next-to-leading order QCD

    Energy Technology Data Exchange (ETDEWEB)

    Harlander, Robert V. [RWTH Aachen University, Institute for Theoretical Particle Physics and Cosmology, Aachen (Germany)

    2016-05-15

    The total inclusive cross section for charged and neutral Higgs production in heavy-quark annihilation is presented through NNLO QCD. It is shown that, aside from an overall factor, the partonic cross section is independent of the initial-state quark flavors, and that any interference terms involving two different Yukawa couplings vanish. A simple criterion for defining the central renormalization and factorization scale is proposed. Its application to the b anti bφ process yields results which are compatible with the values usually adopted for this process. Remarkably, we find little variation in these values for the other initial-state quark flavors. Finally, we disentangle the impact of the different parton luminosities from genuine hard NNLO effects and find that, for the central scales, a naive rescaling by the parton luminosities approximates the full result remarkably well. (orig.)

  14. A fresh look at factorization breaking in diffractive photoproduction of dijets at HERA at next-to-leading order QCD

    CERN Document Server

    Guzey, V

    2016-01-01

    We calculate the cross section of diffractive dijet photoproduction in $ep$ scattering at next-to-leading order (NLO) of perturbative QCD (pQCD), which we supplement by a model of factorization breaking for the resolved-photon contribution. In this model, the suppression depends on the flavor and momentum fraction of the partons in the photon. We show that within experimental and theoretical uncertainties, the resulting approach provides a good description of the available HERA data in most of the bins. Hence, taken together with the observation that NLO pQCD explains well the data on diffractive photoproduction of open charm in $ep$ scattering, our model of factorization breaking presents a viable alternative to the scheme based on the global suppression factor.

  15. A fresh look at factorization breaking in diffractive photoproduction of dijets at HERA at next-to-leading order QCD

    Energy Technology Data Exchange (ETDEWEB)

    Guzey, V. [Petersburg Nuclear Physics Institute (PNPI), National Research Center ' ' Kurchatov Institute' ' , Gatchina (Russian Federation); Klasen, M. [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Theoretische Physik, Muenster (Germany)

    2016-08-15

    We calculate the cross section of diffractive dijet photoproduction in ep scattering at next-to-leading order (NLO) of perturbative QCD (pQCD), which we supplement by a model of factorization breaking for the resolved-photon contribution. In this model, the suppression depends on the flavor and momentum fraction of the partons in the photon. We show that within experimental and theoretical uncertainties, the resulting approach provides a good description of the available HERA data in most of the bins. Hence, taken together with the observation that NLO pQCD explains well the data on diffractive photoproduction of open charm in ep scattering, our model of factorization breaking presents a viable alternative to the scheme based on the global suppression factor. (orig.)

  16. A fresh look at factorization breaking in diffractive photoproduction of dijets at HERA at next-to-leading order QCD

    Science.gov (United States)

    Guzey, V.; Klasen, M.

    2016-08-01

    We calculate the cross section of diffractive dijet photoproduction in ep scattering at next-to-leading order (NLO) of perturbative QCD (pQCD), which we supplement by a model of factorization breaking for the resolved-photon contribution. In this model, the suppression depends on the flavor and momentum fraction of the partons in the photon. We show that within experimental and theoretical uncertainties, the resulting approach provides a good description of the available HERA data in most of the bins. Hence, taken together with the observation that NLO pQCD explains well the data on diffractive photoproduction of open charm in ep scattering, our model of factorization breaking presents a viable alternative to the scheme based on the global suppression factor.

  17. W+W-+3 -jet production at the Large Hadron Collider in next-to-leading-order QCD

    Science.gov (United States)

    Febres Cordero, F.; Hofmann, P.; Ita, H.

    2017-02-01

    We present next-to-leading-order (NLO) QCD predictions to W+W- production in association with up to three jets at hadron colliders. We include contributions from couplings of the W bosons to light quarks as well as trilinear vector couplings. These processes are used in vector-boson coupling measurements, are background to Higgs signals and are needed to constrain many new physics scenarios. For the first time NLO QCD predictions are shown for electroweak di-vector boson production with three jets at a hadron collider. We show total and differential cross sections for the LHC with proton center-of-mass energies of 8 and 13 TeV. To perform the calculation we employ on-shell and unitarity methods implemented in the blackhat library along with the sherpa package. We have produced event files that can be accessed for future dedicated studies.

  18. Global analysis of nuclear parton distribution functions at leading and next-to-leading order perturbative QCD

    CERN Document Server

    Paukkunen, Hannu

    2009-06-01

    This is the introductory part of my PhD thesis which consists of two parts, the separate introduction and four published articles. The introduction begins by a technically detailed description of the DGLAP evolution and the fast numerical solving method for the DGLAP equations, which has been used in the numerical works of the published articles of this thesis. A write-up of the next-to-leading order (NLO) calculations for the deeply inelastic scattering (DIS) and the Drell-Yan (DY) dilepton production cross-sections is also included. The formalism of the inclusive single hadron production at NLO is described as well, although less rigorously. The introductory part ends with a discussion of the global QCD analyses in general, with a special attention paid to the major work of this thesis, the NLO analysis of nuclear parton densities and their uncertainties.

  19. Production of massless bottom jets in p anti p and pp collisions at next-to-leading order of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bierenbaum, Isabella [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2016-03-15

    We present predictions for the inclusive production of bottom jets in proton-antiproton collisions at 1.96 TeV and proton-proton collisions at 7 TeV. The bottom quark is considered massless. In this scheme, we find that at small transverse momentum (p{sub T}) the ratio of the next-to-leading order to the leading-order cross section (K factor) is smaller than one. It increases with increasing p{sub T} and approaches one at larger p{sub T} at a value depending essentially on the choice of the renormalization scale. Adding non-perturbative corrections obtained from PYTHIA Monte Carlo calculations leads to reasonable agreement with experimental b-jet cross sections obtained by the CDF and the CMS collaborations.

  20. QCD next-to-leading order predictions matched to parton showers for vector-like quark models

    CERN Document Server

    Fuks, Benjamin

    2016-01-01

    Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair-production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks...

  1. QCD next-to-leading order predictions matched to parton showers for vector-like quark models

    CERN Document Server

    Fuks, Benjamin

    2017-02-27

    Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair-production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks...

  2. QCD next-to-leading-order predictions matched to parton showers for vector-like quark models.

    Science.gov (United States)

    Fuks, Benjamin; Shao, Hua-Sheng

    2017-01-01

    Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however, rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasise the extra handles that could be provided by novel vector-like-quark probes never envisaged so far.

  3. Next-to-next-to-leading order QCD analysis of the revised CCFR data for $xF_3$ structure function and the higher twist contributions

    CERN Document Server

    Kataev, A L; Parente, G; Sidorov, A V

    1998-01-01

    We present the results of the next-to-next-to-leading order QCD analysis of the recently revised experimental data of the CCFR collaboration for the $xF_3$ structure function using the Jacobi polynomial expansion method. The effects of the higher twist contributions are included into the fits following the infrared renormalon motivated model. The special attention is paid to the checks of the predictive abilities of the infrared renormalon model and to the independent extraction of the $x$-shape of the twist-4 contributions to the $xF_3$ structure function in the process of the leading order, next-to-leading order and next-to-next-to-leading order fits of the revised CCFR data. We stress that at the next-to-next-to-leading order the results for We obtain the following result $\\alpha_s(M_Z)^{NNLO}=0.117 \\pm 0.002(stat) \\pm 0.005 (syst)\\pm 0.003 (theory)$. The comparison of the outcomes of our next-to-leading order and next-to-next-to-leading order analysis indicate that the theoretical QCD uncertainties were u...

  4. Next-to-leading-order electroweak corrections to the production of four charged leptons at the LHC

    CERN Document Server

    Biedermann, Benedikt; Dittmaier, Stefan; Hofer, Lars; Jager, Barbara

    2016-01-01

    We present a state-of-the-art calculation of the next-to-leading-order electroweak corrections to ZZ production, including the leptonic decays of the Z bosons into $\\mu^+\\mu^-\\mathrm{e}^+\\mathrm{e}^-$ or $\\mu^+\\mu^-\\mu^+\\mu^-$ final states. We use complete leading-order and next-to-leading-order matrix elements for four-lepton production, including contributions of virtual photons and all off-shell effects of Z bosons, where the finite Z-boson width is taken into account using the complex-mass scheme. The matrix elements are implemented into Monte Carlo programs allowing for the evaluation of arbitrary differential distributions. We present integrated and differential cross sections for the LHC at 13 TeV both for an inclusive setup where only lepton identification cuts are applied, and for a setup motivated by Higgs-boson analyses in the four-lepton decay channel. The electroweak corrections are divided into photonic and purely weak contributions. The former show the well-known pronounced tails near kinematic...

  5. Next-to-leading-order electroweak corrections to the production of four charged leptons at the LHC

    Science.gov (United States)

    Biedermann, Benedikt; Denner, Ansgar; Dittmaier, Stefan; Hofer, Lars; Jäger, Barbara

    2017-01-01

    We present a state-of-the-art calculation of the next-to-leading-order electroweak corrections to ZZ production, including the leptonic decays of the Z bosons into μ + μ -e+e- or μ + μ - μ + μ - final states. We use complete leading-order and next-to-leading-order matrix elements for four-lepton production, including contributions of virtual photons and all off-shell effects of Z bosons, where the finite Z-boson width is taken into account using the complex-mass scheme. The matrix elements are implemented into Monte Carlo programs allowing for the evaluation of arbitrary differential distributions. We present integrated and differential cross sections for the LHC at 13 TeV both for an inclusive setup where only lepton identification cuts are applied, and for a setup motivated by Higgs-boson analyses in the four-lepton decay channel. The electroweak corrections are divided into photonic and purely weak contributions. The former show the well-known pronounced tails near kinematical thresholds and resonances; the latter are generically at the level of ˜ -5% and reach several -10% in the high-energy tails of distributions. Comparing the results for μ + μ -e+e- and μ + μ - μ + μ - final states, we find significant differences mainly in distributions that are sensitive to the μ + μ - pairing in the μ + μ - μ + μ - final state. Differences between μ + μ -e+e- and μ + μ - μ + μ - channels due to interferences of equal-flavour leptons in the final state can reach up to 10% in off-shell-sensitive regions. Contributions induced by incoming photons, i.e. photon-photon and quark-photon channels, are included, but turn out to be phenomenologically unimportant.

  6. Top-quark pair production at next-to-next-to-leading order QCD in electron positron collisions

    CERN Document Server

    Chen, Long; Heisler, Dennis; Bernreuther, Werner; Si, Zong-Guo

    2016-01-01

    We set up a formalism, within the antenna subtraction framework, for computing the production of a massive quark-antiquark pair in electron positron collisions at next-to-next-to-leading order in the coupling $\\alpha_s$ of quantum chromodynamics at the differential level. Our formalism applies to the calculation of any infrared-safe observable. We apply this set-up to the production of top-quark top antiquark pairs in the continuum. We compute the production cross section and several distributions. We determine, in particular, the top-quark forward-backward asymmetry at order $\\alpha_s^2$. Our result agrees with previous computations of this observable.

  7. Next-to-leading-order electroweak corrections to $pp \\to W^+W^-\\to$ 4 leptons at the LHC

    CERN Document Server

    Biedermann, Benedikt; Denner, Ansgar; Dittmaier, Stefan; Hofer, Lars; Jager, Barbara; Salfelder, Lukas

    2016-01-01

    We present results of the first calculation of next-to-leading-order electroweak corrections to W-boson pair production at the LHC that fully takes into account leptonic W-boson decays and off-shell effects. Employing realistic event selections, we discuss the corrections in situations that are typical for the study of W-boson pairs as a signal process or of Higgs-boson decays $H\\to W W^*$, to which W-boson pair production represents an irreducible background. In particular, we compare the full off-shell results, obtained treating the W-boson resonances in the complex-mass scheme, to previous results in the so-called double-pole approximation, which is based on an expansion of the loop amplitudes about the W resonance poles. At small and intermediate scales, i.e. in particular in angular and rapidity distributions, the two approaches show the expected agreement at the level of fractions of a percent, but larger differences appear in the TeV range. For transverse-momentum distributions, the differences can eve...

  8. Next-to-leading-order electroweak corrections to pp → W+W- → 4 leptons at the LHC

    Science.gov (United States)

    Biedermann, B.; Billoni, M.; Denner, A.; Dittmaier, S.; Hofer, L.; Jäger, B.; Salfelder, L.

    2016-06-01

    We present results of the first calculation of next-to-leading-order electroweak corrections to W-boson pair production at the LHC that fully takes into account leptonic W-boson decays and off-shell effects. Employing realistic event selections, we discuss the corrections in situations that are typical for the study of W-boson pairs as a signal process or of Higgs-boson decays H → WW∗, to which W-boson pair production represents an irreducible background. In particular, we compare the full off-shell results, obtained treating the W-boson resonances in the complex-mass scheme, to previous results in the so-called double-pole approximation, which is based on an expansion of the loop amplitudes about the W resonance poles. At small and intermediate scales, i.e. in particular in angular and rapidity distributions, the two approaches show the expected agreement at the level of fractions of a percent, but larger differences appear in the TeV range. For transverse-momentum distributions, the differences can even exceed the 10% level in the TeV range where "background diagrams" with one instead of two resonant W bosons gain in importance because of recoil effects.

  9. CGC/saturation approach: a new impact-parameter dependent model in the next-to-leading order of perturbative QCD

    CERN Document Server

    Contreras, Carlos; Meneses, Rodrigo; Potashnikova, Irina

    2016-01-01

    This paper is the first attempt to build CGC/saturation model based on the next-to-leading order corrections to linear and non-linear evolution in QCD. We assume that the renormalization scale is the saturation momentum and found that the scattering amplitude has geometric scaling behaviour deep in the saturation domain with the explicit formula of this behaviour at large $\\tau = r^2 Q^2_s$. We built a model that include this behaviour, as well as the ingredients that has been known: (i) the behaviour of the scattering amplitude in the vicinity of the saturation momentum, using the NLO BFKL kernel, (ii) the pre-asymptotic behaviour of $\\ln\\Lb Q^2_s\\Lb Y \\Rb\\Rb$, as function of $Y$ and (iii) the impact parameter behaviour of the saturation momentum, which has exponential behaviour $\\propto \\exp\\Lb -\\, m\\, b\\Rb$ at large $b$.We demonstrated that the model is able to describe the experimental data for the deep inelastic structure function. Despite this, our model has difficulties that are related to the small va...

  10. Three-Body Bound States and The Triton Charge Radius; Perturbative Corrections to Next-to-next-to-leading order in Pionless Effective Field Theory

    CERN Document Server

    Vanasse, Jared

    2015-01-01

    In the three-body system of ${}^3\\mathrm{H}$ we show how perturbative corrections can be added to the leading ordering triton vertex function. Using this new scheme we calculate the triton charge form factor and use it to extract the triton charge radius to next-to-leading-order, yielding a prediction of 1.58~fm. We show that a new counter-term will be needed to predict the triton charge radius at next-to-next-to-leading order.

  11. Top Quark Pair Production in Association with a Jet with Next-to-Leading-Order QCD Off-Shell Effects at the Large Hadron Collider.

    Science.gov (United States)

    Bevilacqua, G; Hartanto, H B; Kraus, M; Worek, M

    2016-02-05

    We present a complete description of top quark pair production in association with a jet in the dilepton channel. Our calculation is accurate to next-to-leading order (NLO) in QCD and includes all nonresonant diagrams, interferences, and off-shell effects of the top quark. Moreover, nonresonant and off-shell effects due to the finite W gauge boson width are taken into account. This calculation constitutes the first fully realistic NLO computation for top quark pair production with a final state jet in hadronic collisions. Numerical results for differential distributions as well as total cross sections are presented for the Large Hadron Collider at 8 TeV. With our inclusive cuts, NLO predictions reduce the unphysical scale dependence by more than a factor of 3 and lower the total rate by about 13% compared to leading-order QCD predictions. In addition, the size of the top quark off-shell effects is estimated to be below 2%.

  12. Global analysis of nuclear parton distribution functions at leading and next-to-leading order perturbative QCD

    Science.gov (United States)

    Pesznyak, Csilla

    The aim of the investigation is to give answer to some questions of the QC in the mega-voltage therapy for the sake of making the treatments more trouble-free. We investigated the terms of the usage of CT and PET/CT equipments in treatment planning that were made originally for diagnostic purposes. We compared the calculation algorithms of the Varian CadPlan(TM) and CMS XiORTM treatment planning systems (TPS) for photon and electron radiations of different energy. We also investigated the terms of usage of the PTW EPID QC PHANTOMRTM in the quality control of the EPID's and the portal images, as well. We laid down the terms in a protocol that make the diagnostic CT and PET/CT equipments capable for radiation treatment planning. The protocols should contain the exact patient setup, the tube voltage, detailed directions for use of patient immobilization tools, the review and use of the necessary QA/QC devices, the time consumption of the procedure, the frequency of controls and the worksheet to be used during the measurements. On the base of the measurements, it can be stated that on photon energies the superposition algorithm can be used for patient treatments in the case of the CMS XiORTM TPS while in the case of Varian CadPlan(TM) TPS the PBMB algorithm is the proper choice. It is not allowed to use the TPS without inhomogeneity correction. The CIRS Thorax IMRT phantom can be used for electron measurement only at higher than 10 MeV since only the Farmer chamber can be inserted into the holes of the phantom. On the base of the electron measurements, it can be stated that both planning systems give good results in soft tissue. In lung equivalent material the calculated values of the Varian CadPlan(TM) are in better agreement with the measured values, but the calculated values behind the bones are not accurate enough. In the QA/QC process the PTW EPID QC PHANTOMRTM is usable not only for the amorphous silicon EPID's but the image quality can be analysed on the video

  13. Next-to-leading order QCD predictions for top-quark pair production with up to two jets merged with a parton shower

    Directory of Open Access Journals (Sweden)

    Stefan Höche

    2015-09-01

    Full Text Available We present differential cross sections for the production of top-quark pairs in conjunction with up to two jets, computed at next-to-leading order in perturbative QCD and consistently merged with a parton shower in the Sherpa+OpenLoops framework. Top quark decays including spin correlation effects are taken into account at leading order accuracy. The calculation yields a unified description of top-pair plus multi-jet production, and detailed results are presented for various key observables at the Large Hadron Collider. A large improvement with respect to the multi-jet merging approach at leading order is found for the total transverse energy spectrum, which plays a prominent role in searches for physics beyond the Standard Model.

  14. Fourth generation CP violation effects on B-->Kpi, phiK, and rhoK in next-to-leading-order perturbative QCD.

    Science.gov (United States)

    Hou, Wei-Shu; Li, Hsiang-nan; Mishima, Satoshi; Nagashima, Makiko

    2007-03-30

    We study the effect from a sequential fourth generation quark on penguin-dominated two-body nonleptonic B meson decays in the next-to-leading order perturbative QCD formalism. With an enhancement of the color-suppressed tree amplitude and possibility of a new CP phase in the electroweak penguin amplitude, we can account better for A(CP)(B(0)-->K+ pi-)-A(CP)(B+-->K+ pi0). Taking |V(t's)V(t'b)| approximately 0.02 with a phase just below 90 degrees, which is consistent with the b-->sl+ l- rate and the B(s) mixing parameter Deltam(B)(s), we find a downward shift in the mixing-induced CP asymmetries of B(0)-->K(S)(pi 0) and phi(K)(S). The predicted behavior for B(0)-->rho(0)(K)(S) is opposite.

  15. $\\bar{B}^0_s \\to (\\pi^0 \\eta^{(*)}, \\eta^{(*)}\\eta^{(*)})$ decays and the effects of next-to-leading order contributions in the perturbative QCD approach

    CERN Document Server

    Xiao, Zhen-Jun; Lin, Dong-Ting; Fan, Ying-Ying; Ma, Ai-Jun

    2014-01-01

    In this paper, we calculate the branching ratios and CP violating asymmetries of the five $\\bar{B}^0_s \\to (\\pi^0\\eta^{(*)},\\eta^{(*)}\\eta^{(*)})$ decays, by employing the perturbative QCD (pQCD) factorization approach and with the inclusion of all currently known next-to-leading order (NLO) contributions. We find that (a) the NLO contributions can provide about 100% enhancements to the LO pQCD predictions for the decay rates of $\\bar{B}_s^0 \\to \\eta\\eta^\\prime$ and $\\eta^\\prime \\eta^\\prime$ decays, but result in small changes to $Br(\\bar{B}_s \\to \\pi^0 \\eta^{(*)})$ and $Br(\\bar{B}_s \\to \\eta\\eta)$; (b) the newly known NLO twist-2 and twist-3 contributions to the relevant form factors can provide about 10% enhancements to the decay rates of the considered decays; (c) for $\\bar{B}_s \\to \\pi^0 \\eta^{(*)}$ decays, their direct CP-violating asymmetries $\\cala_f^{dir}$ could be enhanced significantly by the inclusion of the NLO contributions; and (d) the pQCD predictions for $Br(\\bar{B}_s \\to \\eta \\eta^{(*)})$ and...

  16. Next-to-leading-order corrections to capacity for a nondispersive nonlinear optical fiber channel in the intermediate power region

    Science.gov (United States)

    Panarin, A. A.; Reznichenko, A. V.; Terekhov, I. S.

    2017-01-01

    We consider the optical fiber channel modeled by the nonlinear Schrödinger equation with zero dispersion and additive Gaussian noise. Using the Feynman path-integral approach for the model, we find corrections to conditional probability density function, output signal distribution, conditional and output signal entropies, and the channel capacity at large signal-to-noise ratio. We demonstrate that the correction to the channel capacity is positive for large signal power. Therefore, this correction increases the earlier calculated capacity for a nondispersive nonlinear optical fiber channel in the intermediate power region.

  17. A Comparative Study of fB within QCD Sum Rules with Two Typical Correlators up to Next-to-Leading Order

    Institute of Scientific and Technical Information of China (English)

    WU Xing-Gang; YU Yao; CHEN Gu; HAN Hua-Yong

    2011-01-01

    The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules.We make a detailed discussion on fB from two sum rules up to next-to-leading order, i.e.sum rules Ⅰ and Ⅱ, which are derived from the conventional correlator and the correlator with chiral currents respectively.It is found that these two sum rules are consistent with each other.The sum rules Ⅱ involves less non-perturbative condensates as that of sum rules Ⅰ, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well.It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules Ⅰ and Ⅱ prefer smaller pole b-quark mass, mb = 4.68 ± 0.07 GeV.By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB = 172+23-25 MeV for sum rules Ⅰ and fB = 214+26-34 MeV for sum rules Ⅱ.PACS numbers: 11.55.Hx, 12.38.-t, 13.20.He, 12.38.Lg

  18. Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD

    CERN Document Server

    Abelof, Gabriel; Liu, Xiaohui; Petriello, Frank

    2016-01-01

    We compute the ${\\cal O}(\\alpha^2\\alpha_s^2)$ perturbative corrections to inclusive jet production in electron-nucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). We include all relevant partonic processes, including deep-inelastic scattering contributions, photon-initiated corrections, and parton-parton scattering terms that first appear at this order. Upon integration over the final-state hadronic phase space we validate our results for the deep-inelastic corrections against the known next-to-next-to-leading order (NNLO) structure functions. Our calculation uses the $N$-jettiness subtraction scheme for performing higher-order computations, and allows for a completely differential description of the deep-inelastic scattering process. We describe the application of this method to inclusive jet production in detail, and present phenomenological results for the proposed EIC. The NNLO corrections have a non-trivial dependence on the jet kinem...

  19. Next-to-leading order corrections to the hadron energy distribution from polarized top quark decay in the general two Higgs doublet model

    CERN Document Server

    Nejad, S Mohammad Moosavi

    2016-01-01

    We study the scaled-energy ( x_B) distribution of bottom-flavored mesons (B) inclusively produced in polarized top quark decays at next-to-leading order in the two-Higgs-doublet model. To study the energy spectrum of B-mesons we present, for the first time, an analytical expression for the NLO corrections to the partial decay width t(\\uparrow)-> H^+b taking the H^+ boson to be stable. Specifically, we study the effect of gluon fragmentation which leads to an appreciable reduction in the partial decay width at low values of x_B. To describe both the b-quark and the gluon hadronization we apply fragmentation functions extracted through a global fit to e^+e^- data from CERN LEP1 and SLAC SLC exploiting their universality and scaling violations.

  20. The forward-backward asymmetry for massive bottom quarks at the $Z$ peak at next-to-next-to-leading order QCD

    CERN Document Server

    Bernreuther, Werner; Dekkers, Oliver; Gehrmann, Thomas; Heisler, Dennis

    2016-01-01

    We compute the order $\\alpha_s^2$ QCD corrections to the $b$-quark forward-backward asymmetry in $e^+e^-\\to b{\\bar b}$ collisions at the $Z$ boson resonance, taking the non-zero mass of the $b$ quark into account. We determine these corrections with respect to both the $b$-quark axis and the thrust axis definition of the asymmetry. We compute also the distributions of these axes with respect to the electron beam. If one neglects the flavor singlet contributions to the $b$-quark asymmetry, as was done in previous computations for massless $b$ quarks, then the second-order QCD corrections for $m_b\

  1. Fully differential Higgs pair production in association with a W boson at next-to-next-to-leading order in QCD

    Science.gov (United States)

    Li, Hai Tao; Wang, Jian

    2017-02-01

    To clarify the electroweak symmetry breaking mechanism, we need to probe the Higgs self-couplings, which can be measured in Higgs pair productions. The associated production with a vector boson is special due to a clear tag in the final state. We perform a fully differential next-to-next-to-leading-order calculation of the Higgs pair production in association with a W boson at hadron colliders, and present numerical results at the 14 TeV LHC and a future 100 TeV hadron collider.

  2. Fully Differential Higgs Pair Production in Association With a $W$ Boson at Next-to-Next-to-Leading Order in QCD

    CERN Document Server

    Li, Hai Tao

    2016-01-01

    To clarify the electroweak symmetry breaking mechanism, we need to probe the Higgs self-couplings, which can be measured in Higgs pair productions. The associated production with a vector boson is special due to a clear tag in the final state. We perform a fully differential next-to-next-to-leading-order calculation of the Higgs pair production in association with a $W$ boson at hadron colliders, and present numerical results at the 14 TeV LHC and a future 100 TeV hadron collider.

  3. The forward-backward asymmetry for massive bottom quarks at the Z peak at next-to-next-to-leading order QCD

    Science.gov (United States)

    Bernreuther, Werner; Chen, Long; Dekkers, Oliver; Gehrmann, Thomas; Heisler, Dennis

    2017-01-01

    We compute the order α s 2 QCD corrections to the b-quark forward-backward asymmetry in {e}+{e}-to boverline{b} collisions at the Z boson resonance, taking the non-zero mass of the b quark into account. We determine these corrections with respect to both the b-quark axis and the thrust axis definition of the asymmetry. We compute also the distributions of these axes with respect to the electron beam. If one neglects the flavor singlet contributions to the b-quark asymmetry, as was done in previous computations for massless b quarks, then the second-order QCD corrections for m b ≠ 0 are smaller in magnitude than the corresponding corrections for m b = 0. Including the singlet contributions slightly increases the magnitude of the corrections. The massive α s 2 corrections to the b-quark forwardbackward asymmetry slightly diminish the well-known tension between the bare b-quark asymmetry and the standard model fit from 2 .9 σ to 2 .6 σ.

  4. Photoproduction of the J/{psi} meson at HERA at next-to-leading order within the framework of nonrelativistic QCD

    Energy Technology Data Exchange (ETDEWEB)

    Butenschoen, Mathias

    2009-06-15

    Nonrelativistic QCD (NRQCD) provides a rigorous factorization scheme which describes the production and decay of heavy quarkonia. It has been a desire for 13 years to know the NRQCD NLO predictions for both J/{psi} hadroproduction and photoproduction, in order to be able to check the universality of the color octet long distance matrix elements (MEs) by comparing Tevatron and HERA data. In this work we calculate for the rst time the NRQCD NLO prediction for direct photoproduction at HERA and compare our result with recent H1 data. Our results show clear evidence that the color octet mechanism of NRQCD is indeed realized in J/{psi} photoproduction at HERA. We solved a number of open conceptual problems, probably the most important one being the issue of Coulomb singularities. We found a way to evaluate the virtual corrections without having to deal with them. (orig.)

  5. Next-to-leading-order nonrelativistic QCD disfavors the interpretation of X(3872) as χc1(2P)

    Science.gov (United States)

    Butenschoen, Mathias; He, Zhi-Guo; Kniehl, Bernd A.

    2013-07-01

    We study χc1(2P)-inclusive hadroproduction at next-to-leading-order (NLO), both in αs and v2, within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD), including the color-singlet P1[1]3 and color-octet S1[8]3 cc¯ Fock states as well as the mixing of the latter with the D1[8]3 state. Assuming the recently discovered X(3872) hadron to be the JPC=1++ charmonium state χc1(2P), we perform a fit to the cross sections measured by the CDF, CMS, and LHCb Collaborations. We obtain either an unacceptably high value of χ2, a value of |R2P'(0)| incompatible with well-established potential models, or an intolerable violation of the NRQCD velocity rules. We thus conclude that NLO NRQCD is inconsistent with the hypothesis X(3872)≡χc1(2P).

  6. New insights into properties of large-N holographic thermal QCD at finite gauge coupling at (the non-conformal/next-to) leading order in N

    Energy Technology Data Exchange (ETDEWEB)

    Sil, Karunava; Misra, Aalok [Indian Institute of Technology, Department of Physics, Roorkee, Uttarakhand (India)

    2016-11-15

    It is believed that large-N thermal QCD laboratories like strongly coupled QGP (sQGP) require not only a large 't Hooft coupling but also a finite gauge coupling (Natsuume, String theory and quark-gluon plasma. arXiv:hep-ph/0701201, 2007). Unlike almost all top-down holographic models in the literature, holographic large-N thermal QCD models, based on this assumption, therefore necessarily require addressing this limit from M-theory. This was initiated in Dhuria and Misra (JHEP 1311:001, 2013) which presented a local M-theory uplift of the string theoretic dual of large-N thermal QCD-like theories at finite gauge/string coupling of Mia et al. (Nucl. Phys. B 839:187, arXiv:0902.1540 [hep-th], 2010) (g{sub s} corrections to the conformal results (but at finite g{sub s}), respectively, for the speed of sound, the shear mode diffusion constant, and the shear viscosity η (and (η)/(s)). The new insight gained is that it

  7. Fragmentation Functions at Next-to-Next-to-Leading Order Accuracy

    CERN Document Server

    Anderle, Daniele P; Stratmann, Marco

    2015-01-01

    We present a first analysis of parton-to-pion fragmentation functions at next-to-next-to-leading order accuracy in QCD based on single-inclusive pion production in electron-positron annihilation. Special emphasis is put on the technical details necessary to perform the QCD scale evolution and cross section calculation in Mellin moment space. We demonstrate how the description of the data and the theoretical uncertainties are improved when next-to-next-to-leading order QCD corrections are included.

  8. Next-to-next-to-leading order QCD analysis of spin-dependent parton distribution functions and their uncertainties: Jacobi polynomials approach

    CERN Document Server

    Shahri, F Taghavi; Tehrani, S Atashbar; Yazdi, Z Alizadeh

    2016-01-01

    We present a first global QCD analysis of next-to-next-leading-order (NNLO) contributions of the spin-dependent parton distribution functions (PPDFs) and their uncertainties using the Jacobi polynomial approach. Having the NNLO contributions of the quark-quark and gluon-quark splitting functions in perturbative QCD (Nucl. Phys. B 889 (2014) 351-400), one can obtain the evolution of longitudinally polarized parton densities of hadrons up to NNLO accuracy of QCD. A very large sets of recent and up-to-date experimental data of spin structure functions of the proton $g_1^p$, neutron $g_1^n$, and deuteron $g_1^d$ have been used in this analysis. The predictions for the NNLO calculations of the polarized parton distribution functions as well as the proton, neutron and deuteron polarized structure functions are compared with the corresponding results of the NLO approximation. We form a mutually consistent set of polarized PDFs due to the inclusion of the most available experimental data including the recently publis...

  9. New insights into properties of large- N holographic thermal QCD at finite gauge coupling at (the non-conformal/next-to) leading order in N

    Science.gov (United States)

    Sil, Karunava; Misra, Aalok

    2016-11-01

    It is believed that large- N thermal QCD laboratories like strongly coupled QGP (sQGP) require not only a large `t Hooft coupling but also a finite gauge coupling (Natsuume, String theory and quark-gluon plasma. arXiv:hep-ph/0701201, 2007). Unlike almost all top-down holographic models in the literature, holographic large- N thermal QCD models, based on this assumption, therefore necessarily require addressing this limit from M-theory. This was initiated in Dhuria and Misra (JHEP 1311:001, 2013) which presented a local M-theory uplift of the string theoretic dual of large- N thermal QCD-like theories at finite gauge/string coupling of Mia et al. (Nucl. Phys. B 839:187, arXiv:0902.1540 [hep-th], 2010) (g_s deformation - this paper) or deformed (deformation > resolution - Dhuria and Misra in Eur Phys J C 75(1):16, arXiv:1406.6076 [hep-th], 2015) resolved warped deformed conifold, the local T^3 of Dhuria and Misra (JHEP 1311:001, arXiv:1306.4339 [hep-th], 2013) in the MQGP limit is the T^2-invariant special Lagrangian three-cycle of Ionel and Min-OO (Ill J Math 52(3), 2008) justifying the construction in Dhuria and Misra (JHEP 1311:001, arXiv:1306.4339 [hep-th], 2013) of the delocalized Strominger-Yau-Zaslow Type IIA mirror of the Type IIB background of Mia et al. (Nucl Phys B 839:187, arXiv:0902.1540 [hep-th], 2010).

  10. On Large-N Holographic Thermal QCD at Finite Gauge Coupling at (the Non-Conformal/Next-to) Leading Order in N

    CERN Document Server

    Sil, Karunava

    2016-01-01

    In the context of [1]'s string theoretic dual of large-N thermal QCD-like theories at finite gauge/string coupling (as part of the `MQGP' limit of [2]), we discuss the following. First, up to LO in N, using the results of [3], we show that the local T^3 of [2] is the T^2-invariant sLag of [3] in a resolved conifold. This, together with the results of [4], shows that for a (predominantly resolved or deformed) resolved warped deformed conifold, the local T^3 of [2] in the MQGP limit, is the T^2-invariant sLag of [3] justifying the construction of the delocalized SYZ type IIA mirror of the type IIB background of [1]. Then, using the prescription of [5], we obtain the temperature dependence of the thermal (and electrical) conductivity working up to leading order in N (the number of D3-branes), and upon comparison with [6] show that the results mimic a 1+1-dimensional Luttinger liquid with impurities. Further, including sub-leading non-conformal terms in the metric determined by M (the number of fractional D-brane...

  11. Next-to-leading order corrections to the spin-dependent energy spectrum of hadrons from polarized top quark decay in the general two Higgs doublet model

    Directory of Open Access Journals (Sweden)

    S. Mohammad Moosavi Nejad

    2017-08-01

    Full Text Available In recent years, searches for the light and heavy charged Higgs bosons have been done by the ATLAS and the CMS collaborations at the Large Hadron Collider (LHC in proton–proton collision. Nevertheless, a definitive search is a program that still has to be carried out at the LHC. The experimental observation of charged Higgs bosons would indicate physics beyond the Standard Model. In the present work, we study the scaled-energy distribution of bottom-flavored mesons (B inclusively produced in polarized top quark decays into a light charged Higgs boson and a massless bottom quark at next-to-leading order in the two-Higgs-doublet model; t(↑→bH+→BH++X. This spin-dependent energy distribution is studied in a specific helicity coordinate system where the polarization vector of the top quark is measured with respect to the direction of the Higgs momentum. The study of these energy distributions could be considered as a new channel to search for the charged Higgs bosons at the LHC. For our numerical analysis and phenomenological predictions, we restrict ourselves to the unexcluded regions of the MSSM mH+−tan⁡β parameter space determined by the recent results of the CMS [13] and ATLAS [14] collaborations.

  12. Next-to-leading order corrections to the spin-dependent energy spectrum of hadrons from polarized top quark decay in the general two Higgs doublet model

    Science.gov (United States)

    Moosavi Nejad, S. Mohammad; Abbaspour, S.

    2017-08-01

    In recent years, searches for the light and heavy charged Higgs bosons have been done by the ATLAS and the CMS collaborations at the Large Hadron Collider (LHC) in proton-proton collision. Nevertheless, a definitive search is a program that still has to be carried out at the LHC. The experimental observation of charged Higgs bosons would indicate physics beyond the Standard Model. In the present work, we study the scaled-energy distribution of bottom-flavored mesons (B) inclusively produced in polarized top quark decays into a light charged Higgs boson and a massless bottom quark at next-to-leading order in the two-Higgs-doublet model; t (↑) → bH+ → BH+ + X. This spin-dependent energy distribution is studied in a specific helicity coordinate system where the polarization vector of the top quark is measured with respect to the direction of the Higgs momentum. The study of these energy distributions could be considered as a new channel to search for the charged Higgs bosons at the LHC. For our numerical analysis and phenomenological predictions, we restrict ourselves to the unexcluded regions of the MSSM mH+ - tan ⁡ β parameter space determined by the recent results of the CMS [13] and ATLAS [14] collaborations.

  13. Hadronic Parity Violation at Next-to-Leading Order

    CERN Document Server

    Tiburzi, B C

    2012-01-01

    The flavor-conserving non-leptonic weak interaction can be studied experimentally through the observation of parity violation in nuclear and few-body systems. At hadronic scales, matrix elements of parity-violating four-quark operators ultimately give rise to the parity violating couplings between hadrons, and such matrix elements can be calculated non-perturbatively using lattice QCD. In this work, we investigate the running of isovector parity-violating operators from the weak scale down to hadronic scales using the renormalization group. We work at next-to-leading order in the QCD coupling, and include both neutral-current and charged-current interactions. At this order, results are renormalization scheme dependent, and we utilize 't Hooft-Veltman dimensional regularization. The evolution of Wilson coefficients at leading and next-to-leading order is compared. Next-to-leading order effects are shown to be non-negligible at hadronic scales.

  14. Hadronic parity violation at next-to-leading order

    Science.gov (United States)

    Tiburzi, B. C.

    2012-03-01

    The flavor-conserving nonleptonic weak interaction can be studied experimentally through the observation of parity violation in nuclear and few-body systems. At hadronic scales, matrix elements of parity-violating four-quark operators ultimately give rise to the parity-violating couplings between hadrons, and such matrix elements can be calculated nonperturbatively using lattice QCD. In this work, we investigate the running of isovector parity-violating operators from the weak scale down to hadronic scales using the renormalization group. We work at next-to-leading order in the QCD coupling, and include both neutral-current and charged-current interactions. At this order, results are renormalization-scheme dependent, and we utilize ’t Hooft-Veltman dimensional regularization. The evolution of Wilson coefficients at leading and next-to-leading order is compared. Next-to-leading-order effects are shown to be non-negligible at hadronic scales.

  15. Determination of the strong coupling constant $\\alpha_s(M_Z)$ in next-to-next-to-leading order QCD using H1 jet cross section measurements arXiv

    CERN Document Server

    Andreev, V.; Begzsuren, K.; Belousov, A.; Bertone, V.; Bolz, A.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Buniatyan, A.; Bylinkin, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Chekelian, V.; Contreras, J.G.; Cvach, J.; Currie, J.; Dainton, J.B.; Daum, K.; Diaconu, C.; Dobre, M.; Dodonov, V.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Gehrmann, T.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grindhammer, G.; Gwenlan, C.; Haidt, D.; Henderson, R.C.W.; Hladkỳ, J.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Huss, A.; Jacquet, M.; Janssen, X.; Jung, A.W.; Jung, H.; Kapichine, M.; Katzy, J.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kogler, R.; Kostka, P.; Kretzschmar, J.; Krücker, D.; Krüger, K.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Malinovski, E.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Morozov, A.; Müller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Niehues, J.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Plačakytė, R.; Polifka, R.; Rabbertz, K.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Šálek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schöning, A.; Sefkow, F.; Shushkevich, S.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Straumann, U.; Sutton, M.R.; Sykora, T.; Thompson, P.D.; Traynor, D.; Truöl, P.; Tsakov, I.; Tseepeldorj, B.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wünsch, E.; Žáček, J.; Zhang, Z.; Žlebčík, R.; Zohrabyan, H.; Zomer, F.

    The strong coupling constant $\\alpha_s(M_Z)$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic $ep$ scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of $\\alpha_s(M_Z)$ at the $Z$-boson mass $m_Z$ are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be $\\alpha_s(M_Z)=0.1157\\,(20)_{\\rm exp}\\,(29)_{\\rm th}$. Complementary, \\asmz\\ is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value $\\alpha_s(M_Z)=0.1142\\,(28)_{\\rm tot}$ obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalis...

  16. Next-to-Leading Order Calculation of the Single Transverse Spin Asymmetry in the Drell-Yan Process

    Energy Technology Data Exchange (ETDEWEB)

    Vogelsang, Werner; Yuan, Feng

    2009-03-30

    We calculate the next-to-leading order perturbative QCD corrections to the transverse momentum weighted single transverse spin asymmetry in Drell-Yan lepton pair production in hadronic collisions. We identify the splitting function relevant for the scale evolution of the twist-three quark-gluon correlation function. We comment on the consequences of our results for phenomenology.

  17. Soffer's inequality and the transversely polarized Drell-Yan process at next-to-leading order

    CERN Document Server

    Martin, O; Stratmann, M; Vogelsang, W

    1998-01-01

    We check numerically if Soffer's inequality for quark distributions is preserved by next-to-leading order QCD evolution. Assuming that the inequality is saturated at a low hadronic scale we estimate the maximal transverse double spin asymmetry for Drell-Yan muon pair production to next-to-leading order accuracy.

  18. The matrix element method at next-to-leading order

    Science.gov (United States)

    Campbell, John M.; Giele, Walter T.; Williams, Ciaran

    2012-11-01

    This paper presents an extension of the matrix element method to next-to-leading order in perturbation theory, for electro-weak final states. To accomplish this we have developed a method to calculate next-to-leading order weights on an event-by-event basis. This allows for the definition of next-to-leading order likelihoods in exactly the same fashion as at leading order, thus extending the matrix element method to next-to-leading order. A welcome by-product of the method is the straightforward and efficient generation of unweighted next-to-leading order events. As examples of the application of our next-to-leading order matrix element method we consider the measurement of the mass of the Z boson and also the search for the Higgs boson in the four lepton channel.

  19. The Matrix Element Method at Next-to-Leading Order

    OpenAIRE

    Campbell, John M.; Giele, Walter T.; Williams, Ciaran

    2012-01-01

    This paper presents an extension of the matrix element method to next-to-leading order in perturbation theory. To accomplish this we have developed a method to calculate next-to-leading order weights on an event-by-event basis. This allows for the definition of next-to-leading order likelihoods in exactly the same fashion as at leading order, thus extending the matrix element method to next-to-leading order. A welcome by-product of the method is the straightforward and efficient generation of...

  20. Single top production at next-to-leading order in the Standard Model effective field theory

    CERN Document Server

    Zhang, Cen

    2016-01-01

    Single top production processes at hadron collider provide information on the relation between the top quark and the electroweak sector of the standard model. We compute the next-to-leading order QCD corrections to the three main production channels: $t$-channel, $s$-channel and $tW$ associated production, in the standard model including operators up to dimension-six. The calculation can be matched to parton shower programs and can therefore be directly used in experimental analyses. The QCD corrections are found to significantly impact the extraction of the current limits on the operators, because both of an improved accuracy and a better precision of the theoretical predictions. In addition, the distributions of some of the key discriminating observables are modified in a nontrivial way, which could change the interpretation of measurements in terms of UV complete models.

  1. A Positive-Weight Next-to-Leading-Order Monte Carlo for e+e- Annihilation to Hadrons

    CERN Document Server

    Latunde-Dada, O; Webber, Bryan R; Gieseke, Stefan; Latunde-Dada, Oluseyi; Webber, Bryan

    2007-01-01

    We apply the positive-weight Monte Carlo method of Nason for simulating QCD processes accurate to Next-To-Leading Order to the case of e+e- annihilation to hadrons. The method entails the generation of the hardest gluon emission first and then subsequently adding a `truncated' shower before the emission. We have interfaced our result to the Herwig++ shower Monte Carlo program and obtained better results than those obtained with Herwig++ at leading order with a matrix element correction.

  2. Multi-Parton Loop Amplitudes and Next-to-Leading Order Jet Cross-Sections

    CERN Document Server

    Bern, Zvi; Kosower, David A.; Signer, Adrian

    1998-01-01

    We review recent developments in the calculation of QCD loop amplitudes with several external legs, and their application to next-to-leading order jet production cross-sections. When a number of calculational tools are combined together --- helicity, color and supersymmetry decompositions, plus unitarity and factorization properties --- it becomes possible to compute multi-parton one-loop QCD amplitudes without ever evaluating analytically standard one-loop Feynman diagrams. One-loop helicity amplitudes are now available for processes with five external partons (ggggg, q\\bar{q}ggg and q\\bar{q}q'\\bar{q}'g), and for an intermediate vector boson V \\equiv \\gamma^*,Z,W plus four external partons (Vq\\bar{q}gg and Vq\\bar{q}q'\\bar{q}'). Using these amplitudes, numerical programs have been constructed for the next-to-leading order corrections to the processes p\\bar{p} to 3 jets (ignoring quark contributions so far) and e^+e^- to 4 jets.

  3. Transverse momentum broadening in semi-inclusive deep inelastic scattering at next-to-leading order

    Science.gov (United States)

    Kang, Zhong-Bo; Wang, Enke; Wang, Xin-Nian; Xing, Hongxi

    2016-12-01

    Within the framework of higher-twist collinear factorization, transverse momentum broadening for the final hadrons in semi-inclusive deeply inelastic e +A collisions is studied at the next-to-leading order (NLO) in perturbative QCD. Through explicit calculations of real and virtual corrections at twist 4, the transverse-momentum-weighted differential cross section due to double scattering is shown to factorize at NLO and can be expressed as a convolution of twist-4 nuclear parton correlation functions, the usual twist-2 fragmentation functions and hard parts which are finite and free of any divergences. A QCD evolution equation is also derived for the renormalized twist-4 quark-gluon correlation function which can be applied to future phenomenological studies of transverse momentum broadening and jet quenching at NLO.

  4. Next-to-next-to-next-to-leading order QCD prediction for the top anti-top S-wave pair production cross section near threshold in e{sup +}e{sup -} annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Beneke, Martin [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Kiyo, Yuichiro [Juntendo Univ., Inzai (Japan). Dept. of Physics; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Penin, Alexander [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Piclum, Jan [Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Steinhauser, Matthias [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik

    2015-06-15

    We present the third-order QCD prediction for the production of top-anti-top quark pairs in electron-positron collisions close to the threshold in the dominant S-wave state. We observe a significant reduction of the theoretical uncertainty and discuss the sensitivity to the top quark mass and width.

  5. Next-to-Next-to-Next-to-Leading Order QCD Prediction for the Top Antitop S-Wave Pair Production Cross Section Near Threshold in e(+)e(-) Annihilation.

    Science.gov (United States)

    Beneke, Martin; Kiyo, Yuichiro; Marquard, Peter; Penin, Alexander; Piclum, Jan; Steinhauser, Matthias

    2015-11-06

    We present the third-order QCD prediction for the production of top antitop quark pairs in electron-positron collisions close to the threshold in the dominant S-wave state. We observe a significant reduction of the theoretical uncertainty and discuss the sensitivity to the top quark mass and width.

  6. On top-pair hadro-production at next-to-next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Uwer, P. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences

    2012-03-15

    We study the QCD corrections at next-to-next-to-leading order (NNLO) to the cross section for the hadronic pair-production of top quarks. We present new results in the high-energy limit using the well-known framework of k{sub t}-factorization. We combine these findings with the known threshold corrections and present improved approximate NNLO results over the full kinematic range. This approach is employed to quantify the residual theoretical uncertainty of the approximate NNLO results which amounts to about 4% for the Tevatron and 5% for the LHC cross-section predictions. Our analytic results in the high-energy limit will provide an important check on future computations of the complete NNLO cross sections.

  7. Automatic predictions in the Georgi-Machacek model at next-to-leading order accuracy

    CERN Document Server

    Degrande, Celine; Logan, Heather E; Peterson, Andrea D; Zaro, Marco

    2015-01-01

    We study the phenomenology of the Georgi-Machacek model at next-to-leading order (NLO) in QCD matched to parton shower, using a fully-automated tool chain based on MadGraph5_aMC@NLO and FeynRules. We focus on the production of the fermiophobic custodial fiveplet scalars H_5^0, H_5^+/-, and H_5^++/-- through vector boson fusion (VBF), associated production with a vector boson (V H_5), and scalar pair production (H_5 H_5). For these production mechanisms we compute NLO corrections to production rates as well as to differential distributions. Our results demonstrate that the Standard Model (SM) overall K-factors for such processes cannot in general be directly applied to beyond-the-SM distributions, due both to differences in the scalar electroweak charges and to variation of the K-factors over the differential distributions.

  8. Direct Photon Production at Next-to–Next-to-Leading Order

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, John M.; Ellis, R. Keith; Williams, Ciaran

    2017-05-01

    We present the first calculation of direct photon production at next-to-next-to leading order (NNLO) accuracy in QCD. For this process, although the final state cuts mandate only the presence of a single electroweak boson, the underlying kinematics resembles that of a generic vector boson plus jet topology. In order to regulate the infrared singularities present at this order we use the $N$-jettiness slicing procedure, applied for the first time to a final state that at Born level includes colored partons but no required jet. We compare our predictions to ATLAS 8 TeV data and find that the inclusion of the NNLO terms in the perturbative expansion, supplemented by electroweak corrections, provides an excellent description of the data with greatly reduced theoretical uncertainties.

  9. Top-squark pair production at the LHC: a complete analysis at next-to-leading order

    CERN Document Server

    Germer, Jan; Lindert, Jonas M; Mirabella, Edoardo

    2014-01-01

    We present a complete next-to-leading order study of top-squark pair production at the LHC, including QCD and EW corrections. The calculation is performed within the Minimal Supersymmetric Standard Model and numerical results are presented for parameter regions compatible with the observed Higgs boson. We employ the most recent parton distribution functions including QED corrections and we find corrections to the inclusive stop-pair production cross section up to 25-30 % compared to the leading-order prediction.

  10. Higgs production at next-to-next-to-leading order

    Indian Academy of Sciences (India)

    V Ravindran; J Smith; W L Van Neerven

    2004-03-01

    We describe the calculation of inclusive Higgs boson production at hadronic colliders at next-to-next-to-leading order (NNLO) in perturbative quantum chromodynamics. We have used the technique developed in ref. [4]. Our results agree with those published earlier in the literature.

  11. Fully Differential Vector-Boson-Fusion Higgs Production at Next-to-Next-to-Leading Order.

    Science.gov (United States)

    Cacciari, Matteo; Dreyer, Frédéric A; Karlberg, Alexander; Salam, Gavin P; Zanderighi, Giulia

    2015-08-21

    We calculate the fully differential next-to-next-to-leading-order (NNLO) corrections to vector-boson fusion (VBF) Higgs boson production at proton colliders, in the limit in which there is no cross talk between the hadronic systems associated with the two protons. We achieve this using a new "projection-to-Born" method that combines an inclusive NNLO calculation in the structure-function approach and a suitably factorized next-to-leading-order VBF Higgs plus three-jet calculation, using appropriate Higgs plus two-parton counterevents. An earlier calculation of the fully inclusive cross section had found small NNLO corrections, at the 1% level. In contrast, the cross section after typical experimental VBF cuts receives NNLO contributions of about (5-6)%, while differential distributions show corrections of up to (10-12)% for some standard observables. The corrections are often outside the next-to-leading-order scale-uncertainty band.

  12. Resolving the Tevatron Top Quark Forward-Backward Asymmetry Puzzle: Fully Differential Next-to-Next-to-Leading-Order Calculation.

    Science.gov (United States)

    Czakon, Michal; Fiedler, Paul; Mitov, Alexander

    2015-07-31

    We determine the dominant missing standard model (SM) contribution to the top quark pair forward-backward asymmetry at the Tevatron. Contrary to past expectations, we find a large, around 27%, shift relative to the well-known value of the inclusive asymmetry in next-to-leading order QCD. Combining all known standard model corrections, we find that A(FB)(SM)=0.095±0.007. This value is in agreement with the latest DØ measurement [V. M. Abazov et al. (D0 Collaboration), Phys. Rev. D 90, 072011 (2014)] A(FB)(D∅)=0.106±0.03 and about 1.5σ below that of CDF [T. Aaltonen et al. (CDF Collaboration), Phys. Rev. D 87, 092002 (2013)] A(FB)(CDF)=0.164±0.047. Our result is derived from a fully differential calculation of the next-to-next-to leading order (NNLO) QCD corrections to inclusive top pair production at hadron colliders and includes-without any approximation-all partonic channels contributing to this process. This is the first complete fully differential calculation in NNLO QCD of a two-to-two scattering process with all colored partons.

  13. Chiral effective field theory on the lattice at next-to-leading order

    CERN Document Server

    Borasoy, Bugra; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G

    2007-01-01

    We study nucleon-nucleon scattering on the lattice at next-to-leading order in chiral effective field theory. We determine phase shifts and mixing angles from the properties of two-nucleon standing waves induced by a hard spherical wall in the center-of-mass frame. At fixed lattice spacing we test model independence of the low-energy effective theory by computing next-to-leading-order corrections for two different leading-order lattice actions. The first leading-order action includes instantaneous one-pion exchange and same-site contact interactions. The second leading-order action includes instantaneous one-pion exchange and Gaussian-smeared interactions. We find that in each case the results at next-to-leading order are accurate up to corrections expected at higher order.

  14. Next-to-Leading-Order Monte Carlo Simulation of Diphoton Production in Hadronic Collisions

    CERN Document Server

    D'Errico, Luca

    2011-01-01

    We present a method, based on the positive weight next-to-leading-order matching formalism (POWHEG), to simulate photon production processes at next-to-leading-order (NLO). This technique is applied to the simulation of diphoton production in hadron-hadron collisions. The algorithm consistently combines the parton shower and NLO calculation, producing only positive weight events. The simulation includes both the photon fragmentation contribution and a full implementation of the truncated shower required to correctly describe soft emissions in an angular-ordered parton shower.

  15. Single-Spin Asymmetries in W Boson Production at Next-to-Leading Order

    CERN Document Server

    Ringer, Felix

    2015-01-01

    We present an analytic next-to-leading order QCD calculation of the partonic cross sections for single-inclusive lepton production in hadronic collisions, when the lepton originates from the decay of an intermediate electroweak boson and is produced at high transverse momentum. In particular, we consider the case of incoming longitudinally polarized protons for which parity-violating single-spin asymmetries arise that are exploited in the $W$ boson program at RHIC to constrain the proton's helicity parton distributions. Our calculation enables a very fast and efficient numerical computation of the relevant spin asymmetries at RHIC, which is an important ingredient for the inclusion of RHIC data in a global analysis of nucleon helicity structure. We confirm the validity of our calculation by comparing with an existing code that treats the next-to-leading order cross sections entirely numerically by Monte-Carlo integration techniques. We also provide new comparisons of the present RHIC data with results for som...

  16. The Gluon-Induced Mueller-Tang Jet Impact Factor at Next-to-Leading Order

    CERN Document Server

    Hentschinski, Martin; Murdaca, Beatrice; Vera, Agustín Sabio

    2014-01-01

    We complete the computation of the Mueller-Tang jet impact factor at next-to-leading order (NLO) initiated in arXiv:1406.5625 and presented in arXiv:1404.2937 by computing the real corrections associated to gluons in the initial state making use of Lipatov's effective action. NLO corrections for this effective vertex are an important ingredient for a reliable description of large rapidity gap phenomenology within the BFKL approach.

  17. Driving Missing Data at Next-to-Leading Order

    CERN Document Server

    Bern, Z; Dixon, L J; Cordero, F Febres; Hoeche, S; Ita, H; Kosower, D A; Maitre, D; Ozeren, K J

    2011-01-01

    The prediction of backgrounds to new physics signals in topologies with large missing transverse energy and jets is important to new physics searches at the LHC. Following a CMS study, we investigate theoretical issues in using measurements of gamma + 2-jet production to predict the irreducible background to searches for missing energy plus two jets that originates from Z + 2-jet production where the Z boson decays to neutrinos. We compute ratios of gamma + 2-jet to Z + 2-jet production cross sections and kinematic distributions at next-to-leading order in alpha_s, as well as using a parton shower matched to leading-order matrix elements. We find that the ratios obtained in the two approximations are quite similar, making gamma + 2-jet production a theoretically reliable estimator for the missing energy plus two jets background. We employ a Frixione-style photon isolation, but we also show that for isolated prompt photon production at high transverse momentum the difference between this criterion and the stan...

  18. Charm quark contribution to K+ ---> pi+ nu anti-nu at next-to-next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Buras, Andrzej J.; /Munich, Tech. U.; Gorbahn, Martin; /Durham U., IPPP /Karlsruhe U., TTP; Haisch, Ulrich; /Fermilab /Zurich U.; Nierste, Ulrich; /Karlsruhe U., TTP

    2006-03-01

    The authors calculate the complete next-to-next-to-leading order QCD corrections to the charm contribution of the rare decay K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}. They encounter several new features, which were absent in lower orders. They discuss them in detail and present the results for the two-loop matching conditions of the Wilson coefficients, the three-loop anomalous dimensions, and the two-loop matrix elements of the relevant operators that enter the next-to-next-to-leading order renormalization group analysis of the Z-penguin and the electroweak box contribution. The inclusion of the next-to-next-to-leading order QCD corrections leads to a significant reduction of the theoretical uncertainty from {+-} 9.8% down to {+-} 2.4% in the relevant parameter P{sub c}(X), implying the leftover scale uncertainties in {Beta}(K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}) and in the determination of |V{sub td}|, sin 2{beta}, and {gamma} from the K {yields} {pi}{nu}{bar {nu}} system to be {+-} 1.3%, {+-} 1.0%, {+-} 0.006, and {+-} 1.2{sup o}, respectively. For the charm quark {ovr MS} mass m{sub c}(m{sub c}) = (1.30 {+-} 0.05) GeV and |V{sub us}| = 0.2248 the next-to-leading order value P{sub c}(X) = 0.37 {+-} 0.06 is modified to P{sub c}(X) = 0.38 {+-} 0.04 at the next-to-next-to-leading order level with the latter error fully dominated by the uncertainty in m{sub c}(m{sub c}). They present tables for P{sub c}(X) as a function of m{sub c}(m{sub c}) and {alpha}{sub s}(M{sub z}) and a very accurate analytic formula that summarizes these two dependences as well as the dominant theoretical uncertainties. Adding the recently calculated long-distance contributions they find {Beta}(K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}) = (8.0 {+-} 1.1) x 10{sup -11} with the present uncertainties in m{sub c}(m{sub c}) and the Cabibbo-Kobayashi-Maskawa elements being the dominant individual sources in the quoted error. They also emphasize that improved calculations of the long

  19. Triton charge radius to next-to-next-to-leading order in pionless effective field theory

    Science.gov (United States)

    Vanasse, Jared

    2017-02-01

    The triton point charge radius is calculated to next-to-next-to-leading order (NNLO) in pionless effective field theory ( EFT (π / )) , yielding a prediction of 1.14 ±0.19 fm (leading order), 1.59 ±0.08 fm (next-to leading order), and 1.62 ±0.03 fm (NNLO) in agreement with the current experimental extraction of 1.5978 ±0.040 fm [Angeli and Marinova, At. Data Nucl. Data Tables 99, 69 (2013)], 10.1016/j.adt.2011.12.006. The error at NNLO is due to cutoff variation (˜1 % ) within a reasonable range of calculated cutoffs and from a EFT (π / ) error estimate (˜1.5 % ). In addition new techniques are introduced to add perturbative corrections to bound- and scattering state calculations for short-range effective field theories, but with a focus on their use in EFT (π / ) .

  20. Revisiting the vector form factor at next-to-leading order in 1/N{sub C}

    Energy Technology Data Exchange (ETDEWEB)

    Rosell, Ignasi, E-mail: rosell@uch.ceu.e [Departamento de Ciencias Fisicas, Matematicas y de la Computacion, Universidad CEU Cardenal Herrera, c/ Sant Bartomeu 55, E-46115 Alfara del Patriarca, Valencia (Spain); IFIC, Universitat de Valencia - CSIC, Apt. Correus 22085, E-46071 Valencia (Spain)

    2010-10-15

    Using the Resonance Chiral Theory lagrangian, we perform a calculation of the vector form factor of the pion at the next-to-leading order (NLO) in the 1/N{sub C} expansion. Imposing the correct QCD short-distance constraints, one determines it in terms of F, G{sub V}, F{sub A} and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L{sub 9} and C{sub 88} -C{sub 90} at NLO, keeping full control of their renormalization scale dependence. At {mu}{sub 0} = 0.77 GeV, we obtain L{sup r}{sub 9}({mu}{sub 0}) = (7.6 {+-} 0.6) . 10{sup -3} and C{sup r}{sub 88}({mu}{sub 0}) -C{sup r}{sub 90}({mu}{sub 0}) = (-4.5 {+-} 0.5) . 10{sup -5}.

  1. Next to leading order analysis of DVCS and TCS

    Directory of Open Access Journals (Sweden)

    Wagner J.

    2014-03-01

    Full Text Available The study of O(αs QCD contributions to the timelike and spacelike virtual Compton scattering amplitudes in the generalized Bjorken scaling regime demonstrates that gluonic contributions are by no means negligible even in the medium energy range which will be studied intensely at JLab12 and in the COMPASS-II experiment at CERN.

  2. $B^0-\\bar{B}^0$ Mixing at Next-to-Leading Order

    CERN Document Server

    Grozin, Andrey G; Mannel, Thomas; Pivovarov, Alexei A

    2016-01-01

    We compute the perturbative corrections to the HQET sum rules for the matrix element of the \\Delta B=2 operator that determines the mass shift of $B^0$, $\\bar{B}^0$ states. Technically, we obtain analytically the non-factorizable contributions at order $\\alpha_s$ to the bag parameter that first appear at the three-loop level. Together with the known non-perturbative corrections due to vacuum condensates and $1/m_b$ corrections, the full next-to-leading order result is now available. We present a numerical value for the renormalization group invariant bag parameter that is phenomenologically relevant and discuss comparison with recent lattice determinations.

  3. Next-to-Leading Order Predictions for W + 3-Jet Distributions at Hadron Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, L.J.; /SLAC; Febres Cordero, F.; /UCLA; Forde, D.; Gleisberg, T.; /SLAC; Ita, H.; /UCLA; Kosower, D.A.; /Saclay, SPhT; Maitre, D.; /Durham U.

    2009-12-09

    We present next-to-leading order QCD predictions for a variety of distributions in W + 3-jet production at both the Tevatron and the Large Hadron Collider. We include all subprocesses and incorporate the decay of the W boson into leptons. Our results are in excellent agreement with existing Tevatron data and provide the first quantitatively precise next-to-leading order predictions for the LHC. We include all terms in an expansion in the number of colors, confirming that the specific leading-color approximation used in our previous study is accurate to within three percent. The dependence of the cross section on renormalization and factorization scales is reduced significantly with respect to a leading-order calculation. We study different dynamical scale choices, and find that the total transverse energy is significantly better than choices used in previous phenomenological studies. We compute the one-loop matrix elements using on-shell methods, as numerically implemented in the BlackHat code. The remaining parts of the calculation, including generation of the real-emission contributions and integration over phase space, are handled by the SHERPA package.

  4. Baryon chiral perturbation theory up to next-to-leading order

    CERN Document Server

    Bos, J W; Lee, S C; Lin, Y C; Shih, H H; Bos, J W; Chang, D W; Lee, S C; Lin, Y C; Shih, H H

    1995-01-01

    We examine the general lagrangian for baryon chiral perturbation theory with SU(3) flavor symmetry, up to the next-to-leading order. We consider both the strong and the weak interaction. The inverse of the baryon mass is treated as an additional small expansion parameter, and heavy fermion effective field theory techniques are employed to provide a consistent expansion scheme. A detailed account is given on the restrictions imposed on the lagrangian by the various symmetries. Corrections due to the finite baryon mass are also discussed.

  5. Next-to-Leading Order Jet Physics with BlackHat

    CERN Document Server

    Berger, C F; Dixon, L J; Cordero, F Febres; Forde, D; Gleisberg, T; Ita, H; Kosower, D A; Maitre, D

    2009-01-01

    We present several results obtained using the BlackHat next-to-leading order QCD program library, in conjunction with SHERPA. In particular, we present distributions for vector boson plus 1,2,3-jet production at the Tevatron and at the asymptotic running energy of the Large Hadron Collider, including new Z+3-jet distributions. The Z+2-jet predictions for the second-jet P_T distribution are compared to CDF data. We present the jet-emission probability at NLO in W+2-jet events at the LHC, where the tagging jets are taken to be the ones furthest apart in pseudorapidity. We analyze further the large left-handed W polarization, identified in our previous study, for W bosons produced at high P_T at the LHC.

  6. Next-to-leading Order Calculation for Jets Defined by a Maximized Jet Function

    CERN Document Server

    Kaufmann, Tom; Vogelsang, Werner

    2014-01-01

    We present a next-to-leading order QCD calculation for the single-inclusive production of collimated jets at hadron colliders, when the jet is defined by maximizing a suitable jet function that depends on the momenta of final-state particles in the event. A jet algorithm of this type was initially proposed by Georgi and subsequently further developed into the class of "$J_{E_T}$ algorithms". Our calculation establishes the infrared safety of the algorithms at this perturbative order. We derive analytical results for the relevant partonic cross sections. We discuss similarities and differences with respect to jets defined by cone or (anti-)$k_t$ algorithms and present numerical results for the Tevatron and the LHC.

  7. NLO QCD corrections to the production of two bottom-antibottom pairs at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, Nicolas [Illinois Univ., Urbana-Champaign, IL (United States). Dept. of Physics; Guffanti, Alberto [Freiburg Univ. (Germany). Physikalisches Inst.; Reiter, Thomas [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); Max-Planck-Institut fuer Physik, Muenchen (Germany); Reuter, Juergen [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Freiburg Univ. (Germany). Physikalisches Inst.

    2011-05-15

    We report the results of a computation of the full next-to-leading order QCD corrections to the production of two b anti b pairs at the LHC. This calculation at the parton level provides predictions for well separated b-jets. The results show that the next-to-leading order corrections lead to an enhancement of the cross-section for the central scale choice by roughly 50% with respect to the leading order result. The theoretical uncertainty estimated by variation of the renormalization and factorization scales is strongly reduced by the inclusion of next-to-leading order corrections. (orig.)

  8. Event generation for next to leading order chargino production at the international linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Robens, T.

    2006-10-15

    At the International Linear Collider (ILC), parameters of supersymmetry (SUSY) can be determined with an experimental accuracy matching the precision of next-to-leading order (NLO) and higher-order theoretical predictions. Therefore, these contributions need to be included in the analysis of the parameters. We present a Monte-Carlo event generator for simulating chargino pair production at the ILC at next-to-leading order in the electroweak couplings. We consider two approaches of including photon radiation. A strict fixed-order approach allows for comparison and consistency checks with published semianalytic results in the literature. A version with soft- and hard-collinear resummation of photon radiation, which combines photon resummation with the inclusion of the NLO matrix element for the production process, avoids negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. In addition, it includes further higher-order corrections unaccounted for by the fixed-order method. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations for NLO and higher-order contributions. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC. We closely investigate the two-photon phase space for the resummation method. We present results for cross sections and event generation for both approaches. (orig.)

  9. Herwig++ Monte Carlo At Next-To-Leading Order for e+e- annihilation and lepton pair production

    CERN Document Server

    Latunde-Dada, Oluseyi

    2007-01-01

    This paper describes the MC@NLO method for matching next-to-leading order (NLO) perturbative QCD with the parton shower and hadronization model of the Monte Carlo (MC) event generator tt Herwig++, for e+e- annihilation and Drell-Yan lepton pair production. Details of the event generation method as well as spin, flavour, momentum and colour assignments are presented. We obtain predictions for various distributions which arecompared with experimental data.

  10. Herwig++ Monte Carlo At Next-To-Leading Order for e+e- annihilation and lepton pair production.

    OpenAIRE

    Latunde-Dada, Oluseyi

    2007-01-01

    This paper describes the MC@NLO method for matching next-to-leading order (NLO) perturbative QCD with the parton shower and hadronization model of the Monte Carlo (MC) event generator tt Herwig++, for e+e- annihilation and Drell-Yan lepton pair production. Details of the event generation method as well as spin, flavour, momentum and colour assignments are presented. We obtain predictions for various distributions which arecompared with experimental data.

  11. Towards semi-inclusive deep inelastic scattering at next-to-next-to-leading order

    Science.gov (United States)

    Anderle, Daniele; de Florian, Daniel; Rotstein Habarnau, Yamila

    2017-02-01

    In this paper, we compute the first set of O (αs2) corrections to semi-inclusive deep inelastic scattering structure functions. We start by studying the impact of the contribution of the partonic subprocesses that open at this order for the longitudinal structure function. We perform the full calculation analytically, and obtain the expression of the factorized cross section at this order. Special care is given to the study of their flavor decomposition structure. We analyze the phenomenological effect of the corrections finding that, even though expected to be small a priori, it turns out to be sizable with respect to the previous order known, calling for a full next-to-next-to-leading order calculation.

  12. The epsilon expansion at next-to-next-to-leading order with small imaginary chemical potential

    CERN Document Server

    Lehner, Christoph; Wettig, Tilo

    2010-01-01

    We discuss chiral perturbation theory for two and three quark flavors in the epsilon expansion at next-to-next-to-leading order (NNLO) including a small imaginary chemical potential. We calculate finite-volume corrections to the low-energy constants $\\Sigma$ and $F$ and determine the non-universal modifications of the theory, i.e., modifications that cannot be mapped to random matrix theory (RMT). In the special case of two quark flavors in an asymmetric box we discuss how to minimize the finite-volume corrections and non-universal modifications by an optimal choice of the lattice geometry. Furthermore we provide a detailed calculation of a special version of the massless sunset diagram at finite volume.

  13. Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

    Science.gov (United States)

    Kamiński, Wojciech; Steinhaus, Sebastian

    2013-12-01

    We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol.

  14. Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

    Energy Technology Data Exchange (ETDEWEB)

    Kamiński, Wojciech, E-mail: wkaminsk@fuw.edu.pl [Wydział Fizyki, Uniwersytet Warszawski, Hoża 69, 00-681, Warsaw (Poland); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, D-14476 Potsdam (Germany); Steinhaus, Sebastian, E-mail: steinhaus.sebastian@gmail.com [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, D-14476 Potsdam (Germany)

    2013-12-15

    We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol.

  15. Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

    CERN Document Server

    Kaminski, Wojciech

    2013-01-01

    We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol.

  16. Study of beauty quark production and next-to-leading order at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Nuncio Quiroz, Adriana Elizabeth

    2008-08-15

    In this thesis a study on the production and evolution of beauty quarks in ep collisions at HERA is presented. The emphasis is put on the corresponding Quantum Chromodynamics predictions including next-to-leading order corrections. In the context of this work the FMNR x Pythia interface was developed, which calculates next-to-leading order Quantum Chromodynamics predictions at visible level for heavy-flavour processes in the photoproduction regime. This is achieved using the RedStat routines which transform the FMNR program into a Monte Carlo-like event generator. The parton-level events obtained are interfaced to Pythia using the Le Houches accord routines. All branching ratios and decay channels of the heavy quarks implemented in the Pythia framework are used, and therefore complex cuts on the nal state can be applied. The FMNR x Pythia interface is applied in this thesis to obtain next-to-leading order predictions for the recently finished heavy flavour ZEUS analyses: the ep {yields} b anti bX {yields} D{sup *}{mu}X' and ep {yields} b anti bX {yields} {mu}{sup +}{mu}{sup -}X' channels. A comparison with the H1 D{sup *}{mu} measurement is also performed. Since the use of such double tagging techniques to identify events where heavy flavours are present proved to be very convenient when the nal state is a pair of leptons, another part of this thesis work deals with the implementation of an electron finder, the {sup G}Elec finder. This finder is tested on the reconstruction of the J/{psi} {yields} e{sup +}e{sup -} signal. Finally, a heavy-flavour analysis has been started, namely the ep {yields} b anti bX {yields} e{mu}X' dilepton channel, using an integrated luminosity of 114 pb{sup -1} gated by the ZEUS detector in the years 1996-2000. Compared to previous analyses the study of beauty quark production in this channel extends the phase space of the measurement closer to the kinematic threshold, since electrons provide access to lower p{sub T} values

  17. Next-to-next-to-leading-order subtraction formalism in hadron collisions and its application to Higgs-boson production at the large hadron collider.

    Science.gov (United States)

    Catani, Stefano; Grazzini, Massimiliano

    2007-06-01

    We consider higher-order QCD corrections to the production of colorless high-mass systems (lepton pairs, vector bosons, Higgs bosons, etc.) in hadron collisions. We propose a new formulation of the subtraction method to numerically compute arbitrary infrared-safe observables for this class of processes. To cancel the infrared divergences, we exploit the universal behavior of the associated transverse-momentum (qT) distributions in the small-qT region. The method is illustrated in general terms up to the next-to-next-to-leading order in QCD perturbation theory. As a first explicit application, we study Higgs-boson production through gluon fusion. Our calculation is implemented in a parton level Monte Carlo program that includes the decay of the Higgs boson into two photons. We present selected numerical results at the CERN Large Hadron Collider.

  18. Jet production at next-to-leading order in p+Au collisions at the RHIC

    Institute of Scientific and Technical Information of China (English)

    HE Yun-Cun; ZHANG Ben-Wei; WANG En-Ke

    2012-01-01

    We calculate jet productions in p+Au collisions at the RHIC at next-to-leading order with perturbative QCD.Inclusive jet transverse energy spectrum,dijet invariant mass spectrum,dijet angular distribution,and corresponding nuclear modification factors for the three observables in p+Au collisions at √s =200 GeV are given,where the initial-state cold nuclear matter (CNM) effects are included by taking advantage of four parametrization sets of nuclear parton distribution functions (nPDFs)-EPS,nCTEQ,HKN and DS.We demonstrate that inclusive jet transverse energy (ET) spectrum,dijet invariant mass (MJJ) spectrum with all 4 nPDFs are increased at low ET or MJJ,whereas at high ET or MJJ large deviation of results with different nPDFs is observed.It is found that the dijet angular distributions in p+Au collisions do not vary relative to those in p+p collisions for all 4 nPDFs.

  19. Next-to-next-to-leading order calculation of the strong coupling constant by using moments of event-shape variables

    Indian Academy of Sciences (India)

    Samira Shoeibi Mohsenabadi; Mohammad Ebrahim Zomorrodian

    2013-11-01

    The next-to-next-to-leading order (NNLO) quantum chromodynamics (QCD) correction to the first three moments of the four event-shape variables in electron–positron annihilation, the thrust, heavy jet mass, wide, and total jet broadening, is computed. It is observed that the NNLO correction gives a better agreement between the theory and the experimental data. Also, by using the above observables, the strong coupling constant () is determined and how much its value is affected by the NNLO correction is demonstrated. By combining the results for all variables at different centre-of-mass energies $(M_{Z^{°}})$ = 0.1248 ± 0.0009 $({\\text{exp.}})_{-0.0144}^{+0.0283} ({\\text{theo.}})$ is obtained.

  20. Nuclear forces with Delta-excitations up to next-to-next-to-leading order I: peripheral nucleon-nucleon waves

    CERN Document Server

    Krebs, H; Meissner, U G; Epelbaum, Evgeny; Krebs, Hermann; Mei{\\ss}ner, Ulf-G.

    2007-01-01

    We study the two-nucleon force at next-to-next-to-leading order in a chiral effective field theory with explicit Delta degrees of freedom. Fixing the appearing low-energy constants from a next-to-leading order calculation of pion-nucleon threshold parameters, we find an improved convergence of most peripheral nucleon-nucleon phases compared to the theory with pions and nucleons only. In the delta-full theory, the next-to-leading order corrections are dominant in most partial waves considered.

  1. Next-to-leading order weighted Sivers asymmetry in semi-inclusive deep inelastic scattering: three-gluon correlator

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Lingyun [Indiana University , Bloomington, IN; Prokudin, Alexei [Jefferson Lab, Newport News, VA; Kang, Zhong-Bo [Los Alamos National Laboratory, Los Alamos, NM 87545; Vitev, Ivan [Los Alamos National Laboratory, Los Alamos

    2015-09-01

    We study the three-gluon correlation function contribution to the Sivers asymmetry in semi-inclusive deep inelastic scattering. We first establish the matching between the usual twist-3 collinear factorization approach and transverse momentum dependent factorization formalism for the moderate transverse momentum region. We then derive the so-called coefficient functions used in the usual TMD evolution formalism. Finally, we perform the next-to-leading order calculation for the transverse-momentum-weighted spin-dependent differential cross section, from which we identify the QCD collinear evolution of the twist-3 Qiu-Sterman function: the off-diagonal contribution from the three-gluon correlation functions.

  2. Ground state energy of dilute neutron matter at next-to-leading order in lattice chiral effective field theory

    CERN Document Server

    Epelbaum, Evgeny; Lee, Dean; Meißner, Ulf-G

    2008-01-01

    We present lattice calculations for the ground state energy of dilute neutron matter at next-to-leading order in chiral effective field theory. This study follows a series of recent papers on low-energy nuclear physics using chiral effective field theory on the lattice. In this work we introduce an improved spin- and isospin-projected leading-order action which allows for a perturbative treatment of corrections at next-to-leading order and smaller estimated errors. Using auxiliary fields and Euclidean-time projection Monte Carlo, we compute the ground state of 8, 12, and 16 neutrons in a periodic cube, covering a density range from 2% to 10% of normal nuclear density.

  3. Dilute neutron matter on the lattice at next-to-leading order in chiral effective field theory

    CERN Document Server

    Borasoy, Bugra; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G

    2007-01-01

    We discuss lattice simulations of the ground state of dilute neutron matter at next-to-leading order in chiral effective field theory. In a previous paper the coefficients of the next-to-leading-order lattice action were determined by matching nucleon-nucleon scattering data for momenta up to the pion mass. Here the same lattice action is used to simulate the ground state of up to 12 neutrons in a periodic cube using Monte Carlo. We explore the density range from 2% to 8% of normal nuclear density and analyze the ground state energy as an expansion about the unitarity limit with corrections due to finite scattering length, effective range, and P-wave interactions.

  4. Next-to-leading order unitarity fits in Two-Higgs-Doublet models with soft $\\mathbb{Z}_2$ breaking

    CERN Document Server

    Cacchio, Vincenzo; Eberhardt, Otto; Murphy, Christopher W

    2016-01-01

    We fit the next-to-leading order unitarity conditions to the Two-Higgs-Doublet model with a softly broken $\\mathbb{Z}_2$ symmetry. In doing so, we alleviate the existing uncertainty on how to treat higher order corrections to quartic couplings of its Higgs potential. A simplified approach to implementing the next-to-leading order unitarity conditions is presented. These new bounds are then combined with all other relevant constraints, including the complete set of LHC Run I data. The upper $95\\%$ bounds we find are $4.2$ on the absolute values of the quartic couplings, and $235$ GeV ($100$ GeV) for the mass degeneracies between the heavy Higgs particles in the type I (type II) scenario. In type II, we exclude an unbroken $\\mathbb{Z}_2$ symmetry with a probability of $95\\%$. All fits are performed using the open-source code HEPfit.

  5. Nuclear and partonic dynamics in the EMC effect at Next-to-Next-to-Leading order

    CERN Document Server

    Tehrani, S Atashbar

    2014-01-01

    We study in details the parameterizations of the nuclear parton distributions at the next-to-next-to-leading order (NNLO) of $\\alpha_s$. In low $x$ and $Q_0^2$, we observe negative gluon distribution at this order which signals the saturation condition or the quark-gluon plasma condition. Our study also shows the gluon distribution at (NNLO) is less than next-to-leading order (NLO) of $\\alpha_s$, and the sea quark distribution at (NNLO) is larger than (NLO).

  6. The radiative return at phi- and B-factories: FSR for muon pair production at next-to-leading order

    CERN Document Server

    Czyz, Henryk; Kuhn, Johann H; Rodrigo, Germán; Czyz, Henryk; Grzelinska, Agnieszka; Kuhn, Johann H.; Rodrigo, German

    2005-01-01

    Muon pair production through the radiative return is of importance for a measurement of the hadronic production cross section in two ways: it provides an independent calibration and it may give rise to an important background for a measurement of the pion form factor. With this motivation the Monte Carlo event generator PHOKHARA is extended to include next-to-leading order radiative corrections to the reaction $e^+e^-\\to \\mu^+\\mu^-\\gamma$. Furthermore, virtual ISR corrections to FSR from pions are introduced, which extends the applicability of the generator into a new kinematical regime. Finally, the effect of photon vacuum polarization is introduced into this new version of the generator.

  7. Slepton pair production in association with a jet: NLO-QCD corrections and parton-shower effects

    CERN Document Server

    Jager, Barbara; Thier, Stephan

    2014-01-01

    We present a calculation of the next-to-leading order QCD corrections to slepton pair production in association with a jet at the LHC together with their implementation in the POWHEG BOX. For the simulation of parton-shower effects and the decays of the sleptons we employ the multi-purpose Monte-Carlo program PYTHIA. We discuss the impact of next-to-leading order QCD corrections on experimentally accessible distributions and illustrate how the parton shower can modify observables that are sensitive to QCD radiation effects. Having full control on the hard jet in the process, we provide precise predictions also for monojet analyses.

  8. Chaos in two black holes with next-to-leading order spin-spin interactions

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Guoqing; Ni, Xiaoting; Wu, Xin [Nanchang University, Department of Physics, Nanchang (China)

    2014-08-15

    We take into account the dynamics of a complete third post-Newtonian conservative Hamiltonian of two spinning black holes, where the orbital part arrives at the third post-Newtonian precision level and the spin-spin part with the spin-orbit part includes the leading-order and next-to-leading-order contributions. It is shown through numerical simulations that the next-to-leading-order spin-spin couplings play an important role in chaos. A dynamical sensitivity to the variation of single parameter is also investigated in some cases. In particular, there are a number of observable orbits whose initial radii are large enough and which are chaotic before coalescence. (orig.)

  9. Rapidity evolution of Wilson lines at the next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Balitsky, Ian [JLAB, Old Dominion U.; Chirilli, Giovanni [LBL

    2013-12-01

    At high energies particles move very fast so the proper degrees of freedom for the fast gluons moving along the straight lines are Wilson-line operators - infinite gauge factors ordered along the line. In the framework of operator expansion in Wilson lines the energy dependence of the amplitudes is determined by the rapidity evolution of Wilson lines. We present the next-to-leading order hierarchy of the evolution equations for Wilson-line operators.

  10. Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence.

    Science.gov (United States)

    Borowka, S; Greiner, N; Heinrich, G; Jones, S P; Kerner, M; Schlenk, J; Schubert, U; Zirke, T

    2016-07-01

    We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.

  11. Probing gluon saturation with next-to-leading order photon production at central rapidities in proton-nucleus collisions

    CERN Document Server

    Benic, Sanjin; Garcia-Montero, Oscar; Venugopalan, Raju

    2016-01-01

    We compute the cross section for photons emitted from sea quarks in proton-nucleus collisions at collider energies. The computation is performed within the dilute-dense kinematics of the Color Glass Condensate (CGC) effective field theory. Albeit the result obtained is formally at next-to-leading order in the CGC power counting, it provides the dominant contribution for central rapidities. We observe that the inclusive photon cross section is proportional to all-twist Wilson line correlators in the nucleus. These correlators also appear in quark-pair production; unlike the latter, photon production is insensitive to hadronization uncertainties and therefore more sensitive to multi-parton correlations in the gluon saturation regime of QCD. We demonstrate that $k_\\perp$ and collinear factorized expressions for inclusive photon production are obtained as leading twist approximations to our result. In particular, the collinearly factorized expression is directly sensitive to the nuclear gluon distribution at smal...

  12. Automated Neutrino Jet and Top Jet Predictions at Next-to-Leading-Order with Parton Shower Matching in Effective Left-Right Symmetric Models

    CERN Document Server

    Mattelaer, Olivier; Ruiz, Richard

    2016-01-01

    Hadronic decays of boosted resonances, e.g., top quark jets, at hadronic super colliders are frequent predictions in TeV-scale extensions of the Standard Model of Particle Physics. In such scenarios, accurate modeling of QCD radiation is necessary for trustworthy predictions. We present the automation of fully differential, next-to-leading-order (NLO) in QCD corrections with parton shower (PS) matching for an effective Left-Right Symmetric Model (LRSM) that features $W_R^\\pm, Z_R$ gauge bosons and heavy Majorana neutrinos $N$. Publicly available universal model files require remarkably fewer user inputs for predicting benchmark collider processes than leading order LRSM constructions. We present predictions for inclusive $W_R^\\pm, Z_R$ production at the $\\sqrt{s} = 13$ TeV Large Hadron Collider (LHC) and a hypothetical future 100 TeV Very Large Hadron Collider (VLHC), as well as inclusive $N$ production for a hypothetical Large Hadron Electron Collider (LHeC). As a case study, we investigate at NLO+PS accurac...

  13. Production of massless charm jets in pp collisions at next-to-leading order of QCD

    CERN Document Server

    Bierenbaum, Isabella

    2014-01-01

    We present predictions for the inclusive production of charm jets in proton-proton collisions at 7 TeV. Several CTEQ parton distribution functions (PDFs) of the CTEQ6.6M type are employed, where two of the CTEQ6.6 PDFs have intrinsic charm. At large enough jet transverse momentum and large jet rapidity, the intrinsic charm content can be tested.

  14. Pion production in nucleon-nucleon collisions in chiral effective field theory: next-to-next-to-leading order contributions

    CERN Document Server

    Filin, A A; Epelbaum, E; Hanhart, C; Krebs, H; Kudryavtsev, A E; Myhrer, F

    2012-01-01

    A complete calculation of the pion-nucleon loops that contribute to the transition operator for $NN\\to NN\\pi$ up-to-and-including next-to-next-to-leading order (N$^2$LO) in chiral effective field theory near threshold is presented. The evaluation is based on the so-called momentum counting scheme, which takes into account the relatively large momentum of the initial nucleons inherent in pion-production reactions. We show that the significant cancellations between the loops found at next-to-leading order (NLO) in the earlier studies are also operative at N$^2$LO. In particular, the $1/m_N$ corrections (with $m_N$ being the nucleon mass) to loop diagrams cancel at N$^2$LO, as do the contributions of the pion loops involving the low-energy constants $c_i$, i=1...4. In contrast to the NLO calculation however, the cancellation of loops at N$^2$LO is incomplete, yielding a non-vanishing contribution to the transition amplitude. Together with the one-pion exchange tree-level operators, the loop contributions provide...

  15. Non-contact gears: I. Next-to-leading order contribution to lateral Casimir force between corrugated parallel plates

    CERN Document Server

    Cavero-Pelaez, Ines; Parashar, Prachi; Shajesh, K V

    2008-01-01

    We calculate the lateral Casimir force between corrugated parallel plates, described by $\\delta$-function potentials, interacting through a scalar field, using the multiple scattering formalism. The contributions to the Casimir energy due to uncorrugated parallel plates is treated as a background from the outset. We derive the leading- and next-to-leading-order contribution to the lateral Casimir force for the case when the corrugation amplitudes are small in comparison to corrugation wavelengths. We present explicit results in terms of finite integrals for the case of the Dirichlet limit, and exact results for the weak-coupling limit, for the leading- and next-to-leading-orders. The correction due to the next-to-leading contribution is significant. In the weak coupling limit we calculate the lateral Casimir force exactly in terms of a single integral which we evaluate numerically. Exact results for the case of the weak limit allows us to estimate the error in the perturbative results. We show that the error ...

  16. CGC factorization for forward particle production in proton-nucleus collisions at next-to-leading order

    CERN Document Server

    Iancu, E; Triantafyllopoulos, D N

    2016-01-01

    Within the Color Glass Condensate effective theory, we reconsider the next-to-leading order (NLO) calculation of the single inclusive particle production at forward rapidities in proton-nucleus collisions at high energy. Focusing on quark production for definiteness, we establish a new factorization scheme, valid thru NLO, in which all the radiative corrections are encoded into a single piece: a NLO impact factor, built with the produced quark and its (not necessarily soft) daughter gluon, which together scatter off the gluon distribution in the nucleus and thus measure its high-energy evolution to next-to-leading order. The NLO impact factor was previously computed in [1,2], but the reorganization of the perturbation theory that we propose is new. The non-linear evolution of the dense nucleus is not known beyond leading order, but we manage to reformulate it as the NLO evolution of the dilute projectile, amended by collinear improvement. As compared to the previous proposal in [1,2], in our factorization sch...

  17. Single-inclusive particle production in proton-nucleus collisions at next-to-leading order in the hybrid formalism

    CERN Document Server

    Altinoluk, Tolga; Beuf, Guillaume; Kovner, Alex; Lublinsky, Michael

    2014-01-01

    We reconsider the perturbative next-to-leading calculation of the single inclusive hadron production in the framework of the hybrid formalism, applied to hadron production in proton-nucleus collisions. Our analysis, performed in the wave function approach, differs from the previous works in three points. First, we are careful to specify unambiguously the rapidity interval that has to be included in the evolution of the leading-order eikonal scattering amplitude. This is important, since varying this interval by a number of order unity changes the next-to-leading order correction that the calculation is meant to determine. Second, we introduce the explicit requirement that fast fluctuations in the projectile wave function which only exist for a short time are not resolved by the target. This Ioffe time cutoff also strongly affects the next-to-leading order terms. Third, our result does not employ the approximation of a large number of colors. Our final expressions are unambiguous and do not coincide at next-to...

  18. NLO QCD corrections to electroweak Higgs boson plus three jet production at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Campanario, Francisco [Valencia-CSIC Univ. (Spain). IFIC; Figy, Terrance M. [Manchester Univ. (United Kingdom). School of Physics and Astronomy; Plaetzer, Simon [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Sjoedahl, Malin [Lund Univ. (Sweden). Dept. of Astronomy and Theoretical Physics

    2013-11-15

    The implementation of the full next-to-leading order (NLO) QCD corrections to electroweak Higgs boson plus three jet production at hadron colliders such as the LHC within the Matchbox NLO framework of the Herwig++ event generator is discussed. We present numerical results for integrated cross sections and kinematic distributions.

  19. Heavy-quark pair production in polarized photon-photon collisions at next-to-leading order. Fully integrated total cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A.; Kotikov, A.V.; Merebashvili, Z.V.; Veretin, O.L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2009-05-15

    We consider the production of heavy-quark pairs in the collisions of polarized and unpolarized on-shell photons and present, in analytic form, the fully integrated total cross sections for total photon spins J{sub z}=0,{+-}2 at next-to-leading-order in QCD. Phenomenological applications include b anti b production, which represents an irreducible background to standard-model intermediate-mass Higgs-boson production, as well as t anti t production. (orig.)

  20. Leading- and next-to-leading-order lateral Casimir force on corrugated surfaces

    CERN Document Server

    Cavero-Pelaez, Ines; Parashar, Prachi; Shajesh, K V

    2008-01-01

    We derive explicit analytic expressions for the lateral force for two different configurations with corrugations, parallel plates and concentric cylinders. By making use of the multiple scattering formalism, we calculate the force for a scalar field under the influence of a delta-function potential that has sinusoidal dependence in one direction simulating the corrugations. By making a perturbative expansion in the amplitude of the corrugation we find the leading order for the corrugated concentric cylinders and the next-to-leading order for the corrugated parallel plates.

  1. Hadronic contribution to the muon anomalous magnetic moment to next-to-next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Deutsches Elektronen Synchrotron (DESY), 15738 Zeuthen (Germany); Liu, Tao [Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Marquard, Peter [Deutsches Elektronen Synchrotron (DESY), 15738 Zeuthen (Germany); Steinhauser, Matthias [Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany)

    2014-06-27

    We compute the next-to-next-to-leading order hadronic contribution to the muon anomalous magnetic moment originating from the photon vacuum polarization. The corresponding three-loop kernel functions are calculated using asymptotic expansion techniques which lead to analytic expressions. Our final result, a{sub μ}{sup had,NNLO}=1.24±0.01×10{sup −10}, has the same order of magnitude as the current uncertainty of the leading order hadronic contribution and should thus be included in future analyses.

  2. Hadronic contribution to the muon anomalous magnetic moment to next-to-next-to-leading order

    CERN Document Server

    Kurz, Alexander; Marquard, Peter; Steinhauser, Matthias

    2014-01-01

    We compute the next-to-next-to-leading order hadronic contribution to the muon anomalous magnetic moment originating from the photon vacuum polarization. The corresponding three-loop kernel functions are calculated using asymptotic expansion techniques which lead to analytic expressions. Our final result, $a_\\mu^{\\rm had,NNLO} = 1.24 \\pm 0.01 \\times 10^{-10}$, has the same order of magnitude as the current uncertainty of the leading order hadronic contribution and should thus be included in future analyses.

  3. Hadronic contribution to the muon anomalous magnetic moment to next-to-next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Alexander [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Teilchenphysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Liu, Tao; Steinhauser, Matthias [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Teilchenphysik; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2014-03-15

    We compute the next-to-next-to-leading order hadronic contribution to the muon anomalous magnetic moment originating from the photon vacuum polarization. The corresponding three-loop kernel functions are calculated using asymptotic expansion techniques which lead to analytic expressions. Our final result, a{sup had,NNLO}{sub μ} = 1.24 ± 0.01 x 10{sup -10}, has the same order of magnitude as the current uncertainty of the leading order hadronic contribution and should thus be included in future analyses.

  4. QCD corrections to inclusive $\\Delta S=1,2$ transitions

    OpenAIRE

    Jamin, Matthias

    1994-01-01

    The talk summarises a calculation of the two-point functions for $\\Delta S=1$ current-current and QCD-penguin operators, as well as for the $\\Delta S=2$ operator, at the next-to-leading order. The size of the gluonic corrections to current-current operators is large, providing a qualitative understanding of the observed enhancement in $\\Delta I=1/2$ transitions. In the $\\Delta S=2$ sector the QCD corrections are quite moderate ($\\approx -20\\%$). This work has been done in collaboration with A...

  5. Nonperturbative QCD corrections to electroweak observables

    Energy Technology Data Exchange (ETDEWEB)

    Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies

    2011-12-01

    Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we will examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We will then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we will mention applications to the Adler function, the determination of the strong coupling constant and QCD corrections to muonic-hydrogen.

  6. Nonperturbative QCD corrections to electroweak observables

    Energy Technology Data Exchange (ETDEWEB)

    Renner, Dru B. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Feng, Xu [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus)

    2012-06-15

    Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements, effective field theory techniques and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we mention applications to the Adler function, which can be used to determine the strong coupling constant, and QCD corrections to muonic-hydrogen.

  7. NNLO QCD corrections to t -channel single top quark production and decay

    Science.gov (United States)

    Berger, Edmond L.; Gao, Jun; Yuan, C.-P.; Zhu, Hua Xing

    2016-10-01

    We present a fully differential next-to-next-to-leading-order calculation of t -channel single top quark production and decay at the LHC under a narrow-width approximation and neglecting cross talk between incoming protons. We focus on the fiducial cross sections at 13 TeV, finding that the next-to-next-to-leading-order QCD corrections can reach the level of -6 %. The scale variations are reduced to the level of a percent. Our results can be used to improve experimental acceptance estimates and the measurements of the single top quark production cross section and the top quark electroweak couplings.

  8. The Standard Model Effective Field Theory and Next to Leading Order

    CERN Document Server

    Passarino, Giampiero

    2016-01-01

    We review the status of calculations in the Standard Model Effective Field Theory (SMEFT) beyond leading order (LO). Improving the SMEFT beyond LO allows theoretical errors to be characterized and reduced when considering SMEFT interpretations of the data, which is essential considering the improving experimental precision at LHC. Next to leading order results also allow a more consistent analysis of measurements with different effective scales in the SMEFT. Going beyond LO is clearly important in the event that deviations from the SM are large enough that experimental indications of physics beyond the SM emerge. We discuss a consistent and well defined approach to LO in the SMEFT, so that the improvement to NLO is straightforward. We discuss the basic issues involved in improving calculations to NLO in the SMEFT, and review the advances in this direction that have been achieved to date.

  9. Ising and Gross-Neveu model in next-to-leading order

    CERN Document Server

    Knorr, Benjamin

    2016-01-01

    We study scalar and chiral fermionic models in next-to-leading order with the help of the functional renormalisation group. Their critical behaviour is of special interest in condensed matter systems, in particular graphene. To derive the beta functions, we make extensive use of computer algebra. The resulting flow equations were solved with pseudo-spectral methods to guarantee high accuracy. New estimates on critical quantities for both the Ising and the Gross-Neveu model are provided. For the Ising model, the estimates agree with earlier renormalisation group studies of the same level of approximation. By contrast, the approximation for the Gross-Neveu model retains many more operators than all earlier studies. For two Dirac fermions, the results agree with both lattice and large-$N_f$ calculations, but for a single flavour, different methods disagree quantitatively, and further studies are necessary.

  10. Colour-electric spectral function at next-to-leading order

    CERN Document Server

    Burnier, Y; Langelage, J; Mether, L

    2010-01-01

    The spectral function related to the correlator of two colour-electric fields along a Polyakov loop determines the momentum diffusion coefficient of a heavy quark near rest with respect to a heat bath. We compute this spectral function at next-to-leading order, O(alpha_s^2), in the weak-coupling expansion. The high-frequency part of our result (omega >> T), which is shown to be temperature-independent, is accurately determined thanks to asymptotic freedom; the low-frequency part of our result (omega 0. We also evaluate the colour-electric Euclidean correlator, which could be directly compared with lattice simulations. As an aside we determine the Euclidean correlator in the lattice strong-coupling expansion, showing that through a limiting procedure it can in principle be defined also in the confined phase of pure Yang-Mills theory, even if a practical measurement could be very noisy there.

  11. Next-to-Leading Order Description of Nucleon Structure Function In Valon Model

    CERN Document Server

    Arash, F; Arash, Firooz; Khorramia, Ali Naghi

    1999-01-01

    We have improved and examined the applicability of the valon model where the structure of any hadron is determined by the structure of its constituent quarks. Nucleon structure functions are calculated within this model in the Next-to-Leading order. The results compare well with the experimental data. The model handles the bound state problem and the calculations show a flat or almost flat behavior for $F_{2}$ which sets in at some region of $x\\leq 10^{-5}$at fixed $Q^{2}$. The emergence of this behavior is a consequence of the model and was not put in a priori as a theoretical guess. It seems that such a flatness can be inferred from HERA data, although, not completely confirmed yet. A set of parton distributions are given and their evolutions are tested. Some qualitative implications of the model for the spin structure of the proton is discussed.

  12. Electroweak and QCD Radiative Corrections to Drell-Yan Process for Experiments at the Large Hadron Collider

    CERN Document Server

    Zykunov, Vladimir

    2013-01-01

    Next-to-leading order electroweak and QCD radiative corrections to the Drell-Yan process with high dimuon masses for experiments CMS LHC at CERN have been studied in fully differential form. The FORTRAN code READY for numerical analysis of Drell-Yan observables has been presented. The radiative corrections are found to become significant for CMS LHC experiment setup.

  13. Phenomenological study of weakino pair production processes in the MSSM at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Baglio, Julien; Jaeger, Barbara; Kesenheimer, Matthias [Eberhard Karls Universitaet Tuebingen (Germany)

    2016-07-01

    The Minimal Supersymmetric Standard Model (MSSM) predicts the existence of eight weakly interacting particles which are linear combinations of a higgsino and one wino or one bino. These states are called charginos for the electrically charged particles or neutralinos for the neutral particles. Additionally, if R-parity is conserved every weakino production process with following decay results in at least one stable neutralino, which is a good candidate for a dark matter particle. By studying weakino production processes we can gain information about dark matter and SUSY in general. Furthermore, for the analysis of experimental data precise theoretical calculations of production cross sections are essential. With new constrains on SUSY models, we perform a phenomenological study including higher order QCD corrections of chargino and neutralino production processes. Preliminary results of the production cross-section at √(s) = 14 TeV of pp collisions are presented.

  14. Improved next-to-leading order tidal heating and torquing of a Kerr black hole

    Science.gov (United States)

    Chatziioannou, Katerina; Poisson, Eric; Yunes, Nicolás

    2016-10-01

    We calculate the energy and angular-momentum fluxes across the event horizon of a tidally deformed, rapidly rotating black hole to next-to-leading order in the curvature of the external spacetime. These are expressed in terms of tidal quadrupole moments and their time derivatives, which provide a characterization of a generic tidal environment. As an application of our results, we provide an expression for the energy and angular-momentum fluxes across the horizon when the black hole is a member of a binary system on a slowly moving, quasicircular orbit. Our expressions are accurate to 1.5 post-Newtonian order beyond the leading-order fluxes, but they are valid for arbitrary mass ratios. We compare our results to those previously obtained in the case of an extreme mass ratio binary, and find that they do not agree at the 1.5 post-Newtonian order. We investigate a number of possible sources for this discrepancy, but are ultimately unable to resolve it.

  15. Improved next-to-leading order tidal heating and torquing of a Kerr black hole

    CERN Document Server

    Chatziioannou, Katerina; Yunes, Nicolas

    2016-01-01

    We calculate the energy and angular momentum fluxes across the event horizon of a tidally deformed, rapidly rotating black hole to next-to-leading order in the curvature of the external spacetime. These are expressed in terms of tidal quadrupole moments and their time derivatives, which provide a characterization of a generic tidal environment. As an application of our results, we provide an expression for the energy and angular-momentum fluxes across the horizon when the black hole is a member of a binary system on a slowly-moving, quasi-circular orbit. Our expressions are accurate to 1.5 post-Newtonian order beyond the leading-order fluxes, but they are valid for arbitrary mass ratios. We compare our results to those previously obtained in the case of an extreme mass ratio binary, and find that they do not agree at the 1.5 post-Newtonian order. We investigate a number of possible sources for this discrepancy, but are ultimately unable to resolve it.

  16. Complete next-to-leading-order study on the yield and polarization of Υ(1S,2S,3S) at the Tevatron and LHC.

    Science.gov (United States)

    Gong, Bin; Wan, Lu-Ping; Wang, Jian-Xiong; Zhang, Hong-Fei

    2014-01-24

    Based on the nonrelativistic QCD factorization scheme, we present the first complete next-to-leading-order study on the yield and polarization of Υ(1S,2S,3S) hadroproduction. By using the color-octet long-distance matrix elements obtained from fits of the experimental measurements on Υ yield and polarization at the Tevatron and LHC, our results can explain the measurements on the yield very well, and for the polarizations of Υ(1S,2S,3S), they are in (good, good, bad) agreement with recent CMS measurement, but still have some distance from the CDF measurement.

  17. Analytic derivation of the next-to-leading order proton structure function F2p(x ,Q2) based on the Laplace transformation

    Science.gov (United States)

    Khanpour, Hamzeh; Mirjalili, Abolfazl; Tehrani, S. Atashbar

    2017-03-01

    An analytical solution based on the Laplace transformation technique for the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations is presented at next-to-leading order accuracy in perturbative QCD. This technique is also applied to extract the analytical solution for the proton structure function, F2p(x ,Q2) , in the Laplace s space. We present the results for the separate parton distributions of all parton species, including valence quark densities, the antiquark and strange sea parton distribution functions (PDFs), and the gluon distribution. We successfully compare the obtained parton distribution functions and the proton structure function with the results from GJR08 [Gluck, Jimenez-Delgado, and Reya, Eur. Phys. J. C 53, 355 (2008)], 10.1140/epjc/s10052-007-0462-9 and KKT12 [Khanpour, Khorramian, and Tehrani, J. Phys. G 40, 045002 (2013)], 10.1088/0954-3899/40/4/045002 parametrization models as well as the x -space results using QCDnum code. Our calculations show a very good agreement with the available theoretical models as well as the deep inelastic scattering (DIS) experimental data throughout the small and large values of x . The use of our analytical solution to extract the parton densities and the proton structure function is discussed in detail to justify the analysis method, considering the accuracy and speed of calculations. Overall, the accuracy we obtain from the analytical solution using the inverse Laplace transform technique is found to be better than 1 part in 104 to 105. We also present a detailed QCD analysis of nonsinglet structure functions using all available DIS data to perform global QCD fits. In this regard we employ the Jacobi polynomial approach to convert the results from Laplace s space to Bjorken x space. The extracted valence quark densities are also presented and compared to the JR14, MMHT14, NNPDF, and CJ15 PDFs sets. We evaluate the numerical effects of target mass corrections (TMCs) and higher twist (HT) terms

  18. The Gross-Neveu model at finite temperature at next to leading order in the 1/N expansion

    CERN Document Server

    Blaizot, J P; Wschebor, N

    2003-01-01

    We present new results on the Gross-Neveu model at finite temperature and at next-to-leading order in the 1/N expansion. In particular, a new expression is obtained for the effective potential which is explicitly invariant under renormalization group transformations. The model is used as a playground to investigate various features of field theory at finite temperature. For example we verify that, as expected from general arguments, the cancellation of ultraviolet divergences takes place at finite temperature without the need for introducing counterterms beyond those of zero-temperature. As well known, the discrete chiral symmetry of the 1+1 dimensional model is spontaneously broken at zero temperature and restored, in leading order, at some temperature T_c; we find that the 1/N approximation breaks down for temperatures below T_c: As the temperature increases, the fluctuations become eventually too large to be treated as corrections, and a Landau pole invalidates the calculation of the effective potential in...

  19. QCD Corrections to Higgs Pair Production in Bottom Quark Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Sally; /Brookhaven; Kao, Chung; /Fermilab /Oklahoma U.; Wang, Yili; Williams, Peter; /Oklahoma U.

    2006-10-01

    We present a complete next-to-leading order (NLO) calculation for the total cross section of inclusive Higgs pair production via bottom-quark fusion (b{bar b} {yields} hh) at the CERN Large Hadron Collider (LHC) in the Standard Model. The NLO QCD corrections lead to less dependence on the renormalization scale ({mu}{sub R}) and the factorization scale ({mu}{sub F}) than the leading-order (LO) cross section, and they significantly increase the LO cross section. The rate for inclusive Higgs pair production is small in the Standard Model, but can be large in models with enhanced couplings of the b quark to the Higgs bosons.

  20. Next-to-next-to-leading order contributions to jet photoproduction and determination of αs

    Science.gov (United States)

    Klasen, Michael; Kramer, Gustav; Michael, Markus

    2014-04-01

    We present the first calculation of inclusive jet photoproduction with approximate next-to-next-to-leading-order contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading-order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved approximate next-to-next-to-leading-order contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced.

  1. QCD

    CERN Document Server

    Catani, S; Soper, Davison Eugene; Stirling, William James; Tapprogge, Stefan; Alekhin, S I; Aurenche, Patrick; Balázs, C; Ball, R D; Battistoni, G; Berger, E L; Binoth, T; Brock, R L; Casey, D; Corcella, Gennaro; Del Duca, V; Fabbro, A D; de Roeck, A; Ewerz, C; de Florian, D; Fontannaz, M; Frixione, Stefano; Giele, W T; Grazzini, Massimiliano; Guillet, J P; Marlen-Heinrich, G; Huston, J; Kalk, J; Kataev, A L; Kato, K; Keller, S; Klasen, M; Kosower, D A; Kulesza, A; Kunszt, Zoltán; Kupco, A; Ilyin, V A; Magnea, L; Mangano, Michelangelo L; Martin, A D; Mazumdar, K; Miné, P; Moretti, M; van Neerven, W L; Parente, G; Perret-Gallix, D; Pilon, E; Pukhov, A E; Puljak, I; Pumplin, Jon; Richter-Was, Elzbieta; Roberts, R G; Salam, Gavin P; Seymour, Michael H; Skachkov, N B; Sidorov, A V; Stenzel, H; Stump, D R; Thorne, R S; Treleani, D; Tung, W K; Vogt, A; Webber, Bryan R; Werlen, M; Zmouchko, S; Mine, Ph.

    2000-01-01

    We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

  2. Jet tomography of high-energy nucleus-nucleus collisions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Vitev, Ivan [Los Alamos National Laboratory; Zhang, Ben - Wei [Los Alamos National Laboratory

    2009-01-01

    We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly-interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to {Omicron}({alpha}{sub s}{sup 3}). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.

  3. NLO QCD Corrections to Electroweak Higgs Boson Production in Association with Three Jets at the LHC

    Science.gov (United States)

    Figy, Terrance

    2017-01-01

    In this talk I will discuss the implementation of the next-to-leading order (NLO) perturbative QCD corrections to electroweak Higgs boson plus three jet production at the CERN Large Hadron Collider experiment within the Matchbox framework of the Herwig 7 event generator. Numerical results for integrated cross sections and kinematic distributions will be presented for a fixed-order NLO calculation and for a NLO calculation matched to a parton shower.

  4. QCD corrections to J/psi and Upsilon production at hadron colliders.

    Science.gov (United States)

    Campbell, J; Maltoni, F; Tramontano, F

    2007-06-22

    We calculate the cross section for hadroproduction of a pair of heavy quarks in a (3)S(1) color-singlet state at next-to-leading order in QCD. This corresponds to the leading contribution in the nonrelativistic QCD expansion for J/psi and Upsilon production. The higher-order corrections have a large impact on the p(T) distributions, enhancing the production at high p(T) at both the Fermilab Tevatron and the CERN Large Hadron Collider. The total decay rate of a (3)S(1) into hadrons at next-to-leading order is also computed, confirming for the first time the result obtained by Mackenzie and Lepage in 1981.

  5. Inclusive photoproduction of D{sup *{+-}} mesons at next-to-leading order in the general-mass variable-flavor-number scheme

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A.; Kramer, G. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Schienbein, I. [Univ. Joseph Fourier/CNRS-IN2P3, INPG, Grenoble (France). Lab. de Physique Subatomique et de Cosmologie; Spiesberger, H. [Mainz Univ. (Germany). Inst. fuer Physik

    2009-02-15

    We discuss the inclusive production of D{sup *{+-}} mesons in {gamma}p collisions at DESY HERA, based on a calculation at next-to-leading order in the general-mass variable-flavor-number scheme. In this approach, MS subtraction is applied in such a way that large logarithmic corrections are resummed in universal parton distribution and fragmentation functions and finite mass terms are taken into account. We present detailed numerical results for a comparison with data obtained at HERA and discuss various sources of theoretical uncertainties. (orig.)

  6. Survival probability for diffractive dijet production in p-pbar collisions from next-to-leading order calculations

    CERN Document Server

    Klasen, M

    2009-01-01

    We perform next-to-leading order calculations of the single-diffractive and non-diffractive cross sections for dijet production in proton-antiproton collisions at the Tevatron. By comparing their ratio to the data published by the CDF collaboration for two different center-of-mass energies, we deduce the rapidity-gap survival probability as a function of the momentum fraction of the parton in the antiproton. Assuming Regge factorization, this probability can be interpreted as a suppression factor for the diffractive structure function measured in deep-inelastic scattering at HERA. In contrast to the observations for photoproduction, the suppression factor in proton-antiproton collisions depends on the momentum fraction of the parton in the Pomeron even at next-to-leading order.

  7. Survival probability for diffractive dijet production in pp¯ collisions from next-to-leading order calculations

    Science.gov (United States)

    Klasen, Michael; Kramer, Gustav

    2009-10-01

    We perform next-to-leading order calculations of the single-diffractive and nondiffractive cross sections for dijet production in proton-antiproton collisions at the Tevatron. By comparing their ratio to the data published by the CDF collaboration for two different center-of-mass energies, we deduce the rapidity-gap survival probability as a function of the momentum fraction of the parton in the antiproton. Assuming Regge factorization, this probability can be interpreted as a suppression factor for the diffractive structure function measured in deep-inelastic scattering at HERA. In contrast to the observations for photoproduction, the suppression factor in proton-antiproton collisions depends on the momentum fraction of the parton in the Pomeron even at next-to-leading order.

  8. Survival probability for diffractive dijet production in p anti p collisions from next-to-leading order calculations

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M. [Univ. Joseph Fourier, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Kramer, G. [Univ. Hamburg, II. Inst. fuer Theoretische Physik (Germany)

    2009-08-15

    We perform next-to-leading order calculations of the single-diffractive and non-diffractive cross sections for dijet production in proton-antiproton collisions at the Tevatron. By comparing their ratio to the data published by the CDF collaboration for two different center-of-mass energies, we deduce the rapidity-gap survival probability as a function of the momentum fraction of the parton in the antiproton. Assuming Regge factorization, this probability can be interpreted as a suppression factor for the diffractive structure function measured in deep-inelastic scattering at HERA. In contrast to the observations for photoproduction, the suppression factor in protonantiproton collisions depends on the momentum fraction of the parton in the Pomeron even at next-to-leading order. (orig.)

  9. Complete next-to-next-to-leading order calculation of NN → NNπ in chiral effective field theory

    Directory of Open Access Journals (Sweden)

    Filin A. A.

    2014-01-01

    Full Text Available We present the results of the pion production operator calculated up-to-and-including next-to-next-to-leading order (NNLO in chiral effective field theory. We include explicit Delta degrees of freedom and demonstrate that they provide essential contribution required to understand neutral pion production data. Analysis of chiral loops at NNLO reveals new mechanisms which are important, but haven’t been considered in phenomenological studies so far.

  10. Transverse parton distribution functions at next-to-next-to-leading order: the quark-to-quark case.

    Science.gov (United States)

    Gehrmann, Thomas; Lübbert, Thomas; Yang, Li Lin

    2012-12-14

    We present a calculation of the perturbative quark-to-quark transverse parton distribution function at next-to-next-to-leading order based on a gauge invariant operator definition. We demonstrate for the first time that such a definition works beyond the first nontrivial order. We extract from our calculation the coefficient functions relevant for a next-to-next-to-next-to-leading logarithmic Q(T) resummation in a large class of processes at hadron colliders.

  11. Next-to-leading order improved perturbative QCD + saturation + hydrodynamics model for A+A collisions

    Energy Technology Data Exchange (ETDEWEB)

    Paatelainen, R.; Eskola, K.J. [Department of Physics, P.O.Box 35, FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics, P.O.Box 64, FI-00014 University of Helsinki (Finland); Holopainen, H. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany); Niemi, H. [Department of Physics, P.O.Box 35, FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics, P.O.Box 64, FI-00014 University of Helsinki (Finland); Tuominen, K. [Department of Physics, P.O.Box 64, FI-00014 University of Helsinki (Finland); Helsinki Institute of Physics, P.O.Box 64, FI-00014 University of Helsinki (Finland)

    2014-06-15

    We calculate initial conditions for the hydrodynamical evolution in ultrarelativistic heavy-ion collisions at the LHC and RHIC in an improved next-to-leading order perturbative QCD + saturation framework. Using viscous relativistic hydrodynamics, we show that we obtain a good simultaneous description of the centrality dependence of charged particle multiplicities, transverse momentum spectra and elliptic flow at the LHC and at RHIC. In particular, we discuss how the temperature dependence of the shear viscosity is constrained by these data.

  12. Mixed electroweak-QCD corrections to e+e-→H Z at Higgs factories

    Science.gov (United States)

    Sun, Qing-Feng; Feng, Feng; Jia, Yu; Sang, Wen-Long

    2017-09-01

    The prospective Higgs factories, exemplified by ILC, FCC-ee and CEPC, plan to conduct precision Higgs measurements at the e+e- center-of-mass energy around 250 GeV. The cross sections for the dominant Higgs production channel, the Higgsstrahlung process, can be measured to a (sub)percent accuracy. Merely incorporating the well-known next-to-leading-order (NLO) electroweak corrections appears to be far from sufficient to match the unprecedented experimental precision. In this work, we make an important advancement toward this direction by investigating the mixed electroweak-QCD corrections to e+e-→H Z at next-to-next-to-leading order (NNLO) for both unpolarized and polarized Z bosons. The corrections turn out to reach the 1% level of the Born order results, and thereby must be incorporated in future confrontations with the data.

  13. NLO QCD Corrections for $\\chi_{cJ}$ Inclusive Production at $B$ Factories

    CERN Document Server

    Chen, Long-Bin; Qiao, Cong-Feng

    2014-01-01

    The next-to-leading order (NLO) quantum chromodynamics (QCD) corrections for $\\chi_{cJ}(^3P_J^{[1]},^3S_1^{[8]})$, the P-wave charmoniums inclusive production at $B$ factories are calculated utilizing the non-relativistic QCD (NRQCD) factorization formalism. Large NLO corrections are found, especially for $^3P_0^{[1]}$ and $^3S_1^{[8]}$ configurations. Numerical evaluation indicates that the total cross sections of $\\chi_{cJ}+c+\\bar{c}$ processes are about $1\\sim100$fb, which are accessible in the super-B experiment.

  14. The NLO QCD corrections to associate production of squarks and charginos at LHC

    Science.gov (United States)

    Xiao, Zhen-Jun; Jin, Li-Gang; Yu, Huan; Cheng, Hong-Mei

    2010-02-01

    In this talk, we present our calculations for the next-to-leading order(NLO) QCD corrections to the cross sections (CS) of the associate production processes pp→gq→q˜iχ˜j±+X with q = (u,d) in the constrained minimal supersymmetric standard model in the CERN LHC experiments. The NLO QCD corrections can in general provide a 30-40% enhancement to the corresponding cross sections, and significantly reduce the dependence of the total cross section on the renormalization and factorization scales.

  15. Heavy-to-heavy quark decays at next-to-next-to-leading order

    Science.gov (United States)

    Pak, Alexey; Czarnecki, Andrzej

    2008-12-01

    Details of a recent calculation of O(αs2) corrections to the decay b→cℓνl, taking into account the c-quark mass, are described. Construction of the expansion in the mass ratio mc/mb as well as the evaluation of new four-loop master integrals are presented. The same techniques are applicable to the muon decay, μ→eνμν¯e. Analytical results are presented, for the physical cases as well as for a model with purely-vector couplings.

  16. 2HDM Higgs-to-Higgs Decays at Next-to-Leading Order

    CERN Document Server

    Krause, Marcel; Santos, Rui; Ziesche, Hanna

    2016-01-01

    The detailed investigation of the Higgs sector at present and future colliders necessitates from the theory side as precise predictions as possible, including higher order corrections. An important ingredient for the computation of higher order corrections is the renormalization of the model parameters and fields. In this paper we complete the renormalization of the 2-Higgs-Doublet Model (2HDM) Higgs sector launched in a previous contribution with the investigation of the renormalization of the mixing angles $\\alpha$ and $\\beta$. Here, we treat the renormalization of the mass parameter $m_{12}^2$ that softly breaks the $\\mathbb{Z}_2$ symmetry of the 2HDM Higgs sector. We investigate the impact of two different renormalization schemes on the sample Higgs-to-Higgs decay $H\\to hh$. This decay also allows us to analyze the renormalization of the mixing angles and to confirm the properties extracted before in other Higgs decays. In conclusion we find that a gauge-independent, process-independent and numerically st...

  17. Virasoro vacuum block at next-to-leading order in the heavy-light limit

    Energy Technology Data Exchange (ETDEWEB)

    Beccaria, Matteo; Fachechi, Alberto; Macorini, Guido [Dipartimento di Matematica e Fisica Ennio De Giorgi,Università del Salento & INFN, Via Arnesano, 73100 Lecce (Italy)

    2016-02-11

    We consider the semiclassical limit of the vacuum Virasoro block describing the diagonal 4-point correlation functions on the sphere. At large central charge c, after exponentiation, it depends on two fixed ratios h{sub H}/c and h{sub L}/c, where h{sub H,L} are the conformal dimensions of the 4-point function operators. The semiclassical block may be expanded in powers of the light ratio h{sub L}/c and the leading non-trivial (linear) order is known in closed form as a function of h{sub H}/c. Recently, this contribution has been matched against AdS{sub 3} gravity calculations where heavy operators build up a classical geometry corresponding to a BTZ black hole, while the light operators are described by a geodesic in this background. Here, we compute for the first time the next-to-leading quadratic correction O((h{sub L}/c){sup 2}), again in closed form for generic heavy operator ratio h{sub H}/c. The result is a highly non-trivial extension of the leading order and may be relevant for further refined AdS{sub 3}/CFT{sub 2} tests. Applications to the two-interval Rényi entropy are also presented.

  18. Virasoro vacuum block at next-to-leading order in the heavy-light limit

    CERN Document Server

    Beccaria, Matteo; Macorini, Guido

    2015-01-01

    We consider the semiclassical limit of the vacuum Virasoro block describing the diagonal 4-point correlation functions on the sphere. At large central charge c, after exponentiation, it depends on two fixed ratios h_H/c and h_L/c, where h_{H, L} are the conformal dimensions of the 4-point function operators. The semiclassical block may be expanded in powers of the light ratio h_L/c and the leading non-trivial (linear) order is known in closed form as a function of h_H/c. Recently, this contribution has been matched against AdS_3 gravity calculations where heavy operators build up a classical geometry corresponding to a BTZ black hole, while the light operators are described by a geodesic in this background. Here, we compute for the first time the next-to-leading quadratic correction O((h_L/c)^{2}), again in closed form for generic heavy operator ratio h_H/c. The result is a highly non-trivial extension of the leading order and may be relevant for further refined AdS_{3}/CFT_{2} tests. Applications to the two-...

  19. Lattice chiral effective field theory with three-body interactions at next-to-next-to-leading order

    CERN Document Server

    Epelbaum, Evgeny; Lee, Dean; Meißner, Ulf-G

    2009-01-01

    We consider low-energy nucleons at next-to-next-to-leading order in lattice chiral effective field theory. Three-body interactions first appear at this order, and we discuss several methods for determining three-body interaction coefficients on the lattice. We compute the energy of the triton and low-energy neutron-deuteron scattering phase shifts in the spin-doublet and spin-quartet channels using Luescher's finite volume method. In the four-nucleon system we calculate the energy of the alpha particle using auxiliary fields and projection Monte Carlo.

  20. Uncertainties in next-to-leading order plus parton shower matched simulations of inclusive jet and dijet production

    Energy Technology Data Exchange (ETDEWEB)

    Höche, Stefan; Schönherr, Marek

    2012-11-01

    We quantify uncertainties in the Monte Carlo simulation of inclusive and dijet final states, which arise from using the MC@NLO technique for matching next-to-leading order parton-level calculations and parton showers. We analyse a large variety of data from early measurements at the LHC. In regions of phase space where Sudakov logarithms dominate over high-energy effects, we observe that the main uncertainty can be ascribed to the free parameters of the parton shower. In complementary regions, the main uncertainty stems from the considerable freedom in the simulation of underlying events.

  1. NLO QCD corrections to Higgs boson production plus three jets in gluon fusion

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Deurzen, H. van; Greiner, N.; Luisoni, G.; Mirabella, E.; Peraro, T. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Mastrolia, P. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Padova Univ. (Italy). Dipt. di Fisica e Astronomia; INFN, Sezione di Padova (Italy); Ossola, G. [New York Univ., NY (United States). New York City College of Technology; New York Univ., NY (United States). The Graduate School and University Center; Tramontano, F. [Napoli Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Napoli (Italy)

    2013-07-15

    We report on the calculation of the cross section for Higgs boson production in association with three jets via gluon fusion, at next-to-leading-order (NLO) accuracy in QCD, in the infinite top-mass approximation. After including the complete NLO QCD corrections, we observe a strong reduction in the scale dependence of the result, and an increased steepness in the transverse momentum distributions of both the Higgs and the leading jets. The results are obtained with the combined use of GoSam, Sherpa, and the MadDipole/MadEvent framework.

  2. Next-to-leading-order Analysis Of The Decay B Meson Going To X Meson(short) Gamma

    CERN Document Server

    Wu, F

    2005-01-01

    In this thesis, we study the inclusive decay rate of B → Xsγ. Using the framework of the effective field theory, one can systematically analyze this process at mb scale without knowing the details of the physics happening at high energies. The heavy quark effective theory allows an expansion in powers of Λ QCD/mb. We discuss the scheme dependence in intermediate steps and the scheme independence of the Hamiltonian. We calculate the one- loop short-distance QCD corrections to the non- perturbative contributions. The result is GB →Xsg =G0 &cubl0;1+ 2asmb 3p8- 2p 23 1+l1+3l2 2m2b - 1 +asmb 3p 2p2 9- 1454 6l2m2b +Oa2s +O1m3b &cubr0;.

  3. A next-to-leading-order QCD analysis of neutrino-iron structure functions at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Seligman, W.G.

    1997-06-01

    Nucleon structure functions measured in neutrino-iron and antineutrino-iron charged-current interactions are presented. The data were taken in two high-energy high-statistics runs by the LAB-E detector at the Fermilab Tevatron. Structure functions are extracted from a sample of 950,000 neutrino and 170,000 antineutrino events with neutrino energies from 30 to 360 GeV. The structure functions F{sub 2} and xF{sub 3} are compared with the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives value of {Lambda}NLO,(4)/MS = 337 {+-} 28 (exp.) MeV, which corresponds to {alpha}{sub S}(M{sub Z}{sup 2}) = 0.119 {+-} 0.002 (exp.) {+-} 0.004 (theory), and with a gluon distribution given by xG(x,Q{sub 0}{sup 2} = 5GeV{sup 2}) = (2.22 {+-} 0.34) {times} (1 {minus} x){sup 4.65{+-}0.68}.

  4. A next-to-leading-order QCD analysis of neutrino-iron structure functions at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Seligman, William Glenn [Columbia Univ., New York, NY (United States)

    1997-01-01

    Nucleon structure functions measured in neutrino-iron and antineutrino-iron charged-current interactions are presented. The data were taken in two high-energy high-statistics runs by the LAB-E detector at the Fermilab Tevatron. Structure functions are extracted from a sample of 950,000 neutrino and 170,000 antineutrino events with neutrino energies from 30 to 360 GeV. The structure functions F2 and xF3 are compared with the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives value of ΛNLO,(4)/MS = 337 ± 28 (exp.) MeV, which corresponds to αS(MZ2) = 0.119 ± 0.002 (exp.) ± 0.004 (theory), and with a gluon distribution given by xG(x,Q02 = 5GeV2) = (2.22 ± 0.34) x (1 - x)4.65±0.68.

  5. Leading and Next-to-Leading Order Gluon Polarization in the Nucleon and Longitudinal Double Spin Asymmetries from Open Charm Muoproduction

    CERN Document Server

    Adolph, C; Alexakhin, V Yu; Alexandrov, Yu; Alexeev, G D; Amoroso, A; Antonov, A A; Austregesilo, A; Badelek, B; Balestra, F; Barth, J; Baum, G; Bedfer, Y; Berlin, A; Bernhard, J; Bertini, R; Bettinelli, M; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Braun, C; Bravar, A; Bressan, A; Buchele, M; Burtin, E; Capozza, L; Chiosso, M; Chung, S U; Cicuttin, A; Crespo, M L; Dalla Torre, S; Das, S; Dasgupta, S S; Dasgupta, S; Denisov, O Yu; Dhara, L; Donskov, S V; Doshita, N; Duic, V; Dunnweber, W; Dziewiecki, M; Efremov, A; Elia, C; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; Finger, M Jr; Fischer, H; Franco, C; du Fresne von Hohenesche, N; Friedrich, J M; Frolov, V; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S; Geyer, R; Giorgi, M; Gnesi, I; Gobbo, B; Goertz, S; Grabmuller, S; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Guthorl, T; Haas, F; von Harrach, D; Heinsius, F H; Herrmann, F; Hess, C; Hinterberger, F; Horikawa, N; Hoppner, Ch; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, O; Ivanshin, Yu; Iwata, T; Jahn, R; Jary, V; Jasinski, P; Joosten, R; Kabuss, E; Kang, D; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Kondo, K; Konigsmann, K; Konorov, I; Konstantinov, V F; Korzenev, A; Kotzinian, A M; Kouznetsov, O; Kramer, M; Kroumchtein, Z V; Kunne, F; Kurek, K; Lauser, L; Lednev, A A; Lehmann, A; Levorato, S; Lichtenstadt, J; Liska, T; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Mann, A; Marchand, C; Martin, A; Marzec, J; Matsuda, T; Meshcheryakov, G; Meyer, W; Michigami, T; Mikhailov, Yu V; Morreale, A; Mutter, A; Nagaytsev, A; Nagel, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Nowak, W D; Nunes, A S; Olshevsky, A G; Ostrick, M; Padee, A; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Perevalova, E; Pesaro, G; Peshekhonov, D V; Piragino, G; Platchkov, S; Pochodzalla, J; Polak, J; Polyakov, V A; Pretz, J; Quaresma, M; Quintans, C; Rajotte, J F; Ramos, S; Rapatsky, V; Reicherz, G; Rocco, E; Rondio, E; Rossiyskaya, N S; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Sapozhnikov, M G; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schluter, T; Schmidt, A; Schmidt, K; Schmitt, L; Schmiden, H; Schonning, K; Schopferer, S; Schott, M; Shevchenko, O Yu; Silva, L; Sinha, L; Sissakian, A N; Slunecka, M; Smirnov, G I; Sosio, S; Sozzi, F; Srnka, A; Steiger, L; Stolarski, M; Sulc, M; Sulej, R; Suzuki, H; Sznajder, P; Takekawa, S; Ter Wolbeek, J; Tessaro, S; Tessarotto, F; Tkatchev, L G; Uhl, S; Uman, I; Vandenbroucke, M; Virius, M; Vlassov, N V; Wang, L; Weisrock, T; Wilfert, M; Windmolders, R; Wislicki, W; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zhuravlev, N; Zvyagin, A

    2013-01-01

    The gluon polarisation in the nucleon was measured using open charm production by scattering 160 GeV/c polarised muons off longitudinally polarised protons or deuterons. The data were taken by the COMPASS collaboration between 2002 and 2007. A detailed account is given of the analysis method that includes the application of neural networks. Several decay channels of $D^0$ mesons are investigated. Longitudinal spin asymmetries of the D meson production cross-sections are extracted in bins of $D^0$ transverse momentum and energy. At leading order QCD accuracy the average gluon polarisation is determined as $(\\Delta g/g)^{LO}=-0.06 \\pm 0.21 (stat.) \\pm 0.08 (syst.)$ at the scale $ \\approx 13$ (GeV/c)$^2$ and an average gluon momentum fraction $\\approx$ 0.11. The average gluon polarisation is also obtained at next-to-leading order QCD accuracy as $(\\Delta g/g) NLO = -0.13 \\pm 0.15 (stat.) \\pm 0.15 (syst.)$ at the scale $ \\approx $ 13 (GeV/c)$^2$ and $ \\approx $ 0.20.

  6. Scalar field correlator in de Sitter space at next-to-leading order in a 1/N-expansion

    CERN Document Server

    Gautier, Florian

    2015-01-01

    We study the dynamics of light quantum scalar fields in de Sitter space on superhorizon scales. We compute the self-energy of an O(N) symmetric theory at next-to-leading order in a 1/N-expansion in the regime of superhorizon momenta and we obtain an exact analytical solution of the corresponding Dyson-Schwinger equations for the two-point correlator. This amounts to resumming the infinite series of nonlocal self-energy insertions, which typically generate spurious infrared and/or secular divergences. The potentially large de Sitter logarithms resum into well-behaved power laws from which we extract the field strength and mass renormalization. The nonperturbative 1/N-expansion allows us to discuss the case of vanishing and negative tree-level square mass, which both correspond to strongly coupled effective theories in the infrared.

  7. Next-to-leading order predictions for Z gamma+jet and Z gamma gamma final states at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, John M.; Hartanto, Heribertus B.; Williams, Ciaran

    2012-11-01

    We present next-to-leading order predictions for final states containing leptons produced through the decay of a Z boson in association with either a photon and a jet, or a pair of photons. The effect of photon radiation from the final state leptons is included and we also allow for contributions arising from fragmentation processes. Phenomenological studies are presented for the LHC in the case of final states containing charged leptons and in the case of neutrinos. We also use the procedure introduced by Stewart and Tackmann to provide a reliable estimate of the scale uncertainty inherent in our theoretical calculations of jet-binned Z gamma cross sections. These computations have been implemented in the public code MCFM.

  8. Chiral effective field theory description of the hyperon-nucleon interaction at next-to-leading order

    Directory of Open Access Journals (Sweden)

    Petschauer S.

    2014-06-01

    Full Text Available In this proceeding results for hyperon-nucleon interactions calculated at next-to-leading order (i.e. one-loop order in SU(3 chiral effective field theory are presented. The potentials include contributions from one- and two-meson exchange, and four-baryon contact terms provided by the SU(3 chiral Lagrangian. SU(3 flavor symmetry is imposed for the low-energy constants, while explicit SU(3 symmetry breaking is included only through the physical pseudoscalar-meson and baryon masses. Calculations have been performed for hyperon-nucleon scattering cross sections using a regularized Lippmann-Schwinger equation. A good description of the available data is achieved, comparable to modern phenomenological hyperon-nucleon interaction models. These results provide a new basis for studies of hypernuclei or hyperons in nuclear matter.

  9. J/{psi} plus prompt-photon associated production in two-photon collisions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[Grenoble Univ., 38 (France). Lab. de Physique Subatomique et de Cosmologie; Kniehl, B.A.; Mihaila, L.N.; Steinhauser, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2004-08-01

    We calculate the cross section of J/{psi} plus prompt-photon inclusive production in {gamma}{gamma} collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/{psi} production, we also include the feed-down from directly-produced {chi}{sub cJ} and {psi}' mesons. We discuss the analytical calculation, in particular the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future e{sup +}e{sup -} linear collider TESLA, taking into account both Brems- and beamstrahlung. (orig.)

  10. J/{psi} plus jet associated production in two-photon collisions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M. [Universite Grenoble I, Laboratoire de Physique Subatomique et de Cosmologie, 53 Avenue des Martyrs, 38026 Grenoble (France); Kniehl, B.A. [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)]. E-mail: bernd.kniehl@desy.de; Mihaila, L.N. [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Steinhauser, M. [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2005-05-02

    We calculate the cross section of J/{psi} plus jet inclusive production in {gamma}{gamma} collisions at next-to-leading order within the factorization formalism of non-relativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/{psi} production, we also include the feed-down from directly-produced {chi}{sub cJ} and {psi}{sup '} mesons. We discuss the analytical calculation, in particular, the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future e{sup +}e{sup -} linear collider TESLA, taking into account both brems- and beamstrahlung.

  11. J/{psi} plus jet associated production in two-photon collisions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M. [Grenoble 1 Univ. (France). Lab. de Physique Subatomique et de Cosmologie; Kniehl, B.A.; Mihaila, L.N.; Steinhauser, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2004-06-01

    We calculate the cross section of J/{psi} plus jet inclusive production in {gamma}{gamma} collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/{psi} production, we also include the feed-down from directly-produced X{sub cJ} and {psi}{sup '} mesons. We discuss the analytical calculation, in particular the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future e{sup +}e{sup -} linear collider TESLA, taking into account both brems- and beamstrahlung. (orig.)

  12. Unpolarized Transverse Momentum Dependent Parton Distribution and Fragmentation Functions at next-to-next-to-leading order

    CERN Document Server

    Echevarria, Miguel G; Vladimirov, Alexey

    2016-01-01

    The transverse momentum dependent parton distribution/fragmentation functions (TMDs) are essential in the factorization of a number of processes like Drell-Yan scattering, vector boson production, semi-inclusive deep inelastic scattering, etc. We provide a comprehensive study of unpolarized TMDs at next-to-next-to-leading order, which includes an explicit calculation of these TMDs and an extraction of their matching coefficients onto their integrated analogues, for all flavor combinations. The obtained matching coefficients are important for any kind of phenomenology involving TMDs. In the present study each individual TMD is calculated without any reference to a specific process. We recover the known results for parton distribution functions and provide new results for the fragmentation functions. The results for the gluon transverse momentum dependent fragmentation functions are presented for the first time at one and two loops. We also discuss the structure of singularities of TMD operators and TMD matrix ...

  13. Next-to-leading order predictions for Z gamma+jet and Z gamma gamma final states at the LHC

    CERN Document Server

    Campbell, John M; Williams, Ciaran

    2012-01-01

    We present next-to-leading order predictions for final states containing leptons produced through the decay of a Z boson in association with either a photon and a jet, or a pair of photons. The effect of photon radiation from the final state leptons is included and we also allow for contributions arising from fragmentation processes. Phenomenological studies are presented for the LHC in the case of final states containing charged leptons and in the case of neutrinos. We also use the procedure introduced by Stewart and Tackmann to provide a reliable estimate of the scale uncertainty inherent in our theoretical calculations of jet-binned Z gamma cross sections. These computations have been implemented in the public code MCFM.

  14. Next-to-next-to-leading-order charm-quark contribution to the CP violation parameter ϵ(K) and ΔM(K).

    Science.gov (United States)

    Brod, Joachim; Gorbahn, Martin

    2012-03-23

    The observables ϵ(K) and ΔM(K) play a prominent role in particle physics due to their sensitivity to new physics at short distances. To take advantage of this potential, a firm theoretical prediction of the standard-model background is essential. The charm-quark contribution is a major source of theoretical uncertainty. We address this issue by performing a next-to-next-to-leading-order QCD analysis of the charm-quark contribution η(cc) to the effective |ΔS|=2 Hamiltonian in the standard model. We find a large positive shift of 36%, leading to η(cc)=1.87(76). This result might cast doubt on the validity of the perturbative expansion; we discuss possible solutions. Finally, we give an updated value of the standard-model prediction for |ϵ(K)|=1.81(28)×10(-3) and ΔM(K)(SD)=3.1(1.2)×10(-15)  GeV.

  15. Strangeness S = -2 baryon-baryon interaction at next-to-leading order in chiral effective field theory

    Science.gov (United States)

    Haidenbauer, J.; Meißner, Ulf-G.; Petschauer, S.

    2016-10-01

    The strangeness S = - 2 baryon-baryon interaction is studied in chiral effective field theory up to next-to-leading order. The potential at this order consists of contributions from one- and two-pseudoscalar-meson exchange diagrams and from four-baryon contact terms without and with two derivatives. SU(3) flavor symmetry is imposed for constructing the interaction in the S = - 2 sector. Specifically, the couplings of the pseudoscalar mesons to the baryons are fixed by SU(3) symmetry and, in general, also the contact terms are related via SU(3) symmetry to those determined in a previous study of the S = - 1 hyperon-nucleon interaction. The explicit SU(3) symmetry breaking due to the physical masses of the pseudoscalar mesons (π, K, η) is taken into account. It is argued that the ΞN interaction has to be relatively weak to be in accordance with available experimental constraints. In particular, the published values and upper bounds for the Ξ- p elastic and inelastic cross sections apparently rule out a somewhat stronger attractive ΞN force and, specifically, disfavor any near-threshold deuteron-like bound states in that system.

  16. Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Epelbaum, E.; Krebs, H. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Meissner, U.G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institut fuer Kernphysik, Institute for Advanced Simulation, and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)

    2015-05-15

    We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of previous works (Nucl. Phys. A 747, 362 (2005) and Phys. Rev. C 68, 041001 (2003)) is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in (Nucl. Phys. A 747, 362 (2005)) to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c{sub i} and d{sub i} determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also employ a simple approach for estimating the theoretical uncertainty in few-nucleon calculations from the truncation of the chiral expansion that replaces previous reliance on cutoff variation. (orig.)

  17. Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order

    CERN Document Server

    Epelbaum, E; Meißner, U -G

    2014-01-01

    We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail t...

  18. Antinucleon-nucleon interaction at next-to-next-to-next-to-leading order in chiral effective field theory

    Science.gov (United States)

    Dai, Ling-Yun; Haidenbauer, Johann; Meißner, Ulf-G.

    2017-07-01

    Results for the antinucleon-nucleon (\\overline{N}N) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used for the pion-exchange contributions that has been recently suggested and applied in a pertinent study of the N N force within chiral EFT. Furthermore, an alternative strategy for estimating the uncertainty is utilized that no longer depends on a variation of the cutoffs. The low-energy constants associated with the arising contact terms are fixed by a fit to the phase shifts and inelasticities provided by a phase-shift analysis of \\overline{p}p scattering data. An excellent description of the \\overline{N}N amplitudes is achieved at the highest order considered. Moreover, because of the quantitative reproduction of partial waves up to J = 3, there is also a nice agreement on the level of \\overline{p}p observables. Specifically, total and integrated elastic and charge-exchange cross sections agree well with the results from the partial-wave analysis up to laboratory energies of 300 MeV, while differential cross sections and analyzing powers are described quantitatively up to 200-250 MeV. The low-energy structure of the \\overline{N}N amplitudes is also considered and compared to data from antiprotonic hydrogen.

  19. Next-to-next-to-leading order spin-orbit effects in the equations of motion of compact binary systems

    CERN Document Server

    Marsat, Sylvain; Faye, Guillaume; Blanchet, Luc

    2012-01-01

    We compute next-to-next-to-leading order spin contributions to the post-Newtonian equations of motion for binaries of compact objects, such as black holes or neutron stars. For maximally spinning black holes, those contributions are of third-and-a-half post-Newtonian (3.5PN) order, improving our knowledge of the equations of motion, already known for non-spinning objects up to this order. Building on previous work, we represent the rotation of the two bodies using a pole-dipole matter stress-energy tensor, and iterate Einstein's field equations for a set of potentials parametrizing the metric in harmonic coordinates. Checks of the result include the existence of a conserved energy, the approximate global Lorentz invariance of the equations of motion in harmonic coordinates, and the recovery of the motion of a spinning object on a Kerr background in the test-mass limit. We verified the existence of a contact transformation, together with a redefinition of the spin variables that makes our result equivalent to ...

  20. A new effective-one-body Hamiltonian with next-to-leading order spin-spin coupling

    CERN Document Server

    Balmelli, Simone

    2015-01-01

    We present a new effective-one-body (EOB) Hamiltonian with next-to-leading order (NLO) spin-spin coupling for black hole binaries endowed with arbitrarily oriented spins. The Hamiltonian is based on the model for parallel spins and equatorial orbits developed in [Physical Review D 90, 044018 (2014)], but differs from it in several ways. In particular, the NLO spin-spin coupling is not incorporated by a redefinition of the centrifugal radius $r_c$, but by separately modifying certain sectors of the Hamiltonian, which are identified according to their dependence on the momentum vector. The gauge-fixing procedure we follow allows us to reduce the 25 different terms of the NLO spin-spin Hamiltonian in Arnowitt-Deser-Misner coordinates to only 9 EOB terms. This is an improvement with respect to the EOB model recently proposed in [Physical Review D 91, 064011 (2015)], where 12 EOB terms were involved. Another important advantage is the remarkably simple momentum structure of the spin-spin terms in the effective Ham...

  1. Global analysis of nuclear parton distribution functions and their uncertainties at next-to-next-to-leading order

    CERN Document Server

    Khanpour, Hamzeh

    2016-01-01

    We perform a next-to-next-to-leading order (NNLO) analysis of nuclear parton distribution functions (nPDFs) using neutral current charged-lepton ($\\ell ^\\pm$ + nucleus) deeply inelastic scattering (DIS) data and Drell-Yan (DY) cross-section ratios $\\sigma_{DY}^{A}/\\sigma_{DY}^{A^\\prime}$ for several nuclear targets. We study in details the parameterizations and the atomic mass (A) dependence of the nuclear PDFs at this order. The present nuclear PDFs global analysis provides us a complete set of nuclear PDFs, $f_i^{(A,Z)}(x,Q^2)$, with a full functional dependence on $x$, A, Q$^2$. The uncertainties of the obtained nuclear modification factors for each parton flavour are estimated using the well-known Hessian method. The nuclear charm quark distributions are also added into the analysis. We compare the parametrization results with the available data and the results of other nuclear PDFs groups. We found our nuclear PDFs to be in reasonably good agreement with them. The estimates of errors provided by our glob...

  2. Next-to-leading order γγ+2-jet production at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Z.; Dixon, L. J.; Febres Cordero, F.; Höche, S.; Ita, H.; Kosower, D. A.; Lo Presti, N. A.; Maître, D.

    2014-09-01

    We present next-to-leading-order QCD predictions for cross sections and for a comprehensive set of distributions in γγ+2-jet production at the Large Hadron Collider. We consider the contributions from loop amplitudes for two photons and four gluons, but we neglect top quarks. We use BlackHat together with SHERPA to carry out the computation. We use a Frixione cone isolation for the photons. We study standard sets of cuts on the jets and the photons and also sets of cuts appropriate for studying backgrounds to Higgs-boson production via vector-boson fusion.

  3. Next-to-next-to-leading order Skyrme interaction in nuclear matter: Nuclear bulk quantities at second order in perturbation theory

    CERN Document Server

    Moghrabi, Kassem

    2016-01-01

    We present the explicit form of the next-to-next-to-leading order (N$^2$LO) Skyrme interaction in momentum space by including the fourth-order gradient potentials to the standard Skyrme interaction. With the N$^2$LO Skyrme interaction, we evaluate the second-order corrections to the nuclear bulk quantities of nuclear matter: equation of state (EoS) of isospin symmetric and pure neutron matter, density-dependent in-medium effective nucleon mass, isospin-asymmetry energy, pressure and incompressibility. These second-order contributions are ultraviolet (UV) divergent due to the zero range character of the interaction and renormalized using the techniques of dimensional regularization (DR) with the minimal subtraction scheme (MS). We adjust the 18 parameters of the interaction by performing a global fit to the nuclear bulk quantities. Besides the too strong dependence $k_F^{12}$ of several second-order corrections, a very good reproduction of a realistic nuclear matter saturation curve with all the nuclear bulk q...

  4. Bottom-flavored hadrons from top-quark decay at next-to-leading order in the general-mass variable-flavor-number scheme

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, Bernd A.; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Moosavi Nejad, Seyed M. [Yazd Univ. (Iran, Islamic Republic of). Faculty of Physics; Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of). School of Particles

    2012-03-15

    We study the scaled-energy (x{sub B}) distribution of bottom-flavored hadrons (B) inclusively produced in top-quark decays at next-to-leading order (NLO) in the general-mass variable-flavor-number scheme endowed with realistic, nonperturbative fragmentation functions that are obtained through a global fit to e{sup +}e{sup -} data from CERN LEP1 and SLAC SLC exploiting their universality and scaling violations. Specifically, we study the effects of gluon fragmentation and finite bottom-quark and B-hadron masses. We find the NLO corrections to be significant. Gluon fragmentation leads to an appreciable reduction in the partial decay width at low values of x{sub B}. Hadron masses are responsible for the low-x{sub B} threshold, while the bottom-quark mass is of minor importance. Neglecting the latter, we also study the doubly differential distribution d{sup 2}{gamma}/(dx{sub B}d cos {theta}) of the partial width of the decay t{yields} bW{sup +} {yields} Bl{sup +}{nu}{sub l}+X, where {theta} is the decay angle of the charged lepton in the W-boson rest frame.

  5. Neutral MSSM Higgs-boson production with heavy quarks: NLO supersymmetric QCD corrections

    CERN Document Server

    Dittmaier, Stefan; Krämer, Michael; Spira, Michael; Walser, Manuel

    2014-01-01

    Within the minimal supersymmetric extension of the Standard Model (MSSM) the associated production of neutral Higgs bosons with top and bottom quarks belongs to the most important Higgs-boson production processes at the LHC. At large values of tan(beta), in particular, bottom--Higgs associated production constitutes the dominant production channel within the MSSM. We have calculated the next-to-leading-order supersymmetric QCD corrections to neutral Higgs production through the parton processes q qbar, gg -> t tbar / b bbar + h/H/A and present results for the total cross sections. The genuine SUSY-QCD corrections are of moderate size for small tan(beta), but can be sizable for large tan(beta). In the latter case the bulk of these corrections can be absorbed into effective bottom Yukawa couplings.

  6. Effects of the next-to-leading order terms in the chiral SU(3) Lagrangian on the strangeness -1 s-wave meson-baryon interactions

    CERN Document Server

    Magas, V K; Ramos, A

    2013-01-01

    The meson-baryon interactions in s-wave in the strangeness S=-1 sector are studied using a chiral unitarity approach based on the next-to-leading order chiral SU(3) Lagrangian. The model is fitted to the large set of experimental data in different two-body channels. Particular attention is paid to the $\\Xi$ hyperon production reaction, $\\bar{K} N \\rightarrow K \\Xi$, where the effect of the next-to-leading order terms in the Lagrangian play a crucial role, since the cross section of this reaction at tree level is zero.

  7. Regge-like initial input and evolution of non-singlet structure functions from DGLAP equation up to next-next-to-leading order at low and low 2

    Indian Academy of Sciences (India)

    Nayan Mani Nath; Mrinal Kumar Das; Jayanta Kumar Sarma

    2015-10-01

    This is an attempt to study how the features of Regge theory, along with QCD predictions, lead towards the understanding of unpolarized non-singlet structure functions $F_{2}^{\\text{NS}}$ (, 2) and 3 (, 2) at low and low 2 . Combining the features of perturbative quantum chromodynamics (pQCD) and Regge theory, an ansatz for $F_{2}^{\\text{NS}}$ (, 2) and 3 (, 2) structure functions at small was obtained, which when used as the initial input to Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) equation, gives the 2 evolution of the non-singlet structure functions. The non-singlet structure functions, evolved in accordance with DGLAP evolution equations up to next-next-to-leading order are studied phenomenologically in comparison with the available experimental and parametrization results taken from NMC, CCFR, NuTeV, CORUS, CDHSW, NNPDF and MSTW Collaborations and a very good agreement is observed in this regard.

  8. Automated next-to-leading order predictions for new physics at the LHC: the case of colored scalar pair production

    CERN Document Server

    Degrande, Céline; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng

    2015-01-01

    We present for the first time the full automation of collider predictions matched with parton showers at the next-to-leading accuracy in QCD within non-trivial extensions of the Standard Model. The sole inputs required from the user are the model Lagrangian and the process of interest. As an application of the above, we explore scenarios beyond the Standard Model where new colored scalar particles can be pair produced in hadron collisions. Using simplified models to describe the new field interactions with the Standard Model, we present precision predictions for the LHC within the MadGraph5 aMC@NLO framework.

  9. Mixed electroweak-QCD corrections to $e^+e^-\\to HZ$ at Higgs factories

    CERN Document Server

    Sun, Qing-Feng; Jia, Yu; Sang, Wen-Long

    2016-01-01

    The prospective $e^+e^-$ Higgs factories, exemplified by ILC, FCC-ee, CEPC, plan to conduct the precision Higgs measurements at center-of-mass energy around 250 GeV. The cross sections for the dominant Higgs production channel, the Higgsstrahlung process, can be measured to a sub-percent accuracy. Apart from the well-known next-to-leading order electroweak correction, this unprecedented precision also necessitates our knowledge about the mixed electroweak-QCD corrections. In this work, we calculate the ${\\mathcal O}(\\alpha\\alpha_s)$ correction to $e^+e^-\\to HZ$ for both unpolarized and polarized $Z$ boson. The corrections turn out to reach one percent level of the leading order cross section, thereby must be incorporated in the future confrontation with the data.

  10. NLO QCD and electroweak corrections to W+\\gamma\\ production with leptonic W-boson decays

    CERN Document Server

    Denner, Ansgar; Hecht, Markus; Pasold, Christian

    2014-01-01

    We present a calculation of the next-to-leading-order electroweak corrections to W+\\gamma\\ production, including the leptonic decay of the W boson and taking into account all off-shell effects of the W boson, where the finite width of the W boson is implemented using the complex-mass scheme. Corrections induced by incoming photons are fully included and find particular emphasis in the discussion of phenomenological predictions for the LHC. The corresponding next-to-leading-order QCD corrections are reproduced as well. In order to separate hard photons from jets, a quark-to-photon fragmentation function a la Glover and Morgan is employed. Our results are implemented into Monte Carlo programs allowing for the evaluation of arbitrary differential cross sections. We present integrated cross sections for the LHC at 7TeV, 8TeV, and 14TeV as well as differential distributions at 14TeV for bare muons and dressed leptons. Finally, we discuss the impact of anomalous WW\\gamma\\ couplings.

  11. NLO QCD and electroweak corrections to Z + γ production with leptonic Z-boson decays

    Science.gov (United States)

    Denner, Ansgar; Dittmaier, Stefan; Hecht, Markus; Pasold, Christian

    2016-02-01

    The next-to-leading-order electroweak corrections to ppto {l}+{l}-/overline{ν}ν +\\upgamma +X production, including all off-shell effects of intermediate Z bosons in the complex-mass scheme, are calculated for LHC energies, revealing the typically expected large corrections of tens of percent in the TeV range. Contributions from quark-photon and photon-photon initial states are taken into account as well, but their impact is found to be moderate or small. Moreover, the known next-to-leading-order QCD corrections are reproduced. In order to separate hard photons from jets, both a quark-to-photon fragmentation function á la Glover/Morgan and Frixione's cone isolation are employed. The calculation is available in the form of Monte Carlo programs allowing for the evaluation of arbitrary differential cross sections. Predictions for integrated cross sections are presented for the LHC at 7 TeV, 8 TeV, and 14 TeV, and differential distributions are discussed at 14 TeV for bare muons and dressed leptons. Finally, we consider the impact of anomalous ZZγ and Zγγ couplings.

  12. NLO QCD corrections to Single Top and W associated production at the LHC with forward detector acceptances

    CERN Document Server

    Sun, Hao; Hou, Hong-Sheng

    2014-01-01

    In this paper we study the Single Top and W boson associated photoproduction via the main reaction $\\rm pp\\rightarrow p\\gamma p\\rightarrow pW^{\\pm}t+Y$ at the 14 TeV Large Hadron Collider (LHC) up to next-to-leading order (NLO) QCD level assuming a typical LHC multipurpose forward detector. We use the Five-Flavor-Number Schemes (5FNS) with massless bottom quark assumption in the whole calculation. Our results show that the QCD NLO corrections can reduce the scale uncertainty. The typical K-factors are in the range of 1.15 to 1.2 which lead to the QCD NLO corrections of 15$\\%$ to 20$\\%$ correspond to the leading-order (LO) predictions with our chosen parameters.

  13. Regge behaviour of distribution functions and evolution of gluon distribution function in next-to-leading order at low-x

    Indian Academy of Sciences (India)

    U Jamil; J K Sarma

    2008-09-01

    Evolution of gluon distribution function from Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at low- is presented assuming the Regge behaviour of quark and gluon at this limit. We compare our results of gluon distribution function with MRST2004, GRV98LO and GRV98NLO parametrizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics (PQCD) at low-.

  14. NNLO QCD Corrections to the Drell-Yan Cross Section in Models of TeV-Scale Gravity

    CERN Document Server

    Ahmed, Taushif; Dhani, Prasanna K; Kumar, M C; Mathews, Prakash; Rana, Narayan; Ravindran, V

    2016-01-01

    The first results on the complete next-to-next-to-leading order (NNLO) Quantum Chromodynamic (QCD) corrections to the production of di-leptons at hadron colliders in large extra dimension models with spin-2 particles are reported in this article. In particular, we have computed these corrections to the invariant mass distribution of the di-leptons taking into account all the partonic subprocesses that contribute at NNLO. In these models, spin-2 particles couple through the energy-momentum tensor of the Standard Model (SM) with the universal coupling strength. The tensorial nature of the interaction and the presence of both quark annihilation and gluon fusion channels at the Born level make it challenging computationally and interesting phenomenologically. We have demonstrated numerically the importance of our results at the Large Hadron Collider (LHC) energies. The two loop corrections contribute an additional 10\\% to the total cross section. We find that the QCD corrections are not only large but also import...

  15. QCD radiative corrections for $h\\to b\\bar b$ in the Standard Model Dimension-6 EFT

    CERN Document Server

    Gauld, Rhorry; Scott, Darren J

    2016-01-01

    We calculate the $\\mathcal{O}(\\alpha_s)$ QCD corrections to the inclusive $h\\to b\\bar b$ decay rate in the dimension-6 Standard Model Effective Field Theory (SMEFT). The QCD corrections multiplying the dimension-6 Wilson coefficients which alter the $hb\\bar b$-vertex at tree-level are proportional to the Standard Model (SM) ones, so next-to-leading order results can be obtained through a simple rescaling of the tree-level decay rate. On the other hand, contributions from the operators $Q_{bG}$ and $Q_{HG}$, which alter the $gb\\bar b$-vertex and introduce a $hgg$-vertex respectively, enter at $\\mathcal{O}(\\alpha_s)$ and induce sizeable corrections which are unrelated to the SM ones and cannot be anticipated through a renormalisation-group analysis. We present compact analytic results for these contributions, which we recommend to be included in future phenomenological studies.

  16. The next-to-leading order (NLO) gluon distribution from DGLAP equation and the logarithmic derivatives of the proton structure function 2 (, 2) at low

    Indian Academy of Sciences (India)

    D K Choudhury; P K Sahariah

    2005-08-01

    At low , an analytic solution of the DGLAP equation for gluon in the next-to-leading order (NLO) is obtained by applying the method of characteristics. Its compatibility with double leading logarithmic approximation (DLLA) asymptotics is discussed and comparison with the exact ones like GRV98NLO is made. The solution is then utilized to calculate the derivatives $\\dfrac{ 2 (x, 2)}{ {\\text{ln}} 2}$ and $\\dfrac{ {\\text{ln}} 2 (x, 2)}{ {\\text{ln}} (1/x)}$ and compared with the recent HERA data. Our solution is found to reproduce most of the essential features of the data on the derivatives.

  17. The $\\bar{K} N \\rightarrow K \\Xi$ reaction in coupled channel chiral models up to next-to-leading order

    CERN Document Server

    Feijoo, A; Ramos, A

    2015-01-01

    The meson-baryon interaction in s-wave in the strangeness S=-1 sector has been studied, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the Lagrangian have been fitted to a large set of experimental data in different two-body channels, paying special attention to the $\\bar{K} N \\rightarrow K \\Xi$ reaction, which is particularly sensitive to the NLO terms. With the aim of improving the model in the $K\\Xi$ production channels, effects of the high spin hyperon resonances $\\Sigma(2030)$ and $\\Sigma(2250)$ have been taken into account phenomenologically.

  18. Next-to-next-to-leading order contributions to inclusive jet production in deep-inelastic scattering and determination of α{sub s}

    Energy Technology Data Exchange (ETDEWEB)

    Biekoetter, Thomas; Klasen, Michael [Muenster Univ. (Germany). Institut fuer Theoretische Physik; Kramer, Gustav [Hamburg Univ. (Germany). 2. Institut fuer Theoretische Physik

    2015-09-15

    We present the first calculation of inclusive jet production in deep-inelastic scattering with approximate next-to-next-to-leading order (aNNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients are computed analytically. We show that the aNNLO contributions reduce the theoretical prediction for jet production in deep-inelastic scattering, improve the description of the final HERA data in particular at high photon virtuality Q{sup 2} and increase the central fit value of the strong coupling constant.

  19. Next-to-next-to-leading order contributions to inclusive jet production in deep-inelastic scattering and determination of αs

    Science.gov (United States)

    Biekötter, Thomas; Klasen, Michael; Kramer, Gustav

    2015-10-01

    We present the first calculation of inclusive jet production in deep-inelastic scattering with approximate next-to-next-to-leading order (aNNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients are computed analytically. We show that the aNNLO contributions reduce the theoretical prediction for jet production in deep-inelastic scattering, improve the description of the final HERA data in particular at high photon virtuality Q2 and increase the central fit value of the strong coupling constant.

  20. The impact of quark masses on pQCD thermodynamics

    CERN Document Server

    Graf, Thorben; Fraga, Eduardo S

    2015-01-01

    We present results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including non-vanishing quark masses. These results are compared to lattice data and to higher-order optimized perturbative calculations to investigate the trend brought about by mass corrections.

  1. Electroweak Higgs plus three jet production at NLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Campanario, Francisco [Valencia-CSIC Univ. (Spain). IFIC; Figy, Terrance M. [Manchester Univ. (United Kingdom). School of Physics and Astronomy; Plaetzer, Simon [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Sjoedahl, Malin [Lund Univ. (Sweden). Dept. of Astronomy and Theoretical Physics

    2013-11-15

    We calculate next-to-leading order (NLO) QCD corrections to electroweak Higgs plus three jet production. Both vector boson fusion (VBF) and Higgs-strahlung type contributions are included along with all interferences. The calculation is implemented within the Matchbox NLO framework of the Herwig++ event generator.

  2. The impact of quark masses on pQCD thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Thorben; Schaffner-Bielich, Juergen [Goethe University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Fraga, Eduardo S. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro (Brazil)

    2016-07-15

    We present results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including non-vanishing quark masses. These results are compared to lattice data and to higher-order optimized perturbative calculations to investigate the trend brought about by mass corrections. (orig.)

  3. QCD threshold corrections for gluino pair production at hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Langenfeld, Ulrich [Wuerzburg Univ. (Germany); Moch, Sven-Olaf; Pfoh, Torsten [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2012-11-15

    We present the complete threshold enhanced predictions in QCD for the total cross section of gluino pair production at hadron colliders at next-to-next-to-leading order. Thanks to the computation of the required one-loop hard matching coefficients our results are accurate to the next-to-next-to-leading logarithm. In a brief phenomenological study we provide predictions for the total hadronic cross sections at the LHC and we discuss the uncertainties arising from scale variations and the parton distribution functions.

  4. Two-loop corrections to the triple Higgs boson production cross section

    CERN Document Server

    de Florian, Daniel

    2016-01-01

    In this paper we compute the QCD corrections for the triple Higgs boson production cross section via gluon fusion, within the heavy-top approximation. We present, for the first time, analytical results for the next-to-leading order corrections, and also compute the soft and virtual contributions of the next-to-next-to-leading order cross section. We provide predictions for the total cross section and the triple Higgs invariant mass distribution. We find that the QCD corrections are large at both perturbative orders, and that the scale uncertainty is substantially reduced when the second order perturbative corrections are included.

  5. QCD factorization for hadronic B decays: Proofs and higher-order corrections

    Science.gov (United States)

    Pecjak, Benjamin Dale

    Several issues related to the QCD factorization approach to exclusive hadronic B decays are discussed. This includes a proof of factorization in B → K*gamma using the soft-collinear effective theory, and an examination of higher-order corrections to QCD factorization for two-body decays into heavy-light states, such as B → Dpi, and light-light final states, such as B → Kpi,pipi. The proof of factorization in B → K*gamma is arguably the most complicated QCD factorization formula proven so far. It is shown that reparameterization invariance in the intermediate effective theory restricts the appearance of transverse momentum components and 3-particle Fock states to operators that can be absorbed into the QCD from factor. This proof also includes an extension of SCET to deal with two collinear directions. The examination of higher-order corrections to QCD factorization has implications for using this technique to extract CP violating weal; phases from data taken at the B factories. The renormalon calculus is used to calculate the b0a2s contributions to the hard scattering kernels, and also to analyze the strength of power corrections due to soft gluon exchange. It is shown that while power corrections are generally small, the higher-order perturbative contributions to the hard scattering kernels have much larger imaginary parts than those at next-to-leading order (NLO). This significantly enhances some CP asymmetries compared to the NLO results, which is an effect that would survive a two-loop calculation unless there were large multi-loop corrections not related to the b0a2s terms of the perturbative expansion.

  6. Impact of SUSY-QCD corrections on neutralino-stop co-annihilation and the neutralino relic density

    CERN Document Server

    Harz, J; Klasen, M; Kovarik, K; Boulc'h, Q Le

    2013-01-01

    We have calculated the full O(alpha_s) supersymmetric QCD corrections to neutralino-stop co-annihilation into electroweak vector and Higgs bosons within the Minimal Supersymmetric Standard Model (MSSM). We performed a parameter study within the phenomenological MSSM and demonstrated that the studied co-annihilation processes are phenomenologically relevant, especially in the context of a 126 GeV Higgs-like particle. By means of an example scenario we discuss the effect of the full next-to-leading order corrections on the co-annihilation cross section and show their impact on the predicted neutralino relic density. We demonstrate that the impact of these corrections on the cosmologically preferred region of parameter space is larger than the current experimental uncertainty of WMAP data.

  7. Impact of SUSY-QCD corrections on neutralino-stop co-annihilation and the neutralino relic density

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Herrmann, Bjoern [Savoie Univ./CNRS, Annecy-le-Vieux (France). LAPTh; Klasen, Michael [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Kovarik, Karol [Karlsruher Institut fuer Technologie, Karlsruhe (Germany). Inst. fuer Theoretische Physik; Le Boulc' h, Quentin [Grenoble Univ./CNRS-IN2P3/INPG, Grenoble (France). Lab. de Physique Subatomique et de Cosmologie

    2013-02-15

    We have calculated the full O({alpha}{sub s}) supersymmetric QCD corrections to neutralino-stop coannihilation into electroweak vector and Higgs bosons within the Minimal Supersymmetric Standard Model (MSSM).We performed a parameter study within the phenomenological MSSM and demonstrated that the studied co-annihilation processes are phenomenologically relevant, especially in the context of a 126 GeV Higgs-like particle. By means of an example scenario we discuss the effect of the full next-to-leading order corrections on the co-annihilation cross section and show their impact on the predicted neutralino relic density. We demonstrate that the impact of these corrections on the cosmologically preferred region of parameter space is larger than the current experimental uncertainty of WMAP data.

  8. QCD NLO and EW NLO corrections to tt¯H production with top quark decays at hadron collider

    Directory of Open Access Journals (Sweden)

    Zhang Yu

    2014-11-01

    Full Text Available Higgs boson production associated with a top quark pair is an important process in studying the nature of the newly discovered Higgs boson at the LHC. In this letter, we report on our calculations including the next-to-leading order (NLO QCD and NLO electroweak corrections to the pp→tt¯H process in the standard model. We present the integrated cross sections at the 14 TeV LHC and even at the future proton–proton colliders with s=33 and 100TeV. Our calculation includes the top quark subsequent decays by adopting the narrow width approximation. The kinematic distributions of Higgs boson and top quark decay products at the LHC are provided. We find that the O(αs2αew2 corrections are quantitatively comparable with the O(αs3αew corrections in some kinematic region.

  9. Charge and Matter Form Factors of Two-Neutron Halo Nuclei in Halo Effective Field Theory at Next-to-leading-order

    CERN Document Server

    Vanasse, Jared

    2016-01-01

    Using halo effective field theory (EFT), an expansion in $R_{core}/R_{halo}$, where $R_{core}$ is the radius of the core and $R_{halo}$ the radius of the halo nucleus, we calculate the charge and neutron form factors of the two-neutron halo nuclei $^{11}$Li, $^{14}$Be, and $^{22}$C to next-to-leading-order (NLO) by treating them as an effective three-body system. From the form factors we extract the point charge and point matter radii, inter-neutron distance, and neutron opening angle. Agreement is found with existing experimental extractions. Results are given for the point charge and point matter radii for arbitrary neutron core scattering effective range, $\\rho_{cn}$, that can be used for predictions once $\\rho_{cn}$ is measured. Estimates for $\\rho_{cn}$ are also used to make NLO predictions. Finally, our point charge radii are compared to other halo-EFT predictions, and setting the core mass equal to the neutron mass our point charge radius is found to agree with an analytical prediction in the unitary l...

  10. Effective one body approach to the dynamics of two spinning black holes with next-to-leading order spin-orbit coupling

    CERN Document Server

    Damour, Thibault; Schäfer, Gerhard

    2008-01-01

    Using a recent, novel Hamiltonian formulation of the gravitational interaction of spinning binaries, we extend the Effective One Body (EOB) description of the dynamics of two spinning black holes to next-to-leading order (NLO) in the spin-orbit interaction. The spin-dependent EOB Hamiltonian is constructed from four main ingredients: (i) a transformation between the ``effective'' Hamiltonian and the ``real'' one, (ii) a generalized effective Hamilton-Jacobi equation involving higher powers of the momenta, (iii) a Kerr-type effective metric (with Pad\\'e-resummed coefficients) which depends on the choice of some basic ``effective spin vector'' $\\bf{S}_{\\rm eff}$, and which is deformed by comparable-mass effects, and (iv) an additional effective spin-orbit interaction term involving another spin vector $\\bsigma$. As a first application of the new, NLO spin-dependent EOB Hamiltonian, we compute the binding energy of circular orbits (for parallel spins) as a function of the orbital frequency, and of the spin param...

  11. Nonlinear Effects in Gluon Distribution Predicted by GLR-MQ Evolution Equation at Next-to-leading Order in LHC Data

    Science.gov (United States)

    Lalung, M.; Phukan, P.; Sarma, J. K.

    2017-09-01

    In this work we have solved the nonlinear GLR-MQ evolution equation upto next-to-leading order (NLO) by considering NLO terms of the gluon-gluon splitting functions and running coupling constant α s (Q 2). Here, we have incorporated a Regge-like behaviour of gluon distribution in order to obtain a solution of the GLR-MQ equation in the range of 5G e V 2 ≤ Q 2 ≤ 25G e V 2. We have studied the Q 2 evolution of the gluon distribution function G(x, Q 2) and its nonlinear effects at small-x. It can be observed from our analysis that the nonlinearities increase with decrease in the correlation radius R of two interacting gluons, as expected. We have compared our result of G(x, Q 2) as Q 2 increases and x decreases, for two different values of R, viz. R = 2G e V -1 and 5 G e V -1. We have also checked the sensitivity of the Regge intercept λ G on our results. We compare our computed results with those obtained by the global analysis to parton distribution functions (PDFs) by various collaborations where LHC data have been included viz. ABM12, CT14, MMHT14, PDF4LHC15, NNPDF3.0 and CJ15. Besides we have also shown comparison of our results with HERA PDF data viz. HERAPDF15.

  12. Singularity-free Next-to-leading Order $\\Delta S= 1$ Renormalization Group Evolution and $\\epsilon_{K}^{\\prime}/\\epsilon_{K}$ in the Standard Model and Beyond

    CERN Document Server

    Kitahara, Teppei; Tremper, Paul

    2016-01-01

    The standard analytic solution of the renormalization group (RG) evolution for the $\\Delta S = 1$ Wilson coefficients involves several singularities. In practical applications one either regularizes these singularities or circumvents the problem by using numerical integrations. In this paper we derive a singularity-free solution of the next-to-leading order (NLO) RG equations, which greatly facilitates the calculation of $\\epsilon_K^{\\prime}$, the measure of direct $CP$ violation in $K\\to\\pi\\pi$ decays. Using our new RG evolution and the latest lattice results for the hadronic matrix elements, we calculate the ratio $\\epsilon_{K}^{\\prime}/\\epsilon_{K}$ (with $\\epsilon_{K}$ quantifying indirect $CP$ violation) in the Standard Model (SM) at NLO to $\\epsilon_{K}^{\\prime}/\\epsilon_{K} = ( 0.96 \\pm 4.96 ) \\times 10^{-4}$, which is 2.9$\\,\\sigma$ below the experimental value. We also present the evolution matrix in the high-energy regime for calculations of new physics contributions and derive easy-to-use approximat...

  13. Canonical Angles In A Compact Binary Star System With Spinning Components: Approximative Solution Through Next-To-Leading-Order Spin-Orbit Interaction for Circular Orbits

    CERN Document Server

    Tessmer, Manuel; Schäfer, Gerhard

    2013-01-01

    This publication will deal with an explicit determination of the time evolution of the spin orientation axes and the evolution of the orbital phase in the case of circular orbits under next-to-leading order spin-orbit interactions. We modify the method of Schneider and Cui proposed in ["Theoreme \\"uber Bewegungsintegrale und ihre Anwendungen in Bahntheorien", Verlag der Bayerischen Akademie der Wissenschaften, volume 212, 2005.] to iteratively remove oscillatory terms in the equations of motion for different masses that were not present in the case of equal masses. Our smallness parameter is chosen to be the difference of the symmetric mass ratio to the value 1/4. Before the first Lie transformation, the set of conserved quantities consists of the total angular momentum, the amplitudes of the orbital angular momentum and of the spins, $L, S_1,$ and $S_2$. In contrary, the magnitude of the total spin $S=|S_1+S_2|$ is not conserved and we wish to shift its non-conservation to higher orders of the smallness para...

  14. Top-quark production and QCD

    CERN Document Server

    Kidonakis, Nikolaos

    2012-01-01

    We review theoretical calculations for top-quark production that include complete next-to-leading-order QCD corrections as well as higher-order soft-gluon corrections from threshold resummation. We discuss in detail the differences between various approaches that have appeared in the literature and review results for top-quark total cross sections and differential distributions at the Tevatron and the LHC.

  15. QCD and electroweak corrections to Z Z +jet production with Z -boson leptonic decays at the LHC

    Science.gov (United States)

    Wang, Yong; Zhang, Ren-You; Ma, Wen-Gan; Li, Xiao-Zhou; Guo, Lei

    2016-07-01

    In this paper we present the full next-to-leading-order (NLO) QCD +NLO electroweak (EW) corrections to the Z -boson pair production in association with a hard jet at the LHC. The subsequent Z -boson leptonic decays are included by adopting both the naive narrow-width approximation and madspin methods for comparison. Since the Z Z +jet production is an important background for single Higgs boson production and new physics searches at hadron colliders, the theoretical predictions with high accuracy for the hadronic production of Z Z +jet are necessary. We present the numerical results of the integrated cross section and various kinematic distributions of final particles, and conclude that it is necessary to take into account the spin correlation and finite-width effects from the Z -boson leptonic decays. We also find that the NLO EW correction is quantitatively non-negligible in matching the experimental accuracy at the LHC, particularly in the high-transverse-momentum region.

  16. NNLO QCD corrections to Higgs boson production at large transverse momentum

    CERN Document Server

    Chen, X; Gehrmann, T; Glover, E W N; Jaquier, M

    2016-01-01

    We derive the second-order QCD corrections to the production of a Higgs boson recoiling against a parton with finite transverse momentum, working in the effective field theory in which the top quark contributions are integrated out. To account for quark mass effects, we supplement the effective field theory result by the full quark mass dependence at leading order. Our calculation is fully differential in the final state kinematics and includes the decay of the Higgs boson to a photon pair. It allows one to make next-to-next-to-leading order (NNLO)-accurate theory predictions for Higgs-plus-jet final states and for the transverse momentum distribution of the Higgs boson, accounting for the experimental definition of the fiducial cross sections. The NNLO QCD corrections are found to be moderate and positive, they lead to a substantial reduction of the theory uncertainty on the predictions. We compare our results to 8 TeV LHC data from ATLAS and CMS. While the shape of the data is well-described for both experi...

  17. Associated Higgs boson production with top quarks at the CERN Large Hadron Collider NLO QCD corrections

    CERN Document Server

    Dawson, S; Orr, L H; Reina, L; Wackeroth, D; 10.1103/PhysRevD.68.034022

    2003-01-01

    We present in detail the calculation of the O( alpha /sub s//sup 3/) inclusive total cross section for the process pp to tth, in the standard model, at the CERN Large Hadron Collider with a center-of- mass energy square root s/sub H/=14 TeV. The calculation is based on the complete set of virtual and real O( alpha /sub s/) corrections to the parton level processes qq to tth and gg to tth, as well as the tree level processes (q, q)g to tth+(q, q). The virtual corrections involve the computation of pentagon diagrams with several internal and external massive particles, first encountered in this process. The real corrections are computed using both the single and the two cutoff phase space slicing method. The next-to-leading order QCD corrections significantly reduce the renormalization and factorization scale dependence of the Born cross section and moderately increase the Born cross section for values of the renormalization and factorization scales above m/sub t/. (46 refs).

  18. SUSY-QCD corrections to e{sup +}e{sup -} {yields} t anti bH{sup -} and the Bernstein-Tkachov method of loop integration

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Maniatis, M. [Heidelberg Univ. (Germany). Inst. fuer Theoretische Physik; Weber, M.M. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany)

    2010-09-15

    The discovery of charged Higgs bosons is of particular importance, since their existence is predicted by supersymmetry and they are absent in the Standard Model (SM). If the charged Higgs bosons are too heavy to be produced in pairs at future linear colliders, single production associated with a top and a bottom quark is enhanced in parts of the parameter space. We present the next-to-leading-order calculation in supersymmetric QCD within the minimal supersymmetric SM (MSSM), completing a previous calculation of the SM-QCD corrections. In addition to the usual approach to perform the loop integration analytically, we apply a numerical approach based on the Bernstein-Tkachov theorem. In this framework, we avoid some of the generic problems connected with the analytical method. (orig.)

  19. Perturbative $O(\\alpha_s)$ corrections to the correlation functions of light tetraquark currents

    CERN Document Server

    Groote, S; Niinepuu, D

    2014-01-01

    We calculate the next-to-leading order QCD corrections to the perturbative term in the operator product expansion of the spectral functions of light tetraquark currents. By using also configuration space methods we keep the momentum space four-loop calculation to a manageable level. We find that the next-to-leading order corrections to the perturbative term are large and can amount to $O(100\\%)$. The corrections to the corresponding Borel sum rules, however, are small since the nonperturbative condensate contributions dominate the Borel sum rules.

  20. NNLO QCD corrections to the Drell-Yan cross section in models of TeV-scale gravity

    Science.gov (United States)

    Ahmed, Taushif; Banerjee, Pulak; Dhani, Prasanna K.; Kumar, M. C.; Mathews, Prakash; Rana, Narayan; Ravindran, V.

    2017-01-01

    The first results on the complete next-to-next-to-leading order (NNLO) Quantum Chromodynamic (QCD) corrections to the production of di-leptons at hadron colliders in large extra dimension models with spin-2 particles are reported in this article. In particular, we have computed these corrections to the invariant mass distribution of the di-leptons taking into account all the partonic sub-processes that contribute at NNLO. In these models, spin-2 particles couple through the energy-momentum tensor of the Standard Model with the universal coupling strength. The tensorial nature of the interaction and the presence of both quark annihilation and gluon fusion channels at the Born level make it challenging computationally and interesting phenomenologically. We have demonstrated numerically the importance of our results at Large Hadron Collider energies. The two-loop corrections contribute an additional 10% to the total cross section. We find that the QCD corrections are not only large but also important to make the predictions stable under renormalisation and factorisation scale variations, providing an opportunity to stringently constrain the parameters of the models with a spin-2 particle.

  1. NNLO QCD corrections to the Drell-Yan cross section in models of TeV-scale gravity

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Taushif; Banerjee, Pulak; Dhani, Prasanna K.; Rana, Narayan [The Institute of Mathematical Sciences, Chennai, Tamil Nadu (India); Homi Bhabha National Institute, Mumbai (India); Kumar, M.C. [Indian Institute of Technology Guwahati, Department of Physics, Guwahati (India); Mathews, Prakash [Saha Institute of Nuclear Physics, Kolkata, West Bengal (India); Ravindran, V. [The Institute of Mathematical Sciences, Chennai, Tamil Nadu (India)

    2017-01-15

    The first results on the complete next-to-next-to-leading order (NNLO) Quantum Chromodynamic (QCD) corrections to the production of di-leptons at hadron colliders in large extra dimension models with spin-2 particles are reported in this article. In particular, we have computed these corrections to the invariant mass distribution of the di-leptons taking into account all the partonic sub-processes that contribute at NNLO. In these models, spin-2 particles couple through the energy-momentum tensor of the Standard Model with the universal coupling strength. The tensorial nature of the interaction and the presence of both quark annihilation and gluon fusion channels at the Born level make it challenging computationally and interesting phenomenologically. We have demonstrated numerically the importance of our results at Large Hadron Collider energies. The two-loop corrections contribute an additional 10% to the total cross section. We find that the QCD corrections are not only large but also important to make the predictions stable under renormalisation and factorisation scale variations, providing an opportunity to stringently constrain the parameters of the models with a spin-2 particle. (orig.)

  2. A comparison of NNLO QCD predictions with 7 TeV ATLAS and CMS data for V+jet processes

    Science.gov (United States)

    Boughezal, Radja; Liu, Xiaohui; Petriello, Frank

    2016-09-01

    We perform a detailed comparison of next-to-next-to-leading order (NNLO) QCD predictions for the W+jet and Z+jet processes with 7 TeV experimental data from ATLAS and CMS. We observe excellent agreement between theory and data for most studied observables, which span several orders of magnitude in both cross section and energy. For some observables, such as the HT distribution, the NNLO QCD corrections are essential for resolving existing discrepancies between theory and data.

  3. NNLO QCD corrections to Higgs boson production at large transverse momentum

    Science.gov (United States)

    Chen, X.; Cruz-Martinez, J.; Gehrmann, T.; Glover, E. W. N.; Jaquier, M.

    2016-10-01

    We derive the second-order QCD corrections to the production of a Higgs boson recoiling against a parton with finite transverse momentum, working in the effective field theory in which the top quark contributions are integrated out. To account for quark mass effects, we supplement the effective field theory result by the full quark mass dependence at leading order. Our calculation is fully differential in the final state kinematics and includes the decay of the Higgs boson to a photon pair. It allows one to make next-to-next-to-leading order (NNLO)-accurate theory predictions for Higgs-plus-jet final states and for the transverse momentum distribution of the Higgs boson, accounting for the experimental definition of the fiducial cross sections. The NNLO QCD corrections are found to be moderate and positive, they lead to a substantial reduction of the theory uncertainty on the predictions. We compare our results to 8 TeV LHC data from ATLAS and CMS. While the shape of the data is well-described for both experiments, we agree on the normalization only for CMS. By normalizing data and theory to the inclusive fiducial cross section for Higgs production, good agreement is found for both experiments, however at the expense of an increased theory uncertainty. We make predictions for Higgs production observables at the 13 TeV LHC, which are in good agreement with recent ATLAS data. At this energy, the leading order mass corrections to the effective field theory prediction become significant at large transverse momenta, and we discuss the resulting uncertainties on the predictions.

  4. QCD corrections to vector boson pair production in gluon fusion including interference effects with off-shell Higgs at the LHC

    CERN Document Server

    Caola, Fabrizio; Melnikov, Kirill; Röntsch, Raoul; Tancredi, Lorenzo

    2016-07-18

    We compute next-to-leading order (NLO) QCD corrections to the production of two massive electroweak bosons in gluon fusion. We consider both the prompt production process $gg \\to VV$ and the production mediated by an exchange of an s-channel Higgs boson, $gg \\to H^* \\to V V$. We include final states with both on- and off-shell vector bosons with leptonic decays. The gluonic production of vector bosons is a loop-induced process, including both massless and massive quarks in the loop. For $gg \\to ZZ$ production, we obtain the NLO QCD corrections to the massive loops through an expansion around the heavy top limit. This approximation is valid below the top production threshold, giving a broad range of invariant masses between the Higgs production and the top production thresholds in which our results are valid. We explore the NLO QCD effects in $gg \\to ZZ$ focusing, in particular, on the interference between prompt and Higgs-mediated processes. We find that the QCD corrections to the interference are large and s...

  5. On Hermitian separability of the next-to-leading order BFKL kernel for the adjoint representation of the gauge group in the planar N = 4 SYM

    Energy Technology Data Exchange (ETDEWEB)

    Fadin, V.S. [Budker Institute of Nuclear Physics, SD RAS, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Fiore, R. [Universita della Calabria, Dipartimento di Fisica, Cosenza (Italy); Istituto Nazionale di Fisica, Nucleare Gruppo Collegato di Cosenza (Italy)

    2016-05-15

    We analyze a modification of the BFKL kernel for the adjoint representation of the color group in the maximally supersymmetric (N = 4) Yang-Mills theory in the limit of a large number of colors, related to the modification of the eigenvalues of the kernel suggested by Bondarenko and Prygarin in order to obtain Hermitian separability of the eigenvalues. We restore the modified kernel in the momentum space. It turns out that the modification is related only to the real part of the kernel and that the correction to the kernel cannot be presented by a single analytic function in the entire momentum region, which contradicts the known properties of the kernel. (orig.)

  6. Finite-volume corrections to the CP-odd nucleon matrix elements of the electromagnetic current from the QCD vacuum angle

    Directory of Open Access Journals (Sweden)

    Tarik Akan

    2014-09-01

    Full Text Available Nucleon electric dipole moments originating from strong CP-violation are being calculated by several groups using lattice QCD. We revisit the finite volume corrections to the CP-odd nucleon matrix elements of the electromagnetic current, which can be related to the electric dipole moments in the continuum, in the framework of chiral perturbation theory up to next-to-leading order taking into account the breaking of Lorentz symmetry. A chiral extrapolation of the recent lattice results of both the neutron and proton electric dipole moments is performed, which results in dn=(−2.7±1.2×10−16eθ0 cm and dp=(2.1±1.2×10−16eθ0 cm.

  7. Towards three-loop QCD corrections to the time-like splitting functions

    CERN Document Server

    Gituliar, Oleksandr

    2015-01-01

    We report on the status of a direct computation of the time-like splitting functions at next-to-next-to-leading order in QCD. Time-like splitting functions govern the collinear kinematics of inclusive hadron production and the evolution of the parton fragmentation distributions. Current knowledge about them at three loops has been inferred by means of crossing symmetry from their related space-like counterparts, which has left certain parts of the off-diagonal quark-gluon splitting function undetermined. This motivates an independent calculation from first principles. We review the tools and methods which are applied to attack the problem.

  8. QCD corrections to vector boson pair production in gluon fusion including interference effects with off-shell Higgs at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Caola, Fabrizio [CERN Theory Division,Geneva 23, CH-1211 (Switzerland); Dowling, Matthew; Melnikov, Kirill; Röntsch, Raoul; Tancredi, Lorenzo [Institute for Theoretical Particle Physics, KIT,Karlsruhe (Germany)

    2016-07-18

    We compute next-to-leading order (NLO) QCD corrections to the production of two massive electroweak bosons in gluon fusion. We consider both the prompt production process gg→VV and the production mediated by an exchange of an s-channel Higgs boson, gg→H{sup ∗}→VV. We include final states with both on- and off-shell vector bosons with leptonic decays. The gluonic production of vector bosons is a loop-induced process, including both massless and massive quarks in the loop. For gg→ZZ production, we obtain the NLO QCD corrections to the massive loops through an expansion around the heavy top limit. This approximation is valid below the top production threshold, giving a broad range of invariant masses between the Higgs production and the top production thresholds in which our results are valid. We explore the NLO QCD effects in gg→ZZ focusing, in particular, on the interference between prompt and Higgs-mediated processes. We find that the QCD corrections to the interference are large and similar in size to the corrections to both the signal and the background processes. At the same time, we observe that corrections to the interference change rapidly with the four-lepton invariant mass in the region around the ZZ production threshold. We also study the interference effects in gg→W{sup +}W{sup −} production where, due to technical limitations, we only consider contributions of massless loops. We find that the QCD corrections to the interference in this case are somewhat larger than those for either the signal or the background.

  9. SUSY-QCD corrections for direct detection of neutralino dark matter and correlations with relic density

    Science.gov (United States)

    Klasen, M.; Kovařík, K.; Steppeler, P.

    2016-11-01

    In this paper, we perform a full next-to-leading order (NLO) QCD calculation of neutralino scattering on protons or neutrons in the minimal supersymmetric standard model. We match the results of the NLO QCD calculation to the scalar and axial-vector operators in the effective field theory approach. These govern the spin-independent and spin-dependent detection rates, respectively. The calculations have been performed for general bino, wino and higgsino decompositions of neutralino dark matter and required a novel tensor reduction method of loop integrals with vanishing relative velocities and Gram determinants. Numerically, the NLO QCD effects are shown to be of at least of similar size and sometimes larger than the currently estimated nuclear uncertainties. We also demonstrate the interplay of the direct detection rate with the relic density when consistently analyzed with the program dm@nlo.

  10. The 2PI finite temperature effective potential of the O(N) linear sigma model in 1+1 dimensions, at next-to-leading order in 1/N

    CERN Document Server

    Baacke, J; Baacke, Jurgen; Michalski, Stefan

    2004-01-01

    We study the O(N) linear sigma model in 1+1 dimensions. We use the 2PI formalism of Cornwall, Jackiw and Tomboulis in order to evaluate the effective potential at finite temperature. At next-to-leading order in a 1/N expansion one has to include the sums over "necklace" and generalized "sunset" diagrams. We find that - in contrast to the Hartree approximation - there is no spontaneous symmetry breaking in this approximation, as to be expected for the exact theory. The effective potential becomes convex throughout for all parameter sets which include N=4 and N=10, couplings lambda=0.1 and 0.5 and temperatures between 0.2 and 1. The Green's functions obtained by solving the Schwinger-Dyson equations are enhanced in the infrared region. We also compare the effective potential as function of the external field phi with those obtained in various other approximations.

  11. The Top Quark, QCD, And New Physics.

    Science.gov (United States)

    Dawson, S.

    2002-06-01

    The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

  12. Vector-Boson Fusion Higgs Production at Three Loops in QCD.

    Science.gov (United States)

    Dreyer, Frédéric A; Karlberg, Alexander

    2016-08-12

    We calculate the next-to-next-to-next-to-leading-order (N^{3}LO) QCD corrections to inclusive vector-boson fusion Higgs production at proton colliders, in the limit in which there is no color exchange between the hadronic systems associated with the two colliding protons. We also provide differential cross sections for the Higgs transverse momentum and rapidity distributions. We find that the corrections are at the 1‰-2‰ level, well within the scale uncertainty of the next-to-next-to-leading-order calculation. The associated scale uncertainty of the N^{3}LO calculation is typically found to be below the 2‰ level. We also consider theoretical uncertainties due to missing higher order parton distribution functions, and provide an estimate of their importance.

  13. Vector-Boson Fusion Higgs Production at Three Loops in QCD

    Science.gov (United States)

    Dreyer, Frédéric A.; Karlberg, Alexander

    2016-08-01

    We calculate the next-to-next-to-next-to-leading-order (N3LO ) QCD corrections to inclusive vector-boson fusion Higgs production at proton colliders, in the limit in which there is no color exchange between the hadronic systems associated with the two colliding protons. We also provide differential cross sections for the Higgs transverse momentum and rapidity distributions. We find that the corrections are at the 1‰-2‰ level, well within the scale uncertainty of the next-to-next-to-leading-order calculation. The associated scale uncertainty of the N3LO calculation is typically found to be below the 2‰ level. We also consider theoretical uncertainties due to missing higher order parton distribution functions, and provide an estimate of their importance.

  14. Precise QCD predictions for the production of dijet final states in deep inelastic scattering

    CERN Document Server

    Currie, James; Niehues, Jan

    2016-01-01

    The production of two-jet final states in deep inelastic scattering is an important QCD precision observable. We compute it for the first time to next-to-next-to-leading order (NNLO) in perturbative QCD. Our calculation is fully differential in the lepton and jet variables and allows one to impose cuts on the jets both in the laboratory and the Breit frame. We observe that the NNLO corrections are moderate in size, except at kinematical edges, and that their inclusion leads to a substantial reduction of the scale variation uncertainty on the predictions. Our results will enable the inclusion of deep inelastic dijet data in precision phenomenology studies.

  15. Revisiting the QCD Corrections to the R-Parity Violating Processes pp/pp → eμ + X

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-Ming; HAN Liang; MA Wen-Gan; ZHANG Ren-You; JIANG Yi

    2008-01-01

    We present the theoretical predictions up to QCD next-to-leading order for the cross section of high-mass electronmuon pair production at the Tevatron and at the Large Hadron Collider(LHC),considering only the dominant contributions from the third-generation sneutrino.The dependence of the renormalization and factorization scales on the total cross section,and the effects on the K-factor due to the uncertainty of parton distribution function are carefully inyestigated.By considering soft-gluon resummation effects to all orders in αs of leading logarithm,we present the transverse momentum distributions of the final eμ pair.

  16. Higher-order corrections to the splitting functions from differential equations in QCD

    CERN Document Server

    Gituliar, O

    2016-01-01

    We report on the status an ab initio computation of the time-like splitting functions at next-to-next-to-leading order in QCD. Time-like splitting functions govern the collinear kinematics of inclusive hadron production in $e^+e^-$ annihilation and the evolution of the parton fragmentation distributions. Current knowledge about them at three loops has been inferred by means of crossing symmetry from their related space-like counterparts, the deep-inelastic structure functions and parton densities. In this approach certain parts of the off-diagonal quark-gluon splitting function are left undetermined, which calls for an independent calculation from first principles. We outline the method for calculating master integrals from differential equations which are required to attack the problem.

  17. SUSY-QCD corrections for the direct detection of neutralino dark matter and correlations with the relic density

    CERN Document Server

    Klasen, Michael; Steppeler, Patrick

    2016-01-01

    In this paper, we perform a full next-to-leading order (NLO) QCD calculation of neutralino scattering on protons or neutrons in the MSSM. We match the results of the NLO QCD calculation to the scalar and axial-vector operators in the effective field theory approach. These govern the spin-independent and spin-dependent detection rates, respectively. The calculations have been performed for general bino, wino and higgsino decompositions of neutralino dark matter and required a novel tensor reduction method of loop integrals with vanishing relative velocities and Gram determinants. Numerically, the NLO QCD effects are shown to be of at least of similar size and sometimes larger than the currently estimated nuclear uncertainties. We also demonstrate the interplay of the direct detection rate with the relic density when consistently analyzed with the program \\texttt{DMNLO}.

  18. W -boson plus jet differential distributions at NNLO in QCD

    Science.gov (United States)

    Boughezal, Radja; Liu, Xiaohui; Petriello, Frank

    2016-12-01

    We present a detailed phenomenological study of W -boson production in association with a jet through next-to-next-to-leading order (NNLO) in perturbative QCD. Fiducial cross sections and differential distributions for both 8 TeV and 13 TeV LHC collisions are presented, as are results for both the inclusive one-jet bin and the exclusive one-jet bin. Two different event selection criteria are considered: a general selection with standard cuts used in experimental analyses, and a boosted selection that focuses on high transverse momentum jets. We discuss the higher-order corrections in detail and identify for which observables and phase space regions the QCD perturbative expansion is under good theoretical control, and where additional work is needed. For most distributions and phase space regions the QCD perturbative expansion exhibits good convergence after the inclusion of the NNLO corrections.

  19. QCD-resummation and non-minimal flavour-violation for supersymmetric particle production at hadron colliders; Resommation des corrections radiatives QCD et violation de la saveur non-minimale pour la production de particules supersymetriques aupres des collisionneurs hadroniques

    Energy Technology Data Exchange (ETDEWEB)

    Fuks, B

    2007-06-15

    Cross sections for supersymmetric particles production at hadron colliders have been extensively studied in the past at leading order and also at next-to-leading order of perturbative QCD. The radiative corrections include large logarithms which have to be re-summed to all orders in the strong coupling constant in order to get reliable perturbative results. In this work, we perform a first and extensive study of the resummation effects for supersymmetric particle pair production at hadron colliders. We focus on Drell-Yan like slepton-pair and slepton-sneutrino associated production in minimal supergravity and gauge-mediated supersymmetry-breaking scenarios, and present accurate transverse-momentum and invariant-mass distributions, as well as total cross sections. In non-minimal supersymmetric models, novel effects of flavour violation may occur. In this case, the flavour structure in the squark sector cannot be directly deduced from the trilinear Yukawa couplings of the fermion and Higgs supermultiplets. We perform a precise numerical analysis of the experimentally allowed parameter space in the case of minimal supergravity scenarios with non-minimal flavour violation, looking for regions allowed by low-energy, electroweak precision, and cosmological data. Leading order cross sections for the production of squarks and gauginos at hadron colliders are implemented in a flexible computer program, allowing us to study in detail the dependence of these cross sections on flavour violation. (author)

  20. Neutralino annihilation into massive quarks with supersymmetric QCD corrections

    Science.gov (United States)

    Herrmann, Björn; Klasen, Michael; Kovařík, Karol

    2009-03-01

    We compute the full O(αs) supersymmetric (SUSY)-QCD corrections for neutralino annihilation into massive quarks through gauge or Higgs bosons and squarks in the minimal supersymmetric standard model, including the known resummation of logarithmically enhanced terms. The numerical impact of the corrections on the extraction of SUSY mass parameters from cosmological data is analyzed for gravity-mediated SUSY-breaking scenarios and shown to be sizable, so that these corrections must be included in common analysis tools.

  1. Neutralino Annihilation into Massive Quarks with SUSY-QCD Corrections

    CERN Document Server

    Herrmann, Björn; Kovarik, Karol

    2009-01-01

    We compute the full O(alpha_s) supersymmetric (SUSY) QCD corrections for neutralino annihilation into massive quarks through gauge or Higgs bosons and squarks in the Minimal Supersymmetric Standard Model (MSSM), including the known resummation of logarithmically enhanced terms. The numerical impact of the corrections on the extraction of SUSY mass parameters from cosmological data is analyzed for gravity-mediated SUSY breaking scenarios and shown to be sizable, so that these corrections must be included in common analysis tools.

  2. Charged Higgs production via vector-boson fusion at NNLO in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Zaro, Marco; Maltoni, Fabio [Univ. Catholique de Louvain (Belgium). CP3; Bolzoni, Paolo [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2010-12-15

    We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for single and double charged Higgs production via weak boson fusion. Results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses. (orig.)

  3. Higgs production via vector-boson fusion at NNLO in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, Paolo; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Maltoni, Fabio; Zaro, Marco [Catholique Univ. de Louvain, Louvain-la-Neuve (BE). Center for Particle Physics and Phenomenology (CP3)

    2010-03-15

    We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for Higgs production via weak boson fusion. Our results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses. (orig.)

  4. SUSY-QCD Corrections to B0-B0 Mixing

    Institute of Scientific and Technical Information of China (English)

    FENG TaiFu; LI XueQian; MA WenGan

    2001-01-01

    We study the SUSY-QCD corrections to B0-B0 mixing with a reasonable SUSY parameter space and find that contribution from gluino is proportional to log(m-g/μw) where μw is the weak interaction energy scale and by no means negligible.``

  5. Topics in Effective Field Theory for Lattice QCD

    CERN Document Server

    Walker-Loud, A

    2006-01-01

    In this work, we extend and apply effective field theory techniques to systematically understand a subset of lattice artifacts which pollute the lattice correlation functions for a few processes of physical interest. Where possible, we compare to existing lattice QCD calculations. In particular, we extend the heavy baryon Lagrangian to the next order in partially quenched chiral perturbation theory and use it to compute the masses of the lightest spin-1/2 and spin-3/2 baryons to next-to-next-to leading order. We then construct the twisted mass chiral Lagrangian for baryons and apply it to compute the lattice spacing corrections to the baryon masses simulated with twisted mass lattice QCD. We extend computations of the nucleon electromagnetic structure to account for finite volume effects, as these observables are particularly sensitive to the finite extent of the lattice. We resolve subtle peculiarities for lattice QCD simulations of polarizabilities and we show that using background field techniques, one can...

  6. Wγ and Zγ production at the LHC in NNLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Grazzini, Massimiliano [Physik-Institut, Universität Zürich,Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Kallweit, Stefan [PRISMA Cluster of Excellence, Institute of Physics, Johannes Gutenberg University,Staudingerweg 7, 55128 Mainz (Germany); Rathlev, Dirk [Physik-Institut, Universität Zürich,Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)

    2015-07-16

    We consider the production of Wγ and Zγ pairs at hadron colliders. We report on the complete fully differential computation of radiative corrections at next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation includes the leptonic decay of the vector boson with the corresponding spin correlations, off shell effects and final-state photon radiation. We present numerical results for pp collisions at 7 and 8 TeV and we compare them with available LHC data. In the case of Zγ production, the impact of NNLO corrections is generally moderate, ranging from 8% to 18%, depending on the applied cuts. In the case of Wγ production, the NNLO effects are more important, and range from 19% to 26%, thereby improving the agreement of the theoretical predictions with the data. As expected, the impact of QCD radiative corrections is significantly reduced when a jet veto is applied.

  7. Wgamma and Zgamma production at the LHC in NNLO QCD

    CERN Document Server

    Grazzini, Massimiliano; Rathlev, Dirk

    2016-01-01

    We consider the production of Wgamma and Zgamma pairs at the LHC, and report on the fully differential computation of next-to-next-to-leading order (NNLO) corrections in QCD perturbation theory. The calculation includes leptonic vector-boson decays with the corresponding spin correlations, off-shell effects and final-state photon radiation. We present numerical results for pp collisions at 7 TeV, and compare them with available ATLAS data. In the case of Zgamma production, the impact of NNLO corrections is generally moderate, ranging from 8% to 17%, depending on the applied cuts. In the case of Wgamma production, the NNLO effects are more important, and range from 19% to 26%, thereby improving the agreement of the theoretical predictions with the data. As expected, a veto against jets significantly reduces the impact of QCD radiative corrections.

  8. Higher order QCD corrections in small x physics

    Energy Technology Data Exchange (ETDEWEB)

    Chachamis, G.

    2006-11-15

    We study higher order QCD corrections in small x Physics. The numerical implementation of the full NLO photon impact factor is the remaining necessary piece for the testing of the NLO BFKL resummation against data from physical processes, such as {gamma}{sup *}{gamma}{sup *} collisions. We perform the numerical integration over phase space for the virtual corrections to the NLO photon impact factor. This, along with the previously calculated real corrections, makes feasible in the near future first estimates for the {gamma}*{gamma}* total cross section, since the convolution of the full impact factor with the NLO BFKL gluon Green's function is now straightforward. The NLO corrections for the photon impact factor are sizeable and negative. In the second part of this thesis, we estimate higher order correction to the BK equation. We are mainly interested in whether partonic saturation delays or not in rapidity when going beyond the leading order. In our investigation, we use the so called 'rapidity veto' which forbid two emissions to be very close in rapidity, to 'switch on' higher order corrections to the BK equation. From analytic and numerical analysis, we conclude that indeed saturation does delay in rapidity when higher order corrections are taken into account. In the last part, we investigate higher order QCD corrections as additional corrections to the Electroweak (EW) sector. The question of whether BFKL corrections are of any importance in the Regge limit for the EW sector seems natural; although they arise in higher loop level, the accumulation of logarithms in energy s at high energies, cannot be dismissed without an investigation. We focus on the process {gamma}{gamma}{yields}ZZ. We calculate the pQCD corrections in the forward region at leading logarithmic (LL) BFKL accuracy, which are of the order of few percent at the TeV energy scale. (orig.)

  9. B→ p(ω, φ)η(') Decays and NLO Contributions in pQCD Approach

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Qing; XIAO Zhen-Jun

    2009-01-01

    By employing the perturbative QCD (pQCD) factorization approach, we calculate some important next-to-leading-order (NLO) contributions to the two-body charmless hadronic decays B+→ p+η(1) and(B0 → p0(ω, φ)η(1)),induced by the vertex QCD corrections, the quark-loops as well as the chromo-magnetic penguins. From the numerical results and phenomenological analysis we find that (a) for B± → p±η(1) (B0 → p0(ω, φ)η(1)) decays, the partial NLO contributions to branching ratios are small (large) in magnitude; and (b) the pQCD predictions for A Cpdir( B±→ p±η(1)) are consistent with the data, while the predicted Acp(B0 p0(ω)η(1)) are generally large in magnitude and could be tested by the forthcoming LHCb experiments.

  10. Higher order QCD corrections in exclusive charmless B decays

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.

    2006-10-15

    We discuss exclusive charmless B decays within the Standard Model of particle physics. These decays play a central role in the on-going process to constrain the parameters of the CKM matrix and to clarify the nature of CP violation. In order to exploit the rich source of data that is currently being collected at the experiments, a systematic theoretical treatment of the complicated hadronic dynamics is strongly desired. QCD Factorization represents a model-independent framework to compute hadronic matrix elements from first principles. It is based on a power expansion in {lambda}{sub QCD}/m{sub b} and allows for the systematic implementation of perturbative corrections. In particular, we consider hadronic two-body decays as B {yields} {pi}{pi} and perform a conceptual analysis of heavy-to-light form factors which encode the strong interaction effects in semi-leptonic decays as B {yields} {pi}l{nu}. Concerning the hadronic decays we compute NNLO QCD corrections which are particularly important with respect to strong interaction phases and hence direct CP asymmetries. On the technical level, we perform a 2-loop calculation which is based on an automatized reduction algorithm and apply sophisticated techniques for the calculation of loop-integrals. We indeed find that the considered quantities are well-defined as predicted by QCD Factorization, which is the result of a highly complicated subtraction procedure. We present results for the imaginary part of the topological tree amplitudes and observe that the considered corrections are substantial. The calculation of the real part of the amplitudes is far more complicated and we present a preliminary result which is based on certain simplifications. Our calculation is one part of the full NNLO analysis of nonleptonic B decays within QCD Factorization which is currently pursued by various groups. In our conceptual analysis of the QCD dynamics in heavy-to-light transitions we consider form factors between non

  11. NNLO QCD predictions for single jet inclusive production at the LHC

    CERN Document Server

    Currie, J; Pires, J

    2016-01-01

    We report the first calculation of fully differential jet production in all partonic channels at next-to-next-to leading order (NNLO) in perturbative QCD and compare to the available ATLAS 7 TeV data. We discuss the size and shape of the perturbative corrections along with their associated scale variation across a wide range in jet transverse momentum, $p_{T}$, and rapidity, $y$. We find significant effects, especially at low $p_{T}$, and discuss the possible implications for Parton Distribution Function fits.

  12. Higgs boson gluon–fusion production at threshold in N3LO QCD

    Directory of Open Access Journals (Sweden)

    Charalampos Anastasiou

    2014-10-01

    Full Text Available We present the cross-section for the threshold production of the Higgs boson at hadron-colliders at next-to-next-to-next-to-leading order (N3LO in perturbative QCD. We present an analytic expression for the partonic cross-section at threshold and the impact of these corrections on the numerical estimates for the hadronic cross-section at the LHC. With this result we achieve a major milestone towards a complete evaluation of the cross-section at N3LO which will reduce the theoretical uncertainty in the determination of the strengths of the Higgs boson interactions.

  13. A calculation of the three-loop helicity-dependent splitting functions in QCD

    CERN Document Server

    Vogt, A; Vermaseren, J A M

    2014-01-01

    We have calculated the complete matrix of three-loop helicity-difference (`polarized') splitting functions Delta P_ik^(2), i,k = q,g, in massless perturbative QCD. In this note we briefly discuss some properties of the polarized splitting functions and our non-standard determination of the hitherto missing lower-row quantities Delta P_gq^(2) and Delta P_gg^(2). The resulting next-to-next-to-leading order (NNLO) corrections to the evolution of polarized parton distributions are illustrated and found to be small even at rather large values of the strong coupling constant alpha_s.

  14. Note on QCD corrections to hadronic Higgs decay

    Science.gov (United States)

    Drees, Manuel; Hikasa, Ken-ichi

    1990-04-01

    The O( αs) QCD correction to the hadronic decay of a scalar Higgs boson, for which contradicting results have been reported, is calculated. Our result is in agreement with that of Braaten and Leveille but disagrees with that of Janot. The possible origin of the discrepancy is discussed. The total hadronic decay rate and the differential rate to qq¯g of a pseudoscalar Higgs boson are also presented.

  15. Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators

    Energy Technology Data Exchange (ETDEWEB)

    Backović, Mihailo [Centre for Cosmology, Particle Physics and Phenomenology (CP3), Université catholique de Louvain, 1348, Louvain-la-Neuve (Belgium); Krämer, Michael [Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, 52056, Aachen (Germany); Maltoni, Fabio; Martini, Antony [Centre for Cosmology, Particle Physics and Phenomenology (CP3), Université catholique de Louvain, 1348, Louvain-la-Neuve (Belgium); Mawatari, Kentarou, E-mail: kentarou.mawatari@vub.ac.be [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Pleinlaan 2, 1050, Brussels (Belgium); Pellen, Mathieu [Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, 52056, Aachen (Germany)

    2015-10-07

    Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s-channel mediators. We implement such models in the FeynRules/MadGraph5{sub a}MC@NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s-channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties.

  16. Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators

    Energy Technology Data Exchange (ETDEWEB)

    Backovic, Mihailo; Maltoni, Fabio; Martini, Antony [Universite catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Kraemer, Michael; Pellen, Mathieu [RWTH Aachen University, Institute for Theoretical Particle Physics and Cosmology, Aachen (Germany); Mawatari, Kentarou [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Brussels (Belgium)

    2015-10-15

    Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s-channel mediators. We implement such models in the FeynRules/MadGraph5{sub a}MC rate at NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s-channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties. (orig.)

  17. Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators.

    Science.gov (United States)

    Backović, Mihailo; Krämer, Michael; Maltoni, Fabio; Martini, Antony; Mawatari, Kentarou; Pellen, Mathieu

    Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s-channel mediators. We implement such models in the FeynRules/MadGraph5_aMC@NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s-channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties.

  18. W-boson plus jet differential distributions at NNLO in QCD

    CERN Document Server

    Boughezal, Radja; Petriello, Frank

    2016-01-01

    We present a detailed phenomenological study of W-boson production in association with a jet through next-to-next-to-leading order (NNLO) in perturbative QCD. Fiducial cross sections and differential distributions for both 8 TeV and 13 TeV LHC collisions are presented, as are results for both the inclusive one-jet bin and the exclusive one-jet bin. Two different event selection criteria are considered: a general selection with standard cuts used in experimental analyses, and a boosted selection that focuses on high transverse momentum jets. We discuss the higher-order corrections in detail and identify for which observables and phase space regions the QCD perturbative expansion is under good theoretical control, and where additional work is needed. For most distributions and phase space regions the QCD perturbative expansion exhibits good convergence after the inclusion of the NNLO corrections.

  19. Mass-corrections to double-Higgs production & TopoID

    CERN Document Server

    Grigo, Jonathan

    2014-01-01

    We consider power corrections due to a finite top quark mass M_t to the production of a Higgs boson pair within the Standard Model at next-to-leading order (NLO) in QCD. Previous calculations for this process and at this precision were done in the limit of an inifinitely heavy top quark. Our results for the inclusive production cross section at NLO include terms up to O(1/M_t^12). We present the Mathematica package TopoID which for arbitrary processes aims to perform the necessary steps from Feynman diagrams to unrenormalized results expressed in terms of master integrals. We employ it for advancing in this process towards next-to-next-to-leading order (NNLO) where further automatization is needed.

  20. Leading power corrections in QCD from renormalons to phenomenology

    CERN Document Server

    Akhoury, R

    1995-01-01

    We consider 1/Q corrections to hard processes in QCD where Q is a large mass scale, concentrating on shape variables in e^{+}e^{-} annihilation. While the evidence for such corrections can be and has been established by means of the renormalon technique, theory can be confronted with experiment only after clarifying the properties of the corresponding non-perturbative contribution. We list predictions based on the universality of the 1/Q terms, and compare them with the existing data. We also identify the scale of the non-perturbative contributions in terms of jet masses.

  1. QCD Corrected $1/m_b$ Contributions to $B\\bbar$--Mixixng

    CERN Document Server

    Kilian, W; Kilian, Wolfgang; Mannel, Thomas

    1993-01-01

    We calculate the QCD corrected effective Hamiltonian for $B\\bbar$--Mixing in heavy quark effective theory including corrections of the order $\\Lambda_{QCD} / m_b$. The matrix elements of the subleading operators are estimated using the vacuum insertion assumption. We show that the major part of the subleading corrections may be absorbed into the heavy meson decay constant $f_B$; the remaining corrections are only due to QCD effects and give an enhancement of $\\Delta M$ of 5\\%.

  2. ZZ production at the LHC: Fiducial cross sections and distributions in NNLO QCD

    Directory of Open Access Journals (Sweden)

    Massimiliano Grazzini

    2015-11-01

    Full Text Available We consider QCD radiative corrections to the production of four charged leptons in the ZZ signal region at the LHC. We report on the complete calculation of the next-to-next-to-leading order (NNLO corrections to this process in QCD perturbation theory. Numerical results are presented for s=8 TeV, using typical selection cuts applied by the ATLAS and CMS Collaborations. The NNLO corrections increase the NLO fiducial cross section by about 15%, and they have a relatively small impact on the shape of the considered kinematical distributions. In the case of the ΔΦ distribution of the two Z candidates, the computed corrections improve the agreement of the theoretical prediction with the CMS data.

  3. $\\chi_{cJ}$ production at hadron colliders with QCD radiative corrections

    CERN Document Server

    Ma, Yan-Qing; Chao, Kuang-Ta

    2010-01-01

    In nonrelativistic QCD, we calculate the $\\chi_{cJ}$ production at next-to-leading order (NLO) in $\\alpha_s$ at the Tevatron and LHC. A large but negative NLO contribution at large $p_T$ from the color-singlet $^3P^{[1]}_J$ channel is found. Differing from the leading order (LO) prediction, where the ratio of production cross sections of $\\sigma_{\\chi_{c2}}/\\sigma_{\\chi_{c1}}$ approaches to 5/3 at large $p_T$, we find the $\\chi_{c1}$ production rate can exceed that of $\\chi_{c2}$ at NLO, which gives a theoretical interpretation for the anomalous ratio measured by CDF. Comparing our result with the recent CDF data, we obtain the color-octet matrix element $\\moxs=2.2\\times10^{-3} Gev^3$. We give predictions for the $\\chi_{cJ}$ production rates at the LHC. Feeddown contributions of $\\chi_{cJ}$ to $J/\\psi$ production are also considered.

  4. The $\\rho$-meson longitudinal leading-twist distribution amplitude within QCD background field theory

    CERN Document Server

    Fu, Hai-Bing; Cheng, Wei; Zhong, Tao

    2016-01-01

    We revisit the $\\rho$-meson longitudinal leading-twist distribution amplitude (DA) $\\phi_{2;\\rho}^\\|$ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments $\\langle\\xi_{n;\\rho}^\\|\\rangle$, we include the next-to-leading order QCD correction to the perturbative part and keep all non-perturbative condensates up to dimension-six consistently within the background field theory. The first two moments read $\\langle \\xi_{2;\\rho}^\\| \\rangle|_{1{\\rm GeV}} = 0.241(28)$ and $\\langle \\xi_{4;\\rho}^\\| \\rangle|_{1{\\rm GeV}} = 0.108(27)$, indicating a double humped behavior for $\\phi_{2;\\rho}^\\|$ at low $q^2$-region. As an application, we apply them to the $B\\to \\rho $ transition form factors within the QCD light-cone sum rules, which are key components for the decay width $\\Gamma(B\\to \\rho \\ell \

  5. Single slepton production associated with a top quark at LHC in NLO QCD

    CERN Document Server

    Xiao-Peng, Li; Wen-Gan, Ma; Liang, Han; Ren-You, Zhang; Shao-Ming, Wang

    2012-01-01

    Single slepton production in association with a top quark at the CERN Large Hadron Collider (LHC) is one of the important processes in probing the R-parity violation couplings. We calculate the QCD next-to-leading order (NLO) corrections to the $pp \\to t\\slep^{-}(\\bar{t}\\slep^{+})+X$ process at the LHC and discuss the impacts of the QCD corrections on kinematic distributions. We investigate the dependence of the leading order (LO) and the NLO QCD corrected integrated cross section on the factorization/renormalization energy scale, slepton, stop-quark and gluino masses. We find that the uncertainty of the LO cross section due to the energy scale is obviously improved by the NLO QCD corrections, and the exclusive jet event selection scheme keeps the convergence of the perturbative series better than inclusive scheme. The results show that the polarization asymmetry of the top-quark will be reduced by the NLO QCD corrections, and the QCD corrections generally increase with the increment of $\\tilde{t}_1$ or $\\til...

  6. NLO corrections to $\\chi_{bJ}$ two-body exclusive decay processes

    CERN Document Server

    Chen, Long-Bin

    2014-01-01

    The next-to-leading order QCD corrections for $\\chi_{bJ}$, the p-wave bottomonium, to $J/\\psi$ pair decay processes were evaluated utilizing NRQCD factorization formalism. It was determined that the scale dependence was depressed with NLO corrections, and hence the uncertainties in the leading order results were greatly reduced. The total branch ratios were found to be the order of $10^{-5}$ for all three $\\chi_{bJ}\\rightarrow J/\\psi J/\\psi$ processes,indicating that they were observable in the LHC and super-B experiments.

  7. A QCD analysis of ZEUS diffractive data

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2009-11-15

    ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. (orig.)

  8. Status Report of NNLO QCD Calculations

    CERN Document Server

    Klasen, M

    2005-01-01

    We review recent progress in next-to-next-to-leading order (NNLO) perturbative QCD calculations with special emphasis on results ready for phenomenological applications. Important examples are new results on structure functions and jet or Higgs boson production. In addition, we describe new calculational techniques based on twistors and their potential for efficient calculations of multiparticle amplitudes.

  9. Higgs boson gluon-fusion production in QCD at three loops.

    Science.gov (United States)

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Herzog, Franz; Mistlberger, Bernhard

    2015-05-29

    We present the cross section for the production of a Higgs boson at hadron colliders at next-to-next-to-next-to-leading order (N^{3}LO) in perturbative QCD. The calculation is based on a method to perform a series expansion of the partonic cross section around the threshold limit to an arbitrary order. We perform this expansion to sufficiently high order to obtain the value of the hadronic cross at N^{3}LO in the large top-mass limit. For renormalization and factorization scales equal to half the Higgs boson mass, the N^{3}LO corrections are of the order of +2.2%. The total scale variation at N^{3}LO is 3%, reducing the uncertainty due to missing higher order QCD corrections by a factor of 3.

  10. Two-loop QCD Correction to Massive Spin-2 Resonance $ \\to q ~ \\bar{q} ~ g $

    CERN Document Server

    Ahmed, Taushif; Mathews, Prakash; Rana, Narayan; Ravindran, V

    2016-01-01

    Two-loop QCD correction to massive spin-2 Graviton decaying to $q ~ + ~ \\bar{q}~ + ~g$ is presented considering a generic universal spin-2 coupling to the SM through the conserved energy-momentum tensor. Such a massive spin-2 particle can arise in extra-dimensional models. The ultraviolet and infrared structure of the QCD amplitudes are studied. In dimensional regularisation, the infrared pole structure is in agreement with Catani's proposal, confirming the universal factorization property of QCD amplitudes, even with the spin-2 tensorial coupling. This computation now completes the full two-loop QCD corrections for the production of a spin-2 in association with a jet.

  11. W±Z production at hadron colliders in NNLO QCD

    Directory of Open Access Journals (Sweden)

    Massimiliano Grazzini

    2016-10-01

    Full Text Available We report on the first computation of the next-to-next-to-leading order (NNLO QCD corrections to W±Z production in proton collisions. We consider both the inclusive production of on-shell W±Z pairs at LHC energies and the total W±Z rates including off-shell effects of the W and Z bosons. In the off-shell computation, the invariant mass of the lepton pairs from the Z boson decay is required to be in a given mass window, and the results are compared with the corresponding measurements obtained by the ATLAS and CMS collaborations. The NNLO corrections range from 8% at s=7TeV to 11% at s=14TeV and significantly improve the agreement with the LHC data at s=7 and 8TeV.

  12. Study of weak corrections to Drell-Yan, top-quark pair, and dijet production at high energies with MCFM

    Science.gov (United States)

    Campbell, John M.; Wackeroth, Doreen; Zhou, Jia

    2016-11-01

    Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real W and Z bosons that result in Sudakov-like corrections of the form αWllogn(Q2/MW,Z 2) , where αW=α /(4 π sin2θW) and n ≤2 l -1 . The inclusion of EW corrections in predictions for hadron colliders is, therefore, especially important when searching for signals of possible new physics in distributions probing the kinematic regime Q2≫MV2. Next-to-leading order (NLO) EW corrections should also be taken into account when their size [O (α )] is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) [O (αs2)]. To this end, we have implemented the NLO weak corrections to the neutral-current Drell-Yan process, top-quark pair production and dijet production in the parton-level Monte Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide both the full NLO weak corrections and their Sudakov approximation since the latter is often used for a fast evaluation of weak effects at high energies and can be extended to higher orders. With both the exact and approximate results at hand, the validity of the Sudakov approximation can be readily quantified.

  13. Resummation of QCD Corrections to the eta_c Decay Rate

    CERN Document Server

    Bodwin, Geoffrey T; Bodwin, Geoffrey T.; Chen, Yu-Qi

    2001-01-01

    We examine the ratio of the decay rate of the eta_c into light hadrons to the decay rate into photons and find that most of the large next-to-leading-order (NL0) correction is associated with running of the strong coupling alpha_s. We resum such contributions by analyzing final-state chains of vacuum-polarization bubbles. We show that the nonperturbative parts of the bubble chains can be absorbed into a color-octet matrix element, once one has used contour deformations of the phase-space integrals to cancel certain contributions. We argue that these contributions are incompatible with the uncertainty principle. We also argue that perturbation theory is reliable only if one carries out the phase-space integrations before the perturbation sum. Our results are in good agreement with experiment and differ considerably from those that one obtains by applying the scale-setting method of Brodsky, Lepage, and Mackenzie to the NLO result.

  14. One-loop corrections to neutralino-stop coannihilation revisited

    Science.gov (United States)

    Harz, J.; Herrmann, B.; Klasen, M.; Kovařík, K.

    2015-02-01

    We discuss the O (αs) supersymmetric QCD corrections to neutralino-stop coannihilation into a top quark and a gluon in the minimal supersymmetric Standard Model (MSSM). This particular channel can be numerically important in wide ranges of the MSSM parameter space with rather light stops. We discuss technical details such as the renormalization scheme and the phase-space slicing method with two cutoffs. We also comment on improvements with respect to earlier works on the given process. Further, we study for the first time the phenomenologically very interesting interplay of neutralino-stop coannihilation with neutralino-pair annihilation into quark pairs taking the full next-to-leading order SUSY-QCD corrections into account. We demonstrate that the numerical impact of these corrections on the total (co)annihilation cross section and finally on the theoretically predicted neutralino relic density is significant.

  15. One-loop corrections to neutralino-stop coannihilation revisited

    CERN Document Server

    Harz, J; Klasen, M; Kovarik, K

    2014-01-01

    We discuss the ${\\cal O}(\\alpha_s)$ supersymmetric QCD corrections to neutralino-stop coannihilation into a top quark and a gluon in the Minimal Supersymmetric Standard Model (MSSM). This particular channel can be numerically important in wide ranges of the MSSM parameter space with rather light stops. We discuss technical details such as the renormalization scheme and the phase-space slicing method with two cutoffs. We also comment on improvements with respect to earlier works on the given process. Further, we study for the first time the phenomenologically very interesting interplay of neutralino-stop coannihilation with neutralino-pair annihilation into quark pairs taking the full next-to-leading order SUSY-QCD corrections into account. We demonstrate that the numerical impact of these corrections on the total (co)annihilation cross section and finally on the theoretically predicted neutralino relic density is significant.

  16. NNLO QCD corrections for Drell-Yan $p_T^Z$ and $\\phi^*$ observables at the LHC

    CERN Document Server

    Ridder, A Gehrmann-De; Glover, E W N; Huss, A; Morgan, T A

    2016-01-01

    Drell-Yan lepton pairs with finite transverse momentum are produced when the vector boson recoils against (multiple) parton emission(s), and is determined by QCD dynamics. At small transverse momentum, the fixed order predictions break down due to the emergence of large logarithmic contributions. This region can be studied via the $p_T^Z$ distribution constructed from the energies of the leptons, or through the $\\phi^*$ distribution that relies on the directions of the leptons. For sufficiently small transverse momentum, the $\\phi^*$ observable can be measured experimentally with better resolution. We study the small $p_T^Z$ and $\\phi^*$ distributions up to next-to-next-to-leading order (NNLO) in perturbative QCD. We compute the $\\phi^*$ distributions for the fully inclusive production of lepton pairs via $Z/\\gamma^*$ to NNLO and normalise them to the NNLO cross sections for inclusive $Z/\\gamma^*$ production. We compare our predictions with the $\\phi^*$ distribution measured by the ATLAS collaboration during ...

  17. QCD Corrections to K-Kbar Mixing in R-symmetric Supersymmetric Models

    CERN Document Server

    Blechman, Andrew E

    2008-01-01

    The leading-log QCD corrections to K-Kbar mixing in R-symmetric supersymmetric models are computed using effective field theory techniques. The spectrum topology where the gluino is significantly heavier than the squarks is motivated and focused on. It is found that, like in the MSSM, QCD corrections can tighten the kaon mass difference bound by roughly a factor of three. CP violation is also briefly considered, where QCD corrections can constrain phases to be as much as a factor of ten smaller than the uncorrected value.

  18. QCD Corrections to K-Kbar Mixing in R-symmetric Supersymmetric Models

    OpenAIRE

    Blechman, Andrew E.; Ng, Siew-Phang

    2008-01-01

    The leading-log QCD corrections to K-Kbar mixing in R-symmetric supersymmetric models are computed using effective field theory techniques. The spectrum topology where the gluino is significantly heavier than the squarks is motivated and focused on. It is found that, like in the MSSM, QCD corrections can tighten the kaon mass difference bound by roughly a factor of three. CP violation is also briefly considered, where QCD corrections can constrain phases to be as much as a factor of ten small...

  19. Predictions for diphoton production at the LHC through NNLO in QCD

    CERN Document Server

    Campbell, John M; Li, Ye; Williams, Ciaran

    2016-01-01

    In this paper we present a next-to-next-to-leading order (NNLO) calculation of the process $pp\\rightarrow \\gamma\\gamma$ that we have implemented into the parton level Monte Carlo code MCFM. We do not find agreement with the previous calculation of this process in the literature. In addition to the $\\mathcal{O}(\\alpha_s^2)$ corrections present at NNLO, we include some effects arising at $\\mathcal{O}(\\alpha_s^3)$, namely those associated with gluon-initiated closed fermion loops. We investigate the role of this process in the context of studies of QCD at colliders and as a background for searches for new physics, paying particular attention to the diphoton invariant mass spectrum. We demonstrate that the NNLO QCD prediction for the shape of this spectrum agrees well with functional forms used in recent data-driven fits.

  20. Electroweak corrections and Bloch-Nordsieck violations in 2-to-2 processes at the LHC

    CERN Document Server

    Stirling, W J

    2013-01-01

    We consider the effect of next-to-leading order (NLO) electroweak corrections to Standard Model 2-to-2 processes, taking into account the potentially large double logarithms originating from both real and virtual corrections. A study of the leading Sudakov logarithms is presented and Bloch-Nordsieck (BN) violations are discussed for processes at the CERN Large Hadron Collider. In particular, we focus on the processes Z/photon+jet and also the ratio of Z to photon production. This ratio is known to be insensitive to NLO QCD corrections but this is not expected to be the case for the electroweak corrections. We also comment on the effect of electroweak corrections and the presence of BN violation for QCD processes, in particular dijet production, and also for purely electroweak processes such as W + H and W + Z associated production.

  1. Higher-Order QCD prediction for dark matter pair associated with a b-jet production at the LHC

    CERN Document Server

    Gang, Li; Mao, Song; Yu, Zhang; Ya-Jin, Zhou; Jian-You, Guo

    2016-01-01

    Dark matter associated visible particle production at high energy colliders provides a unique way to determine the microscopic properties of the dark matter. We investigate a pair of fermionic dark matter particles associated with a b-jet production at the LHC, through a mediator which couples to standard model or dark matter particles via either a vector or axial-vector coupling. The calculation is performed by implementing these simplified models in the FeynRules/MadGraph5 aMC@NLO framework. In our calculation, next-to-leading order QCD corrections and parton-shower effects are considered. We find that this process has a sizeable cross section and the QCD correction can reach more than 2 times than LO results. We also investigate the discovery potential in several benchmark scenarios at the 13TeV LHC.

  2. QCD physics with ATLAS and CMS

    CERN Document Server

    Kodolova, Olga

    2015-01-01

    The soft and hard QCD processes are analyzed by the ATLAS and CMS experiments using samples of proton-proton collisions collected by the LHC at sqrt{s}=7 and 8 TeV. Measurements of jet production rates, jet properties, particle multiplicity and particle momentum spectra are presented. The results are compared to predictions of theoretical models at leading- and next-to-leading orders of QCD. The data are used to measure the strong coupling constant and for PDF constraints.

  3. Second order QCD corrections to inclusive semileptonic b \\to Xc l \\bar \

    CERN Document Server

    Biswas, Sandip

    2009-01-01

    We extend previous computations of the second order QCD corrections to semileptonic b \\to c inclusive transitions, to the case where the charged lepton in the final state is massive. This allows accurate description of b \\to c \\tau \\bar \

  4. Charm-quark production in deep-inelastic neutrino scattering at NNLO in QCD

    CERN Document Server

    Berger, Edmond L; Li, Chong Sheng; Liu, Ze Long; Zhu, Hua Xing

    2016-01-01

    We present a fully differential next-to-next-to-leading order calculation of charm quark production in charged-current deep-inelastic scattering, with full charm-quark mass dependence. The next-to-next-to-leading order corrections in perturbative quantum chromodynamics are found to be comparable in size to the next-to-leading order corrections in certain kinematic regions. We compare our predictions with data on dimuon production in (anti-)neutrino scattering from a heavy nucleus. Our results can be used to improve the extraction of the parton distribution function of a strange quark in the nucleon.

  5. Threshold Corrections in Precision LHC Physics: QED otimes QCD

    CERN Document Server

    Ward, B F L; Jadach, Stanislaw; Yost, S A

    2004-01-01

    With an eye toward LHC processes in which theoretical precisions of 1 percent are desired, we introduce the theory of the simultaneous YFS resummation of QED and QCD to compute the size of the expected resummed soft radiative threshold effects in precision studies of heavy particle production at the LHC. Our results show that both QED and QCD soft threshold effects must be controlled to be on the conservative side to achieve such precision goals.

  6. A Study of Weak Corrections to Drell-Yan, Top-quark pair and Di-jet Production at High Energies with MCFM

    CERN Document Server

    Campbell, John M; Zhou, Jia

    2016-01-01

    Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real $W$ and $Z$ bosons that result in Sudakov-like corrections of the form $\\alpha_W^l\\log^n(Q^2/M_{W,Z}^2)$, where $\\alpha_W =\\alpha/(4\\pi\\sin^2\\theta_W)$ and $n\\le 2l-1$. The inclusion of EW corrections in predictions for hadron colliders is therefore especially important when searching for signals of possible new physics in distributions probing the kinematic regime $Q^2 \\gg M_V^2$. Next-to-leading order (NLO) EW corrections should also be taken into account when their size ($\\mathcal{O}(\\alpha)$) is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) ($\\mathcal{O}(\\alpha_s^2)$). To this end we have implemented the NLO weak corrections to the Neutral-Current Drell-Yan process, top-quark pair production and di-jet production in the parton-level Monte-Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide b...

  7. On the NNLO QCD corrections to single-top production at the LHC

    Directory of Open Access Journals (Sweden)

    Mathias Brucherseifer

    2014-09-01

    Full Text Available We present a fully-differential calculation of the NNLO QCD corrections to the t-channel mechanism for producing single top quarks at the LHC. We work in the structure function approximation, computing QCD corrections to the light- and heavy-quark lines separately and neglecting the dynamical cross-talk between the two. The neglected contribution, which appears at NNLO for the first time, is color-suppressed and is expected to be sub-dominant. Within this approximation, we find that, for the total cross section, NNLO QCD corrections are in the few percent range and, therefore, are comparable to NLO QCD corrections. We also find that the scale independence of the theoretical prediction for single-top production improves significantly once NNLO QCD corrections are included. Furthermore, we show how these results change if a cut on the transverse momentum of the top quark is applied and derive the NNLO QCD prediction for the ratio of single top and single anti-top production cross sections at the 8 TeV LHC.

  8. Third-order correction to top-quark pair production near threshold I. Effective theory set-up and matching coefficients

    CERN Document Server

    Beneke, M; Schuller, K

    2013-01-01

    This is the first in a series of papers, in which we compute the third-order QCD corrections to top-antitop production near threshold in e+ e- collisions. The present paper provides a detailed outline of the strategy of computation in the framework of non-relativistic effective theory and the threshold expansion, applicable more generally to heavy-quark pair production near threshold. It summarizes matching coefficients and potentials relevant to the next-to-next-to-next-to-leading order and ends with the master formula for the computation of the third-order Green function. The master formula is evaluated in part II of the series.

  9. Probing the littlest Higgs model with $T$ parity using di-Higgs events through $Z_H$-pair production at the LHC in NLO QCD

    CERN Document Server

    Liang-Wen, Chen; Wen-Gan, Ma; Wei-Hua, Li; Peng-Fei, Duan; Lei, Guo

    2014-01-01

    We investigate the di-Higgs events through $Z_H$-pair production at the CERN Large Hadron Collider including the pure next-to-leading order (NLO) QCD correction and the $gg$-fusion contribution in the framework of the littlest Higgs model with $T$ parity. We employ the diagram subtraction scheme in the QCD NLO calculations to avoid double counting and keep the convergence of the perturbative QCD description for the $Z_H$-pair production. We investigate the dependence of the leading order and QCD corrected integrated cross sections on the renormalization/factorization scale, and find that the total QCD corrections slightly reduce the scale uncertainty in the plotted range. By considering the subsequent decays of the intermediately produced $Z_H$ bosons and adopting the exclusive four-$b$-jet event selection criterion, the QCD correction provides considerable enhancement of the kinematic distributions for final decay products. We find that it is possible to select the signature of the $Z_H$-pair production from...

  10. NLO QCD + EW corrections to $ZZZ$ production with subsequent leptonic decays at LHC

    CERN Document Server

    Hong, Wang; Wen-Gan, Ma; Lei, Guo; Xiao-Zhou, Li; Shao-Ming, Wang

    2016-01-01

    In this paper we present the NLO QCD + NLO EW corrections to the $ZZZ$ production with subsequent $Z$-boson leptonic decays at the LHC by adopting the improved narrow width approximation, which takes into account off-shell contributions and spin correlations. Integrated cross sections at $13$, $14$, $33$ and $100~{\\rm TeV}$ hadron colliders and various kinematic distributions are presented. Our numerical results show that the jet emission correction accounts for a large part of the total QCD correction, especially in the high energy region. By applying a proper cut to the jet transverse momentum, e.g., $p_{{\\rm \\,T,jet}} > p_{{\\rm \\,T,jet}}^{{\\rm \\,\\,\\,cut}}=50~{\\rm GeV}$, the jet emission correction can be reduced and the cross section is less dependent on the factorization/renormalization scale. This work reveals that both the NLO QCD and the NLO EW corrections are significant. For example, the NLO QCD, NLO EW and NLO QCD + EW relative corrections in the inclusive event selection scheme at the $13~{\\rm TeV}...

  11. Threshold Corrections in QED otimes QCD at the LHC

    CERN Document Server

    Ward, B F L; Jadach, Stanislaw; Yost, S A

    2004-01-01

    In some processes at the LHC, theoretical precisions of 1 percent are desired. With an eye toward such precisions, we introduce the theory of the simultaneous YFS resummation of QED and QCD to compute the size of the expected resummed soft radiative threshold effects in precision studies of heavy particle production at the LHC. Our results, that the soft QED threshold effects are at the level of 0.3 percent whereas the soft QCD threshold effects enter at the level of 20 percent, show that both must be controlled to be on the conservative side to achieve such precision goals.

  12. The two-loop QCD correction to massive spin-2 resonance → q anti qg

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Taushif; Rana, Narayan [The Institute of Mathematical Sciences, Chennai (India); Training School Complex, Homi Bhaba National Institute, Mumbai (India); Das, Goutam; Mathews, Prakash [Saha Institute of Nuclear Physics, Theory Division, Kolkata (India); Training School Complex, Homi Bhaba National Institute, Mumbai (India); Ravindran, V. [The Institute of Mathematical Sciences, Chennai (India)

    2016-12-15

    The two-loop QCD correction to massive spin-2 graviton decaying to q + anti q + g is presented considering a generic universal spin-2 coupling to the SM through the conserved energy-momentum tensor. Such a massive spin-2 particle can arise in extra-dimensional models. The ultraviolet and infrared structure of the QCD amplitudes are studied. In dimensional regularization, the infrared pole structure is in agreement with Catani's proposal, confirming the universal factorization property of QCD amplitudes, even with the spin-2 tensorial coupling. (orig.)

  13. W{sup ±}Z production at hadron colliders in NNLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Grazzini, Massimiliano; Wiesemann, Marius [Zuerich Univ. (Switzerland). Physik-Institut; Kallweit, Stefan [Mainz Univ. (Germany). PRISMA Cluster of Excellence, Inst. of Physics; California Univ., Santa Barbara, CA (United States). Kavli Inst. of Theoretical Physics; Rathlev, Dirk [DESY Hamburg (Germany). Theory Group

    2016-04-15

    We report on the first computation of the next-to-next-to-leading order (NNLO) QCD corrections to W{sup ±}Z production in proton collisions. We consider both the inclusive production of on-shell W{sup ±}Z pairs at LHC energies and the total W{sup ±}Z rates including off-shell effects of the W and Z bosons. In the off-shell computation, the invariant mass of the lepton pairs from the Z boson decay is required to be in a given mass window, and the results are compared with the corresponding measurements obtained by the ATLAS and CMS collaborations. The NNLO corrections range from 8% at √(s)=7 TeV to 11% at √(s)=14 TeV and significantly improve the agreement with the LHC data at √(s)=7 and 8 TeV.

  14. Next-to-soft corrections to high energy scattering in QCD and gravity

    CERN Document Server

    Luna, A; Naculich, S G; White, C D

    2016-01-01

    We examine the Regge (high energy) limit of 4-point scattering in both QCD and gravity, using recently developed techniques to systematically compute all corrections up to next-to-leading power in the exchanged momentum i.e. beyond the eikonal approximation. We consider the situation of two scalar particles of arbitrary mass, thus generalising previous calculations in the literature. In QCD, our calculation describes power-suppressed corrections to the Reggeisation of the gluon. In gravity, we confirm a previous conjecture that next-to-soft corrections correspond to two independent deflection angles for the incoming particles. Our calculations in QCD and gravity are consistent with the well-known double copy relating amplitudes in the two theories.

  15. Perturbative QCD corrections to the Z boson width and the Higgs decay rate

    CERN Document Server

    Chetyrkin, K G; Kwiatkowski, A

    1994-01-01

    Radiative QCD corrections significantly influence the theoretical predictions for the decay rates of the Z and the Higgs boson. The status of the QCD calculations to the hadronic Z width is reviewed. The role of mass corrections from bottom quark final states is emphasized. An estimate of the theoretical uncertainties is given. New results for quartic mass terms of order {\\cal O}(\\alpha_s^2) are presented. The impact of secondary radiation of bottom quarks on the determination of \\Gamma(Z\\rightarrow b\\bar{b}) is discussed. Second order QCD corrections to the partial decay rate \\Gamma(H\\rightarrow b\\bar{b}) are also presented in this talk. A recent result for the flavour singlet contribution to this quantity is presented. It includes quark mass effects and completes the otherwise massless calculations of order \\ordas^2).

  16. Higgs boson couplings to bottom quarks: two-loop supersymmetry-QCD corrections.

    Science.gov (United States)

    Noth, David; Spira, Michael

    2008-10-31

    We present two-loop supersymmetry (SUSY) QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the standard model (MSSM). The effective Yukawa couplings include the resummation of the nondecoupling corrections Deltam_{b} for large values of tanbeta. We have derived the two-loop SUSY-QCD corrections to the leading SUSY-QCD and top-quark-induced SUSY-electroweak contributions to Deltam_{b}. The scale dependence of the resummed Yukawa couplings is reduced from O(10%) to the percent level. These results reduce the theoretical uncertainties of the MSSM Higgs branching ratios to the accuracy which can be achieved at a future linear e;{+}e;{-} collider.

  17. QCD threshold corrections to di-lepton and Higgs rapidity distributions beyond N{sup 2}LO

    Energy Technology Data Exchange (ETDEWEB)

    Ravindran, V. [Harish-Chandra Research Institute, Chhatnag road, Jhunsi, Allahabad (India)]. E-mail: ravindra@mri.ernet.in; Smith, J. [C.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794-3840 (United States); Neerven, W.L. van [Lorentz Institute, University of Leiden, P.O. Box 9502, 2300 RA Leiden (Netherlands)

    2007-04-02

    We present threshold enhanced QCD corrections to rapidity distributions of di-leptons in the Drell-Yan process and of Higgs particles in both gluon fusion and bottom quark annihilation processes using Sudakov resummed cross sections. We have used renormalisation group invariance and the mass factorisation theorem that these hard scattering cross sections satisfy as well as Sudakov resummation of QCD amplitudes. We find that these higher order threshold QCD corrections stabilise the theoretical predictions under scale variations.

  18. NLO contributions to B{yields}KK{sup *} decays in the pQCD approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhi-Qing; Xiao, Zhen-Jun [Nanjing Normal University, Department of Physics and Institute of Theoretical Physics, Nanjing, Jiangsu (China)

    2009-01-15

    We calculate the important next-to-leading-order (NLO) contributions to the B{yields}KK{sup *} decays from the vertex corrections, the quark loops, and the magnetic penguins in the perturbative QCD (pQCD) factorization approach. The pQCD predictions for the CP-averaged branching ratios are Br(B{sup +}{yields}K{sup +} anti K{sup *0}){approx}3.2 x 10{sup -7},Br(B{sup +}{yields}anti K{sup 0}K{sup *+}){approx}2.1 x 10{sup -7}, Br(B{sup 0}{yields}K{sup 0} anti K{sup *0}+ anti K{sup 0}K{sup *0}){approx}8.5 x 10{sup -7} and Br(B{sup 0}{yields}K{sup +}K{sup *-}+K{sup -}K{sup *+}){approx}1.3 x 10{sup -7}, which agree well with both the experimental upper limits and the predictions based on the QCD factorization approach. Furthermore, the CP violating asymmetries of the considered decay modes are also evaluated. The NLO pQCD predictions for B{sup +}{yields}K{sup +} anti K{sup *0} and K{sup *+} anti K{sup 0} decays are A{sub CP}{sup dir}(K{sup +} anti K{sup *0}){approx}-6.9% and A{sub CP}{sup dir}(K{sup *+} anti K{sup 0}){approx}6.5%. (orig.)

  19. NNLO corrections to the polarized Drell-Yan coefficient function

    Energy Technology Data Exchange (ETDEWEB)

    Ravindran, V. [Harish-Chandra Research Institute, Chhatnag Road, Jhusii, Allahabad, 211019 (India); Smith, J. [C.N. Yang Institute for Theoretical Physics, State University of New York at Stony Brook, New York 11794-3840 (United States); Neerven, W.L. van [Instituut-Lorentz, Universiteit Leiden, PO Box 9506, 2300 RA Leiden (Netherlands)

    2004-10-01

    We present the full next-to-next-to-leading order (NNLO) corrections to the coefficient function for the polarized cross section d{delta}{sigma}/dQ of the Drell-Yan process. We study the effect of these corrections on the process p+p->l+l-+'X' at an C.M. energy S=200GeV. All QCD partonic subprocesses have been included provided the lepton pair is created by a virtual photon, which is a valid approximation for a lepton pair invariant mass Q50GeV. For this reaction the dominant subprocess is given by q+q-bar ->{gamma}*+'X' and its higher order corrections so that it provides us with an excellent tool to measure the polarized sea-quark densities.

  20. Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction.

    Science.gov (United States)

    Demartin, Federico; Maltoni, Fabio; Mawatari, Kentarou; Page, Ben; Zaro, Marco

    At the LHC the CP properties of the top-quark Yukawa interaction can be probed through Higgs production in gluon fusion or in association with top quarks. We consider the possibility for both CP-even and CP-odd couplings to the top quark to be present, and study CP-sensitive observables at next-to-leading order (NLO) in QCD, including parton-shower effects. We show that the inclusion of NLO corrections sizeably reduces the theoretical uncertainties, and confirm that di-jet correlations in [Formula: see text] jet production through gluon fusion and correlations of the top-quark decay products in [Formula: see text] production can provide sensitive probes of the CP nature of the Higgs interactions.

  1. NLO QCD corrections to Higgs pair production including dimension-6 operators

    Energy Technology Data Exchange (ETDEWEB)

    Groeber, Ramona [INFN, Sezione di Roma Tre, Roma (Italy); Muehlleitner, Margarete; Streicher, Juraj [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Institut fuer Theoretische Physik; Spira, Michael [Paul Scherrer Institut, Villigen (Switzerland)

    2016-07-01

    The role of the Higgs boson has developed from the long-sought particle into a tool for exploring beyond Standard Model (BSM) physics. While the Higgs boson signal strengths are close to the values predicted in the Standard Model (SM), the trilinear Higgs-selfcoupling can still deviate significantly from the SM expectations in some BSM scenarios. The Effective Field Theory (EFT) framework provides a way to describe these deviations in a rather model independent way, by including higher-dimensional operators which modify the Higgs boson couplings and induce novel couplings not present in the SM. The trilinear Higgs-selfcoupling is accessible in Higgs pair production, for which the gluon fusion is the dominant production channel. The next-to-leading (NLO) QCD corrections to this process are important for a proper prediction of the cross section and are known in the limit of heavy top quark masses. In our work, we provide the NLO QCD corrections in the large top quark mass limit to Higgs pair production including dimension-6 operators. The various higher-dimensional contributions are affected differently by the QCD corrections, leading to deviations in the relative NLO QCD corrections of several per-cent, while modifying the cross section by up to an order of magnitude.

  2. NLO Electroweak Corrections to Higgs Decay to Two Photons

    OpenAIRE

    Actis, Stefano

    2009-01-01

    The recent calculation of the next-to-leading order electroweak corrections to the decay of the Standard Model Higgs boson to two photons in the framework of the complex-mass scheme is briefly summarized.

  3. Supersymmetric QCD corrections to dark matter annihilation in the Higgs funnel region

    Science.gov (United States)

    Herrmann, Björn; Klasen, Michael

    2007-12-01

    We compute the full O(αs) SUSY-QCD corrections to dark matter annihilation in the Higgs-funnel, resumming potentially large μtan⁡β and Ab contributions and keeping all finite O(mb,s,1/tan⁡2β) terms. We demonstrate numerically that these corrections strongly influence the extraction of SUSY mass parameters from cosmological data and must therefore be included in common analysis tools such as darksusy or micromegas.

  4. SUSY-QCD Corrections to Dark Matter Annihilation in the Higgs Funnel

    CERN Document Server

    Herrmann, B

    2007-01-01

    We compute the full O(alpha_s) SUSY-QCD corrections to dark matter annihilation in the Higgs-funnel, resumming potentially large mu tan beta and A_b contributions and keeping all finite O(m_b,s,1/tan^2 beta) terms. We demonstrate numerically that these corrections strongly influence the extraction of SUSY mass parameters from cosmological data and must therefore be included in common analysis tools such as DarkSUSY or micrOMEGAs.

  5. Electroweak Corrections at the LHC with MCFM

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, John M. [Fermilab; Wackeroth, Doreen [SUNY, Buffalo; Zhou, Jia [SUNY, Buffalo

    2015-07-10

    Electroweak (EW) corrections at the LHC can be enhanced at high energies due to soft/collinear radiation of W and Z bosons, being dominated by Sudakov-like corrections in the form of $\\alpha_W^l\\log^n(Q^2/M_W^2)$ $(n \\le 2l, \\alpha_W = \\alpha/(4\\pi\\sin\\theta_W^2))$ when the energy scale $Q$ enters the TeV regime. Thus, the inclusion of EW corrections in LHC predictions is important for the search of possible signals of new physics in tails of kinematic distributions. EW corrections should also be taken into account in virtue of their comparable size ($\\mathcal{O}(\\alpha)$) to that of higher order QCD corrections ($\\mathcal{O}(\\alpha_s^2)$). We calculated the next-to-leading-order (NLO) weak corrections to the neutral-current (NC) Drell-Yan process, top-quark pair production and di-jet producion, and implemented them in the Monte-Carlo program MCFM. This enables a combined study with the corresponding NLO QCD corrections. We provide both the full NLO weak corrections and their weak Sudakov approximation valid at high energies. The latter is often used for a fast evaluation of weak effects, and having the exact result available as well allows to quantify the validity of the Sudakov approximation.

  6. $\\bar{B}_{d,s} \\to D^{*}_{d,s} V$ and $\\bar{B}_{d,s}^* \\to D_{d,s} V$ decays with QCD Factorization and Possible Puzzles

    CERN Document Server

    Chang, Qin; Zhang, Yun-Yun; Sun, Jun-Feng; Yang, Yue-Ling

    2016-01-01

    Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic $\\bar{B}_{d,s} \\to D^{*}_{d,s} V$ and $\\bar{B}_{d,s}^* \\to D_{d,s} V$~($V=\\rho\\,,K^*$) decays are performed within the framework of QCD Factorization. Relative to previous works, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured $\\bar{B}_{d,s} \\to D^{*}_{d,s} V$ decays, two tensions between theoretical results and experimental measurements, {\\it i.e.} "$R_{ds}^{V}$ puzzle" and "$D^{*} V$~(or $R_{V/\\ell\\bar{\

  7. Numerical evaluation of virtual corrections to multi-jet production in massless QCD

    DEFF Research Database (Denmark)

    Badger, S.; Yundin, V.; Biedermann, B.

    2013-01-01

    .7.4. Classification: 11.5. External routines: QCDLoop (http://qcdloop.fnal.gov/), qd (http://crd.lbl.gov/dhbailey/mpdist/), both included in the distribution file. Nature of problem:. Evaluation of virtual corrections for multi-jet production in massless QCD. Solution method:. Purely numerical approach based on tree......We present a C++ library for the numerical evaluation of one-loop virtual corrections to multi-jet production in massless QCD. The pure gluon primitive amplitudes are evaluated using NGluon (Badger et al., (2011) [62]). A generalized unitarity reduction algorithm is used to construct arbitrary...... amplitudes obtained via Berends-Giele recursion combined with unitarity method. Restrictions:. Full colour and helicity summed corrections only up to 5 final state jets. Running time:. Full colour and helicity summed 2 ¿ 4 channels take around 0.5-8 s per point depending on the number of fermion lines...

  8. NLO dispersion laws for slow-moving quarks in HTL QCD

    Energy Technology Data Exchange (ETDEWEB)

    Abada, Abdessamad [Laboratoire de Physique des Particules et Physique Statistique, Ecole Normale Supérieure,BP 92 Vieux Kouba, 16050 Alger (Algeria); Physics Department, United Arab Emirates University,POB 17551 Al Ain (United Arab Emirates); Benchallal, Karima; Bouakaz, Karima [Laboratoire de Physique des Particules et Physique Statistique, Ecole Normale Supérieure,BP 92 Vieux Kouba, 16050 Alger (Algeria)

    2015-03-11

    We determine the next-to-leading order dispersion laws for slow-moving quarks in hard-thermal-loop perturbation of high-temperature QCD where weak coupling is assumed. Real-time formalism is used. The next-to-leading order quark self-energy is written in terms of three and four HTL-dressed vertex functions. The hard thermal loops contributing to these vertex functions are calculated ab initio and expressed using the Feynman parametrization which allows the calculation of the solid-angle integrals involved. We use a prototype of the resulting integrals to indicate how finite results are obtained in the limit of vanishing regularizer.

  9. SUSY-QCD corrections to stop annihilation into electroweak final states including Coulomb enhancement effects

    Science.gov (United States)

    Harz, J.; Herrmann, B.; Klasen, M.; Kovařík, K.; Meinecke, M.

    2015-02-01

    We present the full O (αs) supersymmetric QCD corrections for stop-antistop annihilation into electroweak final states within the Minimal Supersymmetric Standard Model. We also incorporate Coulomb corrections due to gluon exchange between the incoming stops. Numerical results for the annihilation cross sections and the predicted neutralino relic density are presented. We show that the impact of the radiative corrections on the cosmologically preferred region of the parameter space can become larger than the current experimental uncertainty, shifting the relic bands within the considered regions of the parameter space by up to a few tens of GeV.

  10. SUSY-QCD corrections to stop annihilation into electroweak final states including Coulomb enhancement effects

    CERN Document Server

    Harz, J; Klasen, M; Kovařík, K; Meinecke, M

    2014-01-01

    We present the full $\\mathcal{O}(\\alpha_s)$ supersymmetric QCD corrections for stop-anti-stop annihilation into electroweak final states within the Minimal Supersymmetric Standard Model (MSSM). We also incorporate Coulomb corrections due to gluon exchange between the incoming stops. Numerical results for the annihilation cross sections and the predicted neutralino relic density are presented. We show that the impact of the radiative corrections on the cosmologically preferred region of the parameter space can become larger than the current experimental uncertainty, shifting the relic bands within the considered regions of the parameter space by up to a few tens of GeV.

  11. O.P.E. and Power Corrections to the QCD coupling constant

    CERN Document Server

    Boucaud, P; Leroy, J P; Le Yaouanc, A; Micheli, J; Moutarde, H; Pène, O; Rodríguez-Quintero, J; Boucaud, Ph.

    2003-01-01

    Lattice data seems to show that power corrections should be convoked to describe appropriately the transition of the QCD coupling constant running from U.V. to I.R. domains. Those power corrections for the Landau-gauge MOM coupling constant in a pure Yang-Mills theory (N_f=0) are analysed in terms of Operator Product Expansion (O.P.E.) of two- and three-point Green functions, the gluon condensate emerging from this study. The semi-classical picture given by instantons can be also used to look for into the nature of the power corrections and gluon condensate.

  12. $(\\alpha')^4$ Corrections in Holographic Large $N_c$ QCD and $\\pi - \\pi$ Scattering

    CERN Document Server

    Parthasarathy, R

    2007-01-01

    We calculate the ${\\alpha'}^4$ corrections to the non-Abelian DBI action on the $D8$-brane in the holographic dual of large $N_c$ QCD proposed by Sakai and Sugimoto. These give rise to higher derivative terms, in particular, four derivative contact terms for the pion field with the coupling uniquely determined. We calculate the pion-pion scattering amplitude near threshold. The results respecting unitarity are in agreement with the experimental curves.

  13. QCD corrections in a class of spontaneous CP-violating models

    Energy Technology Data Exchange (ETDEWEB)

    Tracas, N.D.; Vlachos, N.D.; Zoupanos, G.

    1985-10-31

    We present a study of QCD corrections in a class of spontaneous CP-violating models. We find that the Higgs fields which are responsible for the CP-violating transitions should be one order of magnitude heavier than what is expected fom tree order estimates. This implies so large a self-coupling of the Higgs fields that it makes the use of perturbation expansion questionable. (orig.).

  14. Finite Size Corrected Relativistic Mean-Field Model and QCD Critical End Point

    CERN Document Server

    Uddin, Saeed; Ahmad, Jan Shabir

    2012-01-01

    The effect of finite size of hadrons on the QCD phase diagram is analyzed using relativistic mean field model for the hadronic phase and the Bag model for the QGP phase. The corrections to the EOS for hadronic phase are incorporated in a thermodynamic consistent manner for Van der Waals like interaction. It is found that the effect of finite size of baryons is to shift CEP to higher chemical potential values.

  15. Dominant mixed QCD-electroweak O(αsα corrections to Drell–Yan processes in the resonance region

    Directory of Open Access Journals (Sweden)

    Stefan Dittmaier

    2016-03-01

    Full Text Available A precise theoretical description of W- and Z-boson production in the resonance region is essential for the correct interpretation of high-precision measurements of the W-boson mass and the effective weak mixing angle. Currently, the largest unknown fixed-order contribution is given by the mixed QCD-electroweak corrections of O(αsα. We argue, using the framework of the pole expansion for the NNLO QCD-electroweak corrections established in a previous paper, that the numerically dominant corrections arise from the combination of large QCD corrections to the production with the large electroweak corrections to the decay of the W/Z boson. We calculate these so-called factorizable corrections of “initial–final” type and estimate the impact on the W-boson mass extraction. We compare our results to simpler approximate combinations of electroweak and QCD corrections in terms of naive products of NLO QCD and electroweak correction factors and using leading-logarithmic approximations for QED final-state radiation as provided by the structure-function approach or QED parton-shower programs. We also compute corrections of “final–final” type, which are given by finite counterterms to the leptonic vector-boson decays and are found to be numerically negligible.

  16. Two-Loop QCD Correction to massive spin-2 resonance $\\rightarrow$ 3 gluons

    CERN Document Server

    Ahmed, Taushif; Mathews, Prakash; Rana, Narayan; Ravindran, V

    2014-01-01

    We present the ${\\cal O}(\\alpha_s^3)$ virtual QCD corrections to the process $h \\rightarrow g+g+g$ due to interference of born and two-loop amplitudes, where $h$ is a massive spin-2 particle and $g$ is the gluon. We assume that the SM fields couple to $h$ through the SM energy momentum tensor. Our result constitutes one of the ingredients to full NNLO QCD contribution to production of a massive spin-2 particle along with a jet in the scattering process at the LHC. In particular, this massive spin-2 could be a KK mode of a ADD graviton in large extra dimensional model or a RS KK mode in warped extra dimensional model or a generic massive spin-2. In addition, it provides an opportunity to study the ultraviolet and infrared structures of QCD amplitudes involving tensorial coupling resulting from energy momentum operator. Using dimensional regularization, we find that infrared poles of this amplitude are in agreement with the proposal by Catani confirming the factorization property of QCD amplitudes with tensoria...

  17. Bootstrapping Multi-Parton Loop Amplitudes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Zvi; /UCLA; Dixon, Lance J.; /SLAC; Kosower, David A.; /Saclay, SPhT

    2005-07-06

    The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.

  18. Dominant NNLO Corrections to Four-Fermion Production at the WW Threshold

    CERN Document Server

    Actis, Stefano

    2009-01-01

    The recent evaluation of the parametrically dominant next-to-next-to-leading order corrections to four-fermion production near the W-pair threshold in the framework of unstable-particle effective theory is briefly summarized.

  19. Combination of the inclusive DIS e{sup ±}p cross sections from HERA, QCD and EW analyses and the need for low-Q{sup 2} higher-twist corrections

    Energy Technology Data Exchange (ETDEWEB)

    Myronenko, Volodymyr

    2017-01-15

    A combination of the inclusive lepton-proton cross sections from the ZEUS and H1 experiments is presented. The data are combined taking into account correlations of the systematic uncertainties of the measurements. The resulting combined inclusive neutral- and charged-current e{sup ±}p cross sections derived from ∝1 fb{sup -1} of data, cover the kinematic region of 0.045≤Q{sup 2}≤50000 GeV{sup 2} and 6.10{sup -7}≤x{sub Bj}≤0.65. The combined data is an unique legacy of the HERA collider and the core of any parton-density-function extraction. The parton distribution functions are essential ingredients in the evaluation of QCD predictions for the high-energy processes, studied at modern proton colliders. The methodology of HERAPDF fits is used as an ansatz for the global QCD fit. The charm- and beauty-quark mass parameters in the analyses at next-next-to-leading order were found to be M{sup opt}{sub c}=1.43 GeV and M{sup opt}{sub b}=4.5 GeV, respectively. HERAPDF2.0 sets give reasonable DIS data description. The effect of higher-twist corrections on the DIS structure functions was studied. The twist-4 corrections were introduced to the F{sub 2} and F{sub L} structure functions. A minimal improvement in the data description was found for the F{sub 2} correction. The introduction of a higher-twist correction to the F{sub L} structure function improved the QCD fit quality by up to Δχ{sup 2}=47, predominantly affecting the low-x{sub Bj} and low-Q{sup 2} regions. The twist-4 correction causes an unphysical rise of the predicted F{sub L} in the low x{sub Bj} region. The results indicate a need for further investigations. The electroweak parameters and PDFs are determined simultaneously using the HERA inclusive cross sections together with information on the lepton beam polarisation. The vector- and axial-vector couplings of the u- and d-type quarks to the Z{sup 0} boson are determined simultaneously. The u-type quark couplings were found to be a{sub u}=0

  20. BCFW tree level QCD corrections to WBF Higgs production

    Science.gov (United States)

    Fazio, A. R.; Vargas, S. C.

    2012-07-01

    We explicitly compute analytic tree level amplitudes for the production of a Higgs boson via Weak Boson Fusion (WBF) with one and two additional gluon emissions in the final state. Also, the computation for the additional emission of an arbitrary number of gluons is discussed, obtaining a general result related to the procedure of contraction of 2 Single Weak Boson (SWB) currents which are precisely characterized. The generalization of the Britto-Cachazo-Feng-Witten (BCFW) formula to the massive case is applied obtaining compact results which agree with those calculated with the conventional approach of Feynman diagrams. We show that, in relation to the latter method, the involved BCFW amplitudes are computed through a notably more efficient process (particularly for high numbers of external particles) suggesting that successive corrections to the WBF process can be obtained alike in a swift way. The explicit expressions are provided in a parallel presentation of both approaches, putting the emphasis on the fundamental features and advantages of the BCFW scheme.

  1. Resumming double logarithms in the QCD evolution of color dipoles

    Directory of Open Access Journals (Sweden)

    E. Iancu

    2015-05-01

    Full Text Available The higher-order perturbative corrections, beyond leading logarithmic accuracy, to the BFKL evolution in QCD at high energy are well known to suffer from a severe lack-of-convergence problem, due to radiative corrections enhanced by double collinear logarithms. Via an explicit calculation of Feynman graphs in light cone (time-ordered perturbation theory, we show that the corrections enhanced by double logarithms (either energy-collinear, or double collinear are associated with soft gluon emissions which are strictly ordered in lifetime. These corrections can be resummed to all orders by solving an evolution equation which is non-local in rapidity. This equation can be equivalently rewritten in local form, but with modified kernel and initial conditions, which resum double collinear logs to all orders. We extend this resummation to the next-to-leading order BFKL and BK equations. The first numerical studies of the collinearly-improved BK equation demonstrate the essential role of the resummation in both stabilizing and slowing down the evolution.

  2. Resumming double logarithms in the QCD evolution of color dipoles

    Energy Technology Data Exchange (ETDEWEB)

    Iancu, E., E-mail: edmond.iancu@cea.fr [Institut de Physique Théorique, CEA Saclay, UMR 3681, F-91191 Gif-sur-Yvette (France); Madrigal, J.D., E-mail: jose-daniel.madrigal-martinez@cea.fr [Institut de Physique Théorique, CEA Saclay, UMR 3681, F-91191 Gif-sur-Yvette (France); Mueller, A.H., E-mail: amh@phys.columbia.edu [Department of Physics, Columbia University, New York, NY 10027 (United States); Soyez, G., E-mail: gregory.soyez@cea.fr [Institut de Physique Théorique, CEA Saclay, UMR 3681, F-91191 Gif-sur-Yvette (France); Triantafyllopoulos, D.N., E-mail: trianta@ectstar.eu [European Centre for Theoretical Studies in Nuclear Physics and Related Areas ECT* and Fondazione Bruno Kessler, Strada delle Tabarelle 286, I-38123 Villazzano (Italy)

    2015-05-11

    The higher-order perturbative corrections, beyond leading logarithmic accuracy, to the BFKL evolution in QCD at high energy are well known to suffer from a severe lack-of-convergence problem, due to radiative corrections enhanced by double collinear logarithms. Via an explicit calculation of Feynman graphs in light cone (time-ordered) perturbation theory, we show that the corrections enhanced by double logarithms (either energy-collinear, or double collinear) are associated with soft gluon emissions which are strictly ordered in lifetime. These corrections can be resummed to all orders by solving an evolution equation which is non-local in rapidity. This equation can be equivalently rewritten in local form, but with modified kernel and initial conditions, which resum double collinear logs to all orders. We extend this resummation to the next-to-leading order BFKL and BK equations. The first numerical studies of the collinearly-improved BK equation demonstrate the essential role of the resummation in both stabilizing and slowing down the evolution.

  3. Electroweakino pair production at the LHC: NLO SUSY-QCD corrections and parton-shower effects

    CERN Document Server

    Baglio, Julien; Kesenheimer, Matthias

    2016-01-01

    We present a set of NLO SUSY-QCD calculations for the pair production of neutralinos and charginos at the LHC, and their matching to parton-shower programs in the framework of the POWHEG-BOX program package. The code we have developed provides a SUSY Les Houches Accord interface for setting supersymmetric input parameters. Decays of the neutralinos and charginos and parton-shower effects can be simulated with PYTHIA. To illustrate the capabilities of our program, we present phenomenological results for a representative SUSY parameter point. We find that NLO-QCD corrections increase the production rates for neutralinos and charginos significantly. The impact of parton-shower effects on distributions of the weakinos is small, but non-negligible for jet distributions.

  4. QCD factorization for high $p_T$ heavy quarkonium production

    CERN Document Server

    Ma, Yan-Qing; Sterman, George; Zhang, Hong

    2015-01-01

    In this talk, we present the QCD factorization formula for heavy quarkonium production at large $p_T$ with factorized leading-power and next-to-leading power contributions in the $1/p_T$ expansion. We show that the leading order analytical calculations in this QCD factorization approach can reproduce effectively the full next-to-leading order numerical results derived using non-relativistic QCD (NRQCD) factorization formalism. We demonstrate that the next-to-leading power contributions are crucial to the description of the channels that are the most relevant for the rate as well as polarization of $J/\\psi$ production at current collider energies.

  5. Second order QCD corrections to scalar and pseudoscalar Higgs decays into massive bottom quarks

    CERN Document Server

    Chetyrkin, K G

    1995-01-01

    Quark mass effects in {\\cal O}(\\alpha_s^2) QCD corrections to the decay rates of intermediate Higgs bosons are studied. The total hadronic rate and the partial decay rate into bottom quarks are analyzed for the Standard (scalar) Higgs boson as well as for pseudoscalar Higgs bosons. The calculations of three different contributions are presented. First, the flavour singlet diagrams containing two closed fermion loops are calculated for a nonvanishing bottom mass in the heavy top limit. Their leading contribution, which is of the same order as the quasi-massless nonsinglet corrections, and the subleading terms are found. Large logarithms arise due to the separation of the pure gluon final state from the bottom final states. Second, quadratic bottom mass corrections originating from nonsinglet diagrams are presented.Third, nonsinglet corrections induced by virtual heavy top quarks are calculated in leading and subleading orders. It is demonstrated that, in order \\alpha_s^2, the first contribution numerically dom...

  6. NNLO QCD corrections to $pp \\to \\gamma^* \\gamma^*$ in the large $N_F$ limit

    CERN Document Server

    Anastasiou, Charalampos; Chavez, Federico; Duhr, Claude; Lazopoulos, Achilleas; Mistlberger, Bernhard; Mueller, Romain

    2014-01-01

    We compute the NNLO QCD corrections for the hadroproduction of a pair of off-shell photons in the limit of a large number of quark flavors. We perform a reduction of the two-loop amplitude to master integrals and calculate the latter analytically as a Laurent series in the dimensional regulator using modern integration methods. Real radiation corrections are evaluated numerically with a direct subtraction of infrared limits which we cast in a simple factorized form. The results presented here constitute a gauge invariant part of the full NNLO corrections but are not necessarily dominant. We view this calculation as a step towards a complete computation. Our partial corrections to the total cross-section are about $1\\%-3\\%$ and vary with the virtuality of the two off-shell photons.

  7. EW and QCD One-Loop Amplitudes with RECOLA

    CERN Document Server

    Actis, Stefano; Hofer, Lars; Scharf, Andreas; Uccirati, Sandro

    2013-01-01

    We present the computer code RECOLA for the computation of EW and QCD amplitudes in the Standard Model at next-to-leading order. One-loop amplitudes are represented as linear combinations of tensor integrals whose coefficients are calculated by means of recursive relations similar to Dyson-Schwinger equations. A novel treatment of colour enables us to recursively construct the colour structure of the amplitude efficiently. RECOLA is linked with the library COLLIER for the computation of the tensor integrals.

  8. Overview of parton distributions and the quantum chromodynamics (QCD) framework

    Energy Technology Data Exchange (ETDEWEB)

    Tuni, Wu-Ki (Institute of Gas Technology, Chicago, IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))

    1990-08-01

    The perturbative QCD framework as the basis of the parton model is reviewed with emphasis on several issues pertinent to next-to-leading order (NLO) applications to a wide range of high energy processes. The current status of leading-order and NLO parton distributions is summarized and evaluated. Relevant issues and open questions for second-generation global analyses are discussed in order to provide an overview of topics to be covered by the Workshop. 15 refs., 6 figs., 1 tabs.

  9. ρ -meson longitudinal leading-twist distribution amplitude within QCD background field theory

    Science.gov (United States)

    Fu, Hai-Bing; Wu, Xing-Gang; Cheng, Wei; Zhong, Tao

    2016-10-01

    We revisit the ρ -meson longitudinal leading-twist distribution amplitude (DA) ϕ2;ρ ∥ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments ⟨ξn;ρ ∥⟩ , we include the next-to-leading order QCD correction to the perturbative part and keep all nonperturbative condensates up to dimension-six consistently within the background field theory. The first two moments read ⟨ξ2;ρ ∥⟩|1 GeV=0.241 (28 ) and ⟨ξ4;ρ ∥⟩|1 GeV=0.109 (10 ) , indicating a double humped behavior for ϕ2;ρ ∥ at small energy scale. As an application, we apply them to the B →ρ transition form factors within the QCD light-cone sum rules, which are key components for the decay width Γ (B →ρ ℓνℓ) . To compare with the world average of Γ (B →ρ ℓνℓ) issued by Particle Data Group, we predict |Vub|=3.1 9-0.62+0.65 , which agrees with the BABAR and Omnès parametrization prediction within errors.

  10. Analytic results for virtual QCD corrections to Higgs production and decay

    Energy Technology Data Exchange (ETDEWEB)

    Aglietti, Ugo [Dipartimento di Fisica, Universita di Roma ' La Sapienza' and INFN, Sezione di Roma, P.le Aldo Moro 2, I-00185 Rome (Italy); Bonciani, Roberto [Departament de Fisica Teorica, IFIC, CSIC - Universitat de Valencia, E-46071 Valencia (Spain); Degrassi, Giuseppe [Dipartimento di Fisica, Universita di Roma Tre and INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Vicini, Alessandro [Dipartimento di Fisica, Universita di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milan (Italy)

    2007-01-15

    We consider the production of a Higgs boson via gluon-fusion and its decay into two photons. We compute the NLO virtual QCD corrections to these processes in a general framework in which the coupling of the Higgs boson to the external particles is mediated by a colored fermion and a colored scalar. We present compact analytic results for these two-loop corrections that are expressed in terms of Harmonic Polylogarithms. The expansion of these corrections in the low and high Higgs mass regimes, as well as the expression of the new Master Integrals which appear in the reduction of the two-loop amplitudes, are also provided. For the fermionic contribution, we provide an independent check of the results already present in the literature concerning the Higgs boson and the production and decay of a pseudoscalar particle.

  11. Large mass expansion in two-loop QCD corrections of para-charmonium decay

    CERN Document Server

    Hasegawa, K; Pak, Alexey

    2006-01-01

    We calculate the light-by-light scattering type two-loop QCD corrections due to the light quark loops in the para-charmonium decays $eta_{c} rightarrow gamma gamma$ and $eta_{c} rightarrow g g$. We replace the mass of the internal charm quarks by an artificial large mass and obtain the result as a series in the large mass. The obtained series can be transformed into the good convergent ones by a change of the expansion parameter. The results are supported by two other methods to improve the convergence. We also observe that the color singlet state of $eta_{c}$ eliminates the potential divergences in the two-loop QCD corrections. The obtained corrections to the modes $eta_{c} rightarrow gamma gamma$ and $eta_{c} rightarrow g g$ account for -1.25% and -0.73% of the tree level values, respectively. Comparing the ratio of the decay rates with the experimental value, we find the constrains on the unknown contribution to these decays.

  12. Susy-QCD corrections to neutrlino pair production in association with a jet

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Gavin [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Greiner, Nicolas; Heinrich, Gudrun [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2012-12-15

    We present the NLO Susy-QCD corrections to the production of a pair of the lightest neutralinos plus one jet at the LHC, appearing as a monojet signature in combination with missing energy. We fully include all non-resonant diagrams, i.e. we do not assume that production and decay factorise. We derive a parameter point based on the p19MSSM which is compatible with current experimental bounds and show distributions based on missing transverse energy and jet observables. Our results are produced with the program GoSam for automated one-loop calculations in combination with MadDipole/- MadGraph for the real radiation part.

  13. B→πη('), η(')η(') decays and NLO contributions in the pQCD approach

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Qing; LIU Xin; XIAO Zhen-Jun

    2009-01-01

    By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B→πη(') and η(')η(') decays. For B+B→π+η(') decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of ACPdir(π±η)=-19±7% can also be accommodated by the pQCD approach.

  14. Nested soft-collinear subtractions in NNLO QCD computations

    Energy Technology Data Exchange (ETDEWEB)

    Caola, Fabrizio [CERN, Theoretical Physics Department, Geneva (Switzerland); IPPP, Durham University, Durham (United Kingdom); Melnikov, Kirill; Roentsch, Raoul [Institute for Theoretical Particle Physics, KIT, Karlsruhe (Germany)

    2017-04-15

    We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector where energies and angles of unresolved particles vanish in a correlated fashion is redundant and can be discarded. This simple observation allows us to formulate a transparent iterative subtraction procedure for double-real emission contributions, to demonstrate the cancellation of soft and collinear singularities in an explicit and (almost) process-independent way and to write the result of a NNLO calculation in terms of quantities that can be computed in four space-time dimensions. We illustrate this procedure explicitly in the simple case of O(α{sub s}{sup 2}) gluonic corrections to the Drell-Yan process of q anti q annihilation into a lepton pair. We show that this framework leads to fast and numerically stable computation of QCD corrections. (orig.)

  15. SUSY-QCD corrections to (co)annihilation and their impact on the relic density

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Herrmann, Bjoern [Laboratoire d' Annecy de Physique Theorique, Annecy-le-Vieux (France); Klasen, Michael [Institute for Theoretical Physics, University of Muenster (Germany); Kovarik, Karol [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Le Boulc' h, Quentin [Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France)

    2013-07-01

    We computed the full O(α{sub s}) supersymmetric QCD corrections for neutralino-stop co-annihilation in the Minimal Supersymmetric Standard Model (MSSM). It is shown that these annihilation channels are phenomenologically relevant within the so-called phenomenological MSSM, in particular in the light of the observation of a Higgs-like particle with a mass of about 126 GeV at the LHC. Numerical results for the co-annihilation cross sections and the predicted neutralino relic density are presented. It will be demonstrated that the impact of including these corrections on the cosmologically preferred region of parameter space is larger than the current experimental uncertainty from WMAP data.

  16. Bulk viscous corrections to screening and damping in QCD at high temperatures

    CERN Document Server

    Du, Qianqian; Guo, Yun; Strickland, Michael

    2016-01-01

    Non-equilibrium corrections to the distribution functions of quarks and gluons in a hot and dense QCD medium modify the "hard thermal loops" (HTL). The HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators for gluons with soft momenta as well as the Debye screening and Landau damping mass scales. We compute such corrections to a thermal as well as to a non-thermal fixed point.The screening and damping mass scales are sensitive to the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk viscosity in the vicinity of a second-order critical point. This could be reflected in the properties of quarkonium bound states in the deconfined phase and in the dynamics of soft gluon fields.

  17. Mixed QCD-EW corrections for Higgs boson production at $e^+e^-$ colliders

    CERN Document Server

    Gong, Yinqiang; Xu, Xiaofeng; Yang, Li Lin

    2016-01-01

    Since the discovery of the Higgs boson at the Large Hadron Collider, a future electron-position collider has been proposed for precisely studying its properties. We investigate the production of the Higgs boson at such an $e^+e^-$ collider and calculate for the first time the mixed QCD-electroweak corrections to the total cross sections. We find that the $\\mathcal{O}(\\alpha\\alpha_s)$ corrections amount to a $1.2\\%$ increase of the cross section for a center-of-mass energy around 250 GeV. This is larger than the expected experimental accuracy and has to be included for extracting the properties of the Higgs boson from the measurements of the cross sections in the future.

  18. QCD corrections to B→π form factors from light-cone sum rules

    Directory of Open Access Journals (Sweden)

    Yu-Ming Wang

    2015-09-01

    Full Text Available We compute perturbative corrections to B→π form factors from QCD light-cone sum rules with B-meson distribution amplitudes. Applying the method of regions we demonstrate factorization of the vacuum-to-B-meson correlation function defined with an interpolating current for pion, at one-loop level, explicitly in the heavy quark limit. The short-distance functions in the factorization formulae of the correlation function involves both hard and hard-collinear scales; and these functions can be further factorized into hard coefficients by integrating out the hard fluctuations and jet functions encoding the hard-collinear information. Resummation of large logarithms in the short-distance functions is then achieved via the standard renormalization-group approach. We further show that structures of the factorization formulae for fBπ+(q2 and fBπ0(q2 at large hadronic recoil from QCD light-cone sum rules match that derived in QCD factorization. In particular, we perform an exploratory phenomenological analysis of B→π form factors, paying attention to various sources of perturbative and systematic uncertainties, and extract |Vub|=(3.05−0.38+0.54|th.±0.09|exp.×10−3 with the inverse moment of the B-meson distribution amplitude ϕB+(ω determined by reproducing fBπ+(q2=0 obtained from the light-cone sum rules with π distribution amplitudes. Furthermore, we present the invariant-mass distributions of the lepton pair for B→πℓνℓ (ℓ=μ,τ in the whole kinematic region. Finally, we discuss non-valence Fock state contributions to the B→π form factors fBπ+(q2 and fBπ0(q2 in brief.

  19. NLO QCD Corrections to the Polarized Photo- and Hadroproduction of Heavy Quarks

    CERN Document Server

    Bojak, I

    2000-01-01

    The complete details of our calculation of the NLO QCD corrections to heavy flavor photo- and hadroproduction with longitudinally polarized initial states are presented. The main motivation for investigating these processes is the determination of the polarized gluon density at the COMPASS and RHIC experiments, respectively, in the near future. All methods used in the computation are extensively documented, providing a self-contained introduction to this type of calculations. Some employed tools also may be of general interest, e.g., the series expansion of hypergeometric functions. The relevant parton level results are collected and plotted in the form of scaling functions. However, the simplification of the obtained gluon-gluon virtual contributions has not been completed yet. Thus NLO phenomenological predictions are only given in the case of photoproduction. The theoretical uncertainties of these predictions, in particular with respect to the heavy quark mass, are carefully considered. Also it is shown th...

  20. QCD corrections to the t$\\to$H+b decay within the minimal supersymmetric standard model

    CERN Document Server

    König, H

    1994-01-01

    I present the contribution of gluinos and scalar quarks to the decay rate of the top quark into a charged Higgs boson and a bottom quark within the minimal supersymmetric standard model, including the mixing of the scalar partners of the left- and right-handed top quark. I show that for certain values of the supersymmetric parameters the standard QCD loop corrections to this decay mode are diminished or enhanced by several 10 per cent. I show that not only a small value of 3 GeV for the gluino mass (small mass window) but also much larger values of several hundreds of GeV's have a non-neglible effect on this decay rate, against general belief. Last but not least, if the ratio of the vacuum expectation values of the Higgs bosons are taken in the limit of $v_1\\ll v_2$ I obtain a drastic enhancement due to a $\\tan\\beta$\\ dependence in the couplings.

  1. Heavy quark effective field theory at $O(1/m_{Q}^{2})$; 1, QCD corrections to the Lagrangian

    CERN Document Server

    Balzereit, C; Balzereit, Christopher; Ohl, Thorsten

    1996-01-01

    We present a new calculation of the renormalized HQET Lagrangian at order O(1/m_Q^2) and discuss the consequences of the BRST invariance of QCD and the reparameterization invariance of HQET. Our result corrects earlier, conflicting calculations and sets the stage for the calculation of the renormalized currents at order O(1/m_Q^2).

  2. Penguin-dominated B -> PV decays in NLO perturbative QCD

    CERN Document Server

    Li, H; Li, Hsiang-nan; Mishima, Satoshi

    2006-01-01

    We study the penguin-dominated B -> PV decays, with P (V) representing a pseudo-scalar (vector) meson, in the next-to-leading-order (NLO) perturbative QCD (PQCD) formalism, concentrating on the B -> K phi, pi K^*, rho K, and omega K modes. It is found that the NLO corrections dramatically enhance the B -> rho K, \\omega K branching ratios, which were estimated to be small under the naive factorization assumption. The patterns of the direct CP asymmetries A_{CP}(B^0 -> rho^\\mp K^\\pm) \\approx A_{CP}(B^\\pm -> rho^0 K^\\pm) and |A_{CP}(B^0 -> pi^\\mp K^{*\\pm})| > |A_{CP}(B^\\pm -> pi^0 K^{*\\pm})| are predicted, differing from |A_{CP}(B^0 -> pi^\\mp K^\\pm)| >> |A_{CP}(B^\\pm -> pi^0 K^\\pm)|. The above patterns, if confirmed by data, will support the source of strong phases from the scalar penguin annihilation in PQCD. The results for the mixing-induced CP asymmetries S_f are consistent with those obtained in the literature, except that our S_{rho^0 K_S} is as low as 0.5.

  3. Nucleon spin structure functions at NNLO in the presence of target mass corrections and higher twist effects

    Science.gov (United States)

    Khanpour, Hamzeh; Taheri Monfared, S.; Atashbar Tehrani, S.

    2017-04-01

    We extract polarized parton distribution functions (PPDFs), referred to as "KTA17," together with the highly correlated strong coupling αs from recent and up-to-date g1 and g2 polarized structure functions world data at next-to-next-to-leading order in perturbative QCD. The stability and reliability of the results are ensured by including nonperturbative target mass corrections as well as higher-twist terms which are particularly important at the large-x region at low Q2 . Their role in extracting the PPDFs in the nucleon is studied. Sum rules are discussed and compared with other results from the literature. This analysis is made by means of the Jacobi polynomials expansion technique to the DGLAP evolution. The uncertainties on the observables and on the PPDFs throughout this paper are computed using standard Hessian error propagation which served to provide a more realistic estimate of the PPDFs uncertainties.

  4. Results on {alpha}{sub s} and QCD from (and above) the Z{sup 0}

    Energy Technology Data Exchange (ETDEWEB)

    Burrows, P.N. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center

    1997-09-01

    In electron-positron annihilation hadronic activity is, by construction, limited to the final state, making the study of hadronic events cleaner and simpler relative to lepton-hadron and hadron-hadron collisions, from both the experimental and theoretical points-of-view. To be specific, samples of hadronic events can be selected by experiments at the Z{sup 0} resonance with efficiency and purity of better than 99%. Jet and event-shape observables have been calculated at next-to-leading order, O({alpha}{sub s}{sup 2}), and some inclusive observables have been calculated at O({alpha}{sub s}{sup 3}). Non-perturbative calculations, in the form of power corrections to perturbatively-evaluated observables, have been performed, and there are well-understood models of hadronization that have been carefully tuned to the data collected over the past 20 years. Electron-positron annihilation thus provides an ideal environment for precise tests of QCD, and has yielded spectacular results. Here, measurements of {alpha}{sub s} from e{sup +}e{sup {minus}} annihilation experiments are reviewed and compared with measurements from other processes. Highlights are presented of recent QCD studies in e{sup +}e{sup {minus}} annihilation at the Z{sup 0} resonance.

  5. Short path length pQCD corrections to energy loss in the quark gluon plasma

    CERN Document Server

    Kolbe, Isobel

    2015-01-01

    Recent surprising discoveries of collective behaviour of low-$p_T$ particles in $pA$ collisions at LHC hint at the creation of a hot, fluid-like QGP medium. The seemingly conflicting measurements of non-zero particle correlations and $R_{pA}$ that appears to be consistent with unity demand a more careful analysis of the mechanisms at work in such ostensibly minuscule systems. We study the way in which energy is dissipated in the QGP created in $pA$ collisions by calculating, in pQCD, the short separation distance corrections to the well-known DGLV energy loss formulae that have produced excellent predictions for $AA$ collisions. We find that, shockingly, due to the large formation time (compared to the $1/\\mu$ Debye screening length) assumption that was used in the original DGLV calculation, a highly non-trivial cancellation of correction terms results in a null short path length correction to the DGLV energy loss formula. We investigate the effect of relaxing the large formation time assumption in the final ...

  6. Another mean field treatment in the strong coupling limit of lattice QCD

    OpenAIRE

    Ohnishi, Akira; Miura, Kohtaroh; Nakano, Takashi Z.

    2011-01-01

    We discuss the QCD phase diagram in the strong coupling limit of lattice QCD by using a new type of mean field coming from the next-to-leading order of the large dimensional expansion. The QCD phase diagram in the strong coupling limit recently obtained by using the monomer-dimer-polymer (MDP) algorithm has some differences in the phase boundary shape from that in the mean field results. As one of the origin to explain the difference, we consider another type of auxiliary field, which corresp...

  7. Two-loop current-current operator contribution to the non-leptonic QCD penguin amplitude

    CERN Document Server

    Bell, Guido; Huber, Tobias; Li, Xin-Qiang

    2015-01-01

    The computation of direct CP asymmetries in charmless B decays at next-to-next-to-leading order (NNLO) in QCD is of interest to ascertain the short-distance contribution. Here we compute the two-loop penguin contractions of the current-current operators Q_{1,2} and provide a first estimate of NNLO CP asymmetries in penguin-dominated b -> s transitions.

  8. Supersymmetric QCD corrections and phenomenological studies in relation to coannihilation of dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia

    2013-11-15

    In this thesis, we assume a minimal supersymmetric extension of the Standard Model (MSSM) with conserved R-parity such that the lightest neutralino is the cold dark matter candidate. A stringent constraint on the MSSM parameter space can be set by the comparison of the predicted neutralino relic density with the experimentally determined value. In order to match the high experimental precision, uncertainties within the theoretical calculation have to be reduced. One of the main uncertainties arises from the cross section of annihilation and coannihilation processes of the dark matter particle. In a phenomenological study we investigate the interplay of neutralino-neutralino annihilation, neutralino-stop coannihilation and stop-stop annihilation. We demonstrate that neutralino-stop coannihilation contributes significantly to the neutralino relic density and is furthermore very well motivated due to the recent discovery of a 125 GeV Higgs boson. Due to this ample motivation we have calculated the full O({alpha}{sub s}) supersymmetric QCD corrections to neutralino-squark coannihilation. We show in detail our DR/on-shell renormalization scheme for the treatment of ultraviolet divergences, and describe the phase space slicing method which is used to handle soft and collinear infrared divergences. Further, we comment on the treatment of occurring intermediate onshell states. The whole calculation is provided within the numerical tool DM rate at NLO that serves as an extension to existing relic density calculators, which consider only an effective tree-level calculation. Based on three example scenarios we study the impact of the NLO corrections on the total (co)annihilation cross section, and observe corrections of up to 30 %. This leads to a correction of 5 - 9 % on the relic density, which is larger than the current experimental uncertainty and is, thus, important to be taken into account.

  9. Impact of SUSY-QCD corrections to neutralino-squark coannihilation on the dark matter relic density

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia [Deutsches Elektronen-Synchrotron, Hamburg (Germany); Herrmann, Bjoern [Laboratoire d' Annecy de Physique Theorique, Annecy-le-Vieux (France); Klasen, Michael [Institute for Theoretical Physics, University of Muenster (Germany); Kovarik, Karol [Karlsruhe Institute of Technology, Karlsruhe (Germany); Le Boulc' h, Quentin [Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France)

    2012-07-01

    A powerful method to constrain the parameter space of theories beyond the Standard Model is to compare the predicted dark matter relic density with data from cosmological precision measurements, in particular from the WMAP satellite. On the particle physics side, the main uncertainty on the relic density arises from the (co-)annihilation cross sections of the dark matter particle. After a motivation for including higher order corrections in the prediction of the relic density, the project DM rate at NLO is presented. This software package allows one to compute the neutralino (co-)annihilation cross sections including SUSY-QCD corrections at the one-loop level and to evaluate their effect on the relic density using a link to the public codes MicrOMEGAs and DarkSUSY. Recent results of the impact of SUSY-QCD corrections on the neutralino pair annihilation cross section are discussed, and first results on neutralino-squark coannihilation are shown.

  10. The Matrix Element Method at next-to-leading order accuracy

    CERN Document Server

    Martini, Till

    2015-01-01

    The Matrix Element Method (MEM) has proven beneficial to make maximal use of the information available in experimental data. However, so far it has mostly been used in Born approximation only. In this paper we discuss an extension to NLO accuracy. As a prerequisite we present an efficient method to calculate event weights for jet events at NLO accuracy. As illustration and proof of concept we apply the method to the extraction of the top-quark mass in e+e- annihilation. We observe significant differences when moving from LO to NLO which may be relevant for the interpretation of top-quark mass measurements at hadron colliders relying on the MEM.

  11. {ZZ}\\gamma production in the NLO QCD+EW accuracy at the LHC

    Science.gov (United States)

    Yong, Wang; Ren-You, Zhang; Wen-Gan, Ma; Xiao-Zhou, Li; Shao-Ming, Wang; Huan-Yu, Bi

    2017-08-01

    In this paper we present the first study of the impact of the { O }(α ) electroweak (EW) correction to the {pp}\\to {ZZ}γ +X process at the CERN Large Hadron Collider. The subsequent Z-boson leptonic decays are considered at the leading order using the MadSpin method, which takes into account the spin-correlation and off-shell effects from the Z-boson decays. We provide numerical results of the integrated cross section and the kinematic distributions for this process. In coping with final-state photon-jet separation in the QCD real emission and photon-induced processes, we adopt both the Frixione isolated-photon plus jets algorithm and the phenomenological quark-to-photon fragmentation function method for comparison. We find that the next-to-leading order (NLO) EW correction to the {ZZ}γ production can be sizeable and amounts to about -7 % of the integrated cross section, and provides a non-negligible contribution to the kinematic distributions, particularly in the high energy region. We conclude that the NLO EW correction should be included in precision theoretical predictions in order to match future experimental accuracy.

  12. Form factors of semileptonic B-meson decays from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Heitger, Jochen [Muenster Univ. (Germany)

    2016-11-01

    With the remaining part of our total SuperMUC grant of 41 M core-hours we want to reduce the overall uncertainties of our results to a phenomenologically relevant precision. This amounts to add a second q{sup 2}-value, data at lighter pion mass to stabilize the chiral limit, and to include the next-to-leading order HQET corrections.

  13. SUSY-QCD corrections to the (co)annihilation of neutralino dark matter within the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Meinecke, Moritz

    2015-06-15

    Based on experimental observations, it is nowadays assumed that a large component of the matter content in the universe is comprised of so-called cold dark matter. Furthermore, latest measurements of the temperature fluctuations of the cosmic microwave background provided an estimation of the dark matter relic density at a measurement error of one percent (concerning the experimental 1σ-error). The lightest neutralino χ 0{sub 1}, a particle which subsumes under the phenomenologically interesting category of weakly interacting massive particles, is a viable dark matter candidate for many supersymmetric (SUSY) models whose relic density Ω{sub χ} {sub 0{sub 1}} happens to lie quite naturally within the experimentally favored ballpark of dark matter. The high experimental precision can be used to constrain the SUSY parameter space to its cosmologically favored regions and to pin down phenomenologically interesting scenarios. However, to actually benefit from this progress on the experimental side it is also mandatory to minimize the theoretical uncertainties. An important quantity within the calculation of the neutralino relic density is the thermally averaged sum over different annihilation and coannihilation cross sections of the neutralino and further supersymmetric particles. It is now assumed and also partly proven that these cross sections can be subject to large loop corrections which can even shift the associated Ω{sub χ} {sub 0{sub 1}} by a factor larger than the current experimental error. However, most of these corrections are yet unknown. In this thesis, we calculate higher-order corrections for some of the most important (co)annihilation channels both within the framework of the R-parity conserving Minimal Supersymmetric Standard Model (MSSM) and investigate their impact on the final neutralino relic density Ω{sub χ} {sub 0{sub 1}}. More precisely, this work provides the full O(α{sub s}) corrections of supersymmetric quantum chromodynamics (SUSY-QCD

  14. Up and Down Quark Masses and Corrections to Dashen's Theorem from Lattice QCD and Quenched QED.

    Science.gov (United States)

    Fodor, Z; Hoelbling, C; Krieg, S; Lellouch, L; Lippert, Th; Portelli, A; Sastre, A; Szabo, K K; Varnhorst, L

    2016-08-19

    In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on N_{f}=2+1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen's theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen's theorem, we obtain ϵ=0.73(2)(5)(17), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, m_{u}=2.27(6)(5)(4) and m_{d}=4.67(6)(5)(4)  MeV in the modified minimal subtraction scheme at 2  GeV and the isospin breaking ratios m_{u}/m_{d}=0.485(11)(8)(14), R=38.2(1.1)(0.8)(1.4), and Q=23.4(0.4)(0.3)(0.4). Our results exclude the m_{u}=0 solution to the strong CP problem by more than 24 standard deviations.

  15. Up and Down Quark Masses and Corrections to Dashen's Theorem from Lattice QCD and Quenched QED

    Science.gov (United States)

    Fodor, Z.; Hoelbling, C.; Krieg, S.; Lellouch, L.; Lippert, Th.; Portelli, A.; Sastre, A.; Szabo, K. K.; Varnhorst, L.; Budapest-Marseille-Wuppertal Collaboration

    2016-08-01

    In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on Nf=2 +1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen's theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen's theorem, we obtain ɛ =0.73 (2 )(5 )(17 ), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, mu=2.27 (6 )(5 )(4 ) and md=4.67 (6 )(5 )(4 ) MeV in the modified minimal subtraction scheme at 2 G e V and the isospin breaking ratios mu/md=0.485 (11 )(8 )(14 ), R =38.2 (1.1 )(0.8 )(1.4 ), and Q =23.4 (0.4 )(0.3 )(0.4 ). Our results exclude the mu=0 solution to the strong C P problem by more than 24 standard deviations.

  16. Complete NLO QCD Corrections for Tree Level Delta F = 2 FCNC Processe

    CERN Document Server

    Buras, Andrzej J

    2012-01-01

    Anticipating the important role of tree level FCNC processes in the indirect search for new physics at distance scales as short as 10^-19-10^-21 m, we present complete NLO QCD corrections to tree level Delta F=2 processes mediated by heavy colourless gauge bosons and scalars. Such contributions can be present at the fundamental level when GIM mechanism is absent as in numerous Z' models, gauged flavour models with new heavy neutral gauge bosons and Left-Right symmetric models with heavy neutral scalars. They can also be generated at one loop in models having GIM at the fundamental level and MFV of which Two-Higgs Doublet models with and without SUSY are the best known examples. In models containing vectorial heavy fermions that mix with the standard chiral quarks and models in which Z and SM neutral Higgs H mix with new heavy gauge bosons and scalars also tree-level Z and SM neutral Higgs contributions to Delta F=2 processes are possible. In all these extensions new local operators are generated having Wilson...

  17. QCD corrections to the e+e- cross section and the Z boson decay rate

    CERN Document Server

    Chetyrkin, K G; Kwiatkowski, A; Chetyrkin, K G; Kuhn, J H; Kwiatkowski, A

    1995-01-01

    QCD corrections to the electron positron annihilation cross-section into hadrons and to the hadronic Z boson decay rate are reviewed. Formal developments are introduced in a form particularly suited for practical applications. These include the operator product expansion, the heavy mass expansion, the decoupling of heavy quarks and matching conditions. Exact results for the quark mass depen- dence are presented whenever available, and formulae valid in the limit of small bottom mass (m_{b}^2\\ll s) or of large top mass (m_{t}^2\\gg s) are presen- ted. The differences between vector and axial vector induced rates as well the classification of singlet and nonsinglet rates are discussed. Handy formulae for all contributions are collected and their numerical relevance is investi- gated. Prescriptions for the separation of the total rate into partial rates are formulated. The applicability of the results in the low energy region, relevant for measurements around 10 GeV and below, is investigated and numerical predic...

  18. QCD two-loop corrections for hadronic single top-quark production in the t-channel

    CERN Document Server

    Assadsolimani, M; Tausk, B; Uwer, P

    2014-01-01

    In this article we discuss the calculation of single top-quark production in the t-channel at two-loop order in QCD. In particular we present the decomposition of the amplitude according to its spin and colour structure and present complete results for the two-loop amplitudes in terms of master integrals. For the vertex corrections compact analytic expressions are given. The box contributions are implemented in a publicly available C program.

  19. Higher-order soft corrections to squark hadro-production

    Energy Technology Data Exchange (ETDEWEB)

    Langenfeld, U.; Moch, S.

    2009-01-15

    We present new predictions for the total cross section of squark pair-production at Tevatron and LHC through next-to-next-to-leading order within the Minimal Supersymmetric Standard Model. The results are based on the numerically dominant soft corrections. They are exact in all logarithmically enhanced terms near threshold, include the Coulomb corrections at two loops and exact scale dependence. We translate the increased total cross section at next-to-next-to-leading order into improved exclusion limits for squark masses and we investigate the scale dependence as well as the sensitivity on the parton luminosity. (orig.)

  20. Non-factorizable photonic corrections to resonant production and decay of many unstable particles

    Energy Technology Data Exchange (ETDEWEB)

    Dittmaier, Stefan; Schwan, Christopher [Albert-Ludwigs-Universitaet Freiburg, Physikalisches Institut, Freiburg (Germany)

    2016-03-15

    Electroweak radiative corrections to the production of high-multiplicity final states with several intermediate resonances in most cases can be sufficiently well described by the leading contribution of an expansion about the resonance poles. In this approach, also known as pole approximation, corrections are classified into separately gauge-invariant factorizable and non-factorizable corrections, where the former can be attributed to the production and decay of the unstable particles on their mass shell. The remaining non-factorizable corrections are induced by the exchange of soft photons between different production and decay subprocesses. We give explicit analytical results for the non-factorizable photonic virtual corrections to the production of an arbitrary number of unstable particles at the one-loop level and, thus, present an essential building block in the calculation of next-to-leading-order electroweak corrections in pole approximation. The remaining virtual factorizable corrections can be obtained with modern automated one-loop matrix-element generators, while the evaluation of the corresponding real photonic corrections can be evaluated with full matrix elements by multi-purpose Monte Carlo generators. Our results can be easily modified to non-factorizable QCD corrections, which are induced by soft-gluon exchange. (orig.)

  1. Early Run 2 Hard QCD Results from the ATLAS Collaboration

    Directory of Open Access Journals (Sweden)

    Orlando Nicola

    2016-01-01

    Full Text Available We provide an overview of hard QCD results based on data collected with the ATLAS detector in proton-proton collision at √s = 13 TeV at the Large Hadron Collider. The production of high transverse momentum jets, photons and photon-pairs were studied; the inclusive jet cross section is found to agree well with the prediction of perturbative QCD calculations performed at next-to-leading accuracy. The production cross sections for W and Z bosons in their e and μ decays was measured; in general, agreement is found with the expectation of next-to-next-to leading order QCD calculations and interesting sensitivities to the proton structure functions are already observed. The top production cross sections were measured in different top decay channels and found to agree with the state of the art QCD predictions.

  2. $W^\\pm Z$ production at the LHC: fiducial cross sections and distributions in NNLO QCD arXiv

    CERN Document Server

    Grazzini, Massimiliano; Rathlev, Dirk; Wiesemann, Marius

    We report on the first fully differential calculation for $W^\\pm Z$ production in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. Leptonic decays of the $W$ and $Z$ bosons are consistently taken into account, i.e. we include all resonant and non-resonant diagrams that contribute to the process $pp\\to \\ell^{'\\pm} \

  3. Chiral behavior of light meson form factors in 2+1 flavor QCD with exact chiral symmetry

    CERN Document Server

    Kaneko, T; Cossu, G; Feng, X; Fukaya, H; Hashimoto, S; Noaki, J; Onogi, T

    2016-01-01

    We present a study of chiral behavior of light meson form factors in QCD with three flavors of overlap quarks. Gauge ensembles are generated at single lattice spacing 0.12 fm with pion masses down to 300 MeV. The pion and kaon electromagnetic form factors and the kaon semileptonic form factors are precisely calculated using the all-to-all quark propagator. We discuss their chiral behavior using the next-to-next-to-leading order chiral perturbation theory.

  4. Lattice QCD spectroscopy for hadronic CP violation

    Directory of Open Access Journals (Sweden)

    Jordy de Vries

    2017-03-01

    In this work we propose a strategy to calculate these couplings by using spectroscopic lattice QCD techniques. Instead of directly calculating the pion–nucleon coupling constants, a challenging task, we use chiral symmetry relations that link the pion–nucleon couplings to nucleon sigma terms and mass splittings that are significantly easier to calculate. In this work, we show that these relations are reliable up to next-to-next-to-leading order in the chiral expansion in both SU(2 and SU(3 chiral perturbation theory. We conclude with a brief discussion about practical details regarding the required lattice QCD calculations and the phenomenological impact of an improved understanding of CP-violating matrix elements.

  5. Perturbative Corrections to $\\Lambda_b \\to \\Lambda$ Form Factors from QCD Light-Cone Sum Rules

    CERN Document Server

    Wang, Yu-Ming

    2015-01-01

    We compute radiative corrections to $\\Lambda_b \\to \\Lambda$ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with $\\Lambda_b$-baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-$\\Lambda_b$-baryon correlation function is justified at leading power in $\\Lambda/m_b$, with the aid of the method of regions. Hard functions entering the factorization formulae are identical to the corresponding matching coefficients of heavy-to-light currents from QCD onto soft-collinear effective theory. The universal jet function from integrating out the hard-collinear fluctuations exhibits richer structures compared with the one involved in the factorization expressions of the vacuum-to-$B$-meson correlation function. Based upon the QCD resummation improved sum rules we observe that the perturbative corrections at ${\\cal O}(\\alpha_s)$ shift the $\\Lambda_b \\to \\Lambda$ from factors at large recoil significantly and the dominant contribution originat...

  6. Third-order QCD corrections to heavy quark pair production near threshold

    Energy Technology Data Exchange (ETDEWEB)

    Schuller, Kurt

    2008-11-07

    The measurement of the top quark mass is an important task at the future International Linear Collider. The most promising process is the top quark pair production in the threshold region. In this region the top quarks behave non-relativistically and a perturbative treatment using effective field theories is possible. Current second order theoretical predictions in a fixed order approach show an uncertainty which is bigger than the expected experimental errors. Therefore, an improvement of the cross section calculation is desirable. There are two ways to incorporate higher order effects, one is to calculate the full next order in the fixed order approach, another possibility is to resum large logarithms. In this work, the fixed order calculation has been extended to the third order in perturbation theory for the QCD corrections. The result is a strongly improved scale behavior and a better understanding of heavy quarkonium systems. The Green function result is given in a semi-analytic form. The energy levels and wave functions for heavy quarkonium states have been calculated from the poles of the Green function and are presented for arbitrary quantum number n. The results have been implemented in a Mathematica program which makes the data easily accessible. Once some missing matching coefficients are calculated, and a complete electroweak calculation is available, the results of this work can be used to improve the precision of the top quark mass measurement to an uncertainty of less than 50 MeV. An inclusion of initial state radiation and beam effects are essential for a realistic observable. In the future, the results obtained could be used for a third order resummation of large logarithms. Further applications are also the extraction of the bottom quark mass with sum rules. (orig.)

  7. The K+ K+ scattering length from Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Silas Beane; Thomas Luu; Konstantinos Orginos; Assumpta Parreno; Martin Savage; Aaron Torok; Andre Walker-Loud

    2007-09-11

    The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with fourth-rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of mK + /fK + . We find mK^+ aK^+ K^+ = â~0.352 ± 0.016, where the statistical and systematic errors have been combined in quadrature.

  8. Power corrections to the electromagnetic spectral function and the dilepton rate in QCD plasma within operator product expansion in D=4

    CERN Document Server

    Bandyopadhyay, Aritra

    2016-01-01

    We evaluate the electromagnetic spectral function in QCD plasma in a nonperturbative background of in-medium quark and gluon condensates by incorporating the leading order power corrections in a systematic framework within the ambit of the operator product expansion in D=4 dimension. We explicitly show that the mixing of the composite operators removes mass singularities and renders Wilson coefficients finite and well defined. As a spectral property, we then obtain the nonperturbative dilepton production rate from QCD plasma. The operator product expansion automatically restricts the dilepton rate to the intermediate mass range, which is found to be enhanced due to the power corrections. We also compare our result with those from nonperturbative calculations, e.g., lattice QCD and effective QCD models based on Polyakov loop.

  9. Recent QCD results from ATLAS

    CERN Document Server

    Pleskot, Vojtech; The ATLAS collaboration

    2016-01-01

    ATLAS has has performed several measurements of phenomena connected to QCD at soft scales or at the transition to the hard regime. These include the measurements at different centre-of-mass energies in Run-1 and Run-2 of the elastic, inelastic and total cross sections in pp collisions, the properties of minimum bias and the underlying event interactions, particle production and their correlations, as well as of diffractive and exclusive events. These results are sensitive to non-perturbative models of soft QCD. Jet and photon production cross sections have been measured differentially for inclusive and multi-object final states at 7, 8 and 13 TeV pp collisions with the ATLAS detector and are compared to expectations based on next-to-leading order QCD calculations as well as Monte Carlo simulations. Further studies of jet production properties include the measurements of jet properties, and the determination of the strong coupling constant alpha_s. These measurements provide direct probes of short-distance phy...

  10. NLO QCD corrections to off-shell ttj production at the LHC

    CERN Document Server

    Worek, Malgorzata

    2016-01-01

    A short summary of results for top-quark pair production in association with a jet with NLO QCD off-shell effects at the LHC is given. The calculation is based on the matrix element for the $pp \\to e^+ \

  11. NNLO corrections to the Higgs production cross section

    Energy Technology Data Exchange (ETDEWEB)

    Ravindran, V. [Harish-Chandra Research Institute, Chhatnag Road, Jhusii, Allahabad, 211019 (India); Smith, J. [C.N. Yang Institute for Theoretical Physics, State University of New York at Stony Brook, New York 11794-3840 (United States); Neerven, W.L. van [Instituut-Lorentz, Universiteit Leiden, PO Box 9506, 2300 RA Leiden (Netherlands)

    2004-10-01

    We discuss the next-to-next-to-leading order (NNLO) corrections to the total cross section for (pseudo-) scalar Higgs boson production. The computation is carried out in the e.ective Lagrangian approach which emerges from the standard model by taking the limit mt->{approx} where mt denotes the mass of the top quark.

  12. Loop corrections to pion and kaon neutrinoproduction

    CERN Document Server

    Siddikov, Marat

    2016-01-01

    In this paper we study the next-to-leading order corrections to deeply virtual pion and kaon production in neutrino experiments. We estimate these corrections in the kinematics of the Minerva experiment at FERMILAB, and find that they are sizable and increase the leading order cross-section by up to a factor of two. We provide a code, which can be used for the evaluation of the cross-sections, taking into account these corrections and employing various GPD models.

  13. NLO QCD Corrections for $J/\\psi+ c + \\bar{c}$ Production in Photon-Photon Collision

    CERN Document Server

    Chen, Zi-Qiang; Qiao, Cong-Feng

    2016-01-01

    The $\\gamma+\\gamma\\rightarrow J/\\psi+c+\\bar{c}$ inclusive process is an extremely important subprocess in $J/\\psi$ photoproduction, like at LEP\\uppercase\\expandafter{\\romannumeral2} or various types future electron-positron colliders. In this work we perform the next-to-leading(NLO) QCD corrections to this process in the framework of non-relativistic QCD(NRQCD) factorization formalism, the first NLO calculation for two projectiles to 3-body quarkonium inclusive production process. By setting the center-of-mass energy at LEP\\uppercase\\expandafter{\\romannumeral2}, the $\\sqrt{s}=197$ GeV, we conduct analyses of the $p_t^2$ distribution and total cross section of this process at the NLO accuracy. It turns out that the total cross section is moderately enhanced by the NLO correction with a $K$ factor of about 1.46, and hence the discrepancy between DELPHI data and color-singlet(CS) calculation is reduced while the color-octet(CO) contributions are still inevitable at this order. At the future Circular Electron-Pos...

  14. Two-Loop QCD Corrections to Higgs $\\rightarrow b + \\bar{b} + g$ Amplitude

    CERN Document Server

    Ahmed, Taushif; Mathews, Prakash; Rana, Narayan; Ravindran, V

    2014-01-01

    Exclusive observables involving Higgs boson in association with jets are often well suited to study the Higgs boson properties. They are rates involving cuts on the final state jets or differential distributions of rapidity, transverse momentum of the observed Higgs boson. While they get dominant contributions from gluon initiated partonic subprocesses, it is important to include the subdominant ones coming from other channels. In this article, we study one such channel namely the Higgs production in association with a jet in bottom anti-bottom annihilation process. We compute relevant amplitude $H\\rightarrow b+\\overline b+g$ up to two loop level in QCD where Higgs couples to bottom quark through Yukawa coupling. We use projection operators to obtain the coefficients for each tensorial structure appearing in this process. We have demonstrated that the renormalized amplitudes do have the right infrared structure predicted by the QCD factorization in dimensional regularization. The finite parts of the one and t...

  15. Lattice cut-off effects and their reduction in studies of QCD thermodynamics at non-zero temperature and chemical potential

    CERN Document Server

    Hegde, P; Laermann, E; Shcheredin, S

    2008-01-01

    We clarify the relation between the improvement of dispersion relations in the fermion sector of lattice regularized QCD and the improvement of bulk thermodynamic observables. We show that in the infinite temperature limit the cut-off dependence in dispersion relations can be eliminated up to O(a^n) corrections, if the quark propagator is chosen to be rotationally invariant up to this order. In bulk thermodynamic observables this eliminates cut-off effects up to the same order at vanishing as well as non-vanishing chemical potential. We furthermore show, that in the infinite temperature, ideal gas limit the dependence of finite cut-off corrections on the chemical potential is given by Bernoulli polynomials which are universal as they do not depend on a particular discretization scheme. We explicitly calculate leading and next-to-leading order cut-off corrections for some staggered and Wilson fermion type actions and compare these with exact evaluations of the free fermion partition functions. This also includ...

  16. Event-by-event fluctuations in perturbative QCD + saturation + hydro model: pinning down QCD matter shear viscosity in ultrarelativistic heavy-ion collisions

    CERN Document Server

    Niemi, H; Paatelainen, R

    2015-01-01

    We introduce an event-by-event perturbative-QCD + saturation + hydro ("EKRT") framework for ultrarelativistic heavy-ion collisions, where we compute the produced fluctuating QCD-matter energy densities from next-to-leading order perturbative QCD using a saturation conjecture to control soft particle production, and describe the space-time evolution of the QCD matter with dissipative fluid dynamics, event by event. We perform a simultaneous comparison of the centrality dependence of hadronic multiplicities, transverse momentum spectra, and flow coefficients of the azimuth-angle asymmetries, against the LHC and RHIC measurements. We compare also the computed event-by-event probability distributions of relative fluctuations of elliptic flow, and event-plane angle correlations, with the experimental data from Pb+Pb collisions at the LHC. We show how such a systematic multi-energy and multi-observable analysis tests the initial state calculation and the applicability region of hydrodynamics, and in particular how ...

  17. Numerical Study of Nonperturbative Corrections to the Chiral Separation Effect in Quenched Finite-Density QCD

    Science.gov (United States)

    Puhr, Matthias; Buividovich, P. V.

    2017-05-01

    We demonstrate the nonrenormalization of the chiral separation effect (CSE) in quenched finite-density QCD in both confinement and deconfinement phases using a recently developed numerical method which allows us, for the first time, to address the transport properties of exactly chiral, dense lattice fermions. This finding suggests that CSE can be used to fix renormalization constants for axial current density. Explaining the suppression of the CSE which we observe for topologically nontrivial gauge field configurations on small lattices, we also argue that CSE vanishes for self-dual non-Abelian fields inside instanton cores.

  18. Study of higher-order QCD corrections in the $gg\\rightarrow H\\rightarrow VV$ process

    CERN Document Server

    The ATLAS collaboration

    2016-01-01

    Several studies have shown that the high-mass off-peak regions in the $H\\rightarrow ZZ$ and $H\\rightarrow WW$ channels above the $VV$ mass threshold ($V=W,Z$) have sensitivity to off-shell Higgs production and interference effects. This feature can be exploited to characterize the Higgs boson off-shell signal strength and its associated couplings. This note reports on the treatment of the QCD-related systematic uncertainties for the extraction of the off-shell Higgs boson signal strength related to the comparison of different Monte Carlo modeling for the $gg$-initiated processes, $gg\\rightarrow (H^{*}) \\rightarrow VV$. Higher-order QCD corrections to the transverse momentum $p_{\\mathrm{T}}$ and the rapidity $y$ of the $VV$ system are studied using Sherpa+OpenLoops, which includes matrix-element calculations for the first hard jet emission. A difference of the order of 20% in the ratio of the $p_{\\mathrm{T}}$ of the $VV$ system in the relevant kinematic region is observed when comparing the LO generators with ...

  19. bar{B}_{d,s} → D^{*}_{d,s} V and bar{B}_{d,s}^* → D_{d,s} V decays in QCD factorization and possible puzzles

    Science.gov (United States)

    Chang, Qin; Chen, Ling-Xin; Zhang, Yun-Yun; Sun, Jun-Feng; Yang, Yue-Ling

    2016-10-01

    Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic bar{B}_{d,s} → D^{*}_{d,s} V and bar{B}_{d,s}^* → D_{d,s} V (V=ρ ,K^*) decays are performed within the framework of QCD factorization. Relative to the previous work, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured bar{B}_{d,s} → D^{*}_{d,s} V decays, the tensions between theoretical results and experimental measurements, i.e. the "R_{ds}V puzzle" and "D^{*} V (or R_{V/ℓ bar{ν }_ℓ }) puzzle", are presented after detailed analyses. For the bar{B}_{d,s}^* → D_{d,s} V decays, they have relatively large branching fractions of the order ≳ O(10^{-9}) and are in the scope of Belle-II and LHCb experiments. Moreover, they also provide a way to crosscheck the possible puzzles mentioned above through the similar ratios R_{ds}^' V} and R_{V/ℓ bar{ν }_ℓ }^' }. More refined experimental measurements and theoretical efforts are required to confirm or refute such two anomalies.

  20. Electroweak two-loop corrections to the effective weak mixing angle

    Energy Technology Data Exchange (ETDEWEB)

    Awramik, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[Institute of Nuclear Physics, Cracow (Poland); Czakon, M. [Wuerzburg Univ. (Germany). Inst. fuer Theoretische Physik und Astrophysik]|[Silesia Univ., Katowice (Poland). Dept. of Field Theory and Particle Physics; Freitas, A. [Zuerich Univ. (Switzerland). Inst. fuer Theoretische Physik

    2006-08-15

    Recently exact results for the complete electroweak two-loop contributions to the effective weak mixing angle were published. This paper illustrates the techniques used for this computation, in particular the methods for evaluating the loop diagrams and the proper definition of Z-pole observables at next-to-next -to-leading order. Numerical results are presented in terms of simple parametrization formulae and compared in detail with a previous result of an expansion up to next-to-leading order in the top-quark mass. Finally, an estimate of the remaining theoretical uncertainties from unknown higher-order corrections is given. (Orig.)

  1. Electromagnetic corrections in eta --> 3 pi decays

    CERN Document Server

    Ditsche, Christoph; Meißner, Ulf-G

    2008-01-01

    We re-evaluate the electromagnetic corrections to eta --> 3 pi decays at next-to-leading order in the chiral expansion, arguing that effects of order e^2(m_u-m_d) disregarded so far are not negligible compared to other contributions of order e^2 times a light quark mass. Despite the appearance of the Coulomb pole in eta --> pi+ pi- pi0 and cusps in eta --> 3 pi0, the overall corrections remain small.

  2. A numerical study of non-perturbative corrections to the Chiral Separation Effect in quenched finite-density QCD

    CERN Document Server

    Puhr, M

    2016-01-01

    We use exactly chiral overlap lattice fermions to investigate the Chiral Separation Effect in quenched QCD at finite density. We employ a recently developed numerical method which allows, for the first time, to address the transport properties of exactly chiral lattice fermions with non-zero chemical potential. Studying the axial current along the external magnetic field, we find a linear dependence consistent with the free fermion result for topologically trivial gauge field configurations. However, for configurations with nontrivial topology in the confinement regime the axial current is strongly suppressed due to contributions of topological modes of the Dirac operator, which suggests that non-perturbative corrections to the Chiral Separation Effect have topological origin.

  3. QCD Corrections to Vector-Boson Fusion Processes in Warped Higgsless Models

    CERN Document Server

    Englert, C; Zeppenfeld, D

    2009-01-01

    We discuss the signatures of a representative Higgsless model with ideal fermion delocalization in vector-boson fusion processes, focusing on the gold- and silver-plated decay modes of the gauge bosons at the CERN-Large Hadron Collider. For this purpose, we have developed a fully-flexible parton-level Monte-Carlo program, which allows for the calculation of cross sections and kinematic distributions within experimentally feasible selection cuts at NLO-QCD accuracy. We find that Kaluza-Klein resonances give rise to very distinctive distributions of the decay leptons. Similar to the Standard Model case, within the Higgsless scenario the perturbative treatment of the vector-boson scattering processes is under excellent control.

  4. NLO-QCD corrections to Higgs pair production in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, A.; Degrassi, G. [Dipartimento di Matematica e Fisica, Università di Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Gröber, R. [INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Slavich, P. [LPTHE, UPMC University Paris 06, Sorbonne Universités, 4 Place Jussieu, F-75252 Paris (France); LPTHE, CNRS, 4 Place Jussieu, F-75252 Paris (France)

    2016-04-18

    We take a step towards a complete NLO-QCD determination of the production of a pair of Higgs scalars in the MSSM. Exploiting a low-energy theorem that connects the Higgs-gluon interactions to the derivatives of the gluon self-energy, we obtain analytic results for the one- and two-loop squark contributions to Higgs pair production in the limit of vanishing external momenta. We find that the two-loop squark contributions can have non-negligible effects in MSSM scenarios with stop masses below the TeV scale. We also show how our results can be adapted to the case of Higgs pair production in the NMSSM.

  5. Gluon fusion correction to $H W^+ W^- / H Z Z$ production in the POWHEG-BOX

    CERN Document Server

    Baglio, Julien

    2016-01-01

    The study of the Higgs boson properties is one of the most important tasks to be accomplished in the next years, at the Large Hadron Collider (LHC) and at future colliders such as the Future Circular Collider in hadron-hadron mode (FCC-hh), the potential 100 TeV follow-up of the LHC machine. In this view the precise study of the Higgs couplings to weak gauge bosons is crucial and requires as much information as possible. After the recent calculation of the next-to-leading order QCD corrections to the production cross sections and differential distributions of a Standard Model Higgs boson in association with a pair of weak bosons, matched with parton shower in the POWHEG-BOX framework, we present the gluon fusion correction $g g\\to H W^+_{} W^-_{} ( H Z Z)$ to the process $p p \\to H W^+_{} W^-_{} (H Z Z)$. This correction can be sizeable and amounts to $+3\\,\\%$ ($+10\\,\\%$) in the $H W^+_{} W^-_{}$ process and $+5\\,\\%$ ($+18\\,\\%$) in the $H Z Z$ process at the LHC (FCC-hh). We present results on total cross sec...

  6. The impact of the photon PDF and electroweak corrections on [Formula: see text] distributions.

    Science.gov (United States)

    Pagani, D; Tsinikos, I; Zaro, M

    2016-01-01

    We discuss the impact of EW corrections on differential distributions in top-quark pair production at the LHC and future hadron colliders, focussing on the effects of initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order [Formula: see text] and [Formula: see text]. We present predictions at 13 and 100 TeV, and provide results for the 8 TeV differential measurements performed by ATLAS and CMS. A thorough comparison of results obtained with the NNPDF2.3QED and CT14QED PDF sets is performed. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and show large PDF uncertainties. On the one hand, we show that differential observables in top-pair production, in particular top-quark and [Formula: see text] rapidities, can be used to improve the determination of the photon PDF within the NNPDF approach. On the other hand, with current PDF sets, we demonstrate the necessity of including EW corrections and photon-induced contributions for a correct determination of both the central value and the uncertainties of theoretical predictions.

  7. The impact of the photon PDF and electroweak corrections on t anti t distributions

    Energy Technology Data Exchange (ETDEWEB)

    Pagani, D.; Tsinikos, I. [Universite Catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Zaro, M. [Sorbonne Universites, UPMC University Paris 06, UMR 589, LPTHE, Paris (France); CNRS, UMR 7589, LPTHE, Paris (France)

    2016-09-15

    We discuss the impact of EW corrections on differential distributions in top-quark pair production at the LHC and future hadron colliders, focussing on the effects of initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order α{sub s}α and α{sub s}{sup 2}α. We present predictions at 13 and 100 TeV, and provide results for the 8 TeV differential measurements performed by ATLAS and CMS. A thorough comparison of results obtained with the NNPDF2.3QED and CT14QED PDF sets is performed. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and show large PDF uncertainties. On the one hand, we show that differential observables in top-pair production, in particular top-quark and t anti t rapidities, can be used to improve the determination of the photon PDF within the NNPDF approach. On the other hand, with current PDF sets, we demonstrate the necessity of including EW corrections and photon-induced contributions for a correct determination of both the central value and the uncertainties of theoretical predictions. (orig.)

  8. The impact of the photon PDF and electroweak corrections on t bar{t} distributions

    Science.gov (United States)

    Pagani, D.; Tsinikos, I.; Zaro, M.

    2016-09-01

    We discuss the impact of EW corrections on differential distributions in top-quark pair production at the LHC and future hadron colliders, focussing on the effects of initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order α _sα and α _s^2α . We present predictions at 13 and 100 TeV, and provide results for the 8 TeV differential measurements performed by ATLAS and CMS. A thorough comparison of results obtained with the NNPDF2.3QED and CT14QED PDF sets is performed. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and show large PDF uncertainties. On the one hand, we show that differential observables in top-pair production, in particular top-quark and tbar{t} rapidities, can be used to improve the determination of the photon PDF within the NNPDF approach. On the other hand, with current PDF sets, we demonstrate the necessity of including EW corrections and photon-induced contributions for a correct determination of both the central value and the uncertainties of theoretical predictions.

  9. Testing chiral effective theory with quenched lattice QCD

    CERN Document Server

    Giusti, Leonardo; Necco, S; Peña, C; Wennekers, J; Wittig, H

    2008-01-01

    We investigate two-point correlation functions of left-handed currents computed in quenched lattice QCD with the Neuberger-Dirac operator. We consider two lattice spacings a~0.09,0.12 fm and two different lattice extents L~ 1.5, 2.0 fm; quark masses span both the p- and the epsilon-regimes. We compare the results with the predictions of quenched chiral perturbation theory, with the purpose of testing to what extent the effective theory reproduces quenched QCD at low energy. In the p-regime we test volume and quark mass dependence of the pseudoscalar decay constant and mass; in the epsilon-regime, we investigate volume and topology dependence of the correlators. While the leading order behaviour predicted by the effective theory is very well reproduced by the lattice data in the range of parameters that we explored, our numerical data are not precise enough to test next-to-leading order effects.

  10. Testing chiral effective theory with quenched lattice QCD

    Science.gov (United States)

    Giusti, L.; Hernández, P.; Necco, S.; Pena, C.; Wennekers, J.; Wittig, H.

    2008-05-01

    We investigate two-point correlation functions of left-handed currents computed in quenched lattice QCD with the Neuberger-Dirac operator. We consider two lattice spacings a simeq 0.09,0.12 fm and two different lattice extents L simeq 1.5,2.0 fm; quark masses span both the p- and the epsilon-regimes. We compare the results with the predictions of quenched chiral perturbation theory, with the purpose of testing to what extent the effective theory reproduces quenched QCD at low energy. In the p-regime we test volume and quark mass dependence of the pseudoscalar decay constant and mass; in the epsilon-regime, we investigate volume and topology dependence of the correlators. While the leading order behaviour predicted by the effective theory is very well reproduced by the lattice data in the range of parameters that we explored, our numerical data are not precise enough to test next-to-leading order effects.

  11. More on the renormalization group limit cycle in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Evgeny Epelbaum; Hans-Werner Hammer; Ulf-G. Meissner; Andreas Nogga

    2006-02-26

    We present a detailed study of the recently conjectured infrared renormalization group limit cycle in QCD using chiral effective field theory. We show that small increases in the up and down quark masses, corresponding to a pion mass around 200 MeV, can move QCD to the critical renormalization group trajectory for an infrared limit cycle in the three-nucleon system. At the critical values of the quark masses, the binding energies of the deuteron and its spin-singlet partner are tuned to zero and the triton has infinitely many excited states with an accumulation point at the three-nucleon threshold. At next-to-leading order in the chiral counting, we find three parameter sets where this effect occurs. For one of them, we study the structure of the three-nucleon system using both chiral and contact effective field theories in detail. Furthermore, we calculate the influence of the limit cycle on scattering observables.

  12. Gluon fusion and bb¯ corrections to HW+W−/HZZ production in the POWHEG-BOX

    Directory of Open Access Journals (Sweden)

    Julien Baglio

    2017-01-01

    Full Text Available The study of the Higgs boson properties is one of the most important tasks to be accomplished in the next years, at the Large Hadron Collider (LHC and at future colliders such as the Future Circular Collider in hadron–hadron mode (FCC-hh, the potential 100 TeV follow-up of the LHC machine. In this view the precise study of the Higgs couplings to weak gauge bosons is crucial and requires as much information as possible. After the recent calculation of the next-to-leading order QCD corrections to the production cross sections and differential distributions of a Standard Model Higgs boson in association with a pair of weak bosons, matched with parton shower in the POWHEG-BOX framework, we present the gluon fusion correction gg→HW+W−(HZZ to the process pp→HW+W−(HZZ. This correction can be sizeable and amounts to +3% (+10% in the HW+W− process and +5% (+18% in the HZZ process at the LHC (FCC-hh. We also present the first study of the impact of the bottom-quark initiated channels bb¯→HW+W−/HZZ and find that they induce a significant +18% correction in the HW+W− channel at the FCC-hh. We present results on total cross sections and distributions at the LHC and at the FCC-hh.

  13. Gluon fusion and b b bar corrections to HW+W-/HZZ production in the POWHEG-BOX

    Science.gov (United States)

    Baglio, Julien

    2017-01-01

    The study of the Higgs boson properties is one of the most important tasks to be accomplished in the next years, at the Large Hadron Collider (LHC) and at future colliders such as the Future Circular Collider in hadron-hadron mode (FCC-hh), the potential 100 TeV follow-up of the LHC machine. In this view the precise study of the Higgs couplings to weak gauge bosons is crucial and requires as much information as possible. After the recent calculation of the next-to-leading order QCD corrections to the production cross sections and differential distributions of a Standard Model Higgs boson in association with a pair of weak bosons, matched with parton shower in the POWHEG-BOX framework, we present the gluon fusion correction gg → HW+W- (HZZ) to the process pp → HW+W- (HZZ). This correction can be sizeable and amounts to + 3% (+ 10%) in the HW+W- process and + 5% (+ 18%) in the HZZ process at the LHC (FCC-hh). We also present the first study of the impact of the bottom-quark initiated channels b b bar → HW+W- / HZZ and find that they induce a significant + 18% correction in the HW+W- channel at the FCC-hh. We present results on total cross sections and distributions at the LHC and at the FCC-hh.

  14. Constraints on the annihilation corrections in $B_{u,d}$ ${\\to}$ $PV$ decays within QCD factorization

    CERN Document Server

    Sun, Junfeng; Hu, Xiaohui; Yang, Yueling

    2015-01-01

    In this paper, we investigate the contributions of hard spectator scattering and annihilation in $B$ ${\\to}$ $PV$ decays within QCD factorization framework. With available experimental data on $B$ ${\\to}$ ${\\pi}K^{\\ast}$, ${\\rho}K$, ${\\pi}{\\rho}$ and $K{\\phi}$ decays, comprehensive $\\chi^2$ analyses on parameters $X_{A,H}^{i,f}$ or (${\\rho}_{A,H}^{i,f}$, ${\\phi}_{A,H}^{i,f}$) are performed, where $X_{A}^{f}$ ($X_{A}^{i}$) and $X_{H}$ are used to parameterize the endpoint divergences of the (non)factorizable annihilation and hard spectator scattering amplitudes, respectively. From $\\chi^2$ analyses, it is found that (1) the topology-dependent parameterization is feasible for $B$ ${\\to}$ $PV$ decays; (2) A relatively small value of inverse moment parameter ${\\lambda}_{B}$ ${\\sim}$ 0.2 GeV for $B$ meson wave function is allowed by $B$ ${\\to}$ $PP$, $PV$ decays; (3) At present accurate level of experimental measurements and theoretical evaluations, $X_{H}$ $=$ $X_{A}^{i}$ is a good simplification, but $X_{H}$ $\

  15. Large electroweak corrections to vector-boson scattering at the Large Hadron Collider

    CERN Document Server

    Biedermann, Benedikt; Pellen, Mathieu

    2016-01-01

    For the first time full next-to-leading-order electroweak corrections to off-shell vector-boson scattering are presented. The computation features the complete matrix elements, including all non-resonant and off-shell contributions, to the electroweak process $\\mathrm{p} \\mathrm{p} \\to \\mu^+ \

  16. NLO corrections to the gluon induced forward jet vertex from the high energy effective action

    CERN Document Server

    Chachamis, Grigorios; Madrigal, Jose Daniel; Vera, Agustin Sabio

    2012-01-01

    We determine both real and virtual next-to-leading order corrections to the gluon induced forward jet vertex, from the high energy effective action proposed by Lipatov. For these calculations we employ the same regularization and subtraction formalism developed in our previous work on the quark-initiated vertex. We find agreement with previous results in the literature.

  17. Probing higher-order corrections in dijet production at the LHC

    DEFF Research Database (Denmark)

    Alioli, S.; Andersen, J. R.; Oleari, C.

    2012-01-01

    -angle, hard emissions. In this paper, we identify regions of phase space in dijet production where some observables receive large corrections beyond next-to-leading order and study their theoretical description with two tools that perform these two different resummations: the POWHEG BOX and HEJ. Furthermore...

  18. QCD analysis of W- and Z-boson production at Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Camarda, S.; Glazov, A.; Myronenko, V.; Pirumov, H.; Placakyte, R.; Starovoitov, P. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Belov, P. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); St. Petersburg State University, Department of Physics, St. Petersburg (Russian Federation); Cooper-Sarkar, A.M. [University of Oxford, Department of Physics, Oxford (United Kingdom); Diaconu, C. [Univ. Mediterranee, CPPM, IN2P3-CNRS, Marseille (France); Guffanti, A. [University of Copenhagen, Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, Copenhagen (Denmark); Jung, A. [Fermilab, Batavia, IL (United States); Kolesnikov, V.; Sapronov, A. [Joint Institute for Nuclear Research (JINR), Dubna, Moscow Region (Russian Federation); Lohwasser, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Olness, F. [Southern Methodist University, Dallas, TX (United States); Radescu, V. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Slominski, W. [Jagiellonian University, M. Smoluchowski Institute of Physics, Cracow (Poland); Sutton, M. [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Collaboration: HERAFitter developers' team

    2015-09-15

    Recent measurements of the W-boson charge asymmetry and of the Z-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). The Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the d-valence quark distribution. (orig.)

  19. QCD analysis of W- and Z-boson production at Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Camarda, S. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Belov, P. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Department of Physics, St. Petersburg State University, Ulyanovskaya 1, 198504, St. Petersburg (Russian Federation); Cooper-Sarkar, A. M. [Department of Physics, University of Oxford, Oxford (United Kingdom); Diaconu, C. [CPPM, IN2P3-CNRS, Univ. Mediterranee, Marseille (France); Glazov, A. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Guffanti, A. [Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen (Denmark); Jung, A. [FERMILAB, 60510, Batavia, IL (United States); Kolesnikov, V. [Joint Institute for Nuclear Research (JINR), Joliot-Curie 6, 141980, Dubna, Moscow Region (Russian Federation); Lohwasser, K. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738, Zeuthen (Germany); Myronenko, V. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Olness, F. [Southern Methodist University, Dallas, TX (United States); Pirumov, H.; Plačakytė, R. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Radescu, V. [Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany); Sapronov, A. [Joint Institute for Nuclear Research (JINR), Joliot-Curie 6, 141980, Dubna, Moscow Region (Russian Federation); Slominski, W. [M. Smoluchowski Institute of Physics, Jagiellonian University, Cracow (Poland); Starovoitov, P. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg (Germany); Sutton, M. [Department of Physics and Astronomy, University of Sussex, Sussex House, BN1 9RH, Brighton (United Kingdom)

    2015-09-28

    Recent measurements of the W-boson charge asymmetry and of the Z-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). The Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the d-valence quark distribution.

  20. $\\eta_c$ production at the LHC challenges nonrelativistic-QCD factorization

    CERN Document Server

    Butenschoen, Mathias; Kniehl, Bernd A

    2014-01-01

    We analyze the first measurement of $\\eta_c$ production, performed by the LHCb Collaboration, in the nonrelativistic-QCD (NRQCD) factorization framework at next-to-leading order (NLO) in the strong-coupling constant $\\alpha_s$ and the relative velocity $v$ of the bound quarks including the feeddown from $h_c$ mesons. Converting the long-distance matrix elements (LDMEs) extracted by various groups from $J/\\psi$ yield and polarization data to the $\\eta_c$ case using heavy-quark spin symmetry, we find that the resulting NLO NRQCD predictions greatly overshoot the LHCb data, while the color-singlet model provides an excellent description.

  1. Precise Determination of the I=2 pipi Scattering Length from Mixed-Action Lattice QCD

    CERN Document Server

    Beane, Silas R; Orginos, Kostas; Parreno, Assumpta; Savage, Martin J; Torok, Aaron; Walker-Loud, Andre

    2007-01-01

    The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations (with fourth-rooted staggered sea quarks) at four light-quark masses. Two- and three-flavor mixed-action chiral perturbation theory at next-to-leading order is used to perform the chiral and continuum extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) = -0.04330 +- 0.00042, where the error bar combines the statistical and systematic uncertainties in quadrature.

  2. Precise Determination of the I = 2 Scattering Length from Mixed-Action Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Silas Beane; Paulo Bedaque; Thomas Luu; Konstantinos Orginos; Assumpta Parreno; Martin Savage; Aaron Torok; Andre Walker-Loud

    2008-01-01

    The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations (with fourth-rooted staggered sea quarks) at four light-quark masses. Two- and three-flavor mixed-action chiral perturbation theory at next-to-leading order is used to perform the chiral and continuum extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) = -0.04330 +- 0.00042, where the error bar combines the statistical and systematic uncertainties in quadrature.

  3. η(c) production at the LHC challenges nonrelativistic QCD factorization.

    Science.gov (United States)

    Butenschoen, Mathias; He, Zhi-Guo; Kniehl, Bernd A

    2015-03-06

    We analyze the first measurement of η_{c} production, performed by the LHCb Collaboration, in the nonrelativistic QCD (NRQCD) factorization framework at next-to-leading order (NLO) in the strong-coupling constant α_{s} and the relative velocity v of the bound quarks including the feeddown from h_{c} mesons. Converting the long-distance matrix elements extracted by various groups from J/ψ yield and polarization data to the η_{c} case using heavy-quark spin symmetry, we find that the resulting NLO NRQCD predictions greatly overshoot the LHCb data, while the color-singlet model provides an excellent description.

  4. QCD analysis of $W$- and $Z$-boson production at Tevatron

    CERN Document Server

    Camarda, S; Cooper-Sarkar, A M; Diaconu, C; Glazov, A; Guffanti, A; Jung, A; Kolesnikov, V; Lohwasser, K; Myronenko, V; Olness, F; Pirumov, H; Placakyte, R; Radescu, V; Sapronov, A; Slominski, W; Starovoitov, P

    2015-01-01

    Recent measurements of the $W$-boson charge asymmetry and of the $Z$-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied to assess their impact on the proton parton distribution functions (PDFs), using the \\HERAFitter framework. The Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the $d$-valence quark distribution.

  5. Renormalization scheme dependence of the two-loop QCD corrections to the neutral Higgs-boson masses in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Borowka, S. [University of Zurich, Institute for Physics, Zurich (Switzerland); Hahn, T.; Heinrich, G.; Hollik, W. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany); Heinemeyer, S. [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain)

    2015-09-15

    Reaching a theoretical accuracy in the prediction of the lightest MSSM Higgs-boson mass, M{sub h}, at the level of the current experimental precision requires the inclusion of momentum-dependent contributions at the two-loop level. Recently two groups presented the two-loop QCD momentum-dependent corrections to M{sub h} (Borowka et al., Eur Phys J C 74(8):2994, 2014; Degrassi et al., Eur Phys J C 75(2):61, 2015), using a hybrid on-shell-DR scheme, with apparently different results. We show that the differences can be traced back to a different renormalization of the top-quark mass, and that the claim in Ref. Degrassi et al. (Eur Phys J C 75(2):61, 2015) of an inconsistency in Ref. Borowka et al. (Eur Phys J C 74(8):2994, 2014) is incorrect. We furthermore compare consistently the results for M{sub h} obtained with the top-quark mass renormalized on-shell and DR. The latter calculation has been added to the FeynHiggs package and can be used to estimate missing higher-order corrections beyond the two-loop level. (orig.)

  6. J/ψ(ψ') production at the Tevatron and LHC at O(α(s)4v4) in nonrelativistic QCD.

    Science.gov (United States)

    Ma, Yan-Qing; Wang, Kai; Chao, Kuang-Ta

    2011-01-28

    We present a complete evaluation for J/ψ(ψ') prompt production at the Tevatron and LHC at next-to-leading order in nonrelativistic QCD, including color-singlet, color-octet, and higher charmonia feeddown contributions. The short-distance coefficients of 3P(J)([8]) at next-to-leading order are found to be larger than leading order by more than an order of magnitude but with a minus sign at high transverse momentum p(T). Two new linear combinations of color-octet matrix elements are obtained from the CDF data, and used to predict J/ψ production at the LHC, which agrees with the CMS data. The possibility of (1)S(0)([8]) dominance and the J/ψ polarization puzzle are also discussed.

  7. Higgs production in association with a top-antitop pair in the Standard Model Effective Field Theory at NLO in QCD

    CERN Document Server

    Maltoni, Fabio; Zhang, Cen

    2016-01-01

    We present the results of the computation of the next-to-leading order QCD corrections to the production cross section of a Higgs boson in association with a top-antitop pair at the LHC, including the three relevant dimension-six operators ($O_{t \\varphi }, O_{\\varphi G}, O_{tG}$) of the standard model effective field theory. These operators also contribute to the production of Higgs bosons in loop-induced processes at the LHC, such as inclusive Higgs, $Hj$ and $HH$ production, and modify the Higgs decay branching ratios for which we also provide predictions. We perform a detailed study of the cross sections and their uncertainties at the total as well as differential level and of the structure of the effective field theory at NLO including renormalisation group effects. Finally, we show how the combination of information coming from measurements of these production processes will allow to constrain the three operators at the current and future LHC runs. Our results lead to a significant improvement of the ac...

  8. Higgs production in association with a top-antitop pair in the Standard Model Effective Field Theory at NLO in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Maltoni, Fabio; Vryonidou, Eleni [Centre for Cosmology, Particle Physics and Phenomenology (CP3),Université catholique de Louvain,B-1348 Louvain-la-Neuve (Belgium); Zhang, Cen [Department of Physics, Brookhaven National Laboratory,Upton, NY 11973 (United States)

    2016-10-24

    We present the results of the computation of the next-to-leading order QCD corrections to the production cross section of a Higgs boson in association with a top-antitop pair at the LHC, including the three relevant dimension-six operators (O{sub tφ},O{sub φG},O{sub tG}) of the standard model effective field theory. These operators also contribute to the production of Higgs bosons in loop-induced processes at the LHC, such as inclusive Higgs, Hj and HH production, and modify the Higgs decay branching ratios for which we also provide predictions. We perform a detailed study of the cross sections and their uncertainties at the total as well as differential level and of the structure of the effective field theory at NLO including renormalisation group effects. Finally, we show how the combination of information coming from measurements of these production processes will allow to constrain the three operators at the current and future LHC runs. Our results lead to a significant improvement of the accuracy and precision of the deviations expected from higher-dimensional operators in the SM in both the top-quark and the Higgs-boson sectors and provide a necessary ingredient for performing a global EFT fit to the LHC data at NLO accuracy.

  9. Conserved Charge Fluctuations from Lattice QCD and the Beam Energy Scan

    Science.gov (United States)

    Karsch, F.; Bazavov, A.; Ding, H.-T.; Hegde, P.; Kaczmarek, O.; Laermann, E.; Mukherjee, Swagato; Ohno, H.; Petreczky, P.; Schmidt, C.; Sharma, S.; Soeldner, W.; Steinbrecher, P.; Wagner, M.

    2016-12-01

    We discuss the next-to-leading order Taylor expansion of ratios of cumulants of net-baryon number fluctuations. We focus on the relation between the skewness ratio, SBσB ≡ χ3B/χ1B, and the kurtosis ratio, κB σB2 ≡ χ4B/χ2B. We show that differences in these two cumulant ratios are small for small values of the baryon chemical potential. The next-to-leading order correction to κB σB2 however is approximately three times larger than that for SBσB. The former thus drops much more rapidly with increasing beam energy, √{sNN}. We argue that these generic patterns are consistent with current data on cumulants of net-proton number fluctuations measured by the STAR Collaboration at √{sNN} ≥ 19.6 GeV.

  10. Conserved Charge Fluctuations from Lattice QCD and the Beam Energy Scan

    CERN Document Server

    Karsch, F; Ding, H -T; Hegde, P; Kaczmarek, O; Laermann, E; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Steinbrecher, P; Wagner, M

    2015-01-01

    We discuss the next-to-leading order Taylor expansion of ratios of cumulants of net-baryon number fluctuations. We focus on the relation between the skewness ratio, $S_B\\sigma_B = \\chi_3^B/\\chi_1^B$, and the kurtosis ratio, $\\kappa_B\\sigma_B^2 =\\chi_4^B/\\chi_2^B$. We show that differences in these two cumulant ratios are small for small values of the baryon chemical potential. The next-to-leading order correction to $\\kappa_B\\sigma_B^2$ however is approximately three times larger than that for $S_B\\sigma_B$. The former thus drops much more rapidly with increasing beam energy, $\\sqrt{s_{NN}}$. We argue that these generic patterns are consistent with current data on cumulants of net-proton number fluctuations measured by the STAR Collaboration at $\\sqrt{s_{NN}}\\ge 19.6$~GeV.

  11. Basics of QCD for the LHC: pp → H + X as a case study

    CERN Document Server

    Maltoni, F

    2014-01-01

    Quantum Chromo Dynamics (QCD) provides the theoretical framework for any study of TeV scale physics at LHC. Being familiar with the basic concepts and techniques of QCD is therefore a must for any high-energy physicist. In these notes we consider Higgs production via gluon fusion as an example on how accurate and flexible predictions can be obtained in perturbative QCD. We start by illustrating how to calculate the total cross section at the leading order (yet one loop) in the strong coupling $\\alpha$S and go through the details of the next-to-leading order calculation eventually highlighting the limitations of fixed-order predictions at the parton level. Finally, we briefly discuss how more exclusive (and practical) predictions can be obtained through matching/merging fixed-order results with parton showers.

  12. Hard Corrections in Precision QCD for LHC and FCC Physics: A New Approach

    CERN Document Server

    Ward, B F L

    2016-01-01

    With an eye toward the usual unphysical divergence of hard fixed-order corrections in predictions for the processes probed in high energy colliding hadron beam devices as one approaches the soft limit, we present a new approach to the realization of such corrections, with some emphasis on the LHC and the future FCC devices. We show that the respective divergence is removed in our approach. This means that we would render the standard results to be closer to the observed exclusive distributions. While we stress that the approach has general applicability, we use the single Z and virtual gamma production and decay to lepton pairs as our prototypical example. Accordingly, our work opens another part of the way to rigorous baselines for the determination of the theoretical precision tags for LHC physics, with an attendant generalization to the future FCC.

  13. Two-loop master integrals for the mixed EW-QCD virtual corrections to Drell-Yan scattering

    Science.gov (United States)

    Bonciani, Roberto; Di Vita, Stefano; Mastrolia, Pierpaolo; Schubert, Ulrich

    2016-09-01

    We present the calculation of the master integrals needed for the two-loop QCD × EW corrections to q+overline{q}to {l}-+{l}+ and q+overline{q}^'to {l}-+overline{ν} , for massless external particles. We treat the W and Z bosons as degenerate in mass. We identify three types of diagrams, according to the presence of massive internal lines: the no-mass type, the one-mass type, and the two-mass type, where all massive propagators, when occurring, contain the same mass value. We find a basis of 49 master integrals and evaluate them with the method of the differential equations. The Magnus exponential is employed to choose a set of master integrals that obeys a canonical system of differential equations. Boundary conditions are found either by matching the solutions onto simpler integrals in special kinematic configurations, or by requiring the regularity of the solution at pseudothresholds. The canonical master integrals are finally given as Taylor series around d = 4 space-time dimensions, up to order four, with coefficients given in terms of iterated integrals, respectively up to weight four.

  14. Two-loop master integrals for the mixed EW-QCD virtual corrections to Drell-Yan scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bonciani, Roberto [' ' La Sapienza' ' Univ., Rome (Italy). Dipt. di Fisica; INFN Sezione Roma (Italy); Di Vita, Stefano [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mastrolia, Pierpaolo [Max-Planck-Institut fuer Physik, Muenchen (Germany); Padova Univ. (Italy). Dipt. di Fisica e Astronomia; INFN Sezione di Padova (Italy); Schubert, Ulrich [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2016-04-15

    We present the calculation of the master integrals needed for the two-loop QCD x EW corrections to q+ anti q → l{sup -}+l{sup +} and q+ anti q{sup '} → l{sup -}+ anti ν, for massless external particles. We treat W and Z bosons as degenerate in mass. We identify three types of diagrams, according to the presence of massive internal lines: the no-mass type, the one-mass type, and the two-mass type, where all massive propagators, when occurring, contain the same mass value. We find a basis of 49 master integrals and evaluate them with the method of the differential equations. The Magnus exponential is employed to choose a set of master integrals that obeys a canonical system of differential equations. Boundary conditions are found either by matching the solutions onto simpler integrals in special kinematic configurations, or by requiring the regularity of the solution at pseudo-thresholds. The canonical master integrals are finally given as Taylor series around d=4 space-time dimensions, up to order four, with coefficients given in terms of iterated integrals, respectively up to weight four.

  15. Completing NLO QCD Corrections for Tree Level Non-Leptonic Delta F = 1 Decays Beyond the Standard Model

    CERN Document Server

    Buras, Andrzej J

    2012-01-01

    In various extensions of the Standard Model (SM) tree level non-leptonic decays of hadrons receive contributions from new heavy gauge bosons and scalars. Prominent examples are the right-handed W' bosons in left-right symmetric models and charged Higgs (H^\\pm) particles in models with extended scalar sector like two Higgs doublet models and supersymmetric models. Even in the case of decays with four different quark flavours involved, to which penguin operators cannot contribute, twenty linearly independent operators, instead of two in the SM, have to be considered. Anticipating the important role of such decays at the LHCb, KEKB and Super-B in Rome and having in mind future improved lattice computations, we complete the existing NLO QCD formulae for these processes by calculating O(alpha_s) corrections to matching conditions for the Wilson coefficients of all contributing operators in the NDR-\\bar{MS} scheme. This allows to reduce certain unphysical scale and renormalization scheme dependences in the existing...

  16. Combined effect of QCD resummation and QED radiative correction to W boson observables at the Tevatron.

    Science.gov (United States)

    Cao, Qing-Hong; Yuan, C P

    2004-07-23

    A precise determination of the W boson mass at the Fermilab Tevatron requires a theoretical calculation in which the effects of the initial-state multiple soft-gluon emission and the final-state photonic correction are simultaneously included. Here, we present such a calculation and discuss its prediction on the transverse mass distribution of the W boson and the transverse momentum distribution of its decay charged lepton, which are the most relevant observables for measuring the W boson mass at hadron colliders.

  17. Tidal heating and torquing of a Kerr black hole to next-to-leading order in the tidal coupling

    CERN Document Server

    Chatziioannou, Katerina; Yunes, Nicolas

    2012-01-01

    We calculate the linear vacuum perturbations of a Kerr black hole surrounded by a slowly-varying external spacetime to third order in the ratio of the black-hole mass to the radius of curvature of the external spacetime. This expansion applies to two relevant physical scenarios: (i) a small Kerr black hole immersed in the gravitational field of a much larger external black hole, and (ii) a Kerr black hole moving slowly around another external black hole of comparable mass. This small-hole/slow-motion approximation allows us to parametrize the perturbation through slowly-varying, time-dependent electric and magnetic tidal tensors, which then enables us to separate the Teukolsky equation and compute the Newman-Penrose scalar analytically to third order in our expansion parameter. We obtain generic expressions for the mass and angular momentum flux through the perturbed black hole horizon, as well as the rate of change of the horizon surface area, in terms of certain invariants constructed from the electric and ...

  18. Test of the Flavour Independence of $\\alpha_{s}$ using Next-to-Leading Order Calculations for Heavy Quarks

    CERN Document Server

    Abbiendi, G; Alexander, Gideon; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bellerive, A; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bloodworth, Ian J; Bock, P; Böhme, J; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couchman, J; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Davis, R; De Jong, S; de Roeck, A; Dervan, P J; Desch, Klaus; Dienes, B; Dixit, M S; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Estabrooks, P G; Etzion, E; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fleck, I; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon-Shotkin, S M; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Harder, K; Harel, A; Hargrove, C K; Harin-Dirac, M; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hobson, P R; Höcker, Andreas; Hoffman, K; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Jones, C R; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J I; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klier, A; Kobayashi, T; Kobel, M; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kühl, T; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lauber, J; Lawson, I; Layter, J G; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Lü, J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mader, W F; Mannelli, M; Marcellini, S; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Méndez-Lorenzo, P; Merritt, F S; Mes, H; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Okpara, A N; Oreglia, M J; Orito, S; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Quadt, A; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Sproston, M; Stahl, A; Stephens, K; Steuerer, J; Stoll, K; Strom, D; Ströhmer, R; Surrow, B; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomas, J; Thomson, M A; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Van Kooten, R; Vannerem, P; Verzocchi, M; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; Wetterling, D; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Zacek, V; Zer-Zion, D

    1999-01-01

    We present a test of the flavour independence of the strong coupling constant for charm and bottom quarks with respect to light (uds) quarks, based on a hadronic event sample obtained with the OPAL detector at LEP. Five observables related to global event shapes were used to measure alpha_s in three flavour tagged samples (uds, c and b). The event shape distributions were fitted by Order(alpha_s**2) calculations of jet production taking into account mass effects for the c and b quarks. We find: = 0.997 +- 0.038(stat.) +- 0.030(syst.) +- 0.012(theory) and = 0.993 +- 0.008(stat.) +- 0.006(syst.) +- 0.011(theory) for the ratios alpha_s(charm)/alpha_s(uds) and alpha_s(b)/alpha_s(uds) respectively.

  19. Comment on "On the next-to-leading order gravitational spin(1)-spin(2) dynamics" by J. Steinhoff et al

    CERN Document Server

    Porto, Rafael A

    2007-01-01

    In this comment we explain the discrepancy found between the results in arXiv:0712.1716v1 for the 3PN spin-spin potential and those previously derived in gr-qc/0604099. We point out that to compare one must include sub-leading lower order spin-orbit effects which contribute to the spin-spin potential once one transforms to the PN frame. When these effects are included the results in arXiv:0712.1716v1 do indeed reproduce those found in gr-qc/0604099.

  20. Standard model Wilson coefficients for c → ul{sup +}l{sup -} transitions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Boer, Stefan de [TU Dortmund (Germany); Mueller, Bastian; Seidel, Dirk [Uni Siegen (Germany)

    2016-07-01

    The standard theoretical framework to deal with exclusive, weak decays of heavy mesons is the so-called weak effective Hamiltonian. It involves the short-distance Wilson coefficients, which depend on the renormalization scale μ. For specific calculations one has to evolve the Wilson coefficients down from the electroweak scale μ{sub W} to the typical mass scale of the decay under consideration. This is done by solving a renormalization group equation for the effective operator basis. In this talk the results of a consistent two-step running of the c → ul{sup +}l{sup -} Wilson coefficients are presented. This running involves the intermediate scale μ{sub b} (with μ{sub W} > μ{sub b} > μ{sub c}) where the bottom quark is integrated out. All the matching coefficients and anomalous dimensions are taken to the required order by generalizing and extending results from b → s or s → d transitions available in the literature.

  1. The Kondo lattice state in the presence of Van Hove singularities: Next-to-leading order scaling

    Science.gov (United States)

    Irkhin, V. Yu.

    2017-07-01

    Renormalization group analysis of the Kondo model with a logarithmic Van Hove singularity in the electron density of states has been carried out in the next-to-leading scaling approximation in different magnetic phases. The effective coupling constant remains small, while the renormalized magnetic moment and the frequency of spin fluctuations decrease by several orders of magnitude. In this way, broad regions of non-Fermi-liquid behavior are found from scaling trajectories in a large interval of the bare coupling constant. Applications to the physics of itinerant magnetism are considered.

  2. Finite-Volume QED Corrections to Decay Amplitudes in Lattice QCD

    CERN Document Server

    Lubicz, V.; Sachrajda, C.T.; Sanfilippo, F.; Simula, S.; Tantalo, N.

    2017-01-01

    We demonstrate that the leading and next-to-leading finite-volume effects in the evaluation of leptonic decay widths of pseudoscalar mesons at $O(\\alpha)$ are universal, i.e. they are independent of the structure of the meson. This is analogous to a similar result for the spectrum but with some fundamental differences, most notably the presence of infrared divergences in decay amplitudes. The leading non-universal, structure-dependent terms are of $O(1/L^2)$ (compared to the $O(1/L^3)$ leading non-universal corrections in the spectrum). We calculate the universal finite-volume effects, which requires an extension of previously developed techniques to include a dependence on an external three-momentum (in our case, the momentum of the final state lepton). The result can be included in the strategy proposed in Ref.\\,\\cite{Carrasco:2015xwa} for using lattice simulations to compute the decay widths at $O(\\alpha)$, with the remaining finite-volume effects starting at order $O(1/L^2)$. The methods developed in this...

  3. Charmed-meson fragmentation functions with finite-mass corrections and their application in various processes

    Energy Technology Data Exchange (ETDEWEB)

    Kneesch, Torben

    2010-12-15

    We have calculated the single-inclusive production cross section of massive quarks in electron-positron-annihilation with next-to-leading order QCD corrections. With these results we have extracted fragmentation functions for the fragmentation from partons into D{sup 0}, D{sup +} and D{sup *} mesons, where we have used experimental data from the B factories Belle and CLEO and from the ALEPH and OPAL experiments at the LEP collider. In our analysis we have included the masses of c and b quarks and of the D mesons and tested the evolution of fragmentation functions with a global fit spanning the B factories' center-of-mass energy of {radical}(s)=10.5 GeV to LEP's run at the Z boson resonance at M{sub Z}. We have applied this fragmentation functions in deep inelastic scattering for comparisons with HERA data using parton cross sections from the literature available in program form. We have then modified this cross section to calculate predictions for deep inelastic two-photon-scattering. By applying the Weizsaecker-Williams spectrum on the real photon we have calculated predictions for LEP1, LEP2 and the future ILC experiments. For ILC we have also included a beamstrahlung spectrum. Finally we have calculated production cross sections for the planned e{gamma} mode of the ILC with the help of a Compton spectrum. (orig.)

  4. The impact of the photon PDF and electroweak corrections on $t \\bar t$ distributions

    CERN Document Server

    Pagani, Davide; Zaro, Marco

    2016-01-01

    We discuss the impact of EW corrections on several differential distributions in top-quark pair production at the LHC and future hadron colliders, focusing on the effects induced by initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order $\\alpha_s \\alpha$ and $\\alpha_s^2 \\alpha$. A thorough comparison of predictions obtained with the NNPDF2.3QED and CT14QED PDF sets is performed; we assess the effect due to photon densities in the two sets, which are determined via very different approaches (discussed in the text). We present predictions at 13 and 100 TeV, and we provide results for the 8 TeV differential measurements performed by ATLAS and CMS at the LHC. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and are affected by large PDF uncertainti...

  5. Preweighting method in Monte-Carlo sampling with complex action --- Strong-Coupling Lattice QCD with $1/g^2$ corrections, as an example ---

    CERN Document Server

    Ohnishi, Akira

    2015-01-01

    We investigate the QCD phase diagram in the strong-coupling lattice QCD with fluctuation and $1/g^2$ effects by using the auxiliary field Monte-Carlo simulations. The complex phase of the Fermion determinant at finite chemical potential is found to be suppressed by introducing a complex shift of integral path for one of the auxiliary fields, which corresponds to introducing a repulsive vector mean field for quarks. The obtained phase diagram in the chiral limit shows suppressed $T_c$ in the second order phase transition region compared with the strong-coupling limit results. We also argue that we can approximately guess the statistical weight cancellation from the complex phase in advance in the case where the complex phase distribution is Gaussian. We demonstrate that correct expectation values are obtained by using this guess in the importance sampling (preweighting).

  6. Measurements of the Strong Coupling Constant and the QCD Colour Factors using Four-jet Observables from Hadronic Z Decays

    CERN Document Server

    Heister, A; Barate, R; De Bonis, I; Décamp, D; Goy, C; Lees, J P; Merle, E; Minard, M N; Pietrzyk, B; Boix, G; Bravo, S; Casado, M P; Chmeissani, M; Crespo, J M; Fernández, E; Fernández-Bosman, M; Garrido, L; Graugès-Pous, E; Martínez, M; Merino, G; Miquel, R; Mir, L M; Pacheco, A; Ruiz, H; Colaleo, A; Creanza, D; De Palma, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Azzurri, P; Buchmüller, O L; Cattaneo, M; Cerutti, F; Clerbaux, B; Drevermann, H; Forty, R W; Frank, M; Gianotti, F; Greening, T C; Hansen, J B; Harvey, J; Hutchcroft, D E; Janot, P; Jost, B; Kado, M; Mato, P; Moutoussi, A; Ranjard, F; Rolandi, Luigi; Schlatter, W D; Schneider, O; Sguazzoni, G; Tejessy, W; Teubert, F; Valassi, Andrea; Videau, I; Ward, J; Badaud, F; Falvard, A; Gay, P; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Markou, C; Simopoulou, Errietta; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Rougé, A; Rumpf, M; Swynghedauw, M; Verderi, M; Videau, H L; Ciulli, V; Focardi, E; Parrini, G; Antonelli, A; Antonelli, M; Bencivenni, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Halley, A; Lynch, J G; Negus, P; O'Shea, V; Raine, C; Thompson, A S; Wasserbaech, S R; Cavanaugh, R J; Dhamotharan, S; Geweniger, C; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Stenzel, H; Tittel, K; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, P J; Girone, M; Marinelli, N; Sedgbeer, J K; Thompson, J C; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bouhova-Thacker, E; Bowdery, C K; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Pearson, M R; Robertson, N A; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Sander, H G; Wachsmuth, H W; Zeitnitz, C; Bonissent, A; Coyle, P; Leroy, O; Payre, P; Rousseau, D; Talby, M; Ragusa, F; David, A; Dietl, H; Ganis, G; Hüttmann, K; Lütjens, G; Männer, W; Moser, H G; Settles, Ronald; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacholkowska, A; Lefrançois, J; Veillet, J J; Yuan, C; Bagliesi, G; Boccali, T; Foà, L; Giammanco, A; Giassi, A; Ligabue, F; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Spagnolo, P; Tenchini, Roberto; Venturi, A; Verdini, P G; Xie, Z; Blair, G A; Cowan, G; Green, M G; Medcalf, T; Misiejuk, A; Strong, J A; Teixeira-Dias, P; Clifft, R W; Edgecock, T R; Norton, P R; Tomalin, I R; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Konstantinidis, N P; Litke, A M; Taylor, G; Booth, C N; Cartwright, S L; Combley, F; Lehto, M H; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Grupen, Claus; Ngac, A; Prange, G; Sieler, U; Giannini, G; Rothberg, J E; Armstrong, S R; Berkelman, K; Cranmer, K; Ferguson, D P S; Gao, Y; González, S; Hayes, O J; Hu, H; Jin, S; Kile, J; McNamara, P A; Nielsen, J; Pan, Y B; Von Wimmersperg-Töller, J H; Wu, J; Wu Sau Lan; Wu, X; Zobernig, G

    2003-01-01

    Data from e+e- annihilation into hadrons, taken with the ALEPH detector at the Z resonance, are analyzed. The four-jet rate is studied as a function of the resolution parameter and compared to next-to-leading order calculations combined with resummation of large logarithms. Angular correlations in four-jet events are measured and compared to next-to-leading order QCD predictions. With these observables two different measurements are performed. In a first analysis the strong coupling constant is measured from the four-jet rate yielding alpha_s(M_ Z}) = 0.1170 \\pm 0.0001(stat) \\pm 0.0014(sys) In a second measurement the strong coupling constant and the \\textsc{QCD} colour factors are determined simultaneously from a fit to the four-jet rate and the four-jet angular correlations, giving alpha_s(M_ Z) = 0.119 \\pm 0.006(stat) \\pm 0.026 (sys) C_A = 2.93 \\pm 0.14(stat) \\pm 0.58 (sys) C_F} = 1.35 \\pm 0.07 (stat) \\pm 0.26 (sys) in good agreement with the expectation from QCD.

  7. QCD analysis of DIS structure functions in neutrino-nucleon scattering: Laplace transform and Jacobi polynomials approach

    CERN Document Server

    Nejad, S Mohammad Moosavi; Tehrani, S Atashbar; Mahdavi, Mahdi

    2016-01-01

    We present a detailed QCD analysis of nucleon structure functions $xF_3 (x, Q^2)$, based on Laplace transforms and Jacobi polynomials approach. The analysis corresponds to the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) approximation of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet DGLAP evolution equations at low- and large-$x$ values. The extracted results are used as input to obtain the $x$ and Q$^2$ evolution of $xF_3(x, Q^2)$ structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale $\\Lambda_{\\overline{\\rm MS}}^{(n_f)}$ and the strong coupling constant $\\alpha_s(M_Z^2)$ are determined for four quark flavors ($n_f=4$) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark PDFs sets with those of other collabora...

  8. QCD analysis of nucleon structure functions in deep-inelastic neutrino-nucleon scattering: Laplace transform and Jacobi polynomials approach

    Science.gov (United States)

    Nejad, S. Mohammad Moosavi; Khanpour, Hamzeh; Tehrani, S. Atashbar; Mahdavi, Mahdi

    2016-10-01

    We present a detailed QCD analysis of nucleon structure functions x F3(x ,Q2) , based on Laplace transforms and the Jacobi polynomials approach. The analysis corresponds to the next-to-leading order and next-to-next-to-leading order approximations of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at low- and large-x values. The extracted results are used as input to obtain the x and Q2 evolution of x F3(x ,Q2) structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale ΛMS¯ (nf) and the strong coupling constant αs(MZ2) are determined for four quark flavors (nf=4 ) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark parton distribution functions sets with those of other collaborations, in particular with the CT14, MMHT14, and NNPDF sets, which are contemporary with the present analysis. The obtained results from the analysis are in good agreement with those from the literature.

  9. Measurement and QCD analysis of double-differential inclusive jet cross-sections in pp collisions at $\\sqrt{s} = $ 8 TeV and ratios to 2.76 and 7 TeV

    CERN Document Server

    Khachatryan, Vardan; Tumasyan, Armen; Adam, Wolfgang; Aşılar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krätschmer, Ilse; Liko, Dietrich; Matsushita, Takashi; Mikulec, Ivan; Rabady, Dinyar; Rad, Navid; Rahbaran, Babak; Rohringer, Herbert; Schieck, Jochen; Strauss, Josef; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; De Wolf, Eddi A; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; Daci, Nadir; De Bruyn, Isabelle; Deroover, Kevin; Heracleous, Natalie; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Olbrechts, Annik; Python, Quentin; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Léonard, Alexandre; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cimmino, Anna; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Garcia, Guillaume; Gul, Muhammad; Poyraz, Deniz; Salva Diblen, Sinem; Schöfbeck, Robert; Tytgat, Michael; Van Driessche, Ward; Yazgan, Efe; Zaganidis, Nicolas; Beluffi, Camille; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caudron, Adrien; Ceard, Ludivine; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Forthomme, Laurent; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Nuttens, Claude; Piotrzkowski, Krzysztof; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Matos Figueiredo, Diego; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Moon, Chang-Seong; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Cheng, Tongguang; Jiang, Chun-Hua; Leggat, Duncan; Liu, Zhenan; Romeo, Francesco; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Zhang, Huaqiao; Zhao, Jingzhou; Asawatangtrakuldee, Chayanit; Ban, Yong; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Micanovic, Sasa; Sudic, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Assran, Yasser; Elkafrawy, Tamer; Ellithi Kamel, Ali; Mahrous, Ayman; Calpas, Betty; Kadastik, Mario; Murumaa, Marion; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Peltola, Timo; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Talvitie, Joonas; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Ghosh, Saranya; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Kucher, Inna; Locci, Elizabeth; Machet, Martina; Malcles, Julie; Rander, John; Rosowsky, André; Titov, Maksym; Zghiche, Amina; Abdulsalam, Abdulla; Antropov, Iurii; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Cadamuro, Luca; Chapon, Emilien; Charlot, Claude; Davignon, Olivier; Granier de Cassagnac, Raphael; Jo, Mihee; Lisniak, Stanislav; Miné, Philippe; Naranjo, Ivo Nicolas; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Pigard, Philipp; Regnard, Simon; Salerno, Roberto; Sirois, Yves; Strebler, Thomas; Yilmaz, Yetkin; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Aubin, Alexandre; Bloch, Daniel; Brom, Jean-Marie; Buttignol, Michael; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Coubez, Xavier; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Le Bihan, Anne-Catherine; Merlin, Jeremie Alexandre; Skovpen, Kirill; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Bouvier, Elvire; Carrillo Montoya, Camilo Andres; Chierici, Roberto; Contardo, Didier; Courbon, Benoit; Depasse, Pierre; El Mamouni, Houmani; Fan, Jiawei; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Grenier, Gérald; Ille, Bernard; Lagarde, Francois; Laktineh, Imad Baptiste; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Popov, Andrey; Sabes, David; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Khvedelidze, Arsen; Lomidze, David; Autermann, Christian; Beranek, Sarah; Feld, Lutz; Heister, Arno; Kiesel, Maximilian Knut; Klein, Katja; Lipinski, Martin; Ostapchuk, Andrey; Preuten, Marius; Raupach, Frank; Schael, Stefan; Schomakers, Christian; Schulte, Jan-Frederik; Schulz, Johannes; Verlage, Tobias; Weber, Hendrik; Zhukov, Valery; Brodski, Michael; Dietz-Laursonn, Erik; Duchardt, Deborah; Endres, Matthias; Erdmann, Martin; Erdweg, Sören; Esch, Thomas; Fischer, Robert; Güth, Andreas; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Knutzen, Simon; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Mukherjee, Swagata; Olschewski, Mark; Padeken, Klaas; Papacz, Paul; Pook, Tobias; Radziej, Markus; Reithler, Hans; Rieger, Marcel; Scheuch, Florian; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Cherepanov, Vladimir; Erdogan, Yusuf; Flügge, Günter; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Künsken, Andreas; Lingemann, Joschka; Nehrkorn, Alexander; Nowack, Andreas; Nugent, Ian Michael; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Asin, Ivan; Beernaert, Kelly; Behnke, Olaf; Behrens, Ulf; Bin Anuar, Afiq Aizuddin; Borras, Kerstin; Campbell, Alan; Connor, Patrick; Contreras-Campana, Christian; Costanza, Francesco; Diez Pardos, Carmen; Dolinska, Ganna; Eckerlin, Guenter; Eckstein, Doris; Eren, Engin; Gallo, Elisabetta; Garay Garcia, Jasone; Geiser, Achim; Gizhko, Andrii; Grados Luyando, Juan Manuel; Gunnellini, Paolo; Harb, Ali; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kalogeropoulos, Alexis; Karacheban, Olena; Kasemann, Matthias; Keaveney, James; Kieseler, Jan; Kleinwort, Claus; Korol, Ievgen; Kuprash, Oleg; Lange, Wolfgang; Lelek, Aleksandra; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Mankel, Rainer; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Ntomari, Eleni; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Roland, Benoit; Sahin, Mehmet Özgür; Saxena, Pooja; Schoerner-Sadenius, Thomas; Seitz, Claudia; Spannagel, Simon; Stefaniuk, Nazar; Trippkewitz, Karim Damun; Van Onsem, Gerrit Patrick; Walsh, Roberval; Wissing, Christoph; Blobel, Volker; Centis Vignali, Matteo; Draeger, Arne-Rasmus; Dreyer, Torben; Garutti, Erika; Goebel, Kristin; Gonzalez, Daniel; Haller, Johannes; Hoffmann, Malte; Junkes, Alexandra; Klanner, Robert; Kogler, Roman; Kovalchuk, Nataliia; Lapsien, Tobias; Lenz, Teresa; Marchesini, Ivan; Marconi, Daniele; Meyer, Mareike; Niedziela, Marek; Nowatschin, Dominik; Ott, Jochen; Pantaleo, Felice; Peiffer, Thomas; Perieanu, Adrian; Poehlsen, Jennifer; Sander, Christian; Scharf, Christian; Schleper, Peter; Schmidt, Alexander; Schumann, Svenja; Schwandt, Joern; Stadie, Hartmut; Steinbrück, Georg; Stober, Fred-Markus Helmut; Stöver, Marc; Tholen, Heiner; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Vanhoefer, Annika; Vormwald, Benedikt; Barth, Christian; Baus, Colin; Berger, Joram; Butz, Erik; Chwalek, Thorsten; Colombo, Fabio; De Boer, Wim; Dierlamm, Alexander; Fink, Simon; Friese, Raphael; Giffels, Manuel; Gilbert, Andrew; Haitz, Dominik; Hartmann, Frank; Heindl, Stefan Michael; Husemann, Ulrich; Katkov, Igor; Kornmayer, Andreas; Lobelle Pardo, Patricia; Maier, Benedikt; Mildner, Hannes; Mozer, Matthias Ulrich; Müller, Thomas; Müller, Thomas; Plagge, Michael; Quast, Gunter; Rabbertz, Klaus; Röcker, Steffen; Roscher, Frank; Schröder, Matthias; Sieber, Georg; Simonis, Hans-Jürgen; Ulrich, Ralf; Wagner-Kuhr, Jeannine; Wayand, Stefan; Weber, Marc; Weiler, Thomas; Williamson, Shawn; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Topsis-Giotis, Iasonas; Agapitos, Antonis; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Tziaferi, Eirini; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Loukas, Nikitas; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Filipovic, Nicolas; Bencze, Gyorgy; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Molnar, Jozsef; Szillasi, Zoltan; Bartók, Márton; Makovec, Alajos; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Bahinipati, Seema; Choudhury, Somnath; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Sahoo, Niladribihari; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chawla, Ridhi; Gupta, Ruchi; Bhawandeep, Bhawandeep; Kalsi, Amandeep Kaur; Kaur, Anterpreet; Kaur, Manjit; Kumar, Ramandeep; Mehta, Ankita; Mittal, Monika; Singh, Jasbir; Walia, Genius; Kumar, Ashok; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Garg, Rocky Bala; Keshri, Sumit; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Nishu, Nishu; Ranjan, Kirti; Sharma, Ramkrishna; Sharma, Varun; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Majumdar, Nayana; Modak, Atanu; Mondal, Kuntal; Mukhopadhyay, Supratik; Nandan, Saswati; Purohit, Arnab; Roy, Ashim; Roy, Debarati; Roy Chowdhury, Suvankar; Sarkar, Subir; Sharan, Manoj; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Mohanty, Ajit Kumar; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Dugad, Shashikant; Kole, Gouranga; Mahakud, Bibhuprasad; Mitra, Soureek; Mohanty, Gagan Bihari; Sur, Nairit; Sutar, Bajrang; Banerjee, Sudeshna; Bhowmik, Sandeep; Dewanjee, Ram Krishna; Ganguly, Sanmay; Guchait, Monoranjan; Jain, Sandhya; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Parida, Bibhuti; Sarkar, Tanmay; Wickramage, Nadeesha; Chauhan, Shubhanshu; Dube, Sourabh; Kapoor, Anshul; Kothekar, Kunal; Rane, Aditee; Sharma, Seema; Bakhshiansohi, Hamed; Behnamian, Hadi; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Fahim, Ali; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Caputo, Claudio; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Chiorboli, Massimiliano; Costa, Salvatore; Di Mattia, Alessandro; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Gori, Valentina; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Primavera, Federica; Calvelli, Valerio; Ferro, Fabrizio; Lo Vetere, Maurizio; Monge, Maria Roberta; Robutti, Enrico; Tosi, Silvano; Brianza, Luca; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Marzocchi, Badder; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Pigazzini, Simone; Ragazzi, Stefano; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; De Nardo, Guglielmo; Di Guida, Salvatore; Esposito, Marco; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lanza, Giuseppe; Lista, Luca; Meola, Sabino; Merola, Mario; Paolucci, Pierluigi; Sciacca, Crisostomo; Thyssen, Filip; Azzi, Patrizia; Bacchetta, Nicola; Benato, Lisa; Biasotto, Massimo; Boletti, Alessio; Carvalho Antunes De Oliveira, Alexandra; Dall'Osso, Martino; De Castro Manzano, Pablo; Dorigo, Tommaso; Dosselli, Umberto; Fantinel, Sergio; Fanzago, Federica; Gasparini, Fabrizio; Gasparini, Ugo; Gulmini, Michele; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Torassa, Ezio; Ventura, Sandro; Zanetti, Marco; Zotto, Pierluigi; Zucchetta, Alberto; Zumerle, Gianni; Braghieri, Alessandro; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Leonardi, Roberto; Mantovani, Giancarlo; Menichelli, Mauro; Saha, Anirban; Santocchia, Attilio; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Donato, Silvio; Fedi, Giacomo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; D'imperio, Giulia; Del Re, Daniele; Diemoz, Marcella; Gelli, Simone; Jorda, Clara; Longo, Egidio; Margaroli, Fabrizio; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Finco, Linda; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; La Licata, Chiara; Schizzi, Andrea; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Sangeun; Lee, Seh Wook; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Kim, Hyunsoo; Lee, Ari; Brochero Cifuentes, Javier Andres; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Byounghoon; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Oh, Sung Bin; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Choi, Minkyoo; Kim, Hyunchul; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Ryu, Geonmo; Ryu, Min Sang; Choi, Young-Il; Goh, Junghwan; Hwang, Chanwook; Kim, Donghyun; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Komaragiri, Jyothsna Rani; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Hernandez-Almada, Alberto; Lopez-Fernandez, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Carpinteyro, Severiano; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khan, Wajid Ali; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; Afanasiev, Serguei; Bunin, Pavel; Golutvin, Igor; Karjavin, Vladimir; Korenkov, Vladimir; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Mitsyn, Valeri Valentinovitch; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Tikhonenko, Elena; Voytishin, Nikolay; Zarubin, Anatoli; Chtchipounov, Leonid; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Murzin, Victor; Oreshkin, Vadim; Sulimov, Valentin; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Chistov, Ruslan; Rusinov, Vladimir; Tarkovskii, Evgenii; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Rusakov, Sergey V; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Navarro De Martino, Eduardo; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; de Trocóniz, Jorge F; Missiroli, Marino; Moran, Dermot; Cuevas, Javier; Fernandez Menendez, Javier; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Sanchez Cruz, Sergio; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Castiñeiras De Saa, Juan Ramon; Curras, Esteban; Fernandez, Marcos; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Matorras, Francisco; Piedra Gomez, Jonatan; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Botta, Cristina; Camporesi, Tiziano; Castello, Roberto; Cepeda, Maria; Cerminara, Gianluca; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Gruttola, Michele; De Guio, Federico; De Roeck, Albert; Di Marco, Emanuele; Dobson, Marc; Dordevic, Milos; Dorney, Brian; Du Pree, Tristan; Duggan, Daniel; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Fartoukh, Stephane; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gill, Karl; Girone, Maria; Glege, Frank; Gulhan, Doga; Gundacker, Stefan; Guthoff, Moritz; Hammer, Josef; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kirschenmann, Henning; Knünz, Valentin; Kortelainen, Matti J; Kousouris, Konstantinos; Krammer, Manfred; Lecoq, Paul; Lourenco, Carlos; Lucchini, Marco Toliman; Malgeri, Luca; Mannelli, Marcello; Martelli, Arabella; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Neugebauer, Hannes; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuelle; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Ruan, Manqi; Sakulin, Hannes; Sauvan, Jean-Baptiste; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Sharma, Archana; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Steggemann, Jan; Stoye, Markus; Takahashi, Yuta; Tosi, Mia; Treille, Daniel; Triossi, Andrea; Tsirou, Andromachi; Veckalns, Viesturs; Veres, Gabor Istvan; Wardle, Nicholas; Wöhri, Hermine Katharina; Zagoździńska, Agnieszka; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Eller, Philipp; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; Kasieczka, Gregor; Lecomte, Pierre; Lustermann, Werner; Mangano, Boris; Marionneau, Matthieu; Martinez Ruiz del Arbol, Pablo; Masciovecchio, Mario; Meinhard, Maren Tabea; Meister, Daniel; Micheli, Francesco; Musella, Pasquale; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pata, Joosep; Pauss, Felicitas; Perrin, Gaël; Perrozzi, Luca; Quittnat, Milena; Rossini, Marco; Schönenberger, Myriam; Starodumov, Andrei; Takahashi, Maiko; Tavolaro, Vittorio Raoul; Theofilatos, Konstantinos; Wallny, Rainer; Aarrestad, Thea Klaeboe; Amsler, Claude; Caminada, Lea; Canelli, Maria Florencia; Chiochia, Vincenzo; De Cosa, Annapaola; Galloni, Camilla; Hinzmann, Andreas; Hreus, Tomas; Kilminster, Benjamin; Lange, Clemens; Ngadiuba, Jennifer; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Yang, Yong; Candelise, Vieri; Doan, Thi Hien; Jain, Shilpi; Khurana, Raman; Konyushikhin, Maxim; Kuo, Chia-Ming; Lin, Willis; Lu, Yun-Ju; Pozdnyakov, Andrey; Yu, Shin-Shan; Kumar, Arun; Chang, Paoti; Chang, You-Hao; Chang, Yu-Wei; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Dietz, Charles; Fiori, Francesco; Hou, George Wei-Shu; Hsiung, Yee; Liu, Yueh-Feng; Lu, Rong-Shyang; Miñano Moya, Mercedes; Paganis, Efstathios; Psallidas, Andreas; Tsai, Jui-fa; Tzeng, Yeng-Ming; Asavapibhop, Burin; Singh, Gurpreet; Srimanobhas, Norraphat; Suwonjandee, Narumon; Adiguzel, Aytul; Cerci, Salim; Damarseckin, Serdal; Demiroglu, Zuhal Seyma; Dozen, Candan; Dumanoglu, Isa; Girgis, Semiray; Gokbulut, Gul; Guler, Yalcin; Gurpinar, Emine; Hos, Ilknur; Kangal, Evrim Ersin; Kara, Ozgun; Kayis Topaksu, Aysel; Kiminsu, Ugur; Oglakci, Mehmet; Onengut, Gulsen; Ozdemir, Kadri; Sunar Cerci, Deniz; Topakli, Huseyin; Turkcapar, Semra; Zorbakir, Ibrahim Soner; Zorbilmez, Caglar; Bilin, Bugra; Bilmis, Selcuk; Isildak, Bora; Karapinar, Guler; Yalvac, Metin; Zeyrek, Mehmet; Gülmez, Erhan; Kaya, Mithat; Kaya, Ozlem; Yetkin, Elif Asli; Yetkin, Taylan; Cakir, Altan; Cankocak, Kerem; Sen, Sercan; Grynyov, Boris; Levchuk, Leonid; Sorokin, Pavel; Aggleton, Robin; Ball, Fionn; Beck, Lana; Brooke, James John; Burns, Douglas; Clement, Emyr; Cussans, David; Flacher, Henning; Goldstein, Joel; Grimes, Mark; Heath, Greg P; Heath, Helen F; Jacob, Jeson; Kreczko, Lukasz; Lucas, Chris; Newbold, Dave M; Paramesvaran, Sudarshan; Poll, Anthony; Sakuma, Tai; Seif El Nasr-storey, Sarah; Smith, Dominic; Smith, Vincent J; Bell, Ken W; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Calligaris, Luigi; Cieri, Davide; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Williams, Thomas; Baber, Mark; Bainbridge, Robert; Buchmuller, Oliver; Bundock, Aaron; Burton, Darren; Casasso, Stefano; Citron, Matthew; Colling, David; Corpe, Louie; Dauncey, Paul; Davies, Gavin; De Wit, Adinda; Della Negra, Michel; Dunne, Patrick; Elwood, Adam; Futyan, David; Haddad, Yacine; Hall, Geoffrey; Iles, Gregory; Lane, Rebecca; Laner, Christian; Lucas, Robyn; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Mastrolorenzo, Luca; Nash, Jordan; Nikitenko, Alexander; Pela, Joao; Penning, Bjoern; Pesaresi, Mark; Raymond, David Mark; Richards, Alexander; Rose, Andrew; Seez, Christopher; Tapper, Alexander; Uchida, Kirika; Vazquez Acosta, Monica; Virdee, Tejinder; Zenz, Seth Conrad; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Leslie, Dawn; Reid, Ivan; Symonds, Philip; Teodorescu, Liliana; Turner, Mark; Borzou, Ahmad; Call, Kenneth; Dittmann, Jay; Hatakeyama, Kenichi; Liu, Hongxuan; Pastika, Nathaniel; Charaf, Otman; Cooper, Seth; Henderson, Conor; Rumerio, Paolo; Arcaro, Daniel; Avetisyan, Aram; Bose, Tulika; Gastler, Daniel; Rankin, Dylan; Richardson, Clint; Rohlf, James; Sulak, Lawrence; Zou, David; Benelli, Gabriele; Berry, Edmund; Cutts, David; Garabedian, Alex; Hakala, John; Heintz, Ulrich; Jesus, Orduna; Laird, Edward; Landsberg, Greg; Mao, Zaixing; Narain, Meenakshi; Piperov, Stefan; Sagir, Sinan; Spencer, Eric; Syarif, Rizki; Breedon, Richard; Breto, Guillermo; Burns, Dustin; Calderon De La Barca Sanchez, Manuel; Chauhan, Sushil; Chertok, Maxwell; Conway, John; Conway, Rylan; Cox, Peter Timothy; Erbacher, Robin; Flores, Chad; Funk, Garrett; Gardner, Michael; Ko, Winston; Lander, Richard; Mclean, Christine; Mulhearn, Michael; Pellett, Dave; Pilot, Justin; Ricci-Tam, Francesca; Shalhout, Shalhout; Smith, John; Squires, Michael; Stolp, Dustin; Tripathi, Mani; Wilbur, Scott; Yohay, Rachel; Cousins, Robert; Everaerts, Pieter; Florent, Alice; Hauser, Jay; Ignatenko, Mikhail; Saltzberg, David; Takasugi, Eric; Valuev, Vyacheslav; Weber, Matthias; Burt, Kira; Clare, Robert; Ellison, John Anthony; Gary, J William; Hanson, Gail; Heilman, Jesse; Jandir, Pawandeep; Kennedy, Elizabeth; Lacroix, Florent; Long, Owen Rosser; Malberti, Martina; Olmedo Negrete, Manuel; Paneva, Mirena Ivova; Shrinivas, Amithabh; Wei, Hua; Wimpenny, Stephen; Yates, Brent; Branson, James G; Cerati, Giuseppe Benedetto; Cittolin, Sergio; Derdzinski, Mark; Gerosa, Raffaele; Holzner, André; Klein, Daniel; Letts, James; Macneill, Ian; Olivito, Dominick; Padhi, Sanjay; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Tadel, Matevz; Vartak, Adish; Wasserbaech, Steven; Welke, Charles; Wood, John; Würthwein, Frank; Yagil, Avraham; Zevi Della Porta, Giovanni; Bhandari, Rohan; Bradmiller-Feld, John; Campagnari, Claudio; Dishaw, Adam; Dutta, Valentina; Flowers, Kristen; Franco Sevilla, Manuel; Geffert, Paul; George, Christopher; Golf, Frank; Gouskos, Loukas; Gran, Jason; Heller, Ryan; Incandela, Joe; Mccoll, Nickolas; Mullin, Sam Daniel; Ovcharova, Ana; Richman, Jeffrey; Stuart, David; Suarez, Indara; West, Christopher; Yoo, Jaehyeok; Anderson, Dustin; Apresyan, Artur; Bendavid, Joshua; Bornheim, Adolf; Bunn, Julian; Chen, Yi; Duarte, Javier; Mott, Alexander; Newman, Harvey B; Pena, Cristian; Spiropulu, Maria; Vlimant, Jean-Roch; Xie, Si; Zhu, Ren-Yuan; Andrews, Michael Benjamin; Azzolini, Virginia; Carlson, Benjamin; Ferguson, Thomas; Paulini, Manfred; Russ, James; Sun, Menglei; Vogel, Helmut; Vorobiev, Igor; Cumalat, John Perry; Ford, William T; Jensen, Frank; Johnson, Andrew; Krohn, Michael; Mulholland, Troy; Stenson, Kevin; Wagner, Stephen Robert; Alexander, James; Chaves, Jorge; Chu, Jennifer; Dittmer, Susan; Mirman, Nathan; Nicolas Kaufman, Gala; Patterson, Juliet Ritchie; Rinkevicius, Aurelijus; Ryd, Anders; Skinnari, Louise; Tan, Shao Min; Tao, Zhengcheng; Thom, Julia; Tucker, Jordan; Wittich, Peter; Winn, Dave; Abdullin, Salavat; Albrow, Michael; Apollinari, Giorgio; Banerjee, Sunanda; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Bolla, Gino; Burkett, Kevin; Butler, Joel Nathan; Cheung, Harry; Chlebana, Frank; Cihangir, Selcuk; Cremonesi, Matteo; Elvira, Victor Daniel; Fisk, Ian; Freeman, Jim; Gottschalk, Erik; Gray, Lindsey; Green, Dan; Grünendahl, Stefan; Gutsche, Oliver; Hare, Daryl; Harris, Robert M; Hasegawa, Satoshi; Hirschauer, James; Hu, Zhen; Jayatilaka, Bodhitha; Jindariani, Sergo; Johnson, Marvin; Joshi, Umesh; Klima, Boaz; Kreis, Benjamin; Lammel, Stephan; Linacre, Jacob; Lincoln, Don; Lipton, Ron; Liu, Tiehui; Lopes De Sá, Rafael; Lykken, Joseph; Maeshima, Kaori; Magini, Nicolo; Marraffino, John Michael; Maruyama, Sho; Mason, David; McBride, Patricia; Merkel, Petra; Mrenna, Stephen; Nahn, Steve; Newman-Holmes, Catherine; O'Dell, Vivian; Pedro, Kevin; Prokofyev, Oleg; Rakness, Gregory; Ristori, Luciano; Sexton-Kennedy, Elizabeth; Soha, Aron; Spalding, William J; Spiegel, Leonard; Stoynev, Stoyan; Strobbe, Nadja; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vernieri, Caterina; Verzocchi, Marco; Vidal, Richard; Wang, Michael; Weber, Hannsjoerg Artur; Whitbeck, Andrew; Acosta, Darin; Avery, Paul; Bortignon, Pierluigi; Bourilkov, Dimitri; Brinkerhoff, Andrew; Carnes, Andrew; Carver, Matthew; Curry, David; Das, Souvik; Field, Richard D; Furic, Ivan-Kresimir; Konigsberg, Jacobo; Korytov, Andrey; Ma, Peisen; Matchev, Konstantin; Mei, Hualin; Milenovic, Predrag; Mitselmakher, Guenakh; Rank, Douglas; Shchutska, Lesya; Sperka, David; Thomas, Laurent; Wang, Jian; Wang, Sean-Jiun; Yelton, John; Linn, Stephan; Markowitz, Pete; Martinez, German; Rodriguez, Jorge Luis; Ackert, Andrew; Adams, Jordon Rowe; Adams, Todd; Askew, Andrew; Bein, Samuel; Diamond, Brendan; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Khatiwada, Ajeeta; Prosper, Harrison; Santra, Arka; Weinberg, Marc; Baarmand, Marc M; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Noonan, Daniel; Roy, Titas; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Berry, Douglas; Betts, Russell Richard; Bucinskaite, Inga; Cavanaugh, Richard; Evdokimov, Olga; Gauthier, Lucie; Gerber, Cecilia Elena; Hofman, David Jonathan; Kurt, Pelin; O'Brien, Christine; Sandoval Gonzalez, Irving Daniel; Turner, Paul; Varelas, Nikos; Wu, Zhenbin; Zakaria, Mohammed; Zhang, Jingyu; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Durgut, Süleyman; Gandrajula, Reddy Pratap; Haytmyradov, Maksat; Khristenko, Viktor; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Snyder, Christina; Tiras, Emrah; Wetzel, James; Yi, Kai; Anderson, Ian; Blumenfeld, Barry; Cocoros, Alice; Eminizer, Nicholas; Fehling, David; Feng, Lei; Gritsan, Andrei; Maksimovic, Petar; Osherson, Marc; Roskes, Jeffrey; Sarica, Ulascan; Swartz, Morris; Xiao, Meng; Xin, Yongjie; You, Can; Al-bataineh, Ayman; Baringer, Philip; Bean, Alice; Bowen, James; Bruner, Christopher; Castle, James; Kenny III, Raymond Patrick; Kropivnitskaya, Anna; Majumder, Devdatta; Mcbrayer, William; Murray, Michael; Sanders, Stephen; Stringer, Robert; Tapia Takaki, Daniel; Wang, Quan; Ivanov, Andrew; Kaadze, Ketino; Khalil, Sadia; Makouski, Mikhail; Maravin, Yurii; Mohammadi, Abdollah; Saini, Lovedeep Kaur; Skhirtladze, Nikoloz; Toda, Sachiko; Lange, David; Rebassoo, Finn; Wright, Douglas; Anelli, Christopher; Baden, Drew; Baron, Owen; Belloni, Alberto; Calvert, Brian; Eno, Sarah Catherine; Ferraioli, Charles; Gomez, Jaime; Hadley, Nicholas John; Jabeen, Shabnam; Kellogg, Richard G; Kolberg, Ted; Kunkle, Joshua; Lu, Ying; Mignerey, Alice; Shin, Young Ho; Skuja, Andris; Tonjes, Marguerite; Tonwar, Suresh C; Apyan, Aram; Barbieri, Richard; Baty, Austin; Bi, Ran; Bierwagen, Katharina; Brandt, Stephanie; Busza, Wit; Cali, Ivan Amos; Demiragli, Zeynep; Di Matteo, Leonardo; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Hsu, Dylan; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Krajczar, Krisztian; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew; Luckey, Paul David; Marini, Andrea Carlo; Mcginn, Christopher; Mironov, Camelia; Narayanan, Siddharth; Niu, Xinmei; Paus, Christoph; Roland, Christof; Roland, Gunther; Salfeld-Nebgen, Jakob; Stephans, George; Sumorok, Konstanty; Tatar, Kaya; Varma, Mukund; Velicanu, Dragos; Veverka, Jan; Wang, Jing; Wang, Ta-Wei; Wyslouch, Bolek; Yang, Mingming; Zhukova, Victoria; Benvenuti, Alberto; Chatterjee, Rajdeep Mohan; Evans, Andrew; Finkel, Alexey; Gude, Alexander; Hansen, Peter; Kalafut, Sean; Kao, Shih-Chuan; Kubota, Yuichi; Lesko, Zachary; Mans, Jeremy; Nourbakhsh, Shervin; Ruckstuhl, Nicole; Rusack, Roger; Tambe, Norbert; Turkewitz, Jared; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bartek, Rachel; Bloom, Kenneth; Bose, Suvadeep; Claes, Daniel R; Dominguez, Aaron; Fangmeier, Caleb; Gonzalez Suarez, Rebeca; Kamalieddin, Rami; Knowlton, Dan; Kravchenko, Ilya; Malta Rodrigues, Alan; Meier, Frank; Monroy, Jose; Siado, Joaquin Emilo; Snow, Gregory R; Stieger, Benjamin; Alyari, Maral; Dolen, James; George, Jimin; Godshalk, Andrew; Harrington, Charles; Iashvili, Ia; Kaisen, Josh; Kharchilava, Avto; Kumar, Ashish; Parker, Ashley; Rappoccio, Salvatore; Roozbahani, Bahareh; Alverson, George; Barberis, Emanuela; Baumgartel, Darin; Chasco, Matthew; Hortiangtham, Apichart; Massironi, Andrea; Morse, David Michael; Nash, David; Orimoto, Toyoko; Teixeira De Lima, Rafael; Trocino, Daniele; Wang, Ren-Jie; Wood, Darien; Bhattacharya, Saptaparna; Hahn, Kristan Allan; Kubik, Andrew; Low, Jia Fu; Mucia, Nicholas; Odell, Nathaniel; Pollack, Brian; Schmitt, Michael Henry; Sung, Kevin; Trovato, Marco; Velasco, Mayda; Dev, Nabarun; Hildreth, Michael; Hurtado Anampa, Kenyi; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Marinelli, Nancy; Meng, Fanbo; Mueller, Charles; Musienko, Yuri; Planer, Michael; Reinsvold, Allison; Ruchti, Randy; Smith, Geoffrey; Taroni, Silvia; Valls, Nil; Wayne, Mitchell; Wolf, Matthias; Woodard, Anna; Alimena, Juliette; Antonelli, Louis; Brinson, Jessica; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Francis, Brian; Hart, Andrew; Hill, Christopher; Hughes, Richard; Ji, Weifeng; Liu, Bingxuan; Luo, Wuming; Puigh, Darren; Winer, Brian L; Wulsin, Howard Wells; Cooperstein, Stephane; Driga, Olga; Elmer, Peter; Hardenbrook, Joshua; Hebda, Philip; Luo, Jingyu; Marlow, Daniel; Medvedeva, Tatiana; Mooney, Michael; Olsen, James; Palmer, Christopher; Piroué, Pierre; Stickland, David; Tully, Christopher; Zuranski, Andrzej; Malik, Sudhir; Barker, Anthony; Barnes, Virgil E; Benedetti, Daniele; Folgueras, Santiago; Gutay, Laszlo; Jha, Manoj; Jones, Matthew; Jung, Andreas Werner; Jung, Kurt; Miller, David Harry; Neumeister, Norbert; Radburn-Smith, Benjamin Charles; Shi, Xin; Sun, Jian; Svyatkovskiy, Alexey; Wang, Fuqiang; Xie, Wei; Xu, Lingshan; Parashar, Neeti; Stupak, John; Adair, Antony; Akgun, Bora; Chen, Zhenyu; Ecklund, Karl Matthew; Geurts, Frank JM; Guilbaud, Maxime; Li, Wei; Michlin, Benjamin; Northup, Michael; Padley, Brian Paul; Redjimi, Radia; Roberts, Jay; Rorie, Jamal; Tu, Zhoudunming; Zabel, James; Betchart, Burton; Bodek, Arie; de Barbaro, Pawel; Demina, Regina; Duh, Yi-ting; Ferbel, Thomas; Galanti, Mario; Garcia-Bellido, Aran; Han, Jiyeon; Hindrichs, Otto; Khukhunaishvili, Aleko; Lo, Kin Ho; Tan, Ping; Verzetti, Mauro; Mesropian, Christina; Chou, John Paul; Contreras-Campana, Emmanuel; Gershtein, Yuri; Gómez Espinosa, Tirso Alejandro; Halkiadakis, Eva; Heindl, Maximilian; Hidas, Dean; Hughes, Elliot; Kaplan, Steven; Kunnawalkam Elayavalli, Raghav; Kyriacou, Savvas; Lath, Amitabh; Nash, Kevin; Saka, Halil; Salur, Sevil; Schnetzer, Steve; Sheffield, David; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Foerster, Mark; Heideman, Joseph; Riley, Grant; Rose, Keith; Spanier, Stefan; Thapa, Krishna; Bouhali, Othmane; Celik, Ali; Dalchenko, Mykhailo; De Mattia, Marco; Delgado, Andrea; Dildick, Sven; Eusebi, Ricardo; Gilmore, Jason; Huang, Tao; Juska, Evaldas; Kamon, Teruki; Krutelyov, Vyacheslav; Mueller, Ryan; Pakhotin, Yuriy; Patel, Rishi; Perloff, Alexx; Perniè, Luca; Rathjens, Denis; Rose, Anthony; Safonov, Alexei; Tatarinov, Aysen; Ulmer, Keith; Akchurin, Nural; Cowden, Christopher; Damgov, Jordan; Dragoiu, Cosmin; Dudero, Phillip Russell; Faulkner, James; Kunori, Shuichi; Lamichhane, Kamal; Lee, Sung Won; Libeiro, Terence; Undleeb, Sonaina; Volobouev, Igor; Wang, Zhixing; Delannoy, Andrés G; Greene, Senta; Gurrola, Alfredo; Janjam, Ravi; Johns, Willard; Maguire, Charles; Melo, Andrew; Ni, Hong; Sheldon, Paul; Tuo, Shengquan; Velkovska, Julia; Xu, Qiao; Arenton, Michael Wayne; Barria, Patrizia; Cox, Bradley; Goodell, Joseph; Hirosky, Robert; Ledovskoy, Alexander; Li, Hengne; Neu, Christopher; Sinthuprasith, Tutanon; Sun, Xin; Wang, Yanchu; Wolfe, Evan; Xia, Fan; Clarke, Christopher; Harr, Robert; Karchin, Paul Edmund; Lamichhane, Pramod; Sturdy, Jared; Belknap, Donald; Dasu, Sridhara; Dodd, Laura; Duric, Senka; Gomber, Bhawna; Grothe, Monika; Herndon, Matthew; Hervé, Alain; Klabbers, Pamela; Lanaro, Armando; Levine, Aaron; Long, Kenneth; Loveless, Richard; Ojalvo, Isabel; Perry, Thomas; Pierro, Giuseppe Antonio; Polese, Giovanni; Ruggles, Tyler; Savin, Alexander; Sharma, Archana; Smith, Nicholas; Smith, Wesley H; Taylor, Devin; Woods, Nathaniel

    2017-03-29

    A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum $p_{\\mathrm{T}}$ and the absolute jet rapidity $|y|$ is presented. Data from LHC proton-proton collisions at $ \\sqrt{s} = $ 8 TeV, corresponding to an integrated luminosity of 19.7 fb$^{-1}$, have been collected with the CMS detector. Jets are reconstructed using the anti-$k_{\\mathrm{T}}$ clustering algorithm with a size parameter of 0.7 in a phase space region covering jet $p_{\\mathrm{T}}$ from 74 GeV up to 2.5 TeV and jet absolute rapidity up to $|y|= $ 3.0. The low-$p_{\\mathrm{T}}$ jet range between 21 and 74 GeV is also studied up to $|y|= $ 4.7, using a dedicated data sample corresponding to an integrated luminosity of 5.6 pb$^{-1}$. The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measuremen...

  10. The low-energy effective theory of QCD at small quark masses in a finite volume

    Energy Technology Data Exchange (ETDEWEB)

    Lehner, Christoph

    2010-01-15

    At low energies the theory of quantum chromodynamics (QCD) can be described effectively in terms of the lightest particles of the theory, the pions. This approximation is valid for temperatures well below the mass difference of the pions to the next heavier particles. We study the low-energy effective theory at very small quark masses in a finite volume V. The corresponding perturbative expansion in 1/{radical}(V) is called {epsilon} expansion. At each order of this expansion a finite number of low-energy constants completely determine the effective theory. These low-energy constants are of great phenomenological importance. In the leading order of the {epsilon} expansion, called {epsilon} regime, the theory becomes zero-dimensional and is therefore described by random matrix theory (RMT). The dimensionless quantities of RMT are mapped to dimensionful quantities of the low-energy effective theory using the leading-order lowenergy constants {sigma} and F. In this way {sigma} and F can be obtained from lattice QCD simulations in the '' regime by a fit to RMT predictions. For typical volumes of state-of-the-art lattice QCD simulations, finite-volume corrections to the RMT prediction cannot be neglected. These corrections can be calculated in higher orders of the {epsilon} expansion. We calculate the finite-volume corrections to {sigma} and F at next-to-next-to-leading order in the {epsilon} expansion. We also discuss non-universal modifications of the theory due to the finite volume. These results are then applied to lattice QCD simulations, and we extract {sigma} and F from eigenvalue correlation functions of the Dirac operator. As a side result, we provide a proof of equivalence between the parametrization of the partially quenched low-energy effective theory without singlet particle and that of the super-Riemannian manifold used earlier in the literature. Furthermore, we calculate a special version of the massless sunset diagram at finite volume without

  11. Charm production and QCD analysis at HERA and LHC

    Energy Technology Data Exchange (ETDEWEB)

    Zenaiev, O.

    2017-02-15

    This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10{sup -6}, where x is the proton momentum fraction carried by a parton.

  12. The QCD\\/SM Working Group Summary Report

    CERN Document Server

    Alekhin, S I; Ball, R; Binoth, T; Boos, E; Botje, M; Cacciari, M; Catani, S; Del Duca, V; Dobbs, M; Ellis, S D; Field, R; de Florian, D; Forte, Stefano; Gardi, E; Gehrmann, T; Ridder, A G D; Giele, W T; Glover, E W Nigel; Grazzini, Massimiliano; Guillet, J P; Marlen-Heinrich, G; Huston, J; Hinchliffe, Ian; Ilyin, V A; Kanzaki, J; Kato, K; Kersevan, Borut P; Kidonakis, N; Kulesza, A; Kurihara, Y; Laenen, Eric; Lassila-Perini, K M; Lönnblad, L; Magnea, L; Mangano, Michelangelo L; Mazumudar, K; Moch, S; Mrenna, S; Nadolsky, P M; Nason, P; Olness, F I; Paige, Frank E; Pilon, E; Puljak, I; Pumplin, Jon; Richter-Was, Elzbieta; Salam, Gavin P; Scalise, R; Seymour, Michael H; Sjöstrand, Torbjörn; Sterman, George F; Tonnesmann, M; Tournefier, E; Vogelsang, W; Vogt, A; Vogt, R; Webber, Bryan R; Yuan, C P; Zeppenfeld, Dieter

    2002-01-01

    This Report documents the results obtained by the Working Group on Quantum ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV Colliders'', Les Houches, France, 21 May - 1 June 2001. The account of uncertainties in Parton Distribution Functions is reviewed. Progresses in the description of multiparton final states at Next-to-Leading Order and the extension of calculations for precision QCD observables beyond this order are summarized. Various issues concerning the relevance of resummation for observables at TeV colliders is examined. Improvements to algorithms of jet reconstruction are discussed and predictions for diphoton and photon pi-zero production at the LHC are made for kinematic variables of interest regarding searches for a Higgs boson decaying into two photons. Finally, several improvements implemented in Monte-Carlo event generators are documented.

  13. On-Shell Unitarity Bootstrap for QCD Amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-10-17

    Seeking and measuring new physics at the imminent Large Hadron Collider (LHC) will require extensive calculations of high-multiplicity backgrounds in perturbative QCD to next-to-leading order (NLO). The Les Houches 2005 workshop defined a target list, reproduced in table 1, for theorists to attack. In addition to the processes in the table, one would also like to compute processes such as W, Z + 4 jets, which are important backgrounds to searches for supersymmetry and other models of new electroweak physics. Such computations require one-loop amplitudes with seven external particles, including the vector boson, as depicted in figure 1. These are challenging calculations and Feynman-diagrammatic computations have only recently reached six-point amplitudes. Some of this progress has been described in this conference.

  14. Vector boson fusion NNLO in QCD. SM Higgs and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, Paolo [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Maltoni, Fabio; Zaro, Marco [Catholique Univ. Louvain-la-Neuve (BE). Center for Cosmology, Particle Phyics and Phenomenology (CP3); Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2011-09-15

    Weak vector boson fusion provides a unique channel to directly probe the mechanism of electroweak symmetry breaking at hadron colliders. We present a method that allows to calculate total cross sections to next-to-next-to-leading order (NNLO) in QCD for an arbitrary V{sup *}V{sup *}{yields}X process, the so-called structure function approach. By discussing the case of Higgs production in detail, we estimate several classes of previously neglected contributions and we argue that such method is accurate at a precision level well above the typical residual scale and PDF uncertainties at NNLO. Predictions for cross sections at the Tevatron and the LHC are presented for a variety of cases: the Standard Model Higgs (including anomalous couplings), neutral and charged scalars in extended Higgs sectors and (fermiophobic) vector resonance production. Further results can be easily obtained through the public use of the VBF rate at NNLO code. (orig.)

  15. Lattice QCD spectroscopy for hadronic CP violation

    Science.gov (United States)

    de Vries, Jordy; Mereghetti, Emanuele; Seng, Chien-Yeah; Walker-Loud, André

    2017-03-01

    The interpretation of nuclear electric dipole moment (EDM) experiments is clouded by large theoretical uncertainties associated with nonperturbative matrix elements. In various beyond-the-Standard Model scenarios nuclear and diamagnetic atomic EDMs are expected to be dominated by CP-violating pion-nucleon interactions that arise from quark chromo-electric dipole moments. The corresponding CP-violating pion-nucleon coupling strengths are, however, poorly known. In this work we propose a strategy to calculate these couplings by using spectroscopic lattice QCD techniques. Instead of directly calculating the pion-nucleon coupling constants, a challenging task, we use chiral symmetry relations that link the pion-nucleon couplings to nucleon sigma terms and mass splittings that are significantly easier to calculate. In this work, we show that these relations are reliable up to next-to-next-to-leading order in the chiral expansion in both SU (2) and SU (3) chiral perturbation theory. We conclude with a brief discussion about practical details regarding the required lattice QCD calculations and the phenomenological impact of an improved understanding of CP-violating matrix elements.

  16. Phase diagram of twisted mass lattice QCD

    Science.gov (United States)

    Sharpe, Stephen R.; Wu, Jackson M.

    2004-11-01

    We use the effective chiral Lagrangian to analyze the phase diagram of two-flavor twisted mass lattice QCD as a function of the normal and twisted masses, generalizing previous work for the untwisted theory. We first determine the chiral Lagrangian including discretization effects up to next-to-leading order (NLO) in a combined expansion in which m2π/(4πfπ)2˜aΛ (a being the lattice spacing, and Λ=ΛQCD). We then focus on the region where m2π/(4πfπ)2˜(aΛ)2, in which case competition between leading and NLO terms can lead to phase transitions. As for untwisted Wilson fermions, we find two possible phase diagrams, depending on the sign of a coefficient in the chiral Lagrangian. For one sign, there is an Aoki phase for pure Wilson fermions, with flavor and parity broken, but this is washed out into a crossover if the twisted mass is nonvanishing. For the other sign, there is a first order transition for pure Wilson fermions, and we find that this transition extends into the twisted mass plane, ending with two symmetrical second order points at which the mass of the neutral pion vanishes. We provide graphs of the condensate and pion masses for both scenarios, and note a simple mathematical relation between them. These results may be of importance to numerical simulations.

  17. DM rate at NLO and the impact of SUSY-QCD-corrections to (co-)annihilation-processes on neutralino dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Herrmann, Bjoern [Laboratoire d' Annecy de Physique Theorique, Annecy-le-Vieux (France); Klasen, Michael; Meinecke, Moritz; Steppeler, Patrick [Institute of Theoretical Physics Muenster (Germany); Kovarik, Karol [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Le Boulc' h, Quentin [Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France)

    2013-07-01

    A powerful method to constrain the parameter space of theories beyond the Standard Model is to compare the predicted dark matter relic density with cosmological precision measurements, in particular with WMAP- and the upcoming Planck-data. On the particle physics side, the main uncertainty on the relic density arises from the (co-)annihilation cross sections of the dark matter particle. After a motivation for including higher order corrections in the prediction of the relic density, the DM rate at NLO-project will be presented, a software package that allows for the computation of the neutralino (co-)annihilation cross sections including SUSY-QCD corrections at the one-loop level and the evaluation of their effect on the relic density using a link to the public codes MicrOMEGAs and DarkSUSY. Recent results of the impact of SUSY-QCD corrections on the neutralino (co-)annihilation cross section as well as further ongoing projects in the context of the DM rate at NLO-project are discussed.

  18. A perturbative QCD study of dijets in p+Pb collisions at the LHC

    CERN Document Server

    Eskola, Kari J; Salgado, Carlos A

    2013-01-01

    Inspired by the recent measurements of the CMS collaboration, we report a QCD study of dijet production in proton+lead collisions at the LHC involving large-transverse-momentum jets, $p_T \\gtrsim 100$ GeV. Examining the inherent uncertainties of the next-to-leading order perturbative QCD calculations and their sensitivity to the free proton parton distributions (PDFs), we observe a rather small, typically much less than 5% clearance for the shape of the dijet rapidity distribution within approximately 1.5 units around the midrapidity. Even a more stable observable is the ratio between the yields in the positive and negative dijet rapidity, for which the baseline uncertainty can be made negligible by imposing a symmetric jet rapidity acceptance. Both observables prove sensitive to the nuclear modifications of the gluon distributions, the corresponding uncertainties clearly exceeding the estimated baseline uncertainties from the free-proton PDFs and scale dependence. From a theoretical point of view, these obse...

  19. Decoupling the NLO coupled QED $\\otimes$ QCD, DGLAP evolution equations,Using Laplace Transform Method

    CERN Document Server

    Mottaghizadeh, Marzieh; Taghavi-Shahri, Fatemeh

    2016-01-01

    We analytically solved the QED $\\otimes$ QCD coupled DGLAP evolution equations at leading order (LO) quantum electrodynamics (QED) and next to leading order (NLO) quantum chromodynamics (QCD) approximations, using the Laplace transform method and then computed the proton structure function in terms of the unpolarized parton distributions functions. Our analyitical solutions for parton densities are in good agreement with those from APFEL (A PDF Evolution Library) (Computer Physics Communications 185, 1647-1668 (2014)) and CT14QED (Phys. Rev. D 93, 114015 (2016)) global parameterizations. We also compared the proton structure function, $F_{2}^{p}(x,Q^{2})$, with experimental data released by the ZEUS and H1 collaborations at HERA. There is a nice agreement between them in the range of low and high x and $Q^{2}$.

  20. $W^+W^-$ + 3 Jet Production at the Large Hadron Collider in NLO QCD

    CERN Document Server

    Cordero, F Febres; Ita, H

    2015-01-01

    We present next-to-leading order (NLO) QCD predictions to $W^+W^-$ production in association with up to three jets at hadron colliders. We include contributions from couplings of the $W$ bosons to light quarks as well as trilinear vector couplings. These processes are used in vector-boson coupling measurements, are background to Higgs signals and are needed to constrain many new physics scenarios. For the first time NLO QCD predictions are shown for electroweak di-vector boson production with three jets at a hadron collider. We show total and differential cross sections for the LHC with proton center-of-mass energies of 8 and 13 TeV. To perform the calculation we employ on-shell and unitarity methods implemented in the BlackHat library along with the SHERPA package. We have produced event files that can be accessed for future dedicated studies.

  1. Recent highlights of Electroweak and QCD studies with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00057771; The ATLAS collaboration

    2016-01-01

    The ATLAS Collaboration has carried out a set of measurements at centre-of-mass energies of 7, 8 and 13 TeV which provide stringent tests of the Standard Model. This paper summarizes the latest analysis on QCD and Electroweak. New measurements of the inelastic cross section in pp collisions and the properties of minimum bias interactions are presented. The production cross sections for inclusive jets, $b$-jets and photons are obtained with the ATLAS detector and are compared to the expectations based on the next-to-leading order QCD calculations. Electroweak sector of the Standard Model measurements include inclusive and differential cross sections for the production of two heavy gauge bosons ($WZ$, $ZZ$) in the leptonic or semileptonic decay channels and the search for the production of the $Z$ boson in association with one or two photons.

  2. NLO QCD predictions for off-shell t anti t and t anti tH production and decay at a linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Nejad, Bijan Chokoufe; Reuter, Juergen [DESY Hamburg (Germany). Theory Group; Kilian, Wolfgang [Zuerich Univ. (Switzerland). Physik-Inst.; Lindert, Jonas M.; Pozzorini, Stefano [Emmy-Noether Campus, Siegen (Germany); Weiss, Christian [DESY Hamburg (Germany). Theory Group; Zuerich Univ. (Switzerland). Physik-Inst.

    2016-09-15

    We present predictions for t anti t and t anti tH production and decay at future lepton colliders including non-resonant and interference contributions up to next-to-leading order (NLO) in perturbative QCD. The obtained precision predictions are necessary for a future precise determination of the top-quark Yukawa coupling, and allow for top-quark phenomenology in the continuum at an unprecedented level of accuracy. Simulations are performed with the automated NLO Monte-Carlo framework WHIZARD interfaced to the OpenLoops matrix element generator.

  3. NLO QCD Predictions for off-shell $t \\bar t$ and $t \\bar t H$ Production and Decay at a Linear Collider

    CERN Document Server

    Nejad, Bijan Chokoufé; Lindert, Jonas M; Pozzorini, Stefano; Reuter, Jürgen; Weiss, Christian

    2016-01-01

    We present predictions for $t \\bar t$ and $t \\bar t H$ production and decay at future lepton colliders including non-resonant and interference contributions up to next-to-leading order (NLO) in perturbative QCD. The obtained precision predictions are necessary for a future precise determination of the top-quark Yukawa coupling, and allow for top-quark phenomenology in the continuum at an unprecedented level of accuracy. Simulations are performed with the automated NLO Monte-Carlo framework WHIZARD interfaced to the OpenLoops matrix element generator.

  4. anti B{sub d,s} → D{sup *}{sub d,s}V and anti B{sup *}{sub d,s} → D{sub d,s}V decays in QCD factorization and possible puzzles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Qin [Henan Normal University, Institute of Particle and Nuclear Physics, Henan (China); Central China Normal University, Institute of Particle Physics, Wuhan (China); Chen, Ling-Xin; Zhang, Yun-Yun; Sun, Jun-Feng; Yang, Yue-Ling [Henan Normal University, Institute of Particle and Nuclear Physics, Henan (China)

    2016-10-15

    Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic anti B{sub d,s} → D{sup *}{sub d,s}V and anti B{sup *}{sub d,s} → D{sub d,s}V (V = ρ, K*) decays are performed within the framework of QCD factorization. Relative to the previous work, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured anti B{sub d,s} → D{sup *}{sub d,s}V decays, the tensions between theoretical results and experimental measurements, i.e. the ''R{sub ds}{sup V} puzzle'' and ''D*V (or R{sub V/l} {sub anti} {sub ν{sub l)}} puzzle'', are presented after detailed analyses. For the anti B{sup *}{sub d,s} → D{sub d,s}V decays, they have relatively large branching fractions of the order >or similar O(10{sup -9}) and are in the scope of Belle-II and LHCb experiments. Moreover, they also provide a way to crosscheck the possible puzzles mentioned above through the similar ratios R{sub ds}{sup 'V} and R{sup '}{sub V/l} {sub anti} {sub ν{sub l.}} More refined experimental measurements and theoretical efforts are required to confirm or refute such two anomalies. (orig.)

  5. N-jettiness Subtractions for NNLO QCD Calculations

    CERN Document Server

    Gaunt, Jonathan; Tackmann, Frank J; Walsh, Jonathan R

    2015-01-01

    We present a subtraction method utilizing the N-jettiness observable, Tau_N, to perform QCD calculations for arbitrary processes at next-to-next-to-leading order (NNLO). Our method employs soft-collinear effective theory (SCET) to determine the IR singular contributions of N-jet cross sections for Tau_N -> 0, and uses these to construct suitable Tau_N-subtractions. The construction is systematic and economic, due to being based on a physical observable. The resulting NNLO calculation is fully differential and in a form directly suitable for combining with resummation and parton showers. We explain in detail the application to processes with an arbitrary number of massless partons at lepton and hadron colliders together with the required external inputs in the form of QCD amplitudes and lower-order calculations. We provide explicit expressions for the Tau_N-subtractions at NLO and NNLO. The required ingredients are fully known at NLO, and at NNLO for processes with two external QCD partons. The remaining NNLO ...

  6. QCD corrections to decay-lepton polar and azimuthal angular distributions in $e^{+}e^{-}→ t \\overline{t}$ in the soft-gluon approximation

    Indian Academy of Sciences (India)

    Saurabh D Rindani

    2002-04-01

    QCD corrections to order in the soft-gluon approximation to angular distributions of decay charged leptons in the process $e^{+}e^{-}→ t\\overline{t}$, followed by semileptonic decay of or $\\overline{t}$, are obtained in the $e^{+} e^{-}$ centre-of-mass frame. As compared to distributions in the top rest frame, these have the advantage that they would allow direct comparison with experiment without the need to reconstruct the top rest frame. The results also do not depend on the choice of a spin quantization axis for or $\\overline{t}$. Analytic expression for the triple distribution in the polar angle of and polar and azimuthal angles of the lepton is obtained. Analytic expression is also derived for the distribution in the charged-lepton polar angle. Numerical values are discussed for $\\sqrt{s} = 400$, 800 and 1500 GeV.

  7. QCD Dual

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2009-01-01

    We uncover a novel solution of the 't Hooft anomaly matching conditions for QCD. Interestingly in the perturbative regime the new gauge theory, if interpreted as a possible QCD dual, predicts the critical number of flavors above which QCD in the nonperturbative regime, develops an infrared stable...... fixed point. Remarkably this value is identical to the maximum bound predicted in the nonpertubative regime via the all-orders conjectured beta function for nonsupersymmetric gauge theories.......We uncover a novel solution of the 't Hooft anomaly matching conditions for QCD. Interestingly in the perturbative regime the new gauge theory, if interpreted as a possible QCD dual, predicts the critical number of flavors above which QCD in the nonperturbative regime, develops an infrared stable...

  8. Ehrenfest-time dependence of quantum transport corrections and spectral statistics.

    Science.gov (United States)

    Waltner, Daniel; Kuipers, Jack

    2010-12-01

    The Ehrenfest-time scale in quantum transport separates essentially classical propagation from wave interference and here we consider its effect on the transmission and reflection through quantum dots. In particular, we calculate the Ehrenfest-time dependence of the next-to-leading-order quantum corrections to the transmission and reflection for dc and ac transport and check that our results are consistent with current conservation relations. Looking as well at spectral statistics in closed systems, we finally demonstrate how the contributions analyzed here imply changes in the calculation, given by Brouwer [Phys. Rev. E 74, 066208 (2006)], of the next-to-leading order of the spectral form factor. Our semiclassical result coincides with the result obtained by Tian and Larkin [Phys. Rev. B 70, 035305 (2004)] by field-theoretical methods.

  9. The pi+ pi+ scattering length from maximally twisted mass lattice QCD

    CERN Document Server

    Feng, Xu; Renner, Dru B

    2009-01-01

    We calculate the s-wave pion-pion scattering length in the isospin I=2 channel in lattice QCD for pion masses ranging from 270 Mev to 485 Mev using two flavors of maximally twisted mass fermions at a lattice spacing of 0.086 fm. Additionally, we check for lattice artifacts with one calculation at a finer lattice spacing of 0.067 fm. We use chiral perturbation theory at next-to-leading order to extrapolate our results. At the physical pion mass, we find m_pi a_pipi(I=2)=-0.04385(28)(38) for the scattering length, where the first error is statistical and the second is our estimate of several systematic effects.

  10. Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

    CERN Document Server

    Degrande, Celine; Mawatari, Kentarou; Mimasu, Ken; Sanz, Veronica

    2016-01-01

    We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results.

  11. Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

    CERN Document Server

    Degrande, Celine; Mawatari, Kentarou; Mimasu, Ken; Sanz, Veronica

    2017-04-25

    We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results.

  12. Heavy quark fragmentation functions at next-to-leading perturbative QCD

    CERN Document Server

    Nejad, S M Moosavi

    2016-01-01

    It is well-known that the dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation. This mechanism is described by the fragmentation functions (FFs) which are the universal and process-independent functions. Here, we review the perturbative FFs formalism as an appropriate tool for studying these hadronization processes and detail the extension of this formalism at next-to-leading order (NLO). Using the Suzuki's model, we calculate the perturbative QCD FF for a heavy quark to fragment into a S-wave heavy meson at NLO. As an example, we study the LO and NLO FFs for a charm quark to split into the S-wave $D$-meson and compare our analytic results both with experimental data and well-known phenomenological models.

  13. High Energy QCD at NLO: from light-cone wave function to JIMWLK evolution

    CERN Document Server

    Lublinsky, Michael

    2016-01-01

    Soft components of the light cone wave-function of a fast moving projectile hadron is computed in perturbation theory to third order in QCD coupling constant. At this order, the Fock space of the soft modes consists of one-gluon, two-gluon, and a quark-antiquark states. The hard component of the wave-function acts as a non-Abelian background field for the soft modes and is represented by a valence charge distribution that accounts for non-linear density effects in the projectile. When scattered off a dense target, the diagonal element of the S-matrix reveals the Hamiltonian of high energy evolution, the JIMWLK Hamiltonian. This way we provide a new direct derivation of the JIMWLK Hamiltonian at the Next-to-Leading Order.

  14. Heavy-quark fragmentation functions at next-to-leading perturbative QCD

    Energy Technology Data Exchange (ETDEWEB)

    Moosavi Nejad, S.M. [Yazd University, Faculty of Physics, Yazd (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, Tehran (Iran, Islamic Republic of); Sartipi Yarahmadi, P. [Yazd University, Faculty of Physics, Yazd (Iran, Islamic Republic of)

    2016-10-15

    It is well known that the dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation. This mechanism is described by the fragmentation functions (FFs) which are the universal and process-independent functions. Here, we review the perturbative FFs formalism as an appropriate tool for studying these hadronization processes and detail the extension of this formalism at next-to-leading order (NLO). Using Suzuki's model, we calculate the perturbative QCD FF for a heavy quark to fragment into a S-wave heavy meson at NLO. As an example, we study the LO and NLO FFs for a charm quark to split into the S-wave D-meson and compare our analytic results both with experimental data and well-known phenomenological models. (orig.)

  15. Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Degrande, Celine [CERN, Theory Division, Geneva 23 (Switzerland); Fuks, Benjamin [Sorbonne Universites, UPMC Univ. Paris 06, Paris (France); CNRS, Paris (France); Mawatari, Kentarou [Universite Grenoble-Alpes, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Vrije Universiteit Brussel, Theoretische Natuurkunde and IIHE/ELEM, International Solvay Institutes, Brussels (Belgium); Mimasu, Ken [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Universite catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-04-15

    We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results. (orig.)

  16. Neutron and proton electric dipole moments from Nf=2 +1 domain-wall fermion lattice QCD

    Science.gov (United States)

    Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; Soni, Amarjit; Rbc; Ukqcd Collaborations

    2016-05-01

    We present a lattice calculation of the neutron and proton electric dipole moments (EDMs) with Nf=2 +1 flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the θ vacuum of QCD. In this computation, we use pion masses of 0.33 and 0.42 GeV and 2.7 fm3 lattices with Iwasaki gauge action, and a 0.17 GeV pion and a 4.6 fm3 lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode averaging technique enables an efficient and high statistics calculation. Chiral behavior of lattice EDMs is discussed in the context of baryon chiral perturbation theory. In addition, we also show numerical evidence on the relationship of three- and two-point correlation functions with the local topological charge distribution.

  17. On the low energy end of the QCD spectrum

    CERN Document Server

    Leutwyler, H

    2008-01-01

    The energy gap of QCD is now understood very well. There is no doubt that the expansion in powers of the two lightest quark masses does represent a very useful tool for the analysis of the low energy structure. Concerning the expansion in powers of m_s, however, the current situation leaves much to be desired. While some of the lattice results indicate, for instance, that the violations of the Okubo-Iizuka-Zweig rule in the quark condensate and in the decay constants are rather modest, others point in the opposite direction. I am confident that the dust will settle soon, so that the effective coupling constants that govern the dependence of the various quantities of physical interest on m_s can be determined, to next-to-next-to-leading order of the chiral expansion. The range of validity of ChPT can be extended by means of dispersive methods. The properties of the physical states occurring in the spectrum of QCD below KKbar threshold can reliably be investigated on this basis. In particular, as shown only rat...

  18. Charm Production and QCD Analysis at HERA and LHC

    CERN Document Server

    Zenaiev, Oleksandr; Foster, Brian; McNulty, Ronan

    2015-01-01

    In this thesis the study of charm production in ep and pp collisions is presented. The heavy- quark masses provide a hard scale, allowing the application of perturbative QCD. A measurement of D + -meson production in deep inelastic scattering with the ZEUS detector at HERA is presented. The analysis was performed using a data sample with an integrated luminosity of 354 pb-1. Di erential cross sections were measured as a function of virtuality Q 2 , inelasticity y , transverse momentum and pseudorapidity of the D + mesons. Lifetime infor- mation was used to reduce the combinatorial background significantly. Next-to-leading-order QCD predictions in the fixed-flavour-number scheme were compared to the data. This measurement was combined with other H1 and ZEUS measurements of charm produc- tion. The combination was performed at inclusive level for the reduced charm cross sections, which were obtained from the measured visible cross sections, extrapolated to the full phase space using the shape of the theoretical ...

  19. The phase diagram of twisted mass lattice QCD

    CERN Document Server

    Sharpe, S R; Sharpe, Stephen R.; Wu, Jackson M. S.

    2004-01-01

    We use the effective chiral Lagrangian to analyze the phase diagram of two-flavor twisted mass lattice QCD as a function of the normal and twisted masses, generalizing previous work for the untwisted theory. We first determine the chiral Lagrangian including discretization effects up to next-to-leading order (NLO) in a combined expansion in which m_\\pi^2/(4\\pi f_\\pi)^2 ~ a \\Lambda (a being the lattice spacing, and \\Lambda = \\Lambda_{QCD}). We then focus on the region where m_\\pi^2/(4\\pi f_\\pi)^2 ~ (a \\Lambda)^2, in which case competition between leading and NLO terms can lead to phase transitions. As for untwisted Wilson fermions, we find two possible phase diagrams, depending on the sign of a coefficient in the chiral Lagrangian. For one sign, there is an Aoki phase for pure Wilson fermions, with flavor and parity broken, but this is washed out into a crossover if the twisted mass is non-vanishing. For the other sign, there is a first order transition for pure Wilson fermions, and we find that this transitio...

  20. Combination of Measurements of Inclusive Deep Inelastic $e^{\\pm}p$ Scattering Cross Sections and QCD Analysis of HERA Data

    CERN Document Server

    Abramowicz, H.; Adamczyk, L.; Adamus, M.; Andreev, V.; Antonelli, S.; Antunovic, B.; Aushev, V.; Aushev, Y.; Baghdasaryan, A.; Begzsuren, K.; Behnke, O.; Behrendt Dubak, A.; Behrens, U.; Belousov, A.; Belov, P.; Bertolin, A.; Bloch, I.; Boos, E.G.; Borras, K.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Brock, I.; Brook, N.H.; Brugnera, R.; Bruni, A.; Buniatyan, A.; Bussey, P.J.; Bylinkin, A.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Catterall, C.D.; Ceccopieri, F.; Cerny, K.; Chekelian, V.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Contreras, J.G.; Cooper-Sarkar, A.M.; Corradi, M.; Corriveau, F.; Cvach, J.; Dainton, J.B.; Daum, K.; Dementiev, R.K.; Devenish, R.C.E.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dolinska, G.; Dusini, S.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Ferencei, J.; Figiel, J.; Fleischer, M.; Fomenko, A.; Foster, B.; Gabathuler, E.; Gach, G.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gizhko, A.; Gladilin, L.K.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu. A.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grindhammer, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haidt, D.; Hain, W.; Henderson, R.C.W.; Henkenjohann, P.; Hladky, J.; Hochman, D.; Hoffmann, D.; Hori, R.; Horisberger, R.; Hreus, T.; Huber, F.; Ibrahim, Z.A.; Iga, Y.; Ishitsuka, M.; Iudin, A.; Jacquet, M.; Janssen, X.; Januschek, F.; Jomhari, N.Z.; Jung, H.; Kadenko, I.; Kananov, S.; Kapichine, M.; Karshon, U.; Kaur, M.; Kaur, P.; Kiesling, C.; Kisielewska, D.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kogler, R.; Kondrashova, N.; Kononenko, O.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kovalchuk, N.; Kowalski, H.; Kretzschmar, J.; Kruger, K.; Krupa, B.; Kuprash, O.; Kuze, M.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levchenko, B.B.; Levonian, S.; Levy, A.; Libov, V.; Limentani, S.; Lipka, K.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lobodzinski, B.; Lohr, B.; Lohrmann, E.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Makarenko, I.; Malinovski, E.; Malka, J.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Mergelmeyer, S.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Idris, F.Mohamad; Morozov, A.; Nasir, N.Muhammad; Muller, K.; Myronenko, V.; Nagano, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nobe, T.; Notz, D.; Nowak, G.; Nowak, R.J.; Olsson, J.E.; Onishchuk, Yu.; Ozerov, D.; Pahl, P.; Pascaud, C.; Patel, G.D.; Paul, E.; Perez, E.; Perlanski, W.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Przybycien, M.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roloff, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Rusakov, S.; Ruspa, M.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Saxon, D.H.; Schioppa, M.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schoning, A.; Schorner-Sadenius, T.; Sefkow, F.; Shcheglova, L.M.; Shevchenko, R.; Shkola, O.; Shushkevich, S.; Shyrma, Yu.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Solano, A.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Stanco, L.; Steder, M.; Stefaniuk, N.; Stella, B.; Stern, A.; Stopa, P.; Straumann, U.; Sykora, T.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tassi, E.; Thompson, P.D.; Tokushuku, K.; Tomaszewska, J.; Traynor, D.; Trofymov, A.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turkot, O.; Turnau, J.; Tymieniecka, T.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Verbytskyi, A.; Viazlo, O.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Wichmann, K.; Wing, M.; Wolf, G.; Wunsch, E.; Yamada, S.; Yamazaki, Y.; Zacek, J.; Zakharchuk, N.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zhang, Z.; Zhautykov, B.O.; Zhmak, N.; Zlebcik, R.; Zohrabyan, H.; Zomer, F.; Zotkin, D.S.

    2015-01-01

    A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $e^{\\pm}p$ scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb$^{-1}$ and span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and Bjorken $x$. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisatio...