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

International Nuclear Information System (INIS)

Kurihara, Y.; Fujimoto, J.; 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 resummation 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

On some aspects of optimisation of factorisation scheme dependence at the next-to-leading order in QCD

International Nuclear Information System (INIS)

Chyla, J.

1989-01-01

Several recent papers attempting to apply the optimised QCD perturbation theory to reactions involving real or virtual photons are discussed with particular attention paid to the ambiguity appearing in the definition of parton distribution and fragmentation functions at the next-to-leading order (NLO). The necessity to use NLO parametrisations of quark densities is stressed and the problem with respect to the factorisation mass M for the 'physical' definition of parton densities is pointed out. (orig.)

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

Next-to-leading order QCD predictions for the hadronic WH+jet production

International Nuclear Information System (INIS)

Su Jijuan; Ma Wengan; Zhang Renyou; Guo Lei

2010-01-01

We calculate the next-to-leading order (NLO) QCD corrections to the WH 0 production in association with a jet at hadron colliders. We study the impacts of the complete NLO QCD radiative corrections to the integrated cross sections, the scale dependence of the cross sections, and the differential cross sections ((dσ/dcosθ), (dσ/dp T )) of the final W-, Higgs boson and jet. We find that the corrections significantly modify the physical observables, and reduce the scale uncertainty of the leading-order cross section. Our results show that by applying the inclusive scheme with p T,j cut =20 GeV and taking m H =120 GeV, μ=μ 0 ≡(1/2)(m W +m H ), the K-factor is 1.15 for the process pp→W ± H 0 j+X at the Tevatron, while the K-factors for the processes pp→W - H 0 j+X and pp→W + H 0 j+X at the LHC are 1.12 and 1.08, respectively. We conclude that to understand the hadronic associated WH 0 production, it is necessary to study the NLO QCD corrections to the WH 0 j production process which is part of the inclusive WH 0 production.

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

International Nuclear Information System (INIS)

Moch, S.; Uwer, P.; Vogt, A.

2012-03-01

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 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.

Higgs boson production in association with a jet at next-to-next-to-leading order

CERN Document Server

Boughezal, Radja; Melnikov, Kirill; Petriello, Frank; Schulze, Markus

2015-01-01

We present precise predictions for Higgs boson production in association with a jet. Our calculation is accurate to next-to-next-to-leading order (NNLO) QCD in the Higgs Effective Field Theory and constitutes the first complete NNLO computation for Higgs production with a final-state jet in hadronic collisions. We include all relevant phenomenological channels and present fully-differential results as well as total cross sections for the LHC. Our NNLO predictions reduce the unphysical scale dependence by more than a factor of two and enhance the total rate by about twenty percent compared to NLO QCD predictions. Our results demonstrate for the first time satisfactory convergence of the perturbative series.

Next-to-next-to-leading order evolution of non-singlet fragmentation functions

International Nuclear Information System (INIS)

Mitov, A.; Moch, S.; Vogt, A.

2006-04-01

We have investigated the next-to-next-to-leading order (NNLO) corrections to inclusive hadron production in e + e - annihilation and the related parton fragmentation distributions, the 'time-like' counterparts of the 'space-like' deep-inelastic structure functions and parton densities. We have re-derived the corresponding second-order coefficient functions in massless perturbative QCD, which so far had been calculated only by one group. Moreover we present, for the first time, the third-order splitting functions governing the NNLO evolution of flavour non-singlet fragmentation distributions. These results have been obtained by two independent methods relating time-like quantities to calculations performed in deep-inelastic scattering. We briefly illustrate the numerical size of the NNLO corrections, and make a prediction for the difference of the yet unknown time-like and space-like splitting functions at the fourth order in the strong coupling constant. (Orig.)

Higgs Boson Production at Hadron Colliders: Differential Cross Section Through Next-to-Next-to-Leading Order

International Nuclear Information System (INIS)

Anastasiou, C

2004-01-01

The authors present a calculation of the fully differential cross section for Higgs boson production in the gluon fusion channel through next-to-next-to-leading order in perturbative QCD. They apply the method introduced in [1] to compute double real emission corrections. The calculation permits arbitrary cuts on the final state in the reaction hh → H + X. it can be easily extended to include decays of the Higgs boson into observable final states. In this Letter, they discuss the most important features of the calculation, and present some examples of physical applications that illustrate the range of observables that can be studied using the result. They compute the NNLO rapidity distribution of the Higgs boson, and also calculate the NNLO rapidity distribution with a veto on jet activity

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.)

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

International Nuclear Information System (INIS)

Hendlmeier, Christof

2008-05-01

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.)

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.

A next-to-leading order QCD analysis of the spin structure function $g_1$

CERN Document Server

AUTHOR|(CDS)2067425; Arik, E; Badelek, B; Bardin, G; Baum, G; Berglund, P; Betev, L; Birsa, R; De Botton, N R; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Eichblatt, S; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garzón, J A; Gilly, H; Giorgi, M A; von Goeler, E; Görtz, S; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kiselev, Yu F; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kukhtin, V V; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Litmaath, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Pereira, H; Perrot-Kunne, F; Peshekhonov, V D; Piegia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Puntaferro, R; Rädel, G; Rijllart, A; Reicherz, G; Roberts, J; Rodríguez, M; Rondio, Ewa; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schiller, A; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Tessarotto, F; Thers, D; Tlaczala, W; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Ylöstalo, J; Zanetti, A M; Zaremba, K; Zhao, J

1998-01-01

We present a next-to-leading order QCD analysis of the presently available data on the spin structure function $g_1$ including the final data from the Spin Muon Collaboration (SMC). We present resu lts for the first moments of the proton, deuteron and neutron structure functions, and determine singlet and non-singlet parton distributions in two factorization schemes. We also test the Bjor ken sum rule and find agreement with the theoretical prediction at the level of 10\\%.

The next-next-to-leading QCD approximation for non-singlet moments of deep inelastic structure functions

International Nuclear Information System (INIS)

Larin, S.A.; Ritbergen, T. van; Vermaseren, J.A.M.

1993-12-01

We obtain the analytic next-next-to-leading perturbative QCD corrections in the leading twist approximation for the moments N = 2, 4, 6, 8 of the non-singlet deep inelastic structure functions F 2 and F L . We calculate the three-loop anomalous dimensions of the corresponding non-singlet operators and the three-loop coefficient functions of the structure function F L . (orig.)

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

Indian Academy of Sciences (India)

Instituut-Lorentz, University of Leiden, Leiden, The Netherlands. Abstract. We describe the calculation of inclusive Higgs boson production at hadronic colliders at next-to-next-to-leading order (NNLO) in perturbative quantum chromody- namics. We have used the technique developed in ref. [4]. Our results agree with those.

Heavy-quark pair production in gluon fusion at next-to-next-to-leading O(α4s) order. One-loop squared contributions

International Nuclear Information System (INIS)

Kniehl, B.A.; Merebashvili, Z.

2008-09-01

We calculate the next-to-next-to-leading order O(α 4 s ) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O(α 4 s ) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

The next-next-to-leading QCD approximation for non-singlet moments of deep inelastic structure functions

Energy Technology Data Exchange (ETDEWEB)

Larin, S.A.; Ritbergen, T. van; Vermaseren, J.A.M.

1993-12-01

We obtain the analytic next-next-to-leading perturbative QCD corrections in the leading twist approximation for the moments N = 2, 4, 6, 8 of the non-singlet deep inelastic structure functions F{sub 2} and F{sub L}. We calculate the three-loop anomalous dimensions of the corresponding non-singlet operators and the three-loop coefficient functions of the structure function F{sub L}. (orig.).

Double collinear splitting amplitudes at next-to-leading order

Energy Technology Data Exchange (ETDEWEB)

Sborlini, Germán F.R. [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain); Florian, Daniel de [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Rodrigo, Germán [Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain)

2014-01-07

We compute the next-to-leading order (NLO) QCD corrections to the 1→2 splitting amplitudes in different dimensional regularization (DREG) schemes. Besides recovering previously known results, we explore new DREG schemes and analyze their consistency by comparing the divergent structure with the expected behavior predicted by Catani’s formula. Through the introduction of scalar-gluons, we show the relation among splittings matrices computed using different schemes. Also, we extended this analysis to cover the double collinear limit of scattering amplitudes in the context of QCD+QED.

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

Energy Technology Data Exchange (ETDEWEB)

Chen, Long [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,52056 Aachen (Germany); Dekkers, Oliver [PRISMA Cluster of Excellence and Institut für Physik,Johannes-Gutenberg-Universität Mainz,55099 Mainz (Germany); Heisler, Dennis; Bernreuther, Werner [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,52056 Aachen (Germany); Si, Zong-Guo [School of Physics, Shandong University,Jinan, Shandong 250100 (China)

2016-12-19

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 α{sub 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 α{sub s}{sup 2}. Our result agrees with previous computations of this observable.

Next-to-next-to-leading order N-jettiness soft function for one massive colored particle production at hadron colliders

Energy Technology Data Exchange (ETDEWEB)

Li, Hai Tao [ARC Centre of Excellence for Particle Physics at the Terascale,School of Physics and Astronomy, Monash University, VIC-3800 (Australia); Wang, Jian [PRISMA Cluster of Excellence Mainz Institute for Theoretical Physics, Johannes Gutenberg University, D-55099 Mainz (Germany); Physik Department T31, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany)

2017-02-01

The N-jettiness subtraction has proven to be an efficient method to perform differential QCD next-to-next-to-leading order (NNLO) calculations in the last few years. One important ingredient of this method is the NNLO soft function. We calculate this soft function for one massive colored particle production at hadron colliders. We select the color octet and color triplet cases to present the final results. We also discuss its application in NLO and NNLO differential calculations.

A positive-weight next-to-leading-order Monte Carlo for Z pair hadroproduction

International Nuclear Information System (INIS)

Nason, Paolo; Ridolfi, Giovanni

2006-01-01

We present a first application of a previously published method for the computation of QCD processes that is accurate at next-to-leading order, and that can be interfaced consistently to standard shower Monte Carlo programs. We have considered Z pair production in hadron-hadron collisions, a process whose complexity is sufficient to test the general applicability of the method. We have interfaced our result to the HERWIG and PYTHIA shower Monte Carlo programs. Previous work on next-to-leading order corrections in a shower Monte Carlo (the MC-NLO program) may involve the generation of events with negative weights, that are avoided with the present method. We have compared our results with those obtained with MC-NLO, and found remarkable consistency. Our method can also be used as a standalone, alternative implementation of QCD corrections, with the advantage of positivity, improved convergence, and next-to-leading logarithmic accuracy in the region of small transverse momentum of the radiated parton

Heavy-quark pair production in gluon fusion at next-to-next-to-leading O({alpha}{sup 4}{sub s}) order. One-loop squared contributions

Energy Technology Data Exchange (ETDEWEB)

Kniehl, B.A.; Merebashvili, Z. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Koerner, J.G. [Mainz Univ. (Germany). Inst. fuer Physik; Rogal, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2008-09-15

We calculate the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

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...

Charm production in deep-inelastic e$\\gamma$ scattering to next-to-leading order in QCD

CERN Document Server

Laenen, Eric

1995-01-01

We discuss the calculation of F_2^{\\gamma}({\\rm charm}) to next-to-leading order (NLO) in QCD, including contributions from both hadronlike and pointlike photons. We show that the former dominates strongly below x\\simeq 0.01, and the latter above this value. This fact makes F_2^{\\gamma}({\\rm charm}) for x \\geq 0.01 calculable, whereas for x \\leq 0.01 it serves to constrain the small-x gluon density in the photon. Both ranges in x are accessible at LEP2. Theoretical uncertainties are well under control. We present rates for single-tag events for the process for e^+e^- \\rightarrow e^+e^- c X for LEP2. Although these event rates are small, we believe a measurement of F_2^{\\gamma}({\\rm charm}) is feasible.

Mueller-Navelet jets in next-to-leading order BFKL. Theory versus experiment

Energy Technology Data Exchange (ETDEWEB)

Caporale, F.; Murdaca, B.; Papa, A. [Universita della Calabria, Dipartimento di Fisica, Cosenza (Italy); Gruppo collegato di Cosenza, Istituto Nazionale di Fisica Nucleare, Cosenza (Italy); Ivanov, D.Yu. [Sobolev Institute of Mathematics and Novosibirsk State University, Novosibirsk (Russian Federation)

2014-10-15

We study, within QCD collinear factorization and including BFKL resummation at the next-to-leading order, the production of Mueller-Navelet jets at LHC with center-of-mass energy of 7 TeV. The adopted jet vertices are calculated in the approximation of a small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. We consider several representations of the dijet cross section, differing only beyond the next-to-leading order, to calculate a few observables related with this process. We use various methods of optimization to fix the energy scales entering the perturbative calculation and compare our results with the experimental data from the CMS collaboration. (orig.)

Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory.

Science.gov (United States)

Tews, I; Krüger, T; Hebeler, K; Schwenk, A

2013-01-18

Neutron matter presents a unique system for chiral effective field theory because all many-body forces among neutrons are predicted to next-to-next-to-next-to-leading order (N(3)LO). We present the first complete N(3)LO calculation of the neutron matter energy. This includes the subleading three-nucleon forces for the first time and all leading four-nucleon forces. We find relatively large contributions from N(3)LO three-nucleon forces. Our results provide constraints for neutron-rich matter in astrophysics with controlled theoretical uncertainties.

Multi-parton loop amplitudes and next-to-leading order jet cross-sections

International Nuclear Information System (INIS)

Bern, Z.; Dixon, L.; Kosower, D.A.; Signer, A.

1998-02-01

The authors 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 anti qggg and q anti qq anti q' g), and for an intermediate vector boson V ≡ γ * , Z, W plus four external partons (V q anti q and V q anti qq'anti q'). Using these amplitudes, numerical programs have been constructed for the next-to-leading order corrections to the processes p anti p → 3 jets (ignoring quark contributions so far) and e + e - → 4 jets

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...

Single jet photoproduction at HERA in next-to-leading order QCD

International Nuclear Information System (INIS)

Kramer, G.; Salesch, S.G.

1993-01-01

We present results for next- to-leading order calculations of single jet inclusive cross sections by resolved photons in ep-collisions at HERA. The dependence on the jet recombination cut and on the choice of the renormalization and factorization scales is studied in detail. (orig.). 5 figs

Transverse momentum dependent fragmentation function at next-to-next-to-leading order

NARCIS (Netherlands)

Garcia, M.; Scimemi, I.; Vladimirov, A.

2016-01-01

We calculate the unpolarized transverse momentum dependent fragmentation function at next-to-next-to-leading order, evaluating separately the transverse momentum dependent (TMD) soft factor and the TMD collinear correlator. For the first time, the cancellation of spurious rapidity divergences in a

Comparison of three jet events to predictions from a next-to-leading order calculation

Energy Technology Data Exchange (ETDEWEB)

Brandl, Alexander [Univ. of New Mexico, Albuquerque, NM (United States)

2002-01-01

The properties of three-jet events in data of integrated luminosity 86±4 pb^-1 from CDF Run 1b and with total transverse energy greater than 175 GeV have been analyzed and compared to predictions from a next-to-leading order perturbative QCD calculation.

Next-to-next-to-leading order O(α2α2s) results for top quark pair production in photon-photon collisions. The one-loop squared contribution

International Nuclear Information System (INIS)

Koerner, J.G.

2006-11-01

We calculate the so-called loop-by-loop contributions to the next-to-next-to-leading order O(α 2 α 2 s ) radiative QCD corrections for the production of heavy quark pairs in the collisions of unpolarized on-shell photons. In particular, we present analytical results for the squared matrix elements that correspond to the product of the one-loop amplitudes. All results of the perturbative calculation are given in the dimensional regularization scheme. These results represent the Abelian part of the corresponding gluon-induced next-to-next-to-leading order cross section for heavy quark pair hadroproduction. (orig.)

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.

Next-to-leading-order QCD and electroweak corrections to WWW production at proton-proton colliders

Science.gov (United States)

Dittmaier, Stefan; Huss, Alexander; Knippen, Gernot

2017-09-01

Triple-W-boson production in proton-proton collisions allows for a direct access to the triple and quartic gauge couplings and provides a window to the mechanism of electroweak symmetry breaking. It is an important process to test the Standard Model (SM) and might be background to physics beyond the SM. We present a calculation of the next-to-leading order (NLO) electroweak corrections to the production of WWW final states at proton-proton colliders with on-shell W bosons and combine the electroweak with the NLO QCD corrections. We study the impact of the corrections to the integrated cross sections and to kinematic distributions of the W bosons. The electroweak corrections are generically of the size of 5-10% for integrated cross sections and become more pronounced in specific phase-space regions. The real corrections induced by quark-photon scattering turn out to be as important as electroweak loops and photon bremsstrahlung corrections, but can be reduced by phase-space cuts. Considering that prior determinations of the photon parton distribution function (PDF) involve rather large uncertainties, we compare the results obtained with different photon PDFs and discuss the corresponding uncertainties in the NLO predictions. Moreover, we determine the scale and total PDF uncertainties at the LHC and a possible future 100 TeV pp collider.

Next to leading order semi-inclusive spin asymmetries

International Nuclear Information System (INIS)

Florian, D. de; Epele, L.N.; Fanchiotti, H.; Garcia C, C.A.; Sassot, R.

1996-04-01

We have computed semi-inclusive spin asymmetries for proton and deuteron targets including next to leading order (NLO) QCD corrections and contributions coming from the target fragmentation region. These corrections have been estimated using NLO fragmentation functions, parton distributions and also a model for spin dependent fracture functions which is proposed here. We have found that NLO corrections are small but non-negligible in a scheme where gluons are polarised and that our estimate for target fragmentation effects, which is in agreement with the available semi-inclusive data, does not modify significantly charged asymmetries but is non-negligible for the so called difference asymmetries. (author). 18 refs., 7 figs

Next-to-leading order QCD-analysis of EMC deep inelastic μp and μd scattering data

International Nuclear Information System (INIS)

Bilen'kaya, S.I.; Stamenov, D.B.

1987-01-01

A combined next-to-leading order QCD analysis of the European Muon Collaboration (EMC) μH 2 and μD 2 scattering data is presented. The nucleon structure functions are given in terms of parton distributions. The Buras-Gaemers method is used to solve the QCD equations for these distributions. The higher twist corrections are not taken into account. As has been shown their contribution to the structure functions is negligible in the EMC kinematic region. Unlike most of the papers on this subject the cross section data (not the value for the structure functions obtained from these data by additional extrapolations and assumptions) are fitted. the following values for the QCD scale parameter Λ MS-bar are found: Λ MS-bar =218 ±73 MeV for the non-singlet fit to the data in the range x>0.3 and Λ MS-bar =65±20 MeV if the whole x data are fitted

Quarkonium spectral function in medium at next-to-leading order for any quark mass

International Nuclear Information System (INIS)

Burnier, Yannis

2015-01-01

The vector channel spectral function at zero spatial momentum is calculated at next-to-leading order in thermal QCD for any quark mass. It corresponds to the imaginary part of the massive quark contribution to the photon polarisation tensor. The spectrum shows a well-defined transport peak in contrast to both the heavy quark limit studied previously, where the low frequency domain is exponentially suppressed at this order, and the naive massless case where it vanishes at leading order and diverges at next-to-leading order. From our general expressions, the massless limit can be taken and we show that no divergences occur if done carefully. Finally, we compare the massless limit to results from lattice simulations. (orig.)

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.)

Topics in perturbative QCD beyond the leading order

International Nuclear Information System (INIS)

Buras, A.J.

1979-08-01

The basic structure of QCD formulae for various inclusive and semi-inclusive processes is presented. Next to leading order QCD corrections to inclusive deep-inelastic scattering are discussed in some detail. The methods for calculations of QCD corrections (leading, next to leading) to semi-inclusive processes are outlined. Some results of these calculations are discussed. 58 references

Next-to-leading-order QCD corrections to e+e−→H+γ

Directory of Open Access Journals (Sweden)

Wen-Long Sang

2017-12-01

Full Text Available The associated production of Higgs boson with a hard photon at lepton collider, i.e., e+e−→Hγ, is known to bear a rather small cross section in Standard Model, and can serve as a sensitive probe for the potential new physics signals. Similar to the loop-induced Higgs decay channels H→γγ,Zγ, the e+e−→Hγ process also starts at one-loop order provided that the tiny electron mass is neglected. In this work, we calculate the next-to-leading-order (NLO QCD corrections to this associated H+γ production process, which mainly stem from the gluonic dressing to the top quark loop. The QCD corrections are found to be rather modest at lower center-of-mass energy range (s<300 GeV, thus of negligible impact on Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC energy range (s≈400 GeV, QCD corrections may enhance the leading-order cross section by 20%. In any event, the e+e−→Hγ process has a maximal production rate σmax≈0.08 fb around s=250 GeV, thus CEPC turns out to be the best place to look for this rare Higgs production process. In the high energy limit, the effect of NLO QCD corrections become completely negligible, which can be simply attributed to the different asymptotic scaling behaviors of the LO and NLO cross sections, where the former exhibits a milder decrement ∝1/s , but the latter undergoes a much faster decrease ∝1/s2. Keywords: Standard Model, Higgs boson, QCD corrections

Next-to-next-to-leading order O({alpha}{sup 2}{alpha}{sup 2}{sub s}) results for top quark pair production in photon-photon collisions. The loop-by-loop contribution

Energy Technology Data Exchange (ETDEWEB)

Koerner, J.G. [Johannes Gutenberg Univ., Mainz (Germany). Inst. fuer Phys.; Merebashvili, Z. [Tbilisi State Univ. (Georgia). Inst. of High Energy Physics and Informatization; Rogal, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2006-08-15

We calculate the so-called loop-by-loop contributions to the next-to-next-to-leading order O({alpha}{sup 2}{alpha}{sup 2}{sub s}) radiative QCD corrections for the production of heavy quark pairs in the collisions of unpolarized on-shell photons. In particular, we present analytical results for the squared matrix elements that correspond to the product of the one-loop amplitudes. All results of the perturbative calculation are given in the dimensional regularization scheme. These results represent the Abelian part of the corresponding gluon-induced next-to-next-to-leading order cross section for heavy quark pair hadroproduction. (orig.)

Nuclear forces with Δ excitations up to next-to-next-to-leading order. Part I: Peripheral nucleon-nucleon waves

International Nuclear Information System (INIS)

Krebs, H.; Epelbaum, E.; Meissner, U.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 Δ 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. (orig.)

Next-to-next-leading order correction to 3-jet rate and event-shape ...

Indian Academy of Sciences (India)

The coupling constant, , was measured by two different methods: first by employing the three-jet observables. Combining all the data, the value of as at next-to-next leading order (NNLO) was determined to be 0.117 ± 0.004(hard) ± 0.006(theo). Secondly, from the event-shape distributions, the strong coupling constant, ...

Extending the Matrix Element Method beyond the Born approximation: calculating event weights at next-to-leading order accuracy

International Nuclear Information System (INIS)

Martini, Till; Uwer, Peter

2015-01-01

In this article we illustrate how event weights for jet events can be calculated efficiently at next-to-leading order (NLO) accuracy in QCD. This is a crucial prerequisite for the application of the Matrix Element Method in NLO. We modify the recombination procedure used in jet algorithms, to allow a factorisation of the phase space for the real corrections into resolved and unresolved regions. Using an appropriate infrared regulator the latter can be integrated numerically. As illustration, we reproduce differential distributions at NLO for two sample processes. As further application and proof of concept, we apply the Matrix Element Method in NLO accuracy to the mass determination of top quarks produced in e"+e"− annihilation. This analysis is relevant for a future Linear Collider. We observe a significant shift in the extracted mass depending on whether the Matrix Element Method is used in leading or next-to-leading order.

Inclusive particle production at HERA: Resolved and direct quasi-real photon contributions in next-to-leading order QCD

International Nuclear Information System (INIS)

Kniehl, B.A.; Kramer, G.

1994-01-01

We calculate in next-to-leading order inclusive cross sections of single-particle production via both direct and resolved photons in ep collisions at HERA. Transverse-momentum and rapidity distributions are presented and the dependences on renormalization and factorization scales and subtraction schemes are investigated. (orig.)

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.

Extending the Matrix Element Method beyond the Born approximation: calculating event weights at next-to-leading order accuracy

Energy Technology Data Exchange (ETDEWEB)

Martini, Till; Uwer, Peter [Humboldt-Universität zu Berlin, Institut für Physik,Newtonstraße 15, 12489 Berlin (Germany)

2015-09-14

In this article we illustrate how event weights for jet events can be calculated efficiently at next-to-leading order (NLO) accuracy in QCD. This is a crucial prerequisite for the application of the Matrix Element Method in NLO. We modify the recombination procedure used in jet algorithms, to allow a factorisation of the phase space for the real corrections into resolved and unresolved regions. Using an appropriate infrared regulator the latter can be integrated numerically. As illustration, we reproduce differential distributions at NLO for two sample processes. As further application and proof of concept, we apply the Matrix Element Method in NLO accuracy to the mass determination of top quarks produced in e{sup +}e{sup −} annihilation. This analysis is relevant for a future Linear Collider. We observe a significant shift in the extracted mass depending on whether the Matrix Element Method is used in leading or next-to-leading order.

Next-to-next-to-leading logarithms in four-fermion electroweak processes at high energy

International Nuclear Information System (INIS)

Kuehn, J.H.; Moch, S.; Penin, A.A.; Smirnov, V.A.

2001-01-01

We sum up the next-to-next-to-leading logarithmic virtual electroweak corrections to the high energy asymptotics of the neutral current four-fermion processes for light fermions to all orders in the coupling constants using the evolution equation approach. From this all order result we derive finite order expressions through next-to-next-to leading order for the total cross section and various asymmetries. We observe an amazing cancellation between the sizable leading, next-to-leading and next-to-next-to-leading logarithmic contributions at TeV energies

Next to leading order three jet production at hadron colliders

International Nuclear Information System (INIS)

Kilgore, W.

1997-01-01

Results from a next-to-leading order event generator of purely gluonic jet production are presented. This calculation is the first step in the construction of a full next-to-leading order calculation of three jet production at hadron colliders. Several jet algorithms commonly used in experiments are implemented and their numerical stability is investigated. A numerical instability is found in the iterative cone algorithm which makes it inappropriate for use in fixed order calculations beyond leading order. (author)

The complete vertical stroke ΔS vertical stroke =2-hamiltonian in the next-to-leading order

International Nuclear Information System (INIS)

Herrlich, S.; Nierste, U.

1996-04-01

We present the complete next-to-leading order short-distance QCD corrections to the effective vertical stroke ΔS vertical stroke =2-hamiltonian in the Standard Model. The calculation of the coefficient η 3 is described in great detail. It involves the two-loop mixing of bilocal structures composed of two vertical stroke ΔS vertical stroke =1 operators into vertical stroke ΔS vertical stroke =2 operators. The next-to-leading order corrections enhance η 3 by 27% to η 3 =0.47(+0.03-0.04) thereby affecting the phenomenology of ε K sizeably. η 3 depends on the physical input parameters m t , m c and Λsub(anti M anti S) only weakly. The quoted error stems from renormalization scale dependences, which have reduced compared to the old leading log result. The known calculation of η 1 and η 2 is repeated in order to compare the structure of the three QCD coefficients. We further discuss some field theoretical aspects of the calculation such as the renormalization group equation for Green's functions with two operator insertions and the renormalization scheme dependence caused by the presence of evanescent operators. (orig.)

Next-to-soft corrections to high energy scattering in QCD and gravity

Energy Technology Data Exchange (ETDEWEB)

Luna, A.; Melville, S. [SUPA, School of Physics and Astronomy, University of Glasgow,Glasgow G12 8QQ, Scotland (United Kingdom); Naculich, S.G. [Department of Physics, Bowdoin College,Brunswick, ME 04011 (United States); White, C.D. [Centre for Research in String Theory, School of Physics and Astronomy,Queen Mary University of London,327 Mile End Road, London E1 4NS (United Kingdom)

2017-01-12

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.

Next-to-Leading Order Computation of Exclusive Diffractive Light Vector Meson Production in a Saturation Framework.

Science.gov (United States)

Boussarie, R; Grabovsky, A V; Ivanov, D Yu; Szymanowski, L; Wallon, S

2017-08-18

We perform the first next-to-leading order computation of the γ^{(*)}→V (ρ,ϕ,ω) exclusive impact factor in the QCD shock-wave approach and in the most general kinematics. This paves the way to the very first quantitative study of high-energy nucleon and nucleus saturation beyond the leading order for a whole range of small-x exclusive processes, to be measured in ep, eA, pp, and pA collisions at existing and future colliders.

Determination of the strong coupling constant α{sub s}(m{sub Z}) in next-to-next-to-leading order QCD using H1 jet cross section measurements

Energy Technology Data Exchange (ETDEWEB)

Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Soloviev, Y.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Begzsuren, K.; Ravdandorj, T. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Bertone, V. [Vrije University, Department of Physics and Astronomy, Amsterdam (Netherlands); National Institute for Subatomic Physics (NIKHEF), Amsterdam (Netherlands); Bolz, A.; Britzger, D.; Huber, F.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Boudry, V.; Specka, A. [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Brandt, G. [Universitaet Goettingen, II. Physikalisches Institut, Goettingen (Germany); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [LAL, Universite Paris-Sud, CNRS/IN2P3, Orsay (France); Buniatyan, A.; Newman, P.R.; Thompson, P.D. [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Bylinkin, A. [Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region (Russian Federation); Bystritskaya, L.; Fedotov, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Campbell, A.J.; Dodonov, V.; Eckerlin, G.; Elsen, E.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Haidt, D.; Jung, H.; Katzy, J.; Kleinwort, C.; Kruecker, D.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Schmitt, S.; Sefkow, F.; South, D.; Steder, M.; Wuensch, E.; Zlebcik, R. [DESY, Hamburg (Germany); Cantun Avila, K.B.; Contreras, J.G. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Cerny, K.; Salek, D.; Valkarova, A.; Zacek, J. [Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C.; Lobodzinski, B. [Max-Planck-Institut fuer Physik, Munich (Germany); Cvach, J.; Hladky, J.; Reimer, P. [Academy of Sciences of the Czech Republic, Institute of Physics, Prague (Czech Republic); Currie, J. [Durham University, Institute for Particle Physics Phenomenology, Ogden Centre for Fundamental Physics, Durham (United Kingdom); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kostka, P.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K.; Meyer, H. [Fachbereich C, Universitaet Wuppertal, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Vallee, C. [Aix Marseille Universite, CNRS/IN2P3, CPPM UMR 7346, Marseille (France); Dobre, M.; Rotaru, M. [Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); Egli, S.; Horisberger, R.; Ozerov, D. [Paul Scherrer Institute, Villigen (Switzerland); Favart, L.; Grebenyuk, A.; Hreus, T.; Janssen, X.; Roosen, R.; Mechelen, P.Van [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); Feltesse, J.; Schoeffel, L. [Irfu/SPP, CE Saclay, Gif-sur-Yvette (France); Gehrmann, T.; Mueller, K.; Niehues, J.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zurich (Switzerland); Goerlich, L.; Mikocki, S.; Nowak, G.; Sopicki, P. [Polish Academy of Sciences, Institute of Nuclear Physics, Krakow (Poland); Gouzevitch, M.; Petrukhin, A. [IPNL, Universite Claude Bernard Lyon 1, CNRS/IN2P3, Villeurbanne (France); Grab, C.; Huss, A. [ETH Zuerich, Institut fuer Teilchenphysik, Zurich (Switzerland); Gwenlan, C.; Radescu, V. [Oxford University, Department of Physics, Oxford (United Kingdom); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Jung, A.W. [Purdue University, Department of Physics and Astronomy, West Lafayette, IN (United States); Kapichine, M.; Morozov, A.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kogler, R. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Landon, M.P.J.; Rizvi, E.; Traynor, D. [Queen Mary University of London, School of Physics and Astronomy, London (United Kingdom); Lange, W.; Naumann, T. [DESY, Zeuthen (Germany); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (Germany); Perez, E. [CERN, Geneva (Switzerland); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (Montenegro); Polifka, R. [Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); University of Toronto, Department of Physics, Toronto, ON (Canada); Rabbertz, K. [Karlsruher Institut fuer Technologie (KIT), Institut fuer Experimentelle Teilchenphysik (ETP), Karlsruhe (Germany); Rostovtsev, A. [Institute for Information Transmission Problems RAS, Moscow (Russian Federation); Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (United Kingdom); Sauvan, E. [Aix Marseille Universite, CNRS/IN2P3, CPPM UMR 7346, Marseille (France); Universite de Savoie, CNRS/IN2P3, LAPP, Annecy-le-Vieux (France); Shushkevich, S. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Stella, B. [Universita di Roma Tre, Dipartimento di Fisica, Rome (Italy); INFN Roma 3 (Italy); Sutton, M.R. [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Sykora, T. [Brussels and Universiteit Antwerpen, Inter-University Institute for High Energies ULB-VUB, Antwerp (Belgium); Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Tseepeldorj, B. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (MN); Ulaanbaatar University, Ulaanbaatar (MN); Wegener, D. [TU Dortmund, Institut fuer Physik, Dortmund (DE); Collaboration: H1 Collaboration

2017-11-15

The strong coupling constant α{sub s} 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 α{sub s}(m{sub Z}) at the Z-boson mass m{sub 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 α{sub s}(m{sub Z}) = 0.1157(20){sub exp}(29){sub th}. Complementary, α{sub s}(m{sub Z}) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value α{sub s}(m{sub Z}) = 0.1142(28){sub 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 renormalisation scale and the results are found to be in agreement with expectations. (orig.)

Three-Jet Production in Electron-Positron Collisions at Next-to-Next-to-Leading Order Accuracy

Science.gov (United States)

Del Duca, Vittorio; Duhr, Claude; Kardos, Adam; Somogyi, Gábor; Trócsányi, Zoltán

2016-10-01

We introduce a completely local subtraction method for fully differential predictions at next-to-next-to-leading order (NNLO) accuracy for jet cross sections and use it to compute event shapes in three-jet production in electron-positron collisions. We validate our method on two event shapes, thrust and C parameter, which are already known in the literature at NNLO accuracy and compute for the first time oblateness and the energy-energy correlation at the same accuracy.

FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order

Science.gov (United States)

Gavin, Ryan; Li, Ye; Petriello, Frank; Quackenbush, Seth

2011-11-01

We introduce an improved version of the simulation code FEWZ ( Fully Exclusive W and Z Production) for hadron collider production of lepton pairs through the Drell-Yan process at next-to-next-to-leading order (NNLO) in the strong coupling constant. The program is fully differential in the phase space of leptons and additional hadronic radiation. The new version offers users significantly more options for customization. FEWZ now bins multiple, user-selectable histograms during a single run, and produces parton distribution function (PDF) errors automatically. It also features a significantly improved integration routine, and can take advantage of multiple processor cores locally or on the Condor distributed computing system. We illustrate the new features of FEWZ by presenting numerous phenomenological results for LHC physics. We compare NNLO QCD with initial ATLAS and CMS results, and discuss in detail the effects of detector acceptance on the measurement of angular quantities associated with Z-boson production. We address the issue of technical precision in the presence of severe phase-space cuts. Program summaryProgram title: FEWZ Catalogue identifier: AEJP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 6 280 771 No. of bytes in distributed program, including test data, etc.: 173 027 645 Distribution format: tar.gz Programming language: Fortran 77, C++, Python Computer: Mac, PC Operating system: Mac OSX, Unix/Linux Has the code been vectorized or parallelized?: Yes. User-selectable, 1 to 219 RAM: 200 Mbytes for common parton distribution functions Classification: 11.1 External routines: CUBA numerical integration library, numerous parton distribution sets (see text); these are provided with the code

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.

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%.

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

International Nuclear Information System (INIS)

Borasoy, B.; Epelbaum, E.; Krebs, H.; Meissner, U.G.; Lee, D.

2008-01-01

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. (orig.)

Next-to-leading order corrections to the valon model

Indian Academy of Sciences (India)

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.

Next-to-leading order corrections to the valon model

Indian Academy of Sciences (India)

Next-to-leading order corrections to the valon model. G R BOROUN. ∗ and E ESFANDYARI. Physics Department, Razi University, Kermanshah 67149, Iran. ∗. Corresponding author. E-mail: grboroun@gmail.com; boroun@razi.ac.ir. MS received 17 January 2014; revised 31 October 2014; accepted 21 November 2014.

Neutron-proton scattering at next-to-next-to-leading order in Nuclear Lattice Effective Field Theory

Energy Technology Data Exchange (ETDEWEB)

Alarcon, Jose Manuel [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Thomas Jefferson National Accelerator Facility, Theory Center, Newport News, VA (United States); Du, Dechuan; Laehde, Timo A.; Li, Ning; Lu, Bing-Nan; Luu, Thomas [Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Klein, Nico [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Lee, Dean [North Carolina State University, Department of Physics, Raleigh, NC (United States); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)

2017-05-15

We present a systematic study of neutron-proton scattering in Nuclear Lattice Effective Field Theory (NLEFT), in terms of the computationally efficient radial Hamiltonian method. Our leading-order (LO) interaction consists of smeared, local contact terms and static one-pion exchange. We show results for a fully non-perturbative analysis up to next-to-next-to-leading order (NNLO), followed by a perturbative treatment of contributions beyond LO. The latter analysis anticipates practical Monte Carlo simulations of heavier nuclei. We explore how our results depend on the lattice spacing a, and estimate sources of uncertainty in the determination of the low-energy constants of the next-to-leading-order (NLO) two-nucleon force. We give results for lattice spacings ranging from a = 1.97 fm down to a = 0.98 fm, and discuss the effects of lattice artifacts on the scattering observables. At a = 0.98 fm, lattice artifacts appear small, and our NNLO results agree well with the Nijmegen partial-wave analysis for S-wave and P-wave channels. We expect the peripheral partial waves to be equally well described once the lattice momenta in the pion-nucleon coupling are taken to coincide with the continuum dispersion relation, and higher-order (N3LO) contributions are included. We stress that for center-of-mass momenta below 100 MeV, the physics of the two-nucleon system is independent of the lattice spacing. (orig.)

Imaginary part of the next-to-leading-order static gluon self-energy in an anisotropic plasma

International Nuclear Information System (INIS)

Carrington, M. E.; Rebhan, A.

2009-01-01

Using hard-loop (HL) effective theory for an anisotropic non-Abelian plasma, which even in the static limit involves nonvanishing HL vertices, we calculate the imaginary part of the static next-to-leading-order gluon self-energy in the limit of a small anisotropy and with external momentum parallel to the anisotropy direction. At leading order, the static propagator has spacelike poles corresponding to plasma instabilities. On the basis of a calculation using bare vertices, it has been conjectured that, at next-to-leading order, the static gluon self-energy acquires an imaginary part which regulates these spacelike poles. We find that the one-loop resummed expression taken over naively from the imaginary-time formalism does yield a nonvanishing imaginary part even after including all HL vertices. However, this result is not correct. Starting from the real-time formalism, which is required in a nonequilibrium situation, we construct a resummed retarded HL propagator with correct causality properties and show that the static limit of the retarded one-loop-resummed gluon self-energy is real. This result is also required for the time-ordered propagator to exist at next-to-leading order.

Next-To-Leading Order Determination of Fragmentation Functions

CERN Document Server

Bourhis, L; Guillet, J P; Werlen, M

2001-01-01

We analyse LEP and PETRA data on single inclusive charged hadron cross-sections to establish new sets of Next-to-Leading order Fragmentation Functions. Data on hadro-production of large-$p_{\\bot}$ hadrons are also used to constrain the gluon Fragmentation Function. We carry out a critical comparison with other NLO parametrizations.

Detailed comparison of next-to-leading order predictions for jet photoproduction at HERA.

Energy Technology Data Exchange (ETDEWEB)

Harris, B. W.; Klassen, M.; Vossebeld, J.

1999-06-02

The precision of new HERA data on jet photoproduction opens up the possibility to discriminate between different models of the photon structure. This requires equally precise theoretical predictions from perturbative QCD calculations. In the past years, next-to-leading order calculations for the photoproduction of jets at HERA have become available. Using the kinematic cuts of recent ZEUS analyses, we compare the predictions of three calculations for different dijet and three-jet distributions. We find that in general all three calculations agree within the statistical accuracy of the Monte Carlo integration yielding reliable theoretical predictions. In certain restricted regions of phase space, the calculations differ by up to 5%.

Towards next-to-leading order transport coefficients from the four-particle irreducible effective action

International Nuclear Information System (INIS)

Carrington, M. E.; Kovalchuk, E.

2010-01-01

Transport coefficients can be obtained from two-point correlators using the Kubo formulas. It has been shown that the full leading order result for electrical conductivity and (QCD) shear viscosity is contained in the resummed two-point function that is obtained from the three-loop three-particle irreducible resummed effective action. The theory produces all leading order contributions without the necessity for power counting, and in this sense it provides a natural framework for the calculation. In this article we study the four-loop four-particle irreducible effective action for a scalar theory with cubic and quartic interactions, with a nonvanishing field expectation value. We obtain a set of integral equations that determine the resummed two-point vertex function. A next-to-leading order contribution to the viscosity could be obtained from this set of coupled equations.

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.

High temperature color conductivity at next-to-leading log order

International Nuclear Information System (INIS)

Arnold, Peter; Yaffe, Laurence G.

2000-01-01

The non-Abelian analogue of electrical conductivity at high temperature has previously been known only at leading logarithmic order -- that is, neglecting effects suppressed only by an inverse logarithm of the gauge coupling. We calculate the first sub-leading correction. This has immediate application to improving, to next-to-leading log order, both effective theories of non-perturbative color dynamics, and calculations of the hot electroweak baryon number violation rate

Single Top Production at Next-to-Leading Order in the Standard Model Effective Field Theory.

Science.gov (United States)

Zhang, Cen

2016-04-22

Single top production processes at hadron colliders 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.

Mueller–Navelet small-cone jets at LHC in next-to-leading BFKL

Energy Technology Data Exchange (ETDEWEB)

Caporale, F., E-mail: francesco.caporale@fis.unical.it [Dipartimento di Fisica, Università della Calabria and Istituto Nazionale di Fisica Nucleare, Gruppo collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy); Ivanov, D.Yu., E-mail: d-ivanov@math.nsc.ru [Sobolev Institute of Mathematics and Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Murdaca, B., E-mail: beatrice.murdaca@fis.unical.it [Dipartimento di Fisica, Università della Calabria and Istituto Nazionale di Fisica Nucleare, Gruppo collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy); Papa, A., E-mail: alessandro.papa@fis.unical.it [Dipartimento di Fisica, Università della Calabria and Istituto Nazionale di Fisica Nucleare, Gruppo collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy)

2013-12-01

We consider within QCD collinear factorization the process p+p→jet+jet+X, where two forward high-p{sub T} jets are produced with a large separation in rapidity Δy (Mueller–Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections ∼α{sub s}{sup n}(Δy){sup n}, which can be accounted for in the BFKL approach with next-to-leading logarithmic accuracy, including contributions ∼α{sub s}{sup n}(Δy){sup n−1}. We calculate several observables related with this process, using the next-to-leading order jet vertices, recently calculated in the approximation of small aperture of the jet cone in the pseudorapidity–azimuthal angle plane.

Conformally symmetric contributions to BFKL evolution at next to leading order

International Nuclear Information System (INIS)

Coriano, C.; White, A.R.

1995-01-01

Unitarity corrections to the BFKL evolution at next to leading order determine a new component of the evolution kernel which is shown to possess conformal invariance properties. Expressions for the complete spectrum of the new component and the correction to the intercept of the pomeron trajectory are presented

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.

Next-to-leading-logarithmic power corrections for N -jettiness subtraction in color-singlet production

Science.gov (United States)

Boughezal, Radja; Isgrò, Andrea; Petriello, Frank

2018-04-01

We present a detailed derivation of the power corrections to the factorization theorem for the 0-jettiness event shape variable T . Our calculation is performed directly in QCD without using the formalism of effective field theory. We analytically calculate the next-to-leading logarithmic power corrections for small T at next-to-leading order in the strong coupling constant, extending previous computations which obtained only the leading-logarithmic power corrections. We address a discrepancy in the literature between results for the leading-logarithmic power corrections to a particular definition of 0-jettiness. We present a numerical study of the power corrections in the context of their application to the N -jettiness subtraction method for higher-order calculations, using gluon-fusion Higgs production as an example. The inclusion of the next-to-leading-logarithmic power corrections further improves the numerical efficiency of the approach beyond the improvement obtained from the leading-logarithmic power corrections.

Production of heavy neutrino in next-to-leading order QCD at the LHC and beyond

International Nuclear Information System (INIS)

Das, Arindam; Konar, Partha; 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 √s=8 TeV, 20.3 fb"−"1 and 19.7 fb"−"1 data at the ATLAS and CMS respectively, we obtain prospective scale dependent upper bounds of the light-heavy neutrino mixing angles for the Majorana heavy neutrinos at the 14 TeV LHC and 100 TeV collider. Further exploiting a recent study on the anomalous multilepton search by CMS at √s=8 TeV with 19.5 fb"−"1 data, we also obtain the prospective scale dependent upper bounds on the mixing angles for the pseudo-Dirac neutrinos. We thus project a scale dependent prospective reach using the NLO processes at the 14 TeV LHC.

Automized squark-neutralino production to next-to-leading order

International Nuclear Information System (INIS)

Binoth, Thomas; Wigmore, Ioan; Netto, Dorival Goncalves; Lopez-Val, David; Plehn, Tilman; Mawatari, Kentarou

2011-01-01

The production of one hard jet in association with missing transverse energy is a major LHC search channel motivated by many scenarios for physics beyond the standard model. In scenarios with a weakly interacting dark matter candidate, like supersymmetry, it arises from the associated production of a quark partner with the dark matter agent. We present the next-to-leading-order cross section calculation as the first application of the fully automized MadGolem package. We find moderate corrections to the production rate with a strongly reduced theory uncertainty.

Next-to-leading order strong interaction corrections to the ΔF = 2 effective Hamiltonian in the MSSM

International Nuclear Information System (INIS)

Ciuchini, Marco; Franco, E.; Guadagnoli, D.; Lubicz, Vittorio; Porretti, V.; Silvestrini, L.

2006-01-01

We compute the next-to-leading order strong interaction corrections to gluino-mediated ΔF = 2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coefficients of the ΔF = 2 effective Hamiltonian relevant for neutral meson mixings. We find that the matching scale uncertainty is largely reduced at the next-to-leading order, typically from about 10-15% to few percent

Higher order corrections to mixed QCD-EW contributions to Higgs boson production in gluon fusion

Science.gov (United States)

Bonetti, Marco; Melnikov, Kirill; Tancredi, Lorenzo

2018-03-01

We present an estimate of the next-to-leading-order (NLO) QCD corrections to mixed QCD-electroweak contributions to the Higgs boson production cross section in gluon fusion, combining the recently computed three-loop virtual corrections and the approximate treatment of real emission in the soft approximation. We find that the NLO QCD corrections to the mixed QCD-electroweak contributions are nearly identical to NLO QCD corrections to QCD Higgs production. Our result confirms an earlier estimate of these O (α αs2) effects by Anastasiou et al. [J. High Energy Phys. 04 (2009) 003, 10.1088/1126-6708/2009/04/003] and provides further support for the factorization approximation of QCD and electroweak corrections.

Inclusive hadron production in photon-photon collisions at next-to-leading order

International Nuclear Information System (INIS)

Binnewies, J.

1996-01-01

We study inclusive charged-hadron production in collisions of quasireal photons at next-to-leading order (NLO) in the QCD-improved parton model, using fragmentation functions recently extracted from PEP and LEP1 data of e + e - annihilation. We consistently superimpose the direct (DD), single-resolved (DR), and double-resolved (RR) γγ channels. We consider photon spectra generated by electromagnetic bremsstrahlung and/or beamstrahlung off colliding e + and e - beams as well as those which result from backscattering of laser light off such beams. First, we revisit existing single-tag data taken by TASSO at PETRA and by MARK II at PEP (with e + e - energy √S∼30 GeV) and confront them with our NLO calculations imposing the respective experimental cuts. We also make comparisons with the neutral-kaon to charged-hadron ratio measured by MARK II. Then, we present NLO predictions for LEP2, a next-generation e + e - linear collider (NLC) in the TESLA design with √S=500 GeV, and a Compton collider obtained by converting a 500-GeV NLC. We analyze transverse-momentum and rapidity spectra with regard to the scale dependence, the interplay of the DD, DR, and RR components, the sensitivity to the gluon density inside the resolved photon, and the influence of gluon fragmentation. It turns out that the inclusive measurement of small-p T hadrons at a Compton collider would greatly constrain the gluon density of the photon and the gluon fragmentation function. (orig.)

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.

Production of heavy flavours at the next-to-leading order

International Nuclear Information System (INIS)

Nason, P.; Ridolfi, G.; Frixione, S.; Mangano, M.L.

1993-01-01

The status of next-to-leading calculations of heavy quark production is reviewed. In particular, results on the doubly-differential cross section for the photoproduction of heavy flavours are discussed. The possibility of using heavy flavour production in order to determine the gluon density in the proton at HERA is also discussed. 3 figs., 22 refs

Inclusive two-jet production in photon-photon collisions: Direct and resolved contributions in next-to-leading order QCD

International Nuclear Information System (INIS)

Kleinwort, T.; Kramer, G.

1996-10-01

We have calculated inclusive two-jet production in photon-photon collisions superimposing direct, single-resolved and double-resolved cross sections for center-of-mass energies of TRISTAN and LEP1.5. All three contributions are calculated up to next-to-leading order. The results are compared with recent experimental data. Three NLO sets of parton distributions of the photon are tested. (orig.)

Resonance saturation of the chiral couplings at next-to-leading order in 1/NC

International Nuclear Information System (INIS)

Rosell, Ignasi; Ruiz-Femenia, Pedro; Sanz-Cillero, Juan Jose

2009-01-01

The precision obtainable in phenomenological applications of chiral perturbation theory is currently limited by our lack of knowledge on the low-energy constants (LECs). The assumption that the most important contributions to the LECs come from the dynamics of the low-lying resonances, often referred to as the resonance saturation hypothesis, has stimulated the use of large-N C resonance Lagrangians in order to obtain explicit values for the LECs. We study the validity of the resonance saturation assumption at the next-to-leading order in the 1/N C expansion within the framework of resonance chiral theory. We find that, by imposing QCD short-distance constraints, the chiral couplings can be written in terms of the resonance masses and couplings and do not depend explicitly on the coefficients of the chiral operators in the Goldstone boson sector of resonance chiral theory. As we argue, this is the counterpart formulation of the resonance saturation statement in the context of the resonance Lagrangian. Going beyond leading order in the 1/N C counting allows us to keep full control of the renormalization scale dependence of the LEC estimates.

Transverse energy-energy correlations in next-to-leading order in {alpha}{sub s} at the LHC

Energy Technology Data Exchange (ETDEWEB)

Ali, Ahmed; Wang, Wei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Barreiro, Fernando; Llorente, Javier [Universidad Autonoma de Madrid (Spain). Dept. de Fisica

2012-05-15

We compute the transverse energy-energy correlation (EEC) and its asymmetry (AEEC) in next-to-leading order (NLO) in {alpha}{sub s} in proton-proton collisions at the LHC with the center-of-mass energy E{sub c.m.}=7 TeV. We show that the transverse EEC and the AEEC distributions are insensitive to the QCD factorization- and the renormalization-scales, structure functions of the proton, and for a judicious choice of the jet-size, also the underlying minimum bias events. Hence they can be used to precisely test QCD in hadron colliders and determine the strong coupling {alpha}{sub s}. We illustrate these features by defining the hadron jets using the anti-k{sub T} jet algorithm and an event selection procedure employed in the analysis of jets at the LHC and show the {alpha}{sub s}(M{sub Z})-dependence of the transverse EEC and the AEEC in the anticipated range 0.11{<=} {alpha}{sub s}(M{sub Z}){<=}0.13.

Next-to-next-to-leading order QCD analysis of combined data for xF3 structure function and higher-twist contribution

International Nuclear Information System (INIS)

Sidorov, A.V.

1996-01-01

The simultaneous QCD analysis of the xF 3 structure function measured in deep-inelastic scattering by several collaborations is done up to 3-loop order of QCD. The x dependence of the higher-twist contribution is evaluated and turns out to be in a qualitative agreement with the results of 'old' CCFR data analysis and with renormalon approach predictions. The Gross-Llewellyn Smith sum rule and its higher-twist corrections are evaluated. 32 refs., 1 figs., 1 tab

Anatomy of Bs → PV decays and effects of next-to-leading order contributions in the perturbative QCD factorization approach

Science.gov (United States)

Yan, Da-Cheng; Yang, Ping; Liu, Xin; Xiao, Zhen-Jun

2018-06-01

In this paper, we will make systematic calculations for the branching ratios and the CP-violating asymmetries of the twenty one Bbars0 → PV decays by employing the perturbative QCD (PQCD) factorization approach. Besides the full leading-order (LO) contributions, all currently known next-to-leading order (NLO) contributions are taken into account. We found numerically that: (a) the NLO contributions can provide ∼ 40% enhancement to the LO PQCD predictions for B (Bbars0 →K0K bar * 0) and B (Bbars0 →K±K*∓), or a ∼ 37% reduction to B (Bbars0 →π-K*+); and we confirmed that the inclusion of the known NLO contributions can improve significantly the agreement between the theory and those currently available experimental measurements; (b) the total effects on the PQCD predictions for the relevant Bs0 → P transition form factors after the inclusion of the NLO twist-2 and twist-3 contributions is generally small in magnitude: less than 10% enhancement respect to the leading order result; (c) for the "tree" dominated decay Bbars0 →K+ρ- and the "color-suppressed-tree" decay Bbars0 →π0K*0, the big difference between the PQCD predictions for their branching ratios are induced by different topological structure and by interference effects among the decay amplitude AT,C and AP: constructive for the first decay but destructive for the second one; and (d) for Bbars0 → V (η ,η‧) decays, the complex pattern of the PQCD predictions for their branching ratios can be understood by rather different topological structures and the interference effects between the decay amplitude A (Vηq) and A (Vηs) due to the η-η‧ mixing.

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}.

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

International Nuclear Information System (INIS)

Bierenbaum, Isabella; Kramer, Gustav

2016-03-01

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 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 T and approaches one at larger p 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.

Evolution of spin-dependent structure functions from DGLAP equations in leading order and next to leading order

International Nuclear Information System (INIS)

Baishya, R.; Jamil, U.; Sarma, J. K.

2009-01-01

In this paper the spin-dependent singlet and nonsinglet structure functions have been obtained by solving Dokshitzer, Gribov, Lipatov, Altarelli, Parisi evolution equations in leading order and next to leading order in the small x limit. Here we have used Taylor series expansion and then the method of characteristics to solve the evolution equations. We have also calculated t and x evolutions of deuteron structure functions, and the results are compared with the SLAC E-143 Collaboration data.

First determination of D* -meson fragmentation functions and their uncertainties at next-to-next-to-leading order

Science.gov (United States)

Soleymaninia, Maryam; Khanpour, Hamzeh; Nejad, S. Mohammad Moosavi

2018-04-01

We present, for the first time, a set of next-to-next-to-leading order (NNLO) fragmentation functions (FFs) describing the production of charmed-meson D* from partons. Exploiting the universality and scaling violations of FFs, we extract the NLO and NNLO FFs through a global fit to all relevant data sets from single-inclusive e+e- annihilation. The uncertainties for the resulting FFs as well as the corresponding observables are estimated using the Hessian approach. We evaluate the quality of the SKM18 FFs determined in this analysis by comparing with the recent results in literature and show how they describe the available data for single-inclusive D*±-meson production in electron-positron annihilation. As a practical application, we apply the extracted FFs to make our theoretical predictions for the scaled-energy distributions of D*±-mesons inclusively produced in top quark decays. We explore the implications of SKM18 for LHC phenomenology and show that our findings of this study can be introduced as a channel to indirect search for top-quark properties.

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.

Next-to-next-to-leading order gravitational spin-orbit coupling via the effective field theory for spinning objects in the post-Newtonian scheme

Energy Technology Data Exchange (ETDEWEB)

Levi, Michele [Université Pierre et Marie Curie, CNRS-UMR 7095, Institut d' Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@aei.mpg.de [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute), Am Mühlenberg 1, 14476 Potsdam-Golm (Germany)

2016-01-01

We implement the effective field theory for gravitating spinning objects in the post-Newtonian scheme at the next-to-next-to-leading order level to derive the gravitational spin-orbit interaction potential at the third and a half post-Newtonian order for rapidly rotating compact objects. From the next-to-next-to-leading order interaction potential, which we obtain here in a Lagrangian form for the first time, we derive straightforwardly the corresponding Hamiltonian. The spin-orbit sector constitutes the most elaborate spin dependent sector at each order, and accordingly we encounter a proliferation of the relevant Feynman diagrams, and a significant increase of the computational complexity. We present in detail the evaluation of the interaction potential, going over all contributing Feynman diagrams. The computation is carried out in terms of the ''nonrelativistic gravitational'' fields, which are advantageous also in spin dependent sectors, together with the various gauge choices included in the effective field theory for gravitating spinning objects, which also optimize the calculation. In addition, we automatize the effective field theory computations, and carry out the automated computations in parallel. Such automated effective field theory computations would be most useful to obtain higher order post-Newtonian corrections. We compare our Hamiltonian to the ADM Hamiltonian, and arrive at a complete agreement between the ADM and effective field theory results. Finally, we provide Hamiltonians in the center of mass frame, and complete gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to third and a half post-Newtonian order. The derivation presented here is essential to obtain further higher order post-Newtonian corrections, and to reach the accuracy level required for the successful detection of gravitational radiation.

Mellin moments of the next-to-next-to leading order coefficient functions for the Drell-Yan process and hadronic Higgs-boson production

International Nuclear Information System (INIS)

Bluemlein, J.; Ravindran, V.

2005-01-01

We calculate the Mellin moments of the next-to-next-to leading order coefficient functions for the Drell-Yan and Higgs production cross sections. The results can be expressed in terms of multiple finite harmonic sums of maximal weight w=4. Using algebraic and structural relations between harmonic sums one finds that besides the single harmonic sums only five basic sums and their derivatives w.r.t. the summation index contribute. This representation reduces the large complexity being present in x-space calculations and is well suited for fast numerical implementations. (orig.)

Equivalence of ADM Hamiltonian and Effective Field Theory approaches at next-to-next-to-leading order spin1-spin2 coupling of binary inspirals

Energy Technology Data Exchange (ETDEWEB)

Levi, Michele [Institut d' Astrophysique de Paris, Université Pierre et Marie Curie, CNRS-UMR 7095, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@ist.utl.pt [Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal)

2014-12-01

The next-to-next-to-leading order spin1-spin2 potential for an inspiralling binary, that is essential for accuracy to fourth post-Newtonian order, if both components in the binary are spinning rapidly, has been recently derived independently via the ADM Hamiltonian and the Effective Field Theory approaches, using different gauges and variables. Here we show the complete physical equivalence of the two results, thereby we first prove the equivalence of the ADM Hamiltonian and the Effective Field Theory approaches at next-to-next-to-leading order with the inclusion of spins. The main difficulty in the spinning sectors, which also prescribes the manner in which the comparison of the two results is tackled here, is the existence of redundant unphysical spin degrees of freedom, associated with the spin gauge choice of a point within the extended spinning object for its representative worldline. After gauge fixing and eliminating the unphysical degrees of freedom of the spin and its conjugate at the level of the action, we arrive at curved spacetime generalizations of the Newton-Wigner variables in closed form, which can also be used to obtain further Hamiltonians, based on an Effective Field Theory formulation and computation. Finally, we make use of our validated result to provide gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to fourth post-Newtonian order, including all known sectors up to date.

Extended Holstein-Primakoff mapping for the next-to-leading order of the 1/N expansion at finite temperature

International Nuclear Information System (INIS)

Dzhioev, Alan; Storozhenko, A.; Vdovin, A.; Aouissat, Z.; Wambach, J.

2004-01-01

An extended Holstein-Primakoff mapping which incorporates both single- and double-fermion mappings is used in the context of thermofield dynamics to study the next-to-leading order of the 1/N expansion at finite temperature. For the Lipkin-Meshkov-Glick model it is shown that the extended mapping naturally leads to the correct Fermi statistics both in leading and next-to-leading order

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

Science.gov (United States)

Kumar, M. C.; Mathews, Prakash; Ravindran, V.

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.

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of doubly-real emissions

International Nuclear Information System (INIS)

Somogyi, Gabor; Trocsanyi, Zoltan; Del Duca, Vittorio

2007-01-01

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this first part we deal with the regularization of the doubly-real contribution to the NNLO correction

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of doubly-real emissions

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Del Duca, Vittorio [Istituto Nazionale di Fisica Nucleare, Sez. di Torino, via P. Giuria, 1 - 10125 Turin (Italy)

2007-01-15

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this first part we deal with the regularization of the doubly-real contribution to the NNLO correction.

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of real-virtual emission

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor; Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary)

2007-01-15

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this second part we deal with the regularization of the real-virtual contribution to the NNLO correction.

Regge vertex for quark production in the central rapidity region in the next-to-leading order

Energy Technology Data Exchange (ETDEWEB)

Kozlov, M. G., E-mail: M.G.Kozlov@inp.nsk.su; Reznichenko, A. V., E-mail: A.V.Reznichenko@inp.nsk.su [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

2016-03-15

The effective vertex for quark production in the interaction of a Reggeized quark and a Reggeized gluon is calculated in the next-to-leading order (NLO). The resulting vertex is the missing component of the NLO multi-Regge amplitude featuring quark and gluon exchanges in the t channels. This calculation will make it possible to develop in future the bootstrap approach to proving quark Reggeization in the next-to-leading logarithmic approximation.

Matching the Nagy-Soper parton shower at next-to-leading order

Energy Technology Data Exchange (ETDEWEB)

Kraus, Manfred [Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University (Germany)

2015-07-01

We give a short review of the shower concept, first introduced by Nagy and Soper, that includes full quantum correlations in the shower evolution. We also state the current status of implementation of the publicly available shower program Deductor. However, the main focus of the talk is the matching of the shower at next-to-leading order within the MC rate at NLO formalism. Matching is necessary in order to increase the accuracy of theoretical predictions and to employ a hadronization model. We show first results using Deductor in conjunction with the Helac-NLO framework for top quark pair production in association with one hard jet.

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.

Resummed B→Xulν decay distributions to next-to-leading order

International Nuclear Information System (INIS)

Aglietti, U.

2001-01-01

We perform factorization of the most general distribution in semileptonic B→X u decays and we resum the threshold logarithms to next-to-leading order. From this (triple-differential) distribution, any other distribution is obtained by integration. As an application of our method, we derive simple analytical expressions for a few distributions, resummed to leading approximation. It is shown that the shape function can be directly determined by measuring the distribution in m X 2 /E X 2 , not in m X 2 /m B 2 . We compute the resummed hadron energy spectrum, which has a 'Sudakov shoulder', and we show how the distribution in the singular region is related to the shape function. We also present an improved formula for the photon spectrum in B→X s γ, which includes soft-gluon resummation and non-leading operators in the effective Hamiltonian. We explicitly show that the same non-perturbative function -- namely, the shape function -- controls the non-perturbative effects in all the distributions in the semileptonic and in the rare decay

QCD corrections to $e^{+} e^{-} \\to u \\overline {d} s \\overline {c}$ at LEP 2 and the Next Linear Collider CC11 at O $\\alpha_{s}$

CERN Document Server

Maina, E; Pizzio, M

1998-01-01

QCD one-loop corrections to the full gauge invariant set of electroweak diagrams describing the hadronic process $e^+ e^- \\to u~\\bar d~s~\\bar c$ are computed. Four-jet shape variables for $WW$ events are studied at next-to-leading order and the effects of QCD corrections on the determination of the $W$--mass in the hadronic channel at Lep 2 and NLC is discussed. We compare the exact calculation with a ``naive''approach to strong radiative corrections which has been widely used in the literature.

Next-to-leading-order electroweak corrections to the production of three charged leptons plus missing energy at the LHC

Science.gov (United States)

Biedermann, Benedikt; Denner, Ansgar; Hofer, Lars

2017-10-01

The production of a neutral and a charged vector boson with subsequent decays into three charged leptons and a neutrino is a very important process for precision tests of the Standard Model of elementary particles and in searches for anomalous triple-gauge-boson couplings. In this article, the first computation of next-to-leading-order electroweak corrections to the production of the four-lepton final states μ + μ -e+ ν e, {μ}+{μ}-{e}-{\\overline{ν}}e , μ + μ - μ + ν μ , and {μ}+{μ}-{μ}-{\\overline{ν}}_{μ } at the Large Hadron Collider is presented. We use the complete matrix elements at leading and next-to-leading order, including all off-shell effects of intermediate massive vector bosons and virtual photons. The relative electroweak corrections to the fiducial cross sections from quark-induced partonic processes vary between -3% and -6%, depending significantly on the event selection. At the level of differential distributions, we observe large negative corrections of up to -30% in the high-energy tails of distributions originating from electroweak Sudakov logarithms. Photon-induced contributions at next-to-leading order raise the leading-order fiducial cross section by +2%. Interference effects in final states with equal-flavour leptons are at the permille level for the fiducial cross section, but can lead to sizeable effects in off-shell sensitive phase-space regions.

A positive-weight next-to-leading-order Monte Carlo for heavy flavour hadroproduction

International Nuclear Information System (INIS)

Frixione, Stefano; Ridolfi, Giovanni; Nason, Paolo

2007-01-01

We present a next-to-leading order calculation of heavy flavour production in hadronic collisions that can be interfaced to shower Monte Carlo programs. The calculation is performed in the context of the POWHEG method. It is suitable for the computation of charm, bottom and top hadroproduction. In the case of top production, spin correlations in the decay products are taken into account

A factorization approach to next-to-leading-power threshold logarithms

Energy Technology Data Exchange (ETDEWEB)

Bonocore, D. [Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands); Laenen, E. [Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands); ITFA, University of Amsterdam,Science Park 904, Amsterdam (Netherlands); ITF, Utrecht University,Leuvenlaan 4, Utrecht (Netherlands); Magnea, L. [Dipartimento di Fisica, Università di Torino and INFN, Sezione di Torino,Via P. Giuria 1, I-10125, Torino (Italy); Melville, S. [School of Physics and Astronomy, University of Glasgow,Glasgow, G12 8QQ (United Kingdom); Vernazza, L. [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh,Edinburgh, EH9 3JZ, Scotland (United Kingdom); White, C.D. [School of Physics and Astronomy, University of Glasgow,Glasgow, G12 8QQ (United Kingdom)

2015-06-03

Threshold logarithms become dominant in partonic cross sections when the selected final state forces gluon radiation to be soft or collinear. Such radiation factorizes at the level of scattering amplitudes, and this leads to the resummation of threshold logarithms which appear at leading power in the threshold variable. In this paper, we consider the extension of this factorization to include effects suppressed by a single power of the threshold variable. Building upon the Low-Burnett-Kroll-Del Duca (LBKD) theorem, we propose a decomposition of radiative amplitudes into universal building blocks, which contain all effects ultimately responsible for next-to-leading-power (NLP) threshold logarithms in hadronic cross sections for electroweak annihilation processes. In particular, we provide a NLO evaluation of the radiative jet function, responsible for the interference of next-to-soft and collinear effects in these cross sections. As a test, using our expression for the amplitude, we reproduce all abelian-like NLP threshold logarithms in the NNLO Drell-Yan cross section, including the interplay of real and virtual emissions. Our results are a significant step towards developing a generally applicable resummation formalism for NLP threshold effects, and illustrate the breakdown of next-to-soft theorems for gauge theory amplitudes at loop level.

Model for next-to-leading order threshold resummed form factors

International Nuclear Information System (INIS)

Aglietti, Ugo; Ricciardi, Giulia

2004-01-01

We present a model for next-to-leading order resummed threshold form factors based on a timelike coupling recently introduced in the framework of small x physics. Improved expressions for the form factors in N-space are obtained which are not plagued by Landau-pole singularities, as the included absorptive effects - usually neglected - act as regulators. The physical reason is that, because of faster decay of gluon jets, there is not enough resolution time to observe the Landau pole. Our form factors reduce to the standard ones when the absorptive parts related to the coupling are neglected. The inverse transform from N-space to x-space can be done directly without any prescription and we obtain analytical expressions for the form factors, which are well defined in all x-space

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

Next-to-leading order electroweak corrections to off-shell WWW production at the LHC arXiv

CERN Document Server

Schönherr, Marek

Triboson processes allow for a measurement of the triple and quartic couplings of the Standard Model gauge bosons, which can be used to constrain anomalous gauge couplings. In this paper we calculate the next-to-leading order electroweak corrections to fully off-shell $W^-W^+W^+$ production, namely the production of a $\\ell_1^-\\ell_2^+\\ell_3^+\\bar{\

The gluon Green's function in the BFKL approach at next-to-leading logarithmic accuracy

International Nuclear Information System (INIS)

Andersen, Jeppe R.; Sabio Vera, Agustin

2004-01-01

We investigate the gluon Green's function in the high energy limit of QCD using a recently proposed iterative solution of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation at next-to-leading logarithmic (NLL) accuracy. To establish the applicability of this method in the NLL approximation we solve the BFKL equation as originally written by Fadin and Lipatov, and compare the results with previous studies in the leading logarithmic (LL) approximation

Next-to leading order analysis of target mass corrections to structure functions and asymmetries

International Nuclear Information System (INIS)

Brady, L.T.; Accardi, A.; Hobbs, T.J.; Melnitchouk, W.

2011-01-01

We perform a comprehensive analysis of target mass corrections (TMCs) to spin-averaged structure functions and asymmetries at next-to-leading order. Several different prescriptions for TMCs are considered, including the operator product expansion, and various approximations to it, collinear factorization, and xi-scaling. We assess the impact of each of these on a number of observables, such as the neutron to proton F 2 structure function ratio, and parity-violating electron scattering asymmetries for protons and deuterons which are sensitive to gamma-Z interference effects. The corrections from higher order radiative and nuclear effects on the parity-violating deuteron asymmetry are also quantified.

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

Energy Technology Data Exchange (ETDEWEB)

Benić, Sanjin [Physics Department, Faculty of Science, University of Zagreb,Zagreb 10000 (Croatia); Department of Physics, The University of Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Fukushima, Kenji [Department of Physics, The University of Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Garcia-Montero, Oscar [Institut für Theoretische Physik, Universität Heidelberg,Philosophenweg 16, 69120 Heidelberg (Germany); Venugopalan, Raju [Physics Department, Brookhaven National Laboratory,Bldg. 510A, Upton, NY 11973 (United States)

2017-01-26

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{sub ⊥} 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 small x. Other results of interest include the realization of the Low-Burnett-Kroll soft photon theorem in the CGC framework and a comparative study of how the photon amplitude is obtained in Lorenz and light-cone gauges.

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.)

The BFKL high energy asymptotic in the next-to-leading approximation

International Nuclear Information System (INIS)

Levin, Eugene

1999-01-01

We discuss the high energy asymptotic in the next-to-leading (NLO) BFKL equation. We find a general solution for the Green functions and consider two properties of the NLO BFKL kernel: running QCD coupling and large NLO corrections to the conformal part of the kernel. Both these effects lead to Regge-BFKL asymptotic only in the limited range of energy (y = ln(s/qq 0 ) ≤ (α S ) ((-5)/(3)) ) and change the energy behaviour of the amplitude for higher values of energy. We confirm the oscillation in the total cross section found by D.A. Ross [SHEP-98-06, hep-ph/9804332] in the NLO BFKL asymptotic, which shows that the NLO BFKL has a serious pathology

Next-to-Leading Order Differential Cross Sections for J/ψ, ψ(2S), and Υ Production in Proton-Proton Collisions at a Fixed-Target Experiment Using the LHC Beams

OpenAIRE

Yu Feng; Jian-Xiong Wang

2015-01-01

Using nonrelativistic QCD (NRQCD) factorization, we calculate the yields for J/ψ , ψ(2S) , and Υ(1S) hadroproduction at s=72  GeV and 115 GeV including the next-to-leading order QCD corrections. Both these center-of-mass energies correspond to those obtained with 7 TeV and 2.76 TeV nucleon beam impinging a fixed target. We study the cross section integrated in pt as a function of the (center-of-mass) rapidity as well as the pt differential cross section in the central rapidity region. Using d...

Second-order QCD effects in Higgs boson production through vector boson fusion

Science.gov (United States)

Cruz-Martinez, J.; Gehrmann, T.; Glover, E. W. N.; Huss, A.

2018-06-01

We compute the factorising second-order QCD corrections to the electroweak production of a Higgs boson through vector boson fusion. Our calculation is fully differential in the kinematics of the Higgs boson and of the final state jets, and uses the antenna subtraction method to handle infrared singular configurations in the different parton-level contributions. Our results allow us to reassess the impact of the next-to-leading order (NLO) QCD corrections to electroweak Higgs-plus-three-jet production and of the next-to-next-to-leading order (NNLO) QCD corrections to electroweak Higgs-plus-two-jet production. The NNLO corrections are found to be limited in magnitude to around ± 5% and are uniform in several of the kinematical variables, displaying a kinematical dependence only in the transverse momenta and rapidity separation of the two tagging jets.

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

International Nuclear Information System (INIS)

Klasen, M.; Kramer, G.

2009-08-01

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 protonantiproton collisions depends on the momentum fraction of the parton in the Pomeron even at next-to-leading order. (orig.)

Factorization for groomed jet substructure beyond the next-to-leading logarithm

Energy Technology Data Exchange (ETDEWEB)

Frye, Christopher; Larkoski, Andrew J.; Schwartz, Matthew D.; Yan, Kai [Center for the Fundamental Laws of Nature, Harvard University,17 Oxford Street, Cambridge, MA 02138 (United States)

2016-07-12

Jet grooming algorithms are widely used in experimental analyses at hadron colliders to remove contaminating radiation from within jets. While the algorithms perform a great service to the experiments, their intricate algorithmic structure and multiple parameters has frustrated precision theoretic understanding. In this paper, we demonstrate that one particular groomer called soft drop actually makes precision jet substructure easier. In particular, we derive a factorization formula for a large class of soft drop jet substructure observables, including jet mass. The essential observation that allows for this factorization is that, without the soft wide-angle radiation groomed by soft drop, all singular contributions are collinear. The simplicity and universality of the collinear limit in QCD allows us to show that to all orders, the normalized differential cross section has no contributions from non-global logarithms. It is also independent of process, up to the relative fraction of quark and gluon jets. In fact, soft drop allows us to define this fraction precisely. The factorization theorem also explains why soft drop observables are less sensitive to hadronization than their ungroomed counterparts. Using the factorization theorem, we resum the soft drop jet mass to next-to-next-to-leading logarithmic accuracy. This requires calculating some clustering effects that are closely related to corresponding effects found in jet veto calculations. We match our resummed calculation to fixed order results for both e{sup +}e{sup −}→ dijets and pp→Z+j events, producing the first jet substructure predictions (groomed or ungroomed) to this accuracy for the LHC.

Factorization for groomed jet substructure beyond the next-to-leading logarithm

International Nuclear Information System (INIS)

Frye, Christopher; Larkoski, Andrew J.; Schwartz, Matthew D.; Yan, Kai

2016-01-01

Jet grooming algorithms are widely used in experimental analyses at hadron colliders to remove contaminating radiation from within jets. While the algorithms perform a great service to the experiments, their intricate algorithmic structure and multiple parameters has frustrated precision theoretic understanding. In this paper, we demonstrate that one particular groomer called soft drop actually makes precision jet substructure easier. In particular, we derive a factorization formula for a large class of soft drop jet substructure observables, including jet mass. The essential observation that allows for this factorization is that, without the soft wide-angle radiation groomed by soft drop, all singular contributions are collinear. The simplicity and universality of the collinear limit in QCD allows us to show that to all orders, the normalized differential cross section has no contributions from non-global logarithms. It is also independent of process, up to the relative fraction of quark and gluon jets. In fact, soft drop allows us to define this fraction precisely. The factorization theorem also explains why soft drop observables are less sensitive to hadronization than their ungroomed counterparts. Using the factorization theorem, we resum the soft drop jet mass to next-to-next-to-leading logarithmic accuracy. This requires calculating some clustering effects that are closely related to corresponding effects found in jet veto calculations. We match our resummed calculation to fixed order results for both e + e − → dijets and pp→Z+j events, producing the first jet substructure predictions (groomed or ungroomed) to this accuracy for the LHC.

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

International Nuclear Information System (INIS)

Nuncio Quiroz, Adriana Elizabeth

2008-08-01

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 → b anti bX → D * μX' and ep → b anti bX → μ + μ - X' channels. A comparison with the H1 D * μ 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 G Elec finder. This finder is tested on the reconstruction of the J/ψ → e + e - signal. Finally, a heavy-flavour analysis has been started, namely the ep → b anti bX → eμX' dilepton channel, using an integrated luminosity of 114 pb -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 T values than muons do. The technical part of this thesis consisted in the calibration, maintenance and data

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.

Next to leading order evolution of SIDIS processes in the forward region

International Nuclear Information System (INIS)

Daleo, A.; Sassot, R.

2003-01-01

We compute the order α s 2 quark initiated corrections to semi-inclusive deep inelastic scattering extending the approach developed recently for the gluon contributions. With these corrections we complete the order α s 2 QCD description of these processes, verifying explicitly the factorization of collinear singularities. We also obtain the corresponding NLO evolution kernels, relevant for the scale dependence of fracture functions. We compare the non-homogeneous evolution effects driven by these kernels with those obtained at leading order accuracy and discuss their phenomenological implications

On the next-to-next-to-leading order evolution of flavour-singlet fragmentation functions

International Nuclear Information System (INIS)

Almasy, A.A.; Moch, S.; Vogt, A.

2012-01-01

We present the third-order contributions to the quark-gluon and gluon-quark timelike splitting functions for the evolution of fragmentation functions in perturbative QCD. These quantities have been derived by studying physical evolution kernels for photon- and Higgs-exchange structure functions in deep-inelastic scattering and their counterparts in semi-inclusive annihilation, together with constraints from the momentum sum rule and the supersymmetric limit. For this purpose we have also calculated the second-order coefficient functions for one-hadron inclusive Higgs decay in the heavy-top limit. A numerically tolerable uncertainty remains for the quark-gluon splitting function, which does not affect the endpoint logarithms for small and large momentum fractions. We briefly discuss these limits and illustrate the numerical impact of the third-order corrections. Compact and accurate parametrizations are provided for all third-order timelike splitting functions.

On the next-to-next-to-leading order evolution of flavour-singlet fragmentation functions

Energy Technology Data Exchange (ETDEWEB)

Almasy, A.A.; Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2011-07-15

We present the third-order contributions to the quark-gluon and gluon-quark timelike splitting functions for the evolution of fragmentation functions in perturbative QCD. These quantities have been derived by studying physical evolution kernels for photon- and Higgs-exchange structure functions in deep-inelastic scattering and their counterparts in semi-inclusive annihilation, together with constraints from the momentum sum rule and the supersymmetric limit. For this purpose we have also calculated the second-order coefficient functions for one-hadron inclusive Higgs decay in the heavy-top limit. A numerically tolerable uncertainty remains for the quark-gluon splitting function, which does not affect the endpoint logarithms for small and large momentum fractions. We briefly discuss these limits and illustrate the numerical impact of the third-order corrections. Compact and accurate parametrizations are provided for all third-order timelike splitting functions. (orig.)

Next-to-leading order unitarity fits in Two-Higgs-Doublet models with soft ℤ{sub 2} breaking

Energy Technology Data Exchange (ETDEWEB)

Cacchio, Vincenzo; Chowdhury, Debtosh; Eberhardt, Otto [Istituto Nazionale di Fisica Nucleare, Sezione di Roma,Piazzale Aldo Moro 2, I-00185 Roma (Italy); Murphy, Christopher W. [Scuola Normale Superiore,Piazza dei Cavalieri 7, I-56126 Pisa (Italy)

2016-11-07

We fit the next-to-leading order unitarity conditions to the Two-Higgs-Doublet model with a softly broken ℤ{sub 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 ℤ{sub 2} symmetry with a probability of 95%. All fits are performed using the open-source code HEPfit.

Third-order QCD corrections to the charged-current structure function F3

International Nuclear Information System (INIS)

Moch, S.; Vermaseren, J.A.M.; Vogt, A.

2008-12-01

We compute the coefficient function for the charge-averaged W ± -exchange structure function F 3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling α s and of 1/Q 2 power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F 3 in powers of α s is stable at all values of x relevant to measurements at high scales Q 2 . At small x the third-order coefficient function is dominated by diagrams with the colour structure d abc d abc not present at lower orders. At large x the coefficient function for F 3 is identical to that of F 1 up to terms vanishing for x→1. (orig.)

Threshold resummation and higher order effects in QCD

International Nuclear Information System (INIS)

Ringer, Felix Maximilian

2015-01-01

Quantum chromodynamics (QCD) is a quantum field theory that describes the strong interactions between quarks and gluons, the building blocks of all hadrons. Thanks to the experimental progress over the past decades, there has been an ever-growing need for QCD precision calculations for scattering processes involving hadrons. For processes at large momentum transfer, perturbative QCD offers a systematic approach for obtaining precise predictions. This approach relies on two key concepts: the asymptotic freedom of QCD and factorization. In a perturbative calculation at higher orders, the infrared cancellation between virtual and real emission diagrams generally leaves behind logarithmic contributions. In many observables relevant for hadronic scattering these logarithms are associated with a kinematic threshold and are hence known as ''threshold logarithms''. They become large when the available phase space for real gluon emission shrinks. In order to obtain a reliable prediction from QCD, the threshold logarithms need to be taken into account to all orders in the strong coupling constant, a procedure known as ''threshold resummation''. The main focus of my PhD thesis is on studies of QCD threshold resummation effects beyond the next-to-leading logarithmic order. Here we primarily consider the production of hadron pairs in hadronic collisions as an example. In addition, we also consider hadronic jet production, which is particularly interesting for the phenomenology at the LHC. For both processes, we fully take into account the non-trivial QCD color structure of the underlying partonic hard- scattering cross sections. We find that threshold resummation leads to sizable numerical effects in the kinematic regimes relevant for comparisons to experimental data.

Next-to-next-to-eikonal corrections in the CGC

Energy Technology Data Exchange (ETDEWEB)

Altinoluk, Tolga; Armesto, Néstor [Departamento de Física de Partículas and IGFAE,Universidade de Santiago de Compostela,E-15706 Santiago de Compostela, Galicia (Spain); Beuf, Guillaume [Department of Physics, Ben-Gurion University of the Negev,Beer Sheva 84105 (Israel); Moscoso, Alexis [Departamento de Física de Partículas and IGFAE,Universidade de Santiago de Compostela,E-15706 Santiago de Compostela, Galicia (Spain)

2016-01-19

We extend the study of corrections to the eikonal approximation that was initiated in ref. http://dx.doi.org/10.1007/JHEP07(2014)068 to higher orders. These corrections associated with the finite width of the target are investigated and the gluon propagator in background field is calculated at next-to-next-to-eikonal accuracy. The result is then applied to the single inclusive gluon production cross section at central rapidities and the single transverse spin asymmetry with a transversely polarized target, in pA collisions, in order to analyze these observables beyond the eikonal limit. The next-to-next-to-eikonal corrections to the unpolarized cross section are non-zero and provide the first corrections to the usual k{sub ⊥}-factorized expression. In contrast, the eikonal and next-to-next-to-eikonal contributions to the single transverse spin asymmetry vanish, while the next-to-eikonal ones are non-zero.

Next-to-next-to-leading order gravitational spin-squared potential via the effective field theory for spinning objects in the post-Newtonian scheme

Energy Technology Data Exchange (ETDEWEB)

Levi, Michele [Université Pierre et Marie Curie, CNRS-UMR 7095, Institut d' Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan, E-mail: michele.levi@upmc.fr, E-mail: jan.steinhoff@aei.mpg.de [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute), Am Mühlenberg 1, 14476 Potsdam-Golm (Germany)

2016-01-01

The next-to-next-to-leading order spin-squared interaction potential for generic compact binaries is derived for the first time via the effective field theory for gravitating spinning objects in the post-Newtonian scheme. The spin-squared sector is an intricate one, as it requires the consideration of the point particle action beyond minimal coupling, and mainly involves the spin-squared worldline couplings, which are quite complex, compared to the worldline couplings from the minimal coupling part of the action. This sector also involves the linear in spin couplings, as we go up in the nonlinearity of the interaction, and in the loop order. Hence, there is an excessive increase in the number of Feynman diagrams, of which more are higher loop ones. We provide all the Feynman diagrams and their values. The beneficial ''nonrelativistic gravitational'' fields are employed in the computation. This spin-squared correction, which enters at the fourth post-Newtonian order for rapidly rotating compact objects, completes the conservative sector up to the fourth post-Newtonian accuracy. The robustness of the effective field theory for gravitating spinning objects is shown here once again, as demonstrated in a recent series of papers by the authors, which obtained all spin dependent sectors, required up to the fourth post-Newtonian accuracy. The effective field theory of spinning objects allows to directly obtain the equations of motion, and the Hamiltonians, and these will be derived for the potential obtained here in a forthcoming paper.

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

Energy Technology Data Exchange (ETDEWEB)

Biedermann, Benedikt; Denner, Ansgar [Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg, 97074 Würzburg (Germany); Dittmaier, Stefan [Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg (Germany); Hofer, Lars [Institut de Ciències del Cosmo (ICCUB), Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona - UB, 08028 Barcelona (Spain); Jäger, Barbara [Institut für Theoretische Physik, Eberhard Karls Universität Tübingen, 72076 Tübingen (Germany)

2017-01-09

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{sup +}μ{sup −}e{sup +}e{sup −} or μ{sup +}μ{sup −}μ{sup +}μ{sup −} 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{sup +}μ{sup −}e{sup +}e{sup −} and μ{sup +}μ{sup −}μ{sup +}μ{sup −} final states, we find significant differences mainly in distributions that are sensitive to the μ{sup +}μ{sup −} pairing in the μ{sup +}μ{sup −}μ{sup +}μ{sup −} final state. Differences between μ{sup +}μ{sup −}e{sup +}e{sup −} and μ{sup +}μ{sup −}μ{sup +}μ{sup −} 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.

Third-order QCD corrections to the charged-current structure function F{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Vermaseren, J.A.M. [NIKHEF, Amsterdam (Netherlands); Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences

2008-12-15

We compute the coefficient function for the charge-averaged W{sup {+-}}-exchange structure function F{sub 3} in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling {alpha}{sub s} and of 1/Q{sup 2} power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F{sub 3} in powers of {alpha}{sub s} is stable at all values of x relevant to measurements at high scales Q{sup 2}. At small x the third-order coefficient function is dominated by diagrams with the colour structure d{sup abc}d{sub abc} not present at lower orders. At large x the coefficient function for F{sub 3} is identical to that of F{sub 1} up to terms vanishing for x{yields}1. (orig.)

Next-to-next-leading order correction to 3-jet rate and event-shape ...

Indian Academy of Sciences (India)

portunity to test QCD by measuring the energy dependence of different ... event shape data was not satisfactory largely due to the scale uncertainty of the pertur- .... )3 d ¯C dy. + O. ( α4 s. ) . (5). Here the event-shape distribution is normalized to the ..... [1] A Gehrmann-De Ridder, T Gehrmann, E W N Glover and G Heinrich, J.

Non-abelian factorisation for next-to-leading-power threshold logarithms

International Nuclear Information System (INIS)

Bonocore, D.; Laenen, E.; Magnea, L.; Vernazza, L.; White, C.D.

2016-01-01

Soft and collinear radiation is responsible for large corrections to many hadronic cross sections, near thresholds for the production of heavy final states. There is much interest in extending our understanding of this radiation to next-to-leading power (NLP) in the threshold expansion. In this paper, we generalise a previously proposed all-order NLP factorisation formula to include non-abelian corrections. We define a non-abelian radiative jet function, organising collinear enhancements at NLP, and compute it for quark jets at one loop. We discuss in detail the issue of double counting between soft and collinear regions. Finally, we verify our prescription by reproducing all NLP logarithms in Drell-Yan production up to NNLO, including those associated with double real emission. Our results constitute an important step in the development of a fully general resummation formalism for NLP threshold effects.

Non-abelian factorisation for next-to-leading-power threshold logarithms

Energy Technology Data Exchange (ETDEWEB)

Bonocore, D. [Nikhef, Science Park 105, NL-1098 XG Amsterdam (Netherlands); Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, Sommerfeldstr. 16, 52074 Aachen (Germany); Laenen, E. [Nikhef, Science Park 105, NL-1098 XG Amsterdam (Netherlands); ITFA, University of Amsterdam, Science Park 904, Amsterdam (Netherlands); ITF, Utrecht University, Leuvenlaan 4, Utrecht (Netherlands); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030 (United States); Magnea, L. [Dipartimento di Fisica, Università di Torino and INFN, Sezione di Torino, Via P. Giuria 1, I-10125 Torino (Italy); Vernazza, L. [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); White, C.D. [Centre for Research in String Theory, School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London E1 4NS (United Kingdom)

2016-12-22

Soft and collinear radiation is responsible for large corrections to many hadronic cross sections, near thresholds for the production of heavy final states. There is much interest in extending our understanding of this radiation to next-to-leading power (NLP) in the threshold expansion. In this paper, we generalise a previously proposed all-order NLP factorisation formula to include non-abelian corrections. We define a non-abelian radiative jet function, organising collinear enhancements at NLP, and compute it for quark jets at one loop. We discuss in detail the issue of double counting between soft and collinear regions. Finally, we verify our prescription by reproducing all NLP logarithms in Drell-Yan production up to NNLO, including those associated with double real emission. Our results constitute an important step in the development of a fully general resummation formalism for NLP threshold effects.

Universality of next-to-leading power threshold effects for colourless final states in hadronic collisions

NARCIS (Netherlands)

Duca, Vittorio del; Laenen, E.; Magnea, L.; Vernazza, L.; White, C.D.

2017-01-01

We consider the production of an arbitrary number of colour-singlet particles near partonic threshold, and show that next-to-leading order cross sections for this class of processes have a simple universal form at next-to-leading power (NLP) in the energy of the emitted gluon radiation. Our analysis

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.

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

International Nuclear Information System (INIS)

Greiner, Nicolas; Reuter, Juergen; Freiburg Univ.

2011-05-01

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.)

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.)

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.

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

International Nuclear Information System (INIS)

Kamiński, Wojciech; Steinhaus, Sebastian

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

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.

Regge behaviour of structure functions and evolution of gluon structure function upto next-to-leading order at low-x

International Nuclear Information System (INIS)

Jamil, U.; Sarma, J.K.

2011-01-01

Evolution of gluon structure function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations upto next-to-leading order at low-x is presented assuming the Regge behaviour of structure functions. We compare our results of gluon structure function with GRV 98 global parameterization and show the compatibility of Regge behaviour of structure functions with PQCD. (author)

Next-to-leading order \gamma \gamma +2\text{-}\mathrm{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.

Next-to-leading-order tests of NRQCD factorization with J/{psi} yield and polarization

Energy Technology Data Exchange (ETDEWEB)

Butenschoen, Mathias [Wien Univ. (Austria). Fakultaet fuer Physik; Kniehl, Bernd A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

2012-12-15

We report on recent progress in testing the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) at next-to-leading order (NLO) for J/{psi} yield and polarization. We demonstrate that it is possible to unambiguously determine the leading color-octet long-distance matrix elements (LDMEs) in compliance with the velocity scaling rules through a global fit to experimental data of unpolarized J/{psi} production in pp, p anti p, ep, {gamma}{gamma}, and e{sup +}e{sup -} collisions.Three data sets not included in the fit, from hadroproduction and from photoproduction in the fixed-target and colliding-beam modes, are nicely reproduced. The polarization observables measured in different frames at DESY HERA and CERN LHC reasonably agree with NLO NRQCD predictions obtained using the LDMEs extracted from the global fit, while measurements from the FNAL Tevatron exhibit severe disagreement. We demonstrate that alternative LDME sets recently obtained in two other NLO NRQCD analyses of J/{psi} yield and polarization, with different philosophies, also fail to reconcile the Tevatron polarization data with the other available world data.

Next-order spin-orbit contributions to chaos in compact binaries

International Nuclear Information System (INIS)

Wang Yuzhao; Wu Xin

2011-01-01

This paper is mainly devoted to numerically investigating the effects of the next-order spin-orbit interactions including the 2.5 post-Newtonian order term of the equations of motion and the second post-Newtonian order terms of the spin precession equations on chaos in the conservative Lagrangian dynamics of a spinning compact binary system. It is shown sufficiently through individual orbit simulations, the dependence of the invariant fast Lyapunov indicators on the variations of initial spin angles and the phase space scans for chaos, that the next-order spin-orbit contributions do play an important role in the amplification of chaos.

The quark induced Mueller-Tang jet impact factor at next-to-leading order

CERN Document Server

Hentschinski, M.; Murdaca, B.; Vera, A. Sabio

2014-01-01

We present the NLO corrections for the quark induced forward production of a jet with an associated rapidity gap. We make use of Lipatov's QCD high energy effective action to calculate the real emission contributions to the so-called Mueller-Tang impact factor. We combine them with the previously calculated virtual corrections and verify ultraviolet and collinear finiteness of the final result.

Higher Order Heavy Quark Corrections to Deep-Inelastic Scattering

Science.gov (United States)

Blümlein, Johannes; DeFreitas, Abilio; Schneider, Carsten

2015-04-01

The 3-loop heavy flavor corrections to deep-inelastic scattering are essential for consistent next-to-next-to-leading order QCD analyses. We report on the present status of the calculation of these corrections at large virtualities Q2. We also describe a series of mathematical, computer-algebraic and combinatorial methods and special function spaces, needed to perform these calculations. Finally, we briefly discuss the status of measuring αs (MZ), the charm quark mass mc, and the parton distribution functions at next-to-next-to-leading order from the world precision data on deep-inelastic scattering.

Higher order heavy quark corrections to deep-inelastic scattering

International Nuclear Information System (INIS)

Bluemlein, J.; Freitas, A. de; Johannes Kepler Univ., Linz; Schneider, C.

2014-11-01

The 3-loop heavy flavor corrections to deep-inelastic scattering are essential for consistent next-to-next-to-leading order QCD analyses. We report on the present status of the calculation of these corrections at large virtualities Q 2 . We also describe a series of mathematical, computer-algebraic and combinatorial methods and special function spaces, needed to perform these calculations. Finally, we briefly discuss the status of measuring α s (M Z ), the charm quark mass m c , and the parton distribution functions at next-to-next-to-leading order from the world precision data on deep-inelastic scattering.

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.

The apeNEXT project

International Nuclear Information System (INIS)

Belletti, F.; Bodin, F.; Boucaud, Ph.; Cabibbo, N.; Lonardo, A.; De Luca, S.; Lukyanov, M.; Micheli, J.; Morin, L.; Pene, O.; Pleiter, D.; Rapuano, F.; Rossetti, D.; Schifano, S.F.; Simma, H.; Tripiccione, R.; Vicini, P.

2006-01-01

Numerical simulations in theoretical high-energy physics (Lattice QCD) require huge computing resources. Several generations of massively parallel computers optimised for these applications have been developed within the APE (array processor experiment) project. Large prototype systems of the latest generation, apeNEXT, are currently being assembled and tested. This contribution explains how the apeNEXT architecture is optimised for Lattice QCD, provides an overview of the hardware and software of apeNEXT, and describes its new features, like the SPMD programming model and the C compiler

One-loop QCD and Higgs bosons to partons processes using six-dimensional helicity and generalized unitarity

International Nuclear Information System (INIS)

Davies, Scott

2011-01-01

We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we simultaneously obtain the pieces that are constructible from four-dimensional unitarity cuts and the rational pieces that are missed by them, while retaining a helicity formalism. We illustrate the procedure using four- and five-point one-loop amplitudes in QCD, including examples with external fermions. We also demonstrate the technique's effectiveness in next-to-leading order QCD corrections to Higgs processes by computing the next-to-leading order correction to the Higgs plus three positive-helicity gluons amplitude in the large top-quark mass limit.

Second-order Hydrodynamics in QCD at NLO arXiv

CERN Document Server

Ghiglieri, Jacopo; Teaney, Derek

We compute the hydrodynamic relaxation times $\\tau_\\pi$ and $\\tau_j$ for hot QCD at next-to-leading order in the coupling by using kinetic theory. We show that certain dimensionless ratios of second-order to first-order transport coefficients obey bounds which apply whenever a kinetic theory description is possible; the computed values lie somewhat above these bounds. Strongly coupled theories with holographic duals strongly violate these bounds, highlighting their distance from a quasiparticle description.

Efficient analytic computation of higher-order QCD amplitudes

International Nuclear Information System (INIS)

Bern, Z.; Chalmers, G.; Dunbar, D.C.; Kosower, D.A.

1995-01-01

The authors review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. Particularly useful are the constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes. Certain sequences of one-loop helicity amplitudes with an arbitrary number of external gluons have been obtained using these constraints

Next-to-leading order prediction for the decay μ→e (e{sup +}e{sup −}) νν̄

Energy Technology Data Exchange (ETDEWEB)

Fael, M.; Greub, C. [Albert Einstein Center for Fundamental Physics,Institute for Theoretical Physics, University of Bern,CH-3012 Bern (Switzerland)

2017-01-19

We present the differential decay rates and the branching ratios of the muon decay with internal conversion, μ→e (e{sup +}e{sup −}) νν̄, in the Standard Model at next-to-leading order (NLO) in the on-shell scheme. This rare decay mode of the muon is among the main sources of background to the search for μ→eee decay. We found that in the phase space region where the neutrino energies are small, and the three-electron momenta have a similar signature as in the μ→eee decay, the NLO corrections decrease the leading-order prediction by about 10−20% depending on the applied cut.

Next-to-leading order QCD corrections to the decay of Higgs to vector meson and Z boson

Science.gov (United States)

Sun, Qing-Feng; Wang, An-Min

2018-02-01

The exclusive decay of the Higgs boson to a vector meson (J/ψ or Υ(1S)) and Z boson is studied in this work. The decay amplitudes are separated into two parts in a gauge invariant manner. The first part comes from the direct coupling of the Higgs boson to the charm (bottom) quark and the other from the HZZ* or the loop-induced HZ γ* vertexes in the standard model. While the branching ratios from the direct channel are much smaller than those of the indirect channel, their interference terms give nontrivial contributions. We further calculate the QCD radiative corrections to both channels, which reduce the total branching ratios by around 20% for both (J/ψ or Υ(1S)) production. Our results provide a possible chance to check the SM predictions of the {{Hc}}\\bar{{{c}}}({{Hb}}\\bar{{{b}}}) coupling and to seek for hints of new physics at the High Luminosity LHC or future hadron colliders. Supported by National Natural Science Foundation of China (11375168)

Two-loop current–current operator contribution to the non-leptonic QCD penguin amplitude

Directory of Open Access Journals (Sweden)

G. Bell

2015-11-01

Full Text Available 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 Q1,2 and provide a first estimate of NNLO CP asymmetries in penguin-dominated b→s transitions.

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.

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.

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.

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.

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.)

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

International Nuclear Information System (INIS)

Backovic, Mihailo; Maltoni, Fabio; Martini, Antony; Kraemer, Michael; Pellen, Mathieu; Mawatari, Kentarou

2015-01-01

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 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.)

The development of the light cone in the quantum chromodynamics up to the first non-leading order

International Nuclear Information System (INIS)

Kaschluhn, L.

1986-01-01

For the product of two electromagnetic currents in QCD there is derived in a systematic way a nonlocal light-cone expansion up to next-to-leading order. Thereby the gauge-invariance of the underlying theory has been taken into acccount by using the known general solutions of the Ward identities in axial gauge. (author)

Once more on the radiative corrections to the nucleon structure functions in QCD

International Nuclear Information System (INIS)

Stamenov, D.B.

1994-09-01

A new representation of the next to leading QCD corrections to the nucleon structure functions is given in terms of parton distributions. All O(α s ) corrections to the leading logarithmic approximation (LLA) are included. In contrast to the similar representations in the literature terms of order O(α 2 s ) do not attend in our expressions for the nucleon structure functions taken in the next to leading logarithmic approximation. This result is generalized for any order in α s beyond the LLA. Terms of order O(α n s ) which belong only tot he approximation in consideration are present in such a representation for the structure functions. (author). 11 refs

Real-Time Optimization and Control of Next-Generation Distribution

Science.gov (United States)

-Generation Distribution Infrastructure Real-Time Optimization and Control of Next-Generation Distribution developing a system-theoretic distribution network management framework that unifies real-time voltage and Infrastructure | Grid Modernization | NREL Real-Time Optimization and Control of Next

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.

Inclusive photoproduction of D*± mesons at next-to-leading order in the general-mass variable-flavor-number scheme

International Nuclear Information System (INIS)

Kniehl, B.A.; Kramer, G.; Schienbein, I.; Spiesberger, H.

2009-02-01

We discuss the inclusive production of D *± mesons in γp 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.)

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.)

Quark mass relations to four-loop order in perturbative QCD.

Science.gov (United States)

Marquard, Peter; Smirnov, Alexander V; Smirnov, Vladimir A; Steinhauser, Matthias

2015-04-10

We present results for the relation between a heavy quark mass defined in the on-shell and minimal subtraction (MS[over ¯]) scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS[over ¯] quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS[over ¯] heavy quark masses.

Non-abelian factorisation for next-to-leading-power threshold logarithms

NARCIS (Netherlands)

Bonocore, D.; Laenen, E.; Magnea, L.; Vernazza, L.; White, C.D.

2016-01-01

Soft and collinear radiation is responsible for large corrections to many hadronic cross sections, near thresholds for the production of heavy final states. There is much interest in extending our understanding of this radiation to next-to-leading power (NLP) in the threshold expansion. In this

Unweighted event generation in hadronic WZ production at first order in QCD

CERN Document Server

Dobbs, M

2000-01-01

We present an algorithm for unweighted event generation in the partonic process pp -> WZ(j) with leptonic decays at next-to-leading order in QCD. Monte Carlo programs for processes such as this frequently generate events with negative weights in certain regions of phase space. For simulations of experimental data one would like to have unweighted events only. We demonstrate how the phase space from the matrix elements can be combined to achieve unweighted event generation using a second stage Monte Carlo integration over a volume of real emissions (jets). Observable quantities are kept fixed in the laboratory frame throughout the integration. The algorithm is applicable to a broader class of processes and is CPU intensive.

NNLO QCD corrections to jet production at hadron colliders from gluon scattering

International Nuclear Information System (INIS)

Currie, James; Ridder, Aude Gehrmann-De; Glover, E.W.N.; Pires, João

2014-01-01

We present the next-to-next-to-leading order (NNLO) QCD corrections to dijet production in the purely gluonic channel retaining the full dependence on the number of colours. The sub-leading colour contribution in this channel first appears at NNLO and increases the NNLO correction by around 10% and exhibits a p T dependence, rising from 8% at low p T to 15% at high p T . The present calculation demonstrates the utility of the antenna subtraction method for computing the full colour NNLO corrections to dijet production at the Large Hadron Collider

SUSY-QCD corrections to Higgs boson production at hadron colliders

International Nuclear Information System (INIS)

Djouadi, A.; Spira, M.

1999-12-01

We analyze the next-to-leading order SUSY-QCD corrections to the production of Higgs particles at hadron colliders in supersymmetric extensions of the standard model. Besides the standard QCD corrections due to gluon exchange and emission, genuine supersymmetric corrections due to the virtual exchange of squarks and gluinos are present. At both the Tevatron and the LHC, these corrections are found to be small in the Higgs-strahlung, Drell-Yan-like Higgs pair production and vector boson fusion processes. (orig.)

Two-flavor QCD correction to lepton magnetic moments at leading-order in the electromagnetic coupling

Energy Technology Data Exchange (ETDEWEB)

Dru Renner, Xu Feng, Karl Jansen, Marcus Petschlies

2011-08-01

We present a reliable nonperturbative calculation of the QCD correction, at leading-order in the electromagnetic coupling, to the anomalous magnetic moment of the electron, muon and tau leptons using two-flavor lattice QCD. We use multiple lattice spacings, multiple volumes and a broad range of quark masses to control the continuum, infinite-volume and chiral limits. We examine the impact of the commonly ignored disconnected diagrams and introduce a modification to the previously used method that results in a well-controlled lattice calculation. We obtain 1.513 (43) 10^-12, 5.72 (16) 10^-8 and 2.650 (54) 10^-6 for the leading-order QCD correction to the anomalous magnetic moment of the electron, muon and tau respectively, each accurate to better than 3%.

Heavy Quark Impact Factor at Next-to-leading Level

OpenAIRE

Ciafaloni, Marcello; Rodrigo, German

2000-01-01

We further analyze the definition and the calculation of the heavy quark impact factor at next-to-leading (NL) log(s) level, and we provide its analytical expression in a previously proposed k-factorization scheme. Our results indicate that k-factorization holds at NL level with a properly chosen energy scale, and with the same gluonic Green's function previously found in the massless probe case.

Subtraction method of computing QCD jet cross sections at NNLO accuracy

Science.gov (United States)

Trócsányi, Zoltán; Somogyi, Gábor

2008-10-01

We present a general subtraction method for computing radiative corrections to QCD jet cross sections at next-to-next-to-leading order accuracy. The steps needed to set up this subtraction scheme are the same as those used in next-to-leading order computations. However, all steps need non-trivial modifications, which we implement such that that those can be defined at any order in perturbation theory. We give a status report of the implementation of the method to computing jet cross sections in electron-positron annihilation at the next-to-next-to-leading order accuracy.

Subtraction method of computing QCD jet cross sections at NNLO accuracy

Energy Technology Data Exchange (ETDEWEB)

Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen P.O.Box 51 (Hungary)], E-mail: Zoltan.Trocsanyi@cern.ch; Somogyi, Gabor [University of Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland)], E-mail: sgabi@physik.unizh.ch

2008-10-15

We present a general subtraction method for computing radiative corrections to QCD jet cross sections at next-to-next-to-leading order accuracy. The steps needed to set up this subtraction scheme are the same as those used in next-to-leading order computations. However, all steps need non-trivial modifications, which we implement such that that those can be defined at any order in perturbation theory. We give a status report of the implementation of the method to computing jet cross sections in electron-positron annihilation at the next-to-next-to-leading order accuracy.

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.)

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.)

Two-flavor QCD correction to lepton magnetic moments at leading-order in the electromagnetic coupling

Energy Technology Data Exchange (ETDEWEB)

Feng, Xu [DESY, Zeuthen (Germany). NIC; Muenster Univ. (Germany). Inst. fuer Theoretische Physik; Jansen, Karl; Renner, Dru B. [DESY, Zeuthen (Germany). NIC; Petschlies, Marcus [Humboldt Univ. Berlin (Germany). Inst. fuer Physik

2011-03-15

We present a reliable nonperturbative calculation of the QCD correction, at leading-order in the electromagnetic coupling, to the anomalous magnetic moment of the electron, muon and tau leptons using two-flavor lattice QCD. We use multiple lattice spacings, multiple volumes and a broad range of quark masses to control the continuum, in nite-volume and chiral limits. We examine the impact of the commonly ignored disconnected diagrams and introduce a modi cation to the previously used method that results in a well-controlled lattice calculation. We obtain 1.513(43).10{sup -12}, 5.72(16).10{sup -8} and 2.650(54).10{sup -6} for the leading-order QCD correction to the anomalous magnetic moment of the electron, muon and tau respectively, each accurate to better than 3%. (orig.)

Next to Leading Logarithms and the PHOTOS Monte Carlo

CERN Document Server

Golonka, P

2007-01-01

With the approaching start-up of the experiments at LHC, the urgency to quantify systematic uncertainties of the generators, used in the interpretation of the data, is becoming pressing. The PHOTOS Monte Carlo program is often used for the simulationof experimental, selection-sensitive, QED radiative corrections in decays of Z bosons and other heavy resonances and particles. Thanks to its complete phase-space coverage it is possible, with no approximations for any decay channel, to implement the matrix-element. The present paper will be devoted to those parts of the next-to-leading order corrections for Z decays which are normally missing in PHOTOS. The analytical form of the exact and truncated (standard) kernel used in PHOTOS will be explicitly given. The correction, being the ratio of the exact to the approximate kernel, can be activated as an optional contribution to the internal weight of PHOTOS. To calculate the weight, the information on the effective Born-level Z/gamma* couplings and even directions o...

NLO QCD corrections to the production of a weak boson pair with a jet

International Nuclear Information System (INIS)

Sanguinetti, G.

2008-07-01

The upcoming Large Hadron Collider (LHC) will get soon the first data from the collisions between protons at the TeV energy scale, in order to understand the electroweak symmetry breaking. Precise phenomenological studies for processes involving many particles in the final state are then required. A detailed theoretical knowledge of the Quantum Chromodynamics backgrounds is indispensable for these studies at the LHC. Among the processes with more than four particles, the production of a weak boson pair (W, Z) associated by a hadronic jet is identified as one of the Higgs searches background at the LHC. It is important to calculate the next-to-leading order QCD corrections to this process, which are composed of two parts: the virtual correction (a one-loop amplitude calculation) and the real emission (a tree level amplitude calculation but with one more parton in the final state). Compact analytical expressions have been evaluated numerically for the virtual part and are in agreement with the results obtained by two other independent research groups. Concerning the real emission, all contributions have been calculated by using packages for the generation of tree-level amplitudes. Thus, we are able to give precise predictions about the next-to-leading order corrections to the total cross section of this process at the LHC. (author)

NLO QCD corrections to tt-barbb-bar production at the LHC: 1. quark-antiquark annihilation

International Nuclear Information System (INIS)

Bredenstein, A.; Denner, A.; Dittmaier, S.; Pozzorini, S.

2008-01-01

The process pp → tt-barbb-bar + X represents a very important background reaction to searches at the LHC, in particular to tt-barH production where the Higgs boson decays into a bb-bar pair. A successful analysis of tt-barH at the LHC requires the knowledge of direct tt-barbb-bar production at next-to-leading order in QCD. We take the first step in this direction upon calculating the next-to-leading-order QCD corrections to the subprocess initiated by q q-bar annihilation. We devote an appendix to the general issue of rational terms resulting from ultraviolet or infrared (soft or collinear) singularities within dimensional regularization. There we show that, for arbitrary processes, in the Feynman gauge, rational terms of infrared origin cancel in truncated one-loop diagrams and result only from trivial self-energy corrections.

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.

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

International Nuclear Information System (INIS)

Gituliar, O.; Moch, S.

2015-05-01

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.

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.

Holographic QCD beyond the leading order

International Nuclear Information System (INIS)

Kim, Youngman; Ko, P.; Wu, Xiao-Hong

2008-01-01

We consider a holographic QCD model for light mesons beyond the leading order in the context of 5-dim gauged linear sigma model on the interval in the AdS 5 space. We include two dimension-6 operators in addition to the canonical bulk kinetic terms, and study chiral dynamics of π, ρ, a 1 and some of their KK modes. As novel features of dim-6 operators, we get non-vanishing Br(a 1 → πγ), the electromagnetic form factor and the charge radius of a charged pion, which improve the leading order results significantly and agree well with the experimental results.

Impact of Next-to-Leading Order Contributions to Cosmic Microwave Background Lensing.

Science.gov (United States)

Marozzi, Giovanni; Fanizza, Giuseppe; Di Dio, Enea; Durrer, Ruth

2017-05-26

In this Letter we study the impact on cosmological parameter estimation, from present and future surveys, due to lensing corrections on cosmic microwave background temperature and polarization anisotropies beyond leading order. In particular, we show how post-Born corrections, large-scale structure effects, and the correction due to the change in the polarization direction between the emission at the source and the detection at the observer are non-negligible in the determination of the polarization spectra. They have to be taken into account for an accurate estimation of cosmological parameters sensitive to or even based on these spectra. We study in detail the impact of higher order lensing on the determination of the tensor-to-scalar ratio r and on the estimation of the effective number of relativistic species N_{eff}. We find that neglecting higher order lensing terms can lead to misinterpreting these corrections as a primordial tensor-to-scalar ratio of about O(10^{-3}). Furthermore, it leads to a shift of the parameter N_{eff} by nearly 2σ considering the level of accuracy aimed by future S4 surveys.

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.

NNLO QCD corrections to the polarized top quark decay t (↑)→Xb+W+

Science.gov (United States)

Czarnecki, A.; Groote, S.; Körner, J. G.; Piclum, J. H.

2018-05-01

We compute the next-to-next-to-leading order (NNLO) QCD corrections to the decay t (↑)→Xb+W+ of a polarized top quark. The spin-momentum correlation in this quasi two-body decay is described by the polar angle distribution d Γ /d cos θP=Γ/2 (1 +PtαPcos θP) , where Pt is the polarization of the top quark and αP denotes the asymmetry parameter of the decay. For the latter we find αPNNLO=0.3792 ±0.0037 .

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.

Leading-order hadronic contribution to g-2 from lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Renner, Dru B.; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Feng, Xu [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Muenster Univ. (Germany). Inst. fuer Theoretische Physik; Petschlies, Marcus [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

2011-03-15

We calculate the leading-order hadronic correction to the anomalous magnetic moments of each of the three charged leptons in the Standard Model: the electron, muon and tau. Working in two-flavor lattice QCD, we address essentially all sources of systematic error: lattice artifacts, finite-size effects, quark-mass extrapolation, momentum extrapolation and disconnected diagrams. The most significant remaining systematic error, the exclusion of the strange and charm quark contributions, is addressed in our four-flavor calculation. We achieve a statistical accuracy of 2% or better for the physical values for each of the three leptons and the systematic errors are at most comparable. (orig.)

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.

The next-to-leading order (NLO) gluon distribution from DGLAP ...

Indian Academy of Sciences (India)

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 ...

Diphoton production at the LHC: a QCD study up to NNLO

Science.gov (United States)

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

2018-04-01

We consider the production of prompt-photon pairs at the LHC and we report on a study of QCD radiative corrections up to the next-to-next-to-leading order (NNLO). We present a detailed comparison of next-to-leading order (NLO) results obtained within the standard and smooth cone isolation criteria, by studying the dependence on the isolation parameters. We highlight the role of different partonic subprocesses within the two isolation criteria, and we show that they produce large radiative corrections for both criteria. Smooth cone isolation is a consistent procedure to compute QCD radiative corrections at NLO and beyond. If photon isolation is sufficiently tight, we show that the NLO results for the two isolation procedures are consistent with each other within their perturbative uncertainties. We then extend our study to NNLO by using smooth cone isolation. We discuss the impact of the NNLO corrections and the corresponding perturbative uncertainties for both fiducial cross sections and distributions, and we comment on the comparison with some LHC data. Throughout our study we remark on the main features that are produced by the kinematical selection cuts that are applied to the photons. In particular, we examine soft-gluon singularities that appear in the perturbative computations of the invariant mass distribution of the photon pair, the transverse-momentum spectra of the photons, and the fiducial cross section with asymmetric and symmetric photon transverse-momentum cuts, and we present their behaviour in analytic form.

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

International Nuclear Information System (INIS)

Iancu, E.; Mueller, A.H.; 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, perturbatively correct through NLO, in which there is no ‘rapidity subtraction’. That is, the NLO correction to the impact factor is not explicitly separated from the high-energy evolution. Our construction exploits the skeleton structure of the (NLO) Balitsky-Kovchegov equation, in which the first step of the evolution is explicitly singled out. The NLO impact factor is included by computing this first emission with the exact kinematics for the emitted gluon, rather than by using the eikonal approximation. This particular calculation has already been presented in the literature http://dx.doi.org/10.1103/PhysRevLett.108.122301, http://dx.doi.org/10.1103/PhysRevD.86.054005, but the reorganization of the perturbation theory that we propose is new. As compared to the proposal in http://dx.doi.org/10.1103/PhysRevLett.108.122301, http://dx.doi.org/10.1103/PhysRevD.86.054005, our scheme is free of the fine-tuning inherent in the rapidity subtraction, which might be the origin of the negativity of the NLO cross-section observed in previous studies.

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

Energy Technology Data Exchange (ETDEWEB)

Iancu, E. [Institut de physique théorique, Université Paris Saclay,CNRS, CEA, F-91191 Gif-sur-Yvette (France); Mueller, A.H. [Department of Physics, Columbia University,New York, NY 10027 (United States); Triantafyllopoulos, D.N. [European Centre for Theoretical Studies in Nuclear Physics and Related Areas - ECT*, Trento (Italy); Fondazione Bruno Kessler, Strada delle Tabarelle 286, I-38123 Villazzano (Italy)

2016-12-13

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, perturbatively correct through NLO, in which there is no ‘rapidity subtraction’. That is, the NLO correction to the impact factor is not explicitly separated from the high-energy evolution. Our construction exploits the skeleton structure of the (NLO) Balitsky-Kovchegov equation, in which the first step of the evolution is explicitly singled out. The NLO impact factor is included by computing this first emission with the exact kinematics for the emitted gluon, rather than by using the eikonal approximation. This particular calculation has already been presented in the literature http://dx.doi.org/10.1103/PhysRevLett.108.122301, http://dx.doi.org/10.1103/PhysRevD.86.054005, but the reorganization of the perturbation theory that we propose is new. As compared to the proposal in http://dx.doi.org/10.1103/PhysRevLett.108.122301, http://dx.doi.org/10.1103/PhysRevD.86.054005, our scheme is free of the fine-tuning inherent in the rapidity subtraction, which might be the origin of the negativity of the NLO cross-section observed in previous studies.

Status of the apeNEXT project

CERN Document Server

Ammendola, R.; Boucaud, Philippe; Cabibbo, N.; Di Carlo, F.; De Pietri, R.; Di Renzo, F.; Errico, W.; Fucci, A.; Guagnelli, M.; Kaldass, H.; Lonardo, A.; de Luca, S.; Micheli, J.; Morenas, V.; Pene, O.; Petronzio, R.; Palombi, F.; Pleiter, D.; Paschedag, N.; Rapuano, F.; De Riso, P.; Rossetti, D.; Salamon, A.; Salina, G.; Sartori, L.; Schifano, F.; Simma, H.; Tripiccione, R.; Vicini, P.; Boucaud, Ph.; 10.1016/S0920-5632(03)01755-9

2003-01-01

We present the current status of the apeNEXT project. Aim of this project is the development of the next generation of APE machines which will provide multi-teraflop computing power. Like previous machines, apeNEXT is based on a custom designed processor, which is specifically optimized for simulating QCD. We discuss the machine design, report on benchmarks, and give an overview on the status of the software development.

NNLO QCD corrections to Higgs boson production at large transverse momentum

Energy Technology Data Exchange (ETDEWEB)

Chen, X. [Center for High Energy Physics, Peking University,Beijing 100871 (China); Cruz-Martinez, J. [Institute for Particle Physics Phenomenology, Department of Physics, University of Durham,Durham, DH1 3LE (United Kingdom); Gehrmann, T. [Department of Physics, University of Zürich,CH-8057 Zürich (Switzerland); Glover, E.W.N. [Institute for Particle Physics Phenomenology, Department of Physics, University of Durham,Durham, DH1 3LE (United Kingdom); Jaquier, M. [Albert-Ludwigs-Universität Freiburg, Physikalisches Institut,D-79104 Freiburg (Germany)

2016-10-13

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.

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.

SU(N)-QCD2 meson equation in next-to-leading order

International Nuclear Information System (INIS)

Durgut, M.; Pak, N.K.

1982-08-01

We compute the 1/N corrections to the meson equation in the regular cut-off scheme. We illustrate that although the quark and gluon self energy and vertex corrections do not vanish explicitly as in the singular cut-off scheme, their contributions to the meson Bethe-Salpeter equation get cancelled within the whole set of contributing diagrams. We also argue that 0(1/N) corrections to the meson equation remove the massless boson from the spectrum in accordance with the Coleman theorem. (author)

QCD traveling waves beyond leading logarithms

International Nuclear Information System (INIS)

Peschanski, R.; Sapeta, S.

2006-01-01

We derive the asymptotic traveling-wave solutions of the nonlinear 1-dimensional Balitsky-Kovchegov QCD equation for rapidity evolution in momentum space, with 1-loop running coupling constant and equipped with the Balitsky-Kovchegov-Kuraev-Lipatov kernel at next-to-leading logarithmic accuracy, conveniently regularized by different resummation schemes. Traveling waves allow us to define ''universality classes'' of asymptotic solutions, i.e. independent of initial conditions and of the nonlinear damping. A dependence on the resummation scheme remains, which is analyzed in terms of geometric scaling properties

Large N lattice QCD and its extended strong-weak connection to the hypersphere

International Nuclear Information System (INIS)

Christensen, Alexander S.; Myers, Joyce C.; Pedersen, Peter D.

2014-01-01

We calculate an effective Polyakov line action of QCD at large N c and large N f from a combined lattice strong coupling and hopping expansion working to second order in both, where the order is defined by the number of windings in the Polyakov line. We compare with the action, truncated at the same order, of continuum QCD on S 1 ×S d at weak coupling from one loop perturbation theory, and find that a large N c correspondence of equations of motion found in http://dx.doi.org/10.1007/JHEP10(2012)067 at leading order, can be extended to the next order. Throughout the paper, we review the background necessary for computing higher order corrections to the lattice effective action, in order to make higher order comparisons more straightforward

NNLO QCD corrections to associated W H production and H →b b ¯ decay

Science.gov (United States)

Caola, Fabrizio; Luisoni, Gionata; Melnikov, Kirill; Röntsch, Raoul

2018-04-01

We present a computation of the next-to-next-to-leading-order (NNLO) QCD corrections to the production of a Higgs boson in association with a W boson at the LHC and the subsequent decay of the Higgs boson into a b b ¯ pair, treating the b quarks as massless. We consider various kinematic distributions and find significant corrections to observables that resolve the Higgs decay products. We also find that a cut on the transverse momentum of the W boson, important for experimental analyses, may have a significant impact on kinematic distributions and radiative corrections. We show that some of these effects can be adequately described by simulating QCD radiation in Higgs boson decays to b quarks using parton showers. We also describe contributions to Higgs decay to a b b ¯ pair that first appear at NNLO and that were not considered in previous fully differential computations. The calculation of NNLO QCD corrections to production and decay sub-processes is carried out within the nested soft-collinear subtraction scheme presented by some of us earlier this year. We demonstrate that this subtraction scheme performs very well, allowing a computation of the coefficient of the second-order QCD corrections at the level of a few per mill.

BFKL equation for the adjoint representation of the gauge group in the next-to-leading approximation at N=4 SUSY

Energy Technology Data Exchange (ETDEWEB)

Fadin, V.S. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Budker Nuclear Physics Institute, Novosibirsk (Russian Federation); Novosibirskij Gosudarstvennyj Univ., Novosibirsk (Russian Federation); Lipatov, L.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); St. Petersburg State Univ., Gatchina (Russian Federation)

2011-12-15

We calculate the eigenvalues of the next-to-leading kernel for the BFKL equation in the adjoint representation of the gauge group SU(N{sub c}) in the N=4 supersymmetric Yang-Mills model. These eigenvalues are used to obtain the high energy behavior of the remainder function for the 6-point scattering amplitude with the maximal helicity violation in the kinematical regions containing the Mandelstam cut contribution. The leading and next-to-leading singularities of the corresponding collinear anomalous dimension are calculated in all orders of perturbation theory. We compare our result with the known collinear limit and with the recently suggested ansatz for the remainder function in three loops and obtain the full agreement providing that the numerical parameters in this anzatz are chosen in an appropriate way.

TMD parton distributions based on three-body decay functions in NLL order of QCD

International Nuclear Information System (INIS)

Tanaka, Hidekazu

2015-01-01

Three-body decay functions in space-like parton branches are implemented to evaluate transverse-momentum-dependent (TMD) parton distribution functions in the next-to-leading logarithmic (NLL) order of quantum chromodynamics (QCD). Interference contributions due to the next-to-leading-order terms are taken into account for the evaluation of the transverse momenta in initial state parton radiations. Some properties of the decay functions are also examined. As an example, the calculated results are compared with those evaluated by an algorithm proposed in [M. A. Kimber, A. D. Martin, and M. G. Ryskin, Eur. Phys. J. C 12, 655 (2000)], [M. A. Kimber, A. D. Martin, and M. G. Ryskin, Phys. Rev. D 63, 11402 (2001)], [G. Watt, A. D. Martin, and M. G. Ryskin, Eur. Phys. J. C 31, 73 (2003)], and [A. D. Martin, M. G. Ryskin, and G. Watt, Eur. Phys. J. C 66, 167 (2010)], in which the TMD parton distributions are defined based on the k t -factorization method with angular ordering conditions due to interference effects

QCD predictions for weak neutral current structure functions

International Nuclear Information System (INIS)

Wu Jimin

1987-01-01

Employing the analytic expression (to the next leading order) for non-singlet component of structure function which the author got from QCD theory and putting recent experiment result of neutral current structure function at Q 2 = 11 (GeV/C) 2 as input, the QCD prediction for neutral current structure function of their scaling violation behaviours was given

QCD parton showers and NLO EW corrections to Drell-Yan

CERN Document Server

Richardson, P; Sapronov, A A; Seymour, M H; Skands, P Z

2012-01-01

We report on the implementation of an interface between the SANC generator framework for Drell-Yan hard processes, which includes next-to-leading order electroweak (NLO EW) corrections, and the Herwig++ and Pythia8 QCD parton shower Monte Carlos. A special aspect of this implementation is that the initial-state shower evolution in both shower generators has been augmented to handle the case of an incoming photon-in-a-proton, diagrams for which appear at the NLO EW level. The difference between shower algorithms leads to residual differences in the relative corrections of 2-3% in the p_T(mu) distributions at p_T(mu)>~50 GeV (where the NLO EW correction itself is of order 10%).

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

-to-two ratio and are promising candidates for future αs measurements. Furthermore, we present a detailed analysis of uncertainties related to parton distribution functions. The full color virtual matrix elements used in the computation were obtained with the NJet package [1], a publicly available library...

Heavy-quark production in gluon fusion at two loops in QCD

International Nuclear Information System (INIS)

Czakon, M.

2007-07-01

We present the two-loop virtual QCD corrections to the production of heavy quarks in gluon fusion. The results are exact in the limit when all kinematical invariants are large compared to the mass of the heavy quark up to terms suppressed by powers of the heavy-quark mass. Our derivation uses a simple relation between massless and massive QCD scattering amplitudes as well as a direct calculation of the massive amplitude at two loops. The results presented here together with those obtained previously for quark-quark scattering form important parts of the next-to-next-to-leading order QCD corrections to heavy-quark production in hadron-hadron collisions. (orig.)

NNLO time-like splitting functions in QCD

International Nuclear Information System (INIS)

Moch, S.; Vogt, A.

2008-07-01

We review the status of the calculation of the time-like splitting functions for the evolution of fragmentation functions to the next-to-next-to-leading order in perturbative QCD. By employing relations between space-like and time-like deep-inelastic processes, all quark-quark and the gluon-gluon time-like splitting functions have been obtained to three loops. The corresponding quantities for the quark-gluon and gluon-quark splitting at this order are presently still unknown except for their second Mellin moments. (orig.)

Second-order contributions to the structure functions in deep inelastic scattering III The singlet

CERN Document Server

González-Arroyo, A

1980-01-01

For pt.II see ibid., vol.159, p.512 (1979). Pointlike QCD predictions for the singlet part of the structure functions are given up to next- to-leading order of perturbation theory. This generalises the result obtained in pt.I (see ibid., vol.153, p.161, 1979) which deals with the non-singlet case. An interesting by-product is an exact and simple analytical expression for the anomalous dimension matrix to second non-trivial order in the QCD coupling constant. (18 refs).

Heavy flavor production in QCD

International Nuclear Information System (INIS)

Hoyer, P.

1989-01-01

In this paper a brief survey is given of the status of heavy quark hadroproduction in QCD. The next-to-leading order calculation allows an estimate of the theoretical uncertainties to be made. They are manageable for top, but considerable for charm. The data on charm continues to show an excess of events at large x F , compared to QCD expectations. This may be linked to the measured anomalous A-dependence of the cross section on nuclear targets, also present at large x F . QCD models for the diffractive production of heavy quarks remain to be tested experimentally

Matching of singly- and doubly-unresolved limits of tree-level QCD squared matrix elements

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Duca, Vittorio Del [Istituto Nazionale di Fisica Nucleare, Sez. di Torino, via P. Giuria, 1 - 10125 Torino (Italy)

2005-06-01

We describe how to disentangle the singly- and doubly-unresolved (soft and/or collinear) limits of tree-level QCD squared matrix elements. Using the factorization formulae presented in this paper, we outline a viable general subtraction scheme for computing next-to-next-to-leading order corrections for electron-positron annihilation into jets.

Precision tests of SM and pQCD with jets and photons at LHC

CERN Document Server

Sawyer, Lee; The ATLAS collaboration

2015-01-01

In this talk, I will present several aspects of jet and isolated photon production in pp collisions that have been measured by the ATLAS and CMS collaborations. The measurements of the production cross sections of inclusive jets, di-jet, tri-jet are presented double-differentially as function of jet pT and rapidity for the inclusive measurement and masses and the jet rapidity separation for the di- and tri-jet cases. They probe the dynamics of QCD and can constrain the parton structure of the proton. The cross sections are measured are compared to expectations based on next-to-leading order QCD calculations, as well as to next-to-leading order Monte Carlo simulations. A QCD analysis of these complementary data set is presented. Jet cross sections measurements of di-jet systems with a veto on additional jets, probe QCD radiation effects. The measurements of inclusive prompt photons and di-photons probe the dynamics of QCD and can constrain the parton proton structure. The inclusive prompt photon cross sections...

QCD leading order study of the J/ψ leptoproduction at HERA within the nonrelativistic QCD framework

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhan [Guizhou Minzu University, School of Science, Guiyang (China); Zhang, Hong-Fei [Third Military Medical University, Department of Physics, School of Biomedical Engineering, Chongqing (China)

2017-11-15

As indicated in our previous paper (Zhang and Sun in Phys. Rev. D 96:034002, 2017), the existing literature studying the J/ψ production in deeply inelastic scattering (DIS) in collinear factorisation is on the basis of a formalism that will lead to wrong results when the ranges of the transverse momentum or the rapidity of the J/ψ in the laboratory frame do not cover all values possible for them. In this paper, we present the renewed results for the J/ψ production in DIS at HERA within the nonrelativistic QCD framework at QCD leading order (LO). Three different sets of the long-distance matrix elements are employed for comparison. The predictions via the colour-singlet (CS) model at QCD LO are generally below the experimental data especially in the regions where perturbation theory are expected to work well, while the colour-octet contributions are of the same order of magnitude as the CS ones, however, in general make the agreement between theory and experiment better. (orig.)

Perturbative corrections to Λ_b→Λ form factors from QCD light-cone sum rules

International Nuclear Information System (INIS)

Wang, Yu-Ming; Shen, Yue-Long

2016-01-01

We compute radiative corrections to Λ_b→Λ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with Λ_b-baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-Λ_b-baryon correlation function is justified at leading power in Λ/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 O(α_s) shift the Λ_b→Λ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the Λ_b→Λ from factors we further investigate several decay observables in the electro-weak penguin Λ_b→Λ ℓ"+ℓ"− transitions in the factorization limit (i.e., ignoring the “non-factorizable' hadronic effects which cannot be expressed in terms of the Λ_b→Λ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

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

Energy Technology Data Exchange (ETDEWEB)

Florian, Daniel de [International Center for Advanced Studies (ICAS), ECyT-UNSAM, Campus Miguelete, 25 de Mayo y Francia (1650) Buenos Aires (Argentina); Mazzitelli, Javier [International Center for Advanced Studies (ICAS), ECyT-UNSAM, Campus Miguelete, 25 de Mayo y Francia (1650) Buenos Aires (Argentina); Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)

2017-02-22

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.

On γ5 in higher-order QCD calculations and the NNLO evolution of the polarized valence distribution

International Nuclear Information System (INIS)

Moch, S.; Vogt, A.

2015-06-01

We discuss the prescription for the Dirac matrix γ 5 in dimensional regularization used in most second- and third-order QCD calculations of collider cross sections. We provide an alternative implementation of this approach that avoids the use of an explicit form of γ 5 and of its (anti-) commutation relations in the most important case of no more than one γ 5 in each fermion trace. This treatment is checked by computing the third-order corrections to the structure functions F 2 and g 1 in charged-current deep-inelastic scattering with axial-vector couplings to the W-bosons. We derive the so far unknown third-order helicity-difference splitting function ΔP ns (2)s that contributes to the next-to-next-to-leading order (NNLO) evolution of the polarized valence quark distribution of the nucleon. This function is negligible at momentum fractions x>or similar 0.3 but relevant at x<<1.

QCDNUM: Fast QCD evolution and convolution

Science.gov (United States)

Botje, M.

2011-02-01

The QCDNUM program numerically solves the evolution equations for parton densities and fragmentation functions in perturbative QCD. Un-polarised parton densities can be evolved up to next-to-next-to-leading order in powers of the strong coupling constant, while polarised densities or fragmentation functions can be evolved up to next-to-leading order. Other types of evolution can be accessed by feeding alternative sets of evolution kernels into the program. A versatile convolution engine provides tools to compute parton luminosities, cross-sections in hadron-hadron scattering, and deep inelastic structure functions in the zero-mass scheme or in generalised mass schemes. Input to these calculations are either the QCDNUM evolved densities, or those read in from an external parton density repository. Included in the software distribution are packages to calculate zero-mass structure functions in un-polarised deep inelastic scattering, and heavy flavour contributions to these structure functions in the fixed flavour number scheme. Program summaryProgram title: QCDNUM version: 17.00 Catalogue identifier: AEHV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU Public Licence No. of lines in distributed program, including test data, etc.: 45 736 No. of bytes in distributed program, including test data, etc.: 911 569 Distribution format: tar.gz Programming language: Fortran-77 Computer: All Operating system: All RAM: Typically 3 Mbytes Classification: 11.5 Nature of problem: Evolution of the strong coupling constant and parton densities, up to next-to-next-to-leading order in perturbative QCD. Computation of observable quantities by Mellin convolution of the evolved densities with partonic cross-sections. Solution method: Parametrisation of the parton densities as linear or quadratic splines on a discrete grid, and evolution of the spline

The heavy quarkonium spectrum at order $m\\alpha_{s}^{5}\\ln\\alpha_{s}$

CERN Document Server

Brambilla, Nora; Soto, Joan; Vairo, Antonio

1999-01-01

We compute the complete leading-log terms of the next-to-next-to-next-to-leading-order corrections to potential NRQCD. As a by-product we obtain the leading logs at $O(m\\alpha_s^5)$ in the heavy quarkonium spectrum. These leading logs, when $\\Lambda_{QCD} \\ll m\\alpha_s^2$, give the complete $O(m\\alpha_s^5 \\ln \\alpha_s)$ corrections to the heavy quarkonium spectrum.

The electric dipole moment of the deuteron from the QCD {theta}-term

Energy Technology Data Exchange (ETDEWEB)

Bsaisou, J.; Liebig, S. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Hanhart, C.; Nogga, A.; Wirzba, A. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Forschungszentrum Juelich, JARA - Forces And Matter Experiments, Juelich (Germany); Meissner, U.G. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Forschungszentrum Juelich, JARA - Forces And Matter Experiments, Juelich (Germany); Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Universitaet Bonn, Bethe Center for Theoretical Physics, Bonn (Germany)

2013-03-15

The two-nucleon contributions to the electric dipole moment (EDM) of the deuteron, induced by the QCD {theta}-term, are calculated in the framework of effective field theory up-to-and-including next-to-next-to-leading order. In particular we find for the difference of the deuteron EDM and the sum of proton and neutron EDM induced by the QCD {theta}-term a value of (- 5.4 {+-}3.9) anti {theta} x 10{sup -} {sup 4} e fm. The by far dominant uncertainty comes from the CP- and isospin-violating {pi}NN coupling constant. (orig.)

Higher order light-cone distribution amplitudes of the Lambda baryon

International Nuclear Information System (INIS)

Liu, Yong-Lu; Huang, Ming-Qiu; Cui, Chun-Yu

2014-01-01

The improved light-cone distribution amplitudes (LCDAs) of the Λ baryon are examined on the basis of the QCD conformal partial wave expansion approach. The calculations are carried out to the next-to-leading order of conformal spin accuracy with consideration of twist 6. The next leading order conformal expansion coefficients are related to the nonperturbative parameters defined by the local three-quark operator matrix elements with different Lorentz structures with a covariant derivative. The nonperturbative parameters are determined with the QCD sum rule method. The explicit expressions of the LCDAs are provided as the main results. (orig.)

Higher order light-cone distribution amplitudes of the Lambda baryon

Energy Technology Data Exchange (ETDEWEB)

Liu, Yong-Lu; Huang, Ming-Qiu [National University of Defense Technology, College of Science, Hunan (China); Cui, Chun-Yu [Third Military Medical University, Department of Physics, School of Biomedical Engineering, Chongqing (China)

2014-09-15

The improved light-cone distribution amplitudes (LCDAs) of the Λ baryon are examined on the basis of the QCD conformal partial wave expansion approach. The calculations are carried out to the next-to-leading order of conformal spin accuracy with consideration of twist 6. The next leading order conformal expansion coefficients are related to the nonperturbative parameters defined by the local three-quark operator matrix elements with different Lorentz structures with a covariant derivative. The nonperturbative parameters are determined with the QCD sum rule method. The explicit expressions of the LCDAs are provided as the main results. (orig.)

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.

An approach to next step device optimisation

International Nuclear Information System (INIS)

Salpietro, E.

2000-01-01

The requirements for ITER EDA were to achieve ignition with a good safety margin, and controlled long inductive burn. These requirements lead to a big device, which requested a too ambitious step to be undertaken by the world fusion community. More realistic objectives for a next step device shall be to demonstrate the net production of energy with a high energy gain factor (Q) and a high boot strap current fraction (>60%) which is required for a Fusion Power Plant (FPP). The Next Step Device (NSD) shall also allow operation flexibility in order to explore a large range of plasma parameters to find out the optimum concept for the fusion power plant prototype. These requirements could be too demanding for one single device and could probably be better explored in a strongly integrated world programme. The cost of one or more devices is the decisive factor for the choice of the fusion power development programme strategy. The plasma elongation and triangularity have a strong impact in the cost of the device and are limited by the plasma vertical position control issue. The distance between plasma separatrix and the toroidal field conductor does not vary a lot between devices. It is determined by the sum of the distance between first wall-plasma sepratrix and the thickness of the nuclear shield required to protect the toroidal field coil insultation. The thickness of the TF coil is determined by the allowable stresses and superconducting characteristics. The outer radius of the central solenoid is the result of an optimisation to provide the magnetic flux to inductively drive the plasma. Therefore, in order to achieve the objectives for Q and boot-strap current fractions at the minimum cost, the plasma aspect ratio and magnetic field value shall be determined. The paper will present the critical issues for the next device and will make considerations on the optimal way to proceed towards the realisation of the fusion power plant

On a residual freedom of the next-to-leading BFKL eigenvalue in color adjoint representation in planar N=4 SYM

Energy Technology Data Exchange (ETDEWEB)

Bondarenko, Sergey; Prygarin, Alex [Physics Department, Ariel University,Ariel 40700, territories administered by (Israel)

2016-07-15

We discuss a residual freedom of the next-to-leading BFKL eigenvalue that originates from ambiguity in redistributing the next-to-leading (NLO) corrections between the adjoint BFKL eigenvalue and eigenfunctions in planar N=4 super-Yang-Mills (SYM) Theory. In terms of the remainder function of the Bern-Dixon-Smirnov (BDS) amplitude this freedom is translated to reshuffling correction between the eigenvalue and the impact factors in the multi-Regge kinematics (MRK) in the next-to-leading logarithm approximation (NLA). We show that the modified NLO BFKL eigenvalue suggested by the authors in ref. http://arxiv.org/abs/1510.00589 can be introduced in the MRK expression for the remainder function by shifting the anomalous dimension in the impact factor in such a way that the two and three loop remainder function is left unchanged to the NLA accuracy.

Wong's equations and the small x effective action in QCD

International Nuclear Information System (INIS)

Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju

2001-01-01

We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong's equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the action may be particularly useful in computing next-to-leading-order results in QCD at small x

Wong's equations and the small x effective action in QCD

International Nuclear Information System (INIS)

Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju

2000-01-01

We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong's equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the action may be particularly useful in computing next-to-leading-order results in QCD at small x

Electroweak Higgs plus three jet production at NLO QCD

International Nuclear Information System (INIS)

Campanario, Francisco; Figy, Terrance M.; Plaetzer, Simon; Sjoedahl, Malin

2013-11-01

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.

Analytic integration of real-virtual counterterms in NNLO jet cross sections II

Energy Technology Data Exchange (ETDEWEB)

Bolzoni, Paolo; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Somogyi, Gabor [Zurich Univ. (Switzerland). Inst. fuer Theoretische Physik; Trocsanyi, Zoltan [Debrecen Univ. (Hungary); Hungarian Academy of Sciences, Debrecen (Hungary). Inst. of Nuclear Research

2009-05-15

We present analytic expressions of all integrals required to complete the explicit evaluation of the real-virtual integrated counterterms needed to define a recently proposed subtraction scheme for jet cross sections at next-to-next-to-leading order in QCD. We use the Mellin-Barnes representation of these integrals in 4-2{epsilon} dimensions to obtain the coefficients of their Laurent expansions around {epsilon}=0. These coefficients are given by linear combinations of multidimensional Mellin-Barnes integrals. We compute the coefficients of such expansions in {epsilon} both numerically and analytically by complex integration over the Mellin-Barnes contours. (orig.)

Analytic integration of real-virtual counterterms in NNLO jet cross sections II

International Nuclear Information System (INIS)

Bolzoni, Paolo; Moch, Sven-Olaf; Somogyi, Gabor; Trocsanyi, Zoltan

2009-01-01

We present analytic expressions of all integrals required to complete the explicit evaluation of the real-virtual integrated counterterms needed to define a recently proposed subtraction scheme for jet cross sections at next-to-next-to-leading order in QCD. We use the Mellin-Barnes representation of these integrals in 4 - 2ε dimensions to obtain the coefficients of their Laurent expansions around ε = 0. These coefficients are given by linear combinations of multidimensional Mellin-Barnes integrals. We compute the coefficients of such expansions in ε both numerically and analytically by complex integration over the Mellin-Barnes contours.

Analytic integration of real-virtual counterterms in NNLO jet cross sections II

Science.gov (United States)

Bolzoni, Paolo; Moch, Sven-Olaf; Somogyi, Gábor; Trócsányi, Zoltán

2009-08-01

We present analytic expressions of all integrals required to complete the explicit evaluation of the real-virtual integrated counterterms needed to define a recently proposed subtraction scheme for jet cross sections at next-to-next-to-leading order in QCD. We use the Mellin-Barnes representation of these integrals in 4 - 2epsilon dimensions to obtain the coefficients of their Laurent expansions around epsilon = 0. These coefficients are given by linear combinations of multidimensional Mellin-Barnes integrals. We compute the coefficients of such expansions in epsilon both numerically and analytically by complex integration over the Mellin-Barnes contours.

Analytic integration of real-virtual counterterms in NNLO jet cross sections II

International Nuclear Information System (INIS)

Bolzoni, Paolo; Moch, Sven-Olaf; Somogyi, Gabor; Trocsanyi, Zoltan; Hungarian Academy of Sciences, Debrecen

2009-05-01

We present analytic expressions of all integrals required to complete the explicit evaluation of the real-virtual integrated counterterms needed to define a recently proposed subtraction scheme for jet cross sections at next-to-next-to-leading order in QCD. We use the Mellin-Barnes representation of these integrals in 4-2ε dimensions to obtain the coefficients of their Laurent expansions around ε=0. These coefficients are given by linear combinations of multidimensional Mellin-Barnes integrals. We compute the coefficients of such expansions in ε both numerically and analytically by complex integration over the Mellin-Barnes contours. (orig.)

The angular ordering in soft-gluon emission

International Nuclear Information System (INIS)

Tesima, K.

1987-01-01

The way to evaluate multi-parton cross-sections systematically is discussed. In the leading-double-log approximation in QCD, the successive emission of soft gluons is at successively smaller angles. The angular ordering, however, is violated in the next-to-leading order

Next generation light water reactors

International Nuclear Information System (INIS)

Omoto, Akira

1992-01-01

In the countries where the new order of nuclear reactors has ceased, the development of the light water reactors of new type has been discussed, aiming at the revival of nuclear power. Also in Japan, since it is expected that light water reactors continue to be the main power reactor for long period, the technology of light water reactors of next generation has been discussed. For the development of nuclear power, extremely long lead time is required. The light water reactors of next generation now in consideration will continue to be operated till the middle of the next century, therefore, they must take in advance sufficiently the needs of the age. The improvement of the way men and the facilities should be, the simple design, the flexibility to the trend of fuel cycle and so on are required for the light water reactors of next generation. The trend of the development of next generation light water reactors is discussed. The construction of an ABWR was started in September, 1991, as No. 6 plant in Kashiwazaki Kariwa Power Station. (K.I.)

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.)

NNLO QCD analysis of CCFR data on xF3 structure function and Gross-Llewellyn Smith sum rule with higher twist and nuclear corrections

International Nuclear Information System (INIS)

Sidorov, A.V.; Tokarev, M.V.

1997-01-01

A detailed NNLO QCD analysis of new CCFR data on xF 3 structure function including the target mass, higher twist and nuclear corrections was performed and parametrizations of the perturbative and power terms of the structure function were constructed. The results of QCD analysis of the structure function were used to study the Q 2 -dependence of the Gross-Llewellyn Smith sum rule. The α S /π-expansion of S GLS (Q 2 ) was studied and parameters of the expansion were found to be s 1 =2.74±0.01, s 2 =-2.22±0.23, s 3 =-7.86±1.74 which are in good agreement with the perturbative QCD predictions for the Gross-Llewellyn Smith sum rule in the next-to-leading and next-to-next-to-leading order

Higgs production via vector-boson fusion at NNLO in QCD

International Nuclear Information System (INIS)

Bolzoni, Paolo; Moch, Sven-Olaf; Maltoni, Fabio; Zaro, Marco

2010-03-01

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.)

Measurement of Dijet Cross Sections in ep Interactions with a Leading Neutron at HERA

CERN Document Server

Aktas, A.; Anthonis, T.; Aplin, S.; Asmone, A.; Babaev, A.; Backovic, S.; Bahr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Chekelian, V.; Contreras, J.G.; Coughlan, J.A.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, W.; Essenov, S.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flucke, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Frising, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grindhammer, Guenter; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R.C.W.; Henschel, H.; Henshaw, O.; Herrera, G.; Herynek, I.; Heuer, R.-D.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, H.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Koutouev, R.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kuckens, J.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebedev, A.; Leiner, B.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Luke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxeld, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Poschl, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauvan, E.; Schatzel, S.; Scheins, J.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schroder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, Marcel; Usik, A.; Utkin, D.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Winter, G.-G.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zimmermann, J.; Zohrabyan, H.; Zomer, F.

2005-01-01

Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and deep inelastic scattering are presented as a function of several kinematic variables. Leading order QCD simulation programs are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are able to describe the data. Next-to-leading order perturbative QCD calculations based on pion exchange are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined. The dijet events with a leading neutron have a lower fraction of resolved photon processes than do the inclusive dijet data.

Next-to-next-to-leading order calculation of the strong coupling ...

Indian Academy of Sciences (India)

Pramana – J. Phys., Vol. 81, No. ... of the higher moments of the different shape variable is similar to what was observed for the first moments. Although ... Figure 1. First moment of four event-shape variables: (a) 1 − T, (b) ρ, (c) BT,. (d) Bw. 3.

Higher order constraints on the Higgs production rate from fixed-target DIS data

International Nuclear Information System (INIS)

Alekhin, S.; Bluemlein, J.; Moch, S.

2011-01-01

The constraints of fixed-target DIS data in fits of parton distributions including QCD corrections to next-to-next-to leading order are studied. We point out a potential problem in the analysis of the NMC data which can lead to inconsistencies in the extracted value for α s (M Z ) and the gluon distribution at higher orders in QCD. The implications for predictions of rates for Standard Model Higgs boson production at hadron colliders are investigated. We conclude that the current range of excluded Higgs boson masses at the Tevatron appears to be much too large. (orig.)

The α3S corrections to the Bjorken sum rule for polarized electro-production and to the Gross-Llewellyn Smith sum rule

International Nuclear Information System (INIS)

Larin, S.A.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica; Vermaseren, J.A.M.

1990-01-01

The next-next-to-leading order QCD corrections to the Gross-Llewellyn Smith sum rule for deep inelastic neutrino-nucleon scattering and to the Bjorken sum rule for polarized electron-nucleon scattering have been computed. This involved the proper treatment of γ 5 inside the loop integrals with dimensional regularization. It is found that the difference between the two sum rules are entirely due to a class of 6 three loop graphs and is of the order of 1% of the leading QCD term. Hence the Q 2 behavior of both sum rules should be the same if the physics is described adequately by the lower order terms of perturbative QCD. (author). 12 refs.; 2 figs.; 4 tabs

Electron-Ion Collider: The next QCD frontier. Understanding the glue that binds us all

Energy Technology Data Exchange (ETDEWEB)

Accardi, A. [Hampton University, Hampton, VA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Albacete, J.L. [Universite Paris-Sud 11, CNRS/IN2P3, IPNO, Orsay (France); Anselmino, M. [Torino University (Italy); INFN, Torino (Italy); Armesto, N. [University of Santiago de Campostela, Santiago de Compostela (Spain); Aschenauer, E.C.; Burton, T.; Fazio, S.; Hao, Y.; Lamont, M.A.C.; Lee, J.H.; Lee, Y.; Litvinenko, V.; Ludlam, T.W.; Ptitsyn, V.; Qiu, J.W.; Roser, T.; Toll, T.; Trbojevic, D.; Ullrich, T.; Venugopalan, R.; Vigdor, S. [Brookhaven National Laboratory, Upton, NY (United States); Bacchetta, A. [University of Pavia, Pavia (Italy); Boer, D. [University of Groningen, Groningen (Netherlands); Brooks, W.K.; Hakobyan, H.; Kopeliovich, B. [Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Chang, N.B.; Huang, M. [Shandong University, Shandong (China); Deng, W.T. [Frankfurt University, FIAS, Frankfurt (Germany); Shandong University, Shandong (China); Deshpande, A.; Kumar, K. [Stony Brook University, Stony Brook, NY (United States); Diehl, M. [DESY, Hamburg (Germany); Dumitru, A.; Jalilian-Marian, J. [Baruch College, CUNY, New York, NY (United States); Dupre, R.; Sabatie, F. [Centre de Saclay, CEA, Gif-sur-Yvette (France); Ent, R.; Guzey, V.; Hutton, A.; Lin, F.L.; McKeown, R.; Morozov, V.S.; Nadel-Turonski, P.; Prokudin, A.; Weiss, C.; Zhang, Y.H. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Gao, H. [Duke University, Durham, NC (United States); Hasch, D. [INFN, LNF, Frascati (Italy); Holt, R. [Argonne National Laboratory, Argonne, IL (United States); Horn, T. [The Catholic University of America, N.E. Washington, DC (United States); Hyde, C. [Old Dominion University, Norfolk, VA (United States); Klein, S.; Sichtermann, E.; Yuan, F. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Kovchegov, Y. [The Ohio State University, Columbus, OH (United States); Kumericki, K. [University of Zagreb, Zagreb (Croatia); Lappi, T.; Paukkunen, H. [University of Jyvaskyla, Jyvaskyla (Finland); Levin, E.M. [Tel Aviv University, Tel Aviv (Israel); Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Marquet, C. [CERN, Geneva (Switzerland); Meziani, Z.E.; Metz, A. [Temple University, Philadelphia, PA (United States); Milner, R. [Massachusetts Institute of Technology, Cambridge, MA (United States); Mueller, A.H. [Columbia University, New York, NY (US); Mueller, B. [Brookhaven National Laboratory, Upton, NY (US); Duke University, Durham, NC (US); Mueller, D. [Ruhr-University Bochum, Bochum (DE); Qian, X. [California Institute of Technology, Pasadena, CA (US); Ramsey-Musolf, M. [University of Massachusetts at Amherst, Amherst, MA (US); Sassot, R. [University of Buenos Aires, Buenos Aires (AR); Schnell, G. [University of Basque Country, Bilbao (ES); Schweitzer, P. [University of Connecticut, Storrs, CT (US); Stratmann, M.; Vogelsang, W. [University of Tuebingen, Tuebingen (DE); Strikman, M. [Pennsylvania State University, Philadelphia, PA (US); Sullivan, M. [Stanford Linear Accelerator Center, Menlo Park, CA (US); Taneja, S. [Dalhousie University, Halifax, Nova Scotia (CA); Stony Brook University, Stony Brook, NY (US); Xiao, B.W. [Central China Normal University, Wuhan, Hubei (CN); Zheng, L. [Brookhaven National Laboratory, Upton, NY (US); Central China Normal University, Wuhan, Hubei (CN)

2016-09-15

This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on ''Gluons and quark sea at high energies'' at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users' communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier. (orig.)

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

International Nuclear Information System (INIS)

Zaro, Marco; Maltoni, Fabio

2010-12-01

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.)

Measurement of the transverse momentum distribution of $\\rm{W}$ bosons in $\\rm{pp}$ collisions at $\\sqrt{s}$ = 8 TeV

CERN Document Server

CMS Collaboration

2014-01-01

of $18.4~\\pm0.5~\\rm{pb^{-1}}$. The measured cross section is compared to three theoretical predictions: (1) ResBos, a next-to-next-to-leading logarithmic/next-to-leading-order quantum chromodynamics (QCD) calculation with resummation, (2) $\\rm{POWHEG}$, a next-to-leading-order QCD calculation, and (3) FEWZ, a next-to-next-to-leading-order QCD calculation. The predictions of all three calculations are in agreement with the experimental measurement within uncertainties, but can deviate from the data in some regions by up to 20$\\%$.

apeNEXT A Multi-Tflops LQCD Computing Project

CERN Document Server

Alfieri, R; Onofri, E.; Bartoloni, A.; Battista, C.; Cabibbo, N.; Cosimi, M.; Lonardo, A.; Michelotti, A.; Rapuano, F.; Proietti, B.; Rossetti, D.; Sacco, G.; Tassa, S.; Torelli, M.; Vicini, P.; Boucaud, Philippe; Pene, O.; Errico, W.; Magazzu, G.; Sartori, L.; Schifano, F.; Tripiccione, R.; De Riso, P.; Petronzio, R.; Destri, C.; Frezzotti, R.; Marchesini, G.; Gensch, U.; Kretzschmann, A.; Leich, H.; Paschedag, N.; Schwendicke, U.; Simma, H.; Sommer, R.; Sulanke, K.; Wegner, P.; Pleiter, D.; Jansen, K.; Fucci, A.; Martin, B.; Pech, J.; Panizzi, E.; Petricola, A.

2001-01-01

This paper is a slightly modified and reduced version of the proposal of the {\\bf apeNEXT} project, which was submitted to DESY and INFN in spring 2000. .It presents the basic motivations and ideas of a next generation lattice QCD (LQCD) computing project, whose goal is the construction and operation of several large scale Multi-TFlops LQCD engines, providing an integrated peak performance of tens of TFlops, and a sustained (double precision) performance on key LQCD kernels of about 50% of peak speed.

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.)

A QCD analysis of ZEUS diffractive data

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-11-01

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.)

Tests of α{sub s} running from QCD fits to collider data

Energy Technology Data Exchange (ETDEWEB)

Kuprash, Oleg; Geiser, Achim [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Hamburg University, Institute of Experimental Physics, Hamburg (Germany)

2015-07-01

The running of the strong coupling constant, α{sub s}(μ), is tested in a QCD analysis using jet measurements at LHC, Tevatron and HERA in combination with inclusive DIS data. Here μ is associated with the energy scale in the process, typically with the jet transverse energy. For the α{sub s} running test, the parameter n{sub f} of the running, which gives the number of active quarks contributing to loop corrections of the jet and DIS cross sections, is replaced by n{sub f} + Δn{sub f} at energy scales greater than μ > μ{sub thresh}. A series of simultaneous α{sub s}(M{sub Z}) + Δn{sub f} + proton PDF fits to world collider cross section data is done at Next-to-Leading Order QCD, for μ{sub thresh} values ranging from 1 GeV to 1 TeV. The fitted Δn{sub f} is consistent with zero at all tested scales, which gives a precise quantitative confirmation of the QCD running of α{sub s} over 3 orders of magnitude in energy scale. The presented study also provides a new way for indirect searches of the physics beyond the Standard Model.

MS-on-shell quark mass relation up to four loops in QCD and a general SU(N) gauge group

International Nuclear Information System (INIS)

Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias; Wellmann, David

2016-06-01

In this paper we compute the relation between heavy quark masses defined in the modified minimal subtraction and on-shell scheme. Detailed results are presented for all coefficients of the SU(N_c) colour factors. The reduction of the four-loop on-shell integrals is performed for a general QCD gauge parameter. Some of the about 380 master integrals are computed analytically, others with high numerical precision based on Mellin-Barnes representations, and the rest numerically with the help of FIESTA. We discuss in detail the precise numerical evaluation of the four-loop master integrals. Updated relations between various short-distance masses and the MS quark mass to next-to-next-to-next-to-leading order accuracy are provided for the charm, bottom and top quark. We discuss the dependence on the renormalization and factorization scale.

A general algorithm for calculating jet cross sections in NLO QCD

CERN Document Server

Catani, S.; Catani, Stefano; Seymour, Michael H

1997-01-01

We present a new general algorithm for calculating arbitrary jet cross sections in arbitrary scattering processes to next-to-leading accuracy in perturbative QCD. The algorithm is based on the subtraction method. The key ingredients are new factorization formulae, called dipole formulae, which implement in a Lorentz covariant way both the usual soft and collinear approximations, smoothly interpolating the two. The corresponding dipole phase space obeys exact factorization, so that the dipole contributions to the cross section can be exactly integrated analytically over the whole of phase space. We obtain explicit analytic results for any jet observable in any scattering or fragmentation process in lepton, lepton-hadron or hadron-hadron collisions. All the analytical formulae necessary to construct a numerical program for next-to-leading order QCD calculations are provided. The algorithm is straightforwardly implementable in general purpose Monte Carlo programs.

Reducing cutoff effects in maximally twisted lattice QCD close to the chiral limit

International Nuclear Information System (INIS)

Frezzotti, R.; Papinutto, M.; Rossi, G.C.; Istituto Nazionale di Fisica Nucleare, Rome; Deutsches Elektronen-Synchrotron

2005-03-01

When analyzed in terms of the Symanzik expansion, the expectation values of multi-local (gauge-invariant) operators with non-trivial continuum limit exhibit in maximally twisted lattice QCD ''infrared divergent'' cutoff effects of the type a 2k /(m π 2 ) h , 2k ≥ h ≥ 1, which become numerically dangerous when the pion mass gets small. We prove that, if the critical mass counter-term is chosen in some ''optimal'' way or, alternatively, the action is O(a) improved a la Symanzik, the leading cutoff effects of this kind (i.e. those with h = 2k) can all be eliminated. Once this is done, the remaining next-to-leading ''infrared divergent'' effects are only of the kind a 2 (a 2 /m π 2 ) k , k ≥ 1. This implies that the continuum extrapolation of lattice results is smooth at least down to values of the quark mass, m q , satisfying the order of magnitude inequality m q > a 2 Λ QCD 3 . (orig.)

Next-to-next-to-leading order calculation of the strong coupling ...

Indian Academy of Sciences (India)

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 ...

Wong's equations and the small x effective action in QCD

Energy Technology Data Exchange (ETDEWEB)

Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju

2000-07-13

We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong's equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the action may be particularly useful in computing next-to-leading-order results in QCD at small x.

First Demonstration of Real-Time End-to-End 40 Gb/s PAM-4 System using 10-G Transmitter for Next Generation Access Applications

DEFF Research Database (Denmark)

Wei, Jinlong; Eiselt, Nicklas; Griesser, Helmut

We demonstrate the first known experiment of a real-time end-to-end 40-Gb/s PAM-4 system for next generation access applications using 10G class transmitters only. Up to 25-dB upstream link budget for 20 km SMF is achieved.......We demonstrate the first known experiment of a real-time end-to-end 40-Gb/s PAM-4 system for next generation access applications using 10G class transmitters only. Up to 25-dB upstream link budget for 20 km SMF is achieved....

Extra dimension searches at hadron colliders to next-to-leading ...

Indian Academy of Sciences (India)

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 ...

When semantics turns to substance: reformulating QCD analysis of F2{γ}(x,Q2)}

International Nuclear Information System (INIS)

Chyla, J.

2000-01-01

QCD analysis of F 2 {γ} (x,Q 2 ) is revisited. It is emphasized that the presence of the inhomogeneous term in the evolution equations for quark distribution functions of the photon implies important difference in the way factorization mechanism works in photon-hadron and photon-photon collisions as compared to the hadronic ones. Moreover, a careful definitions of the very concepts of the ''leading order'' and ''next-to-leading order'' QCD analysis of F 2 {γ} are needed in order to separate genuine QCD effects from those of pure QED origin. After presenting such definitions, I show that all existing allegedly LO, as well as NLO analyses of F 2 {γ} (x,Q 2 ) are incomplete. The source of this incompleteness of the conventional approach is traced back to the lack of clear identification of QCD effects and to the misinterpretation of the behaviour of q {γ} (x,M) as a function of /α s (M). Complete LO and NLO QCD analyses of F 2 {γ} (x,Q 2 ) are shown to differ substantially from the conventional ones. Whereas complete NLO analysis requires the knowledge of two so far uncalculated quantities, a complete LO one is currently possible, but compared to the conventional formulation requires the inclusion of four known, but in the existing LO analyses unused quantities. The arguments recently advanced in favour of the conventional approach are analyzed and shown to contain a serious flaw. If corrected, they actually lend support to my claim. (author)

High energy QCD at NLO: from light-cone wave function to JIMWLK evolution

Energy Technology Data Exchange (ETDEWEB)

Lublinsky, Michael [Department of Physics, Ben-Gurion University of the Negev,Beer-Sheva 84105 (Israel); Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269-3046 (United States); Mulian, Yair [Department of Physics, Ben-Gurion University of the Negev,Beer-Sheva 84105 (Israel)

2017-05-17

Soft components of the light cone wave-function of a fast moving projectile hadron is computed in perturbation theory to the 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.

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.)

Scrutinizing the top quark at lepton colliders with higher orders. From fixed order to resummation and matching

International Nuclear Information System (INIS)

Nejad, Bijan Chokoufe

2017-01-01

In this thesis, we present detailed studies of top-pair production with (t anti tH) and without association of a Higgs boson (t anti t) in e"+e"- collisions. These processes are of utmost interest for the top physics program of future lepton colliders. They allow in particular a precise measurement of the top quark mass and the Yukawa coupling. For this purpose, we present predictions for off-shell t anti t and t anti tH production including non-resonant and interference contributions up to next-to-leading order (NLO) in perturbative quantum chromodynamics (QCD). This allows for top-quark phenomenology in the continuum at an unprecedented level of accuracy. We show that off-shell effects and NLO QCD corrections for these processes do not factorize in general. In particular, we present the Yukawa coupling dependence of the cross section, which receives negative corrections due to sizable interference terms. We also add a discussion of p_T resummation in the form of combining the NLO prediction via POWHEG matching with the parton shower and the associated uncertainties. To handle large Coulomb singularities at threshold, we include the next-to-leading log (NLL) threshold resummation derived in nonrelativistic QCD (NRQCD) for t anti t production. This results in a form factor that we incorporate in a fully relativistic cross section, which is factorized within an extended double-pole approximation. Fixed-order QCD corrections are included, hereby, for the top decay. We combine this calculation with the full fixed-order QCD results at NLO for W"+W"-b anti b production to obtain a computation that is not only valid at threshold but smoothly interpolates to the continuum. This allows us to present the first prediction for exclusive W"+W"-b anti b production at a lepton collider with a consistent matching between the top-antitop threshold and continuum regions. This computation is not only required to describe the intermediate energy region but also allows to study

Perturbative corrections to Λ{sub b}→Λ form factors from QCD light-cone sum rules

Energy Technology Data Exchange (ETDEWEB)

Wang, Yu-Ming [Fakultät für Physik, Universität Wien,Boltzmanngasse 5, 1090 Vienna (Austria); Physik Department T31, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany); Shen, Yue-Long [College of Information Science and Engineering, Ocean University of China,Songling Road 238, Qingdao, Shandong 266100 (China)

2016-02-29

We compute radiative corrections to Λ{sub b}→Λ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with Λ{sub b}-baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-Λ{sub b}-baryon correlation function is justified at leading power in Λ/m{sub 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 O(α{sub s}) shift the Λ{sub b}→Λ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the Λ{sub b}→Λ from factors we further investigate several decay observables in the electro-weak penguin Λ{sub b}→Λ ℓ{sup +}ℓ{sup −} transitions in the factorization limit (i.e., ignoring the “non-factorizable' hadronic effects which cannot be expressed in terms of the Λ{sub b}→Λ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

Determination of the strong coupling constant αs(MZ2) under regardment of completely resummed leading and next-to-leading logarithms. Analysis of global event variables measured in hadronic Z decays

International Nuclear Information System (INIS)

Wehr, A.

1994-06-01

The value of the strong coupling constant α s is determined from a combined analysis of the global event shape variables thrust, heavy jet mass and total and wide jet broadening. The extraction of α s includes the full calculation of O(α s 2 ) terms and leading and next-to-leading logarithms resummed to all orders of α s . The analysis is based on data taken with the DELPHI detector at LEP during 1991 and 1992. The dependence of the result on the detailed matching of the resummed and fixed order terms is studied. The result from the combined theory is compared with values coming from a pure NLLA analysis and as pure O(α s 2 ) analysis, respectively. It is found that the inclusion of the resummed logarithms allows the description of the data in the two jet range and reduces the scale dependence of α s (M Z 2 ) compared to pure O(α s 2 ) theory. The value using the combined NLLA+O(α s 2 ) theory at the scale μ 2 =M Z 2 is α S (M Z 2 )=0.118±0.007. The running of α s is measured from the 1991 data in an energy range from 88.5 to 93.7 GeV. The slope of α s obtained at the Z peak is dα s /dQ/ Q=Mz =-(2.9±2.8)x10 -4 GeV -1 . This value is compatible with QCD and exludes an abelian gluon model with more than two standard deviations. (orig.)

NextGEOSS: The Next Generation Data Hub For Earth Observations

Science.gov (United States)

Lilja Bye, Bente; De Lathouwer, Bart; Catarino, Nuno; Concalves, Pedro; Trijssenaar, Nicky; Grosso, Nuno; Meyer-Arnek, Julian; Goor, Erwin

2017-04-01

The Group on Earth observation embarked on the next 10 year phase with an ambition to streamline and further develop its achievements in building the Global Earth Observing System of Systems (GEOSS). The NextGEOSS project evolves the European vision of GEOSS data exploitation for innovation and business, relying on the three main pillars of engaging communities, delivering technological developments and advocating the use of GEOSS, in order to support the creation and deployment of Earth observation based innovative research activities and commercial services. In this presentation we will present the NextGEOSS concept, a concept that revolves around providing the data and resources to the users communities, together with Cloud resources, seamlessly connected to provide an integrated ecosystem for supporting applications. A central component of NextGEOSS is the strong emphasis put on engaging the communities of providers and users, and bridging the space in between.

NNLO QCD corrections for the differential Higgs boson production cross-section in gluon fusion

International Nuclear Information System (INIS)

Anastasiou, Charalampos

2006-01-01

I describe a recent computation of the NNLO QCD corrections for the fully differential cross-section for Higgs boson production in the gluon fusion channel. This result is an application of a new method for calculating perturbative corrections beyond the next-to-leading order

NNLO QCD analysis of CCFR data on xF3 structure function and Gross-Llewellyn-Smith sum rule with higher twist and nuclear corrections

International Nuclear Information System (INIS)

Sidorov, A.V.; Tokarev, M.V.

1997-01-01

A detailed NNLO QCD analysis of new CCFR data on xF 3 structure function including the target mass, higher twist and nuclear corrections was performed and parametrizations of the perturbative and power terms of the structure function were constructed. The results of QDC analysis of the structure function were used to study the Q 2 -dependence of the Gross-Llewellyn-Smith sum rule. The α s /π-expansion of S GLS (Q 2 ) was studied and parameters of the expansion were found to be s 1 =2.74±0.01, s 2 =-2.22±0.23, s 3 =-7.86±1.74 which are in good agreement with the perturbative QCD predictions for the Gross-Llewellyn-Smith sum rule in the next-to-leading and next-to-next-leading order

Automation of one-loop QCD corrections

CERN Document Server

Hirschi, Valentin; Frixione, Stefano; Garzelli, Maria Vittoria; Maltoni, Fabio; Pittau, Roberto

2011-01-01

We present the complete automation of the computation of one-loop QCD corrections, including UV renormalization, to an arbitrary scattering process in the Standard Model. This is achieved by embedding the OPP integrand reduction technique, as implemented in CutTools, into the MadGraph framework. By interfacing the tool so constructed, which we dub MadLoop, with MadFKS, the fully automatic computation of any infrared-safe observable at the next-to-leading order in QCD is attained. We demonstrate the flexibility and the reach of our method by calculating the production rates for a variety of processes at the 7 TeV LHC.

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

High-Energy QCD Asymptotics of Photon--Photon Collisions

Energy Technology Data Exchange (ETDEWEB)

Brodsky, Stanley J.

2002-07-26

The high-energy behavior of the total cross section for highly virtual photons, as predicted by the BFKL equation at next-to-leading order (NLO) in QCD, is discussed. The NLO BFKL predictions, improved by the BLM optimal scale setting, are in good agreement with recent OPAL and L3 data at CERN LEP2. NLO BFKL predictions for future linear colliders are presented.

High-Energy QCD Asymptotics of Photon-Photon Collisions

CERN Document Server

Brodsky, S J; Kim, V T; Lipatov, L N; Pivovarov, G B

2002-01-01

The high-energy behaviour of the total cross section for highly virtual photons, as predicted by the BFKL equation at next-to-leading order (NLO) in QCD, is discussed. The NLO BFKL predictions, improved by the BLM optimal scale setting, are in good agreement with recent OPAL and L3 data at CERN LEP2. NLO BFKL predictions for future linear colliders are presented.

Wgamma and Zgamma production at the LHC in NNLO QCD

International Nuclear Information System (INIS)

Grazzini, Massimiliano; Kallweit, Stefan; Rathlev, Dirk

2016-01-01

We consider the production of Wγ and Zγ 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 Zγ production, the impact of NNLO corrections is generally moderate, ranging from 8% to 17%, 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, a veto against jets significantly reduces the impact of QCD radiative corrections.

Next Gen One Portal Usability Evaluation

Science.gov (United States)

Cross, E. V., III; Perera, J. S.; Hanson, A. M.; English, K.; Vu, L.; Amonette, W.

2018-01-01

Each exercise device on the International Space Station (ISS) has a unique, customized software system interface with unique layouts / hierarchy, and operational principles that require significant crew training. Furthermore, the software programs are not adaptable and provide no real-time feedback or motivation to enhance the exercise experience and/or prevent injuries. Additionally, the graphical user interfaces (GUI) of these systems present information through multiple layers resulting in difficulty navigating to the desired screens and functions. These limitations of current exercise device GUI's lead to increased crew time spent on initiating, loading, performing exercises, logging data and exiting the system. To address these limitations a Next Generation One Portal (NextGen One Portal) Crew Countermeasure System (CMS) was developed, which utilizes the latest industry guidelines in GUI designs to provide an intuitive ease of use approach (i.e., 80% of the functionality gained within 5-10 minutes of initial use without/limited formal training required). This is accomplished by providing a consistent interface using common software to reduce crew training, increase efficiency & user satisfaction while also reducing development & maintenance costs. Results from the usability evaluations showed the NextGen One Portal UI having greater efficiency, learnability, memorability, usability and overall user experience than the current Advanced Resistive Exercise Device (ARED) UI used by astronauts on ISS. Specifically, the design of the One-Portal UI as an app interface similar to those found on the Apple and Google's App Store, assisted many of the participants in grasping the concepts of the interface with minimum training. Although the NextGen One-Portal UI was shown to be an overall better interface, observations by the test facilitators noted specific exercise tasks appeared to have a significant impact on the NextGen One-Portal UI efficiency. Future updates to

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.

Higgs production at NNLO in QCD. The VBF channel

International Nuclear Information System (INIS)

Bolzoni, P.; Moch, S.; Zaro, M.; Maltoni, F.

2010-06-01

We present a phenomenological study for the production of the Higgs boson at next-to-next-to-leading order (NNLO) in QCD via the vector boson fusion (VBF) process. After a general discussion about the different production channels of the Higgs, we show results for hadron colliders like LHC and Tevatron in VBF. The theoretical predictions are obtained using the structure function approach. This approximation turns out to be more accurate than the precision to which the VBF Higgs production channel can be considered a well defined process by itself and the theoretical uncertainty which are of the order of 1-2%. The uncertainties due to parton distributions are also discussed and are estimated to be at the same level. (orig.)

Fixation of theoretical ambiguities in the improved fits to $xF_{3}$ CCFR data at the next-to-next-to-leading order and beyond

CERN Document Server

Kataev, A L; Sidorov, A V

2003-01-01

Using new theoretical information on the NNLO and N$^3$LO perturbative QCD corrections to renormalization-group quantities of odd $xF_3$ Mellin moments, we perform the reanalysis of the CCFR'97 data for $xF_3$ structure function. The fits were done without and with twist-4 power suppressed terms. Theoretical questions of applicability of the renormalon-inspired large-$\\beta_0$ approximation for estimating NNLO and N$^3$LO terms in the coefficient functions of odd $xF_3$ moments and even non-singlet moments of $F_2$ are considered. The comparison with [1/1] Pad\\'e estimates is presented. The small $x$ behaviour of the phenomenological model for $xF_3$ is compared with available theoretical predictions. The $x$-shape of the twist-4 contributions is determined. Indications of oscillating-type behaviour of $h(x)$ are obtained from more detailed NNLO fits when only statistical uncertainties are taken into account. The scale-dependent uncertainties of $\\alpha_s(M_Z)$ are analyzed. The obtained NNLO and approximate ...

Scrutinizing the top quark at lepton colliders with higher orders. From fixed order to resummation and matching

Energy Technology Data Exchange (ETDEWEB)

Nejad, Bijan Chokoufe

2017-07-12

In this thesis, we present detailed studies of top-pair production with (t anti tH) and without association of a Higgs boson (t anti t) in e{sup +}e{sup -} collisions. These processes are of utmost interest for the top physics program of future lepton colliders. They allow in particular a precise measurement of the top quark mass and the Yukawa coupling. For this purpose, we present predictions for off-shell t anti t and t anti tH production including non-resonant and interference contributions up to next-to-leading order (NLO) in perturbative quantum chromodynamics (QCD). This allows for top-quark phenomenology in the continuum at an unprecedented level of accuracy. We show that off-shell effects and NLO QCD corrections for these processes do not factorize in general. In particular, we present the Yukawa coupling dependence of the cross section, which receives negative corrections due to sizable interference terms. We also add a discussion of p{sub T} resummation in the form of combining the NLO prediction via POWHEG matching with the parton shower and the associated uncertainties. To handle large Coulomb singularities at threshold, we include the next-to-leading log (NLL) threshold resummation derived in nonrelativistic QCD (NRQCD) for t anti t production. This results in a form factor that we incorporate in a fully relativistic cross section, which is factorized within an extended double-pole approximation. Fixed-order QCD corrections are included, hereby, for the top decay. We combine this calculation with the full fixed-order QCD results at NLO for W{sup +}W{sup -}b anti b production to obtain a computation that is not only valid at threshold but smoothly interpolates to the continuum. This allows us to present the first prediction for exclusive W{sup +}W{sup -}b anti b production at a lepton collider with a consistent matching between the top-antitop threshold and continuum regions. This computation is not only required to describe the intermediate energy

Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

CERN Document Server

Adolph, C.; Akhunzyanov, R.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anfimov, N.V.; Anosov, V.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.D.R.; Badelek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E.R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buchele, M.; Chang, W.C.; Chiosso, M.; Choi, I.; Chung, S.U.; Cicuttin, A.; Crespo, M.L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Dhara, L.; Donskov, S.V.; Doshita, N.; Duic, V.; Dunnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; M. Finger jr; Fischer, H.; Franco, C.; von Hohenesche, N. du Fresne; Friedrich, J.M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmuller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F.H.; Heitz, R.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Joosten, R.; Jorg, P.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Konigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.M.; Kramer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z.V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G.K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; J.Matou s; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.V.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Mikhasenko, M.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.C.; Pereira, F.; M. Pe s; Peshekhonov, D.V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N.S.; Ryabchikov, D.I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V.D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I.A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schonning, K.; Schopferer, S.; Seder, E.; Selyunin, A.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Weisrock, T.; Wilfert, M.; Wolbeek, J. ter; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

2017-01-01

Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality $Q^2>1~({\\rm GeV}/c)^2$. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/$c$ polarised muon beam impinging on a polarised $^6$LiD target. By analysing the full range in hadron transverse momentum $p_T$, the different $p_T$-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation $\\Delta g/g$ is evaluated at leading order in pQCD at a hard scale of $\\mu^2 = \\langle Q^2\\rangle = 3(GeV=c)^2$. It is determined in three intervals of the nucleon momentum fraction carried by gluons, $x_g$, covering the range $0.04 \\!<\\! x_{ \\rm g}\\! <\\! 0.28$ . and does not exhibit a significant dependence on $x_{\\rm g}$. Average...

Spin nematics next to spin singlets

Science.gov (United States)

Yokoyama, Yuto; Hotta, Chisa

2018-05-01

We provide a route to generate nematic order in a spin-1/2 system. Unlike the well-known magnon-binding mechanism, our spin nematics requires neither the frustration effect nor spin polarization in a high field or in the vicinity of a ferromagnet, but instead appears next to the spin singlet phase. We start from a state consisting of a quantum spin-1/2 singlet dimer placed on each site of a triangular lattice, and show that interdimer ring exchange interactions efficiently dope the SU(2) triplets that itinerate and interact, easily driving a stable singlet state to either Bose-Einstein condensates or a triplet crystal, some hosting a spin nematic order. A variety of roles the ring exchange serves includes the generation of a bilinear-biquadratic interaction between nearby triplets, which is responsible for the emergent nematic order separated from the singlet phase by a first-order transition.

Jet calculus beyond leading logarithms

International Nuclear Information System (INIS)

Kalinowski, J.; Konishi, K.; Taylor, T.R.

1981-01-01

It is shown that the evolution of hadronic jets produced in hard processes can be studied in terms of a simple parton branching picture, beyond the leading log approximation of QCD. The jet calculus is generalized to any given order of logs (but always to all orders of αsub(s)). We discuss the general structure of the formalism. Universality of jet evolution is discussed. We consider also a jet calorimetry measure and the multiplicity distribution of final states in a form which allows a systematic improvement of approximation. To the next-to-leading order, we prove the finiteness and elucidate the scheme dependence of parton subprocess probabilities. The physical inclusive cross section is shown to be scheme independent: next-to-leading results for e + e - → q (nonsinglet) + X agree with those of Curci and others. (orig.)

Higher order QCD corrections in small x physics

International Nuclear Information System (INIS)

Chachamis, G.

2006-11-01

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 γ * γ * 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 γ*γ* 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 γγ→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.)

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.)

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

International Nuclear Information System (INIS)

Vogt, A.

2014-05-01

We have calculated the complete matrix of three-loop helicity-difference ('polarized') splitting functions ΔP ik (2) (x), 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 ΔP gq (2) and ΔP 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 α s .

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

International Nuclear Information System (INIS)

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

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→tl - (anti tl + ) + 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 the 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 the t 1 or g mass value. (orig.)

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.)

Probing QCD with the ATLAS Detector

CERN Document Server

Kulchitsky, Yuri; The ATLAS collaboration

2018-01-01

Perturbative QCD calculations at next-to-next-to leading order (NNLO) are available for many processes since several years and can be rigorously tested with a large variety of final states. In this talk, we present the latest results from the ATLAS collaboration involving jets, dijets, photons in association with heavy flavors and vector bosons in association with jets, measured at center of mass energies of 8 and 13 TeV. All measured cross-sections are compared to state-of-the art theory predictions. Moreover, we present two measurements of dijet energy correlations allowing to test the renormalization group equation and to extract the strong coupling constant. The talk concludes with the latest results of jet-substructure studies at 13 TeV, in particular the measurement of the jet soft-drop mass.

Ultrahigh energy neutrinos and nonlinear QCD dynamics

International Nuclear Information System (INIS)

Machado, Magno V.T.

2004-01-01

The ultrahigh energy neutrino-nucleon cross sections are computed taking into account different phenomenological implementations of the nonlinear QCD dynamics. Based on the color dipole framework, the results for the saturation model supplemented by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution as well as for the Balitskii-Fadin-Kuraev-Lipatov (BFKL) formalism in the geometric scaling regime are presented. They are contrasted with recent calculations using next-to-leading order DGLAP and unified BFKL-DGLAP formalisms

Energy evolution of the moments of the hadron distribution in QCD jets including NNLL resummation and NLO running-coupling corrections

CERN Document Server

Perez-Ramos, Redamy

2014-01-01

The moments of the single inclusive momentum distribution of hadrons in QCD jets, are studied in the next-to-modified-leading-log approximation (NMLLA) including next-to-leading-order (NLO) corrections to the alpha_s strong coupling. The evolution equations are solved using a distorted Gaussian parametrisation, which successfully reproduces the spectrum of charged hadrons of jets measured in e+e- collisions. The energy dependencies of the maximum peak, multiplicity, width, kurtosis and skewness of the jet hadron distribution are computed analytically. Comparisons of all the existing jet data measured in e+e- collisions in the range sqrt(s)~2-200 GeV to the NMLLA+NLO* predictions allow one to extract a value of the QCD parameter Lambda_QCD, and associated two-loop coupling constant at the Z resonance alpha_s(m_Z^2)= 0.1195 +/- 0.0022, in excellent numerical agreement with the current world average obtained using other methods.

Jet Substructure Measurements Sensitive to Soft QCD effects with the ATLAS Detector

CERN Document Server

Asquith, Lily; The ATLAS collaboration

2017-01-01

Calculations of jet substructure observables which are accurate beyond leading-logarithmic accuracy have recently become available. Such observables are significant not only for probing a new regime of QCD at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. In this talk, we discuss first measurement of jet substructure quantities at a hadron collider, calculated at next-to-next-to-leading-logarithm accuracy. The soft drop mass is measured in dijet events with the ATLAS detector at 13 TeV, unfolded to particle-level and compared to Monte Carlo simulations. In addition, we present a measurement of the splitting scales in the kt jet-clustering algorithm for final states containing a Z-boson candidate at a centre-of-mass energy of 8 TeV.  The data are also corrected for detector effects and are compared to state-of-the-art Monte Carlo predictions.

N-jettiness Subtractions for NNLO QCD calculations

International Nuclear Information System (INIS)

Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.; Walsh, Jonathan R.; California Univ., CA

2015-05-01

We present a subtraction method utilizing the N-jettiness observable, Τ 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 Τ N → 0, and uses these to construct suitable Τ 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 Τ 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 ingredient for three or more external partons can be obtained numerically with existing NNLO techniques. As an example, we employ our method to obtain the NNLO rapidity spectrum for Drell-Yan and gluon-fusion Higgs production. We discuss aspects of numerical accuracy and convergence and the practical implementation. We also discuss and comment on possible extensions, such as more-differential subtractions, necessary steps for going to N 3 LO, and the treatment of massive quarks.

Non-perturbative Debye mass in finite-T QCD

CERN Document Server

Kajantie, Keijo; Peisa, J; Rajantie, A; Rummukainen, K; Shaposhnikov, Mikhail E

1997-01-01

Employing a non-perturbative gauge invariant definition of the Debye screening mass m_D in the effective field theory approach to finite T QCD, we use 3d lattice simulations to determine the leading O(g^2) and to estimate the next-to-leading O(g^3) corrections to m_D in the high temperature region. The O(g^2) correction is large and modifies qualitatively the standard power-counting hierarchy picture of correlation lengths in high temperature QCD.

QCD analysis of polarized deep inelastic scattering data

International Nuclear Information System (INIS)

Bluemlein, Johannes; Boettcher, Helmut

2010-05-01

A QCD analysis of the world data on polarized deep inelastic scattering is presented in next-to-leading order, including the heavy flavor Wilson coefficient in leading order in the fixed flavor number scheme. New parameterizations are derived for the quark and gluon distributions and the value of α s (M z 2 ) is determined. The impact of the variation of both the renormalization and factorization scales on the distributions and the value of α s is studied. We obtain α s NLO (M Z 2 )=0.1132 -0.0095 +0.0056 . The first moments of the polarized twist-2 parton distribution functions are calculated with correlated errors to allow for comparisons with results from lattice QCD simulations. Potential higher twist contributions to the structure function g 1 (x,Q 2 ) are determined and found to be compatible with zero both for proton and deuteron targets. (orig.)

Lattice simulations of QCD-like theories at finite baryon density

Energy Technology Data Exchange (ETDEWEB)

Scior, Philipp Friedrich

2016-07-13

The exploration of the phase diagram of quantum chromodynamics (QCD) is of great importance to describe e.g. the properties of neutron stars or heavy-ion collisions. Due to the sign problem of lattice QCD at finite chemical potential we need effective theories to study QCD at finite density. Here, we use a three-dimensional Polyakov-loop theory to study the phase diagrams of QCD-like theories. In particular, we investigate the heavy quark limit of the QCD-like theories where the effective theory can be derived from the full theory by a combined strong coupling and hopping expansion. This expansion can be systematically improved order by order. Since there is no sign problem for the QCD-like theories we consider, we can compare our results to data from lattice calculations of the full theories to make qualitative and quantitative statements of the effective theory's validity. We start by deriving the effective theory up to next-to-next-to leading-order, in particular for two-color and G{sub 2}-QCD where replace the three colors in QCD with only two colors or respectively replace the gauge group SU(3) of QCD with G{sub 2}. We will then apply the effective theory at finite temperature mainly to test the theory and the implementation but also to make some predictions for the deconfinement phase transition in G{sub 2} Yang-Mills theory. Finally, we turn our attention to the cold and dense regime of the phase diagram where we observe a sharp increase of the baryon density with the quark chemical potential μ, when μ reaches half the diquark mass. At vanishing temperature this is expected to happen in a quantum phase transition with Bose-Einstein-condensation of diquarks. In contrast to the liquid-gas transition in QCD, the phase transition to the Bose-Einstein condensate is continuous. We find evidence that the effective theories for heavy quarks are able to describe the qualitative difference between first and second order phase transitions. For even higher μ we

Lattice simulations of QCD-like theories at finite baryon density

International Nuclear Information System (INIS)

Scior, Philipp Friedrich

2016-01-01

The exploration of the phase diagram of quantum chromodynamics (QCD) is of great importance to describe e.g. the properties of neutron stars or heavy-ion collisions. Due to the sign problem of lattice QCD at finite chemical potential we need effective theories to study QCD at finite density. Here, we use a three-dimensional Polyakov-loop theory to study the phase diagrams of QCD-like theories. In particular, we investigate the heavy quark limit of the QCD-like theories where the effective theory can be derived from the full theory by a combined strong coupling and hopping expansion. This expansion can be systematically improved order by order. Since there is no sign problem for the QCD-like theories we consider, we can compare our results to data from lattice calculations of the full theories to make qualitative and quantitative statements of the effective theory's validity. We start by deriving the effective theory up to next-to-next-to leading-order, in particular for two-color and G_2-QCD where replace the three colors in QCD with only two colors or respectively replace the gauge group SU(3) of QCD with G_2. We will then apply the effective theory at finite temperature mainly to test the theory and the implementation but also to make some predictions for the deconfinement phase transition in G_2 Yang-Mills theory. Finally, we turn our attention to the cold and dense regime of the phase diagram where we observe a sharp increase of the baryon density with the quark chemical potential μ, when μ reaches half the diquark mass. At vanishing temperature this is expected to happen in a quantum phase transition with Bose-Einstein-condensation of diquarks. In contrast to the liquid-gas transition in QCD, the phase transition to the Bose-Einstein condensate is continuous. We find evidence that the effective theories for heavy quarks are able to describe the qualitative difference between first and second order phase transitions. For even higher μ we find the rise of the

Special Issue: Next Generation DNA Sequencing

Directory of Open Access Journals (Sweden)

Paul Richardson

2010-10-01

Full Text Available Next Generation Sequencing (NGS refers to technologies that do not rely on traditional dideoxy-nucleotide (Sanger sequencing where labeled DNA fragments are physically resolved by electrophoresis. These new technologies rely on different strategies, but essentially all of them make use of real-time data collection of a base level incorporation event across a massive number of reactions (on the order of millions versus 96 for capillary electrophoresis for instance. The major commercial NGS platforms available to researchers are the 454 Genome Sequencer (Roche, Illumina (formerly Solexa Genome analyzer, the SOLiD system (Applied Biosystems/Life Technologies and the Heliscope (Helicos Corporation. The techniques and different strategies utilized by these platforms are reviewed in a number of the papers in this special issue. These technologies are enabling new applications that take advantage of the massive data produced by this next generation of sequencing instruments. [...

QCD analysis of first b cross section data at 1.96 TeV

CERN Document Server

Cacciari, M; Mangano, Michelangelo L; Nason, P; Ridolfi, G

2004-01-01

The first data on bottom quark production in p-pbar collisions at 1.96 TeV have recently been obtained by the CDF collaboration. These data probe the region of pt~0, providing a new invaluable input on the issue of the compatibility between next-to-leading-order (NLO) QCD and data. We reconsider the evaluation of the $b$ cross section, in view of recent theoretical developments, and of the latest inputs on structure function fits. We show that the new CDF measurements are in good agreement with NLO QCD. If CDF preliminary data are confirmed, a long-standing discrepancy between NLO QCD predictions and hadron-collider data can be settled.

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.)

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.

2015-12-08

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...

Development of QCD jets emitted by color-singlet sources

International Nuclear Information System (INIS)

Ellis, R.K.; Gunion, J.F.; Kalinowski, J.; Webber, B.R.

1985-01-01

We compare the angular-ordering approximation to QCD jet development with full calculations to order αsub(s) in the following cases: emission of quark jets by a color-singlet vector source (as in e + e - annihilation) and emission of gluon jets by a color-singlet scalar (Fsup(a)sub(μν)Fsup(aμν)) source. In contrast to the case of a color-octet (gluon) source, we find that the approximation is good in those regions of phase space where the next-to-leading corrections to the amplitude are large. (orig.)

Next-to-leading order corrections to e+e-→W+W-Z and e+e-→ZZZ

International Nuclear Information System (INIS)

Boudjema, Fawzi; Hao Sun; Ninh, Le Duc; Weber, Marcus M.

2010-01-01

We calculate the one-loop electroweak corrections to e + e - →W + W - Z and e + e - →ZZZ and analyze their impacts on both the total cross section and some key distributions. These processes are important for the measurements of the quartic couplings of the massive gauge bosons which can be a window on the mechanism of spontaneous symmetry breaking. We find that even after subtracting the leading QED corrections, the electroweak corrections can still be large, especially as the energy increases. We compare and implement different methods of dealing with potential instabilities in the routines pertaining to the loop integrals. For the real corrections we apply a dipole subtraction formalism and compare it to a phase-space slicing method.

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

International Nuclear Information System (INIS)

Seligman, W.G.

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 F 2 and xF 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 ΛNLO,(4)/MS = 337 ± 28 (exp.) MeV, which corresponds to α S (M Z 2 ) = 0.119 ± 0.002 (exp.) ± 0.004 (theory), and with a gluon distribution given by xG(x,Q 0 2 = 5GeV 2 ) = (2.22 ± 0.34) x (1 - x) 4.65±0.68

A Next-to-Leading Order QCD Analysis of Neutrino - Iron Structure Functions at the Tevatron

Energy Technology Data Exchange (ETDEWEB)

Seligman, William Glenn [Nevis Labs, Columbia U.

1997-01-01

Nucleon structure functions measured in neutrino-iron and antineutrinoiron 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 Ge V. The structure functions $F_2$ and $xF_3$ are compared with the the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives NL0(4) . 2 value of $\\Lambda^{NLO,(4)}_{\\overline MS}$ = 337 ± 28 (exp.) MeV, which corresponds to $\\alpha_s$ ($M^2_z$) = 0.119 ± 0.002 (exp.) ± 0.004 (theory), and with a gluon distribution given by $xG(x,Q^2_0 = 5 GeV^2$ ) = (2.22±0.34) x ($1-x)^{4.65 \\pm 0.68}$

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 α_S(M_Z²) = 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.

A next-to-leading determination of the singlet axial charge and the polarized gluon content of the nucleon

CERN Document Server

Ball, R D; Ridolfi, G

1996-01-01

We perform a full next-to-leading analysis of the the available experimental data on the polarized structure function g_1 of the nucleon, and give a precise determination of its singlet axial charge together with a thorough assessment of the theoretical uncertainties. We find that the data are now sufficient to separately determine first moments of the polarized quark and gluon distributions and show in particular that the gluon contribution is large and positive.

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

International Nuclear Information System (INIS)

Sil, Karunava; Misra, Aalok

2016-01-01

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 to the same. First, up to LO in N (the number of D3-branes), by calculating the temperature dependence of the thermal (and electrical) conductivity and the consequent deviation from the Wiedemann-Franz law, upon comparison with Garg et al. (Phys. Rev. Lett. 103:096402, 2009), we show that, remarkably, the results qualitatively mimic a 1+1-dimensional Luttinger liquid with impurities. Second, by looking at, respectively, the scalar, vector, and tensor modes of metric perturbations and using the prescription of Kovtun and Starinets (Phys. Rev. D 72:086009, arXiv:hep-th/0506184, 2005) for constructing appropriate gauge-invariant perturbations, we obtain the non-conformal corrections to the conformal results (but at finite g 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 turns out

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} to the same. First, up to LO in N (the number of D3-branes), by calculating the temperature dependence of the thermal (and electrical) conductivity and the consequent deviation from the Wiedemann-Franz law, upon comparison with Garg et al. (Phys. Rev. Lett. 103:096402, 2009), we show that, remarkably, the results qualitatively mimic a 1+1-dimensional Luttinger liquid with impurities. Second, by looking at, respectively, the scalar, vector, and tensor modes of metric perturbations and using the prescription of Kovtun and Starinets (Phys. Rev. D 72:086009, arXiv:hep-th/0506184, 2005) for constructing appropriate gauge-invariant perturbations, we obtain the non-conformal 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

Answers to Teachers' Questions about the Next Generation Science Standards

Science.gov (United States)

Workosky, Cindy; Willard, Ted

2015-01-01

K-12 teachers of science have been digging into the "Next Generation Science Standards" ("NGSS") (NGSS Lead States 2013) to begin creating plans and processes for translating them for classroom instruction. As teachers learn about the NGSS, they have asked about the general structure of the standards document and how to read…

Two-Loop Gluon to Gluon-Gluon Splitting Amplitudes in QCD

International Nuclear Information System (INIS)

Bern, Z.

2004-01-01

Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g → gg splitting amplitudes in QCD, N = 1, and N = 4 super-Yang-Mills theories, which describe the limits of two-loop n-point amplitudes where two gluon momenta become parallel. They also represent an ingredient in a direct x-space computation of DGLAP evolution kernels at next-to-next-to-leading order. To obtain the splitting amplitudes, we use the unitarity sewing method. In contrast to the usual light-cone gauge treatment, our calculation does not rely on the principal-value or Mandelstam-Leibbrandt prescriptions, even though the loop integrals contain some of the denominators typically encountered in light-cone gauge. We reduce the integrals to a set of 13 master integrals using integration-by-parts and Lorentz invariance identities. The master integrals are computed with the aid of differential equations in the splitting momentum fraction z. The ε-poles of the splitting amplitudes are consistent with a formula due to Catani for the infrared singularities of two-loop scattering amplitudes. This consistency essentially provides an inductive proof of Catani's formula, as well as an ansatz for previously-unknown 1/ε pole terms having non-trivial color structure. Finite terms in the splitting amplitudes determine the collinear behavior of finite remainders in this formula

The complete NLO corrections to dijet hadroproduction

Science.gov (United States)

Frederix, R.; Frixione, S.; Hirschi, V.; Pagani, D.; Shao, H.-S.; Zaro, M.

2017-04-01

We study the production of jets in hadronic collisions, by computing all contributions proportional to α S n α m , with n + m = 2 and n + m = 3. These correspond to leading and next-to-leading order results, respectively, for single-inclusive and dijet observables in a perturbative expansion that includes both QCD and electroweak effects. We discuss issues relevant to the definition of hadronic jets in the context of electroweak corrections, and present sample phenomenological predictions for the 13-TeV LHC. We find that both the leading and next-to-leading order contributions largely respect the relative hierarchy established by the respective coupling-constant combinations.

The complete NLO corrections to dijet hadroproduction

Energy Technology Data Exchange (ETDEWEB)

Frederix, R. [Physik Department T31, Technische Universität München,James-Franck-Str. 1, D-85748 Garching (Germany); Frixione, S. [INFN - Sezione di Genova,Via Dodecaneso 33, I-16146, Genoa (Italy); Hirschi, V. [SLAC, National Accelerator Laboratory,2575 Sand Hill Road, Menlo Park, CA 94025-7090 (United States); Pagani, D. [Physik Department T31, Technische Universität München,James-Franck-Str. 1, D-85748 Garching (Germany); Centre for Cosmology, Particle Physics and Phenomenology (CP3),Université Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Shao, H.-S. [TH Department, CERN, CH-1211 Geneva 23 (Switzerland); Zaro, M. [Sorbonne Universités, UPMC University Paris 06,UMR 7589, LPTHE, F-75005, Paris (France); CNRS,UMR 7589, LPTHE, F-75005, Paris (France)

2017-04-12

We study the production of jets in hadronic collisions, by computing all contributions proportional to α{sub S}{sup n}α{sup m}, with n+m=2 and n+m=3. These correspond to leading and next-to-leading order results, respectively, for single-inclusive and dijet observables in a perturbative expansion that includes both QCD and electroweak effects. We discuss issues relevant to the definition of hadronic jets in the context of electroweak corrections, and present sample phenomenological predictions for the 13-TeV LHC. We find that both the leading and next-to-leading order contributions largely respect the relative hierarchy established by the respective coupling-constant combinations.

Demonstration of the First Real-Time End-to-End 40-Gb/s PAM-4 for Next-Generation Access Applications using 10-Gb/s Transmitter

DEFF Research Database (Denmark)

Wei, J. L.; Eiselt, Nicklas; Griesser, Helmut

2016-01-01

We demonstrate the first known experiment of a real-time end-to-end 40-Gb/s PAM-4 system for next-generation access applications using 10-Gb/s class transmitters only. Based on the measurement of a real-time 40-Gb/s PAM system, low-cost upstream and downstream link power budgets are estimated. Up...

Spin-dependent hadro- and photoproduction of heavy quarks at next-to-leading order of QCD

International Nuclear Information System (INIS)

Riedl, Johann

2014-01-01

In this thesis, we have studied heavy quark hadro- and photoproduction in detail and examined the possibilities of using heavy quark production for the extraction of the polarised parton distribution functions. All calculations are performed at O(α s 3 ) and O(αα s 2 ) accuracy, respectively, and theoretical uncertainties due to the choice of scales μ f,r and the heavy quark mass m Q have been discussed in detail. Based on our theoretical results we have presented detailed phenomenological studies for the existing PHENIX and STAR experiments at BNL-RHIC and the COMPASS experiment at CERN. Predictions have been made for possible future experiments at a low-energy antiproton-proton collider at GSI-FAIR, a proton-proton collider at J-PARC and an upcoming high-energy electron-ion collider (EIC).

Wind energy in the next millennium and the next year

International Nuclear Information System (INIS)

Chabot, B.

1999-01-01

The rapid development of wind energy was once again confirmed in 1998 and everything points to the fact that this road will in the next century rapidly become the third channel of primary electricity production in the world, both in terms of annual sales and contribution of energy. In particular, a scenario for the development, of wind energy in the coming century is proposed, taking as model and minimum objective the historical development of success of wind energy should prove perfectly feasible, it is difficult to foresee in the short term the actual impact of the liberalization of electricity markets on existing inducements in favour of wind energy and even more difficult to estimate the effectiveness of new inducements more in line with this liberalization process. These difficulties may be overcome by selecting - for the long term scenario - a starting point within the next decade which is in line with the best market studies currently available and by constructing the model for variations in operational stock world-wide on the basis of a Rayleigh distribution, adjusted for the market conditions defined in the short term, in order that the future contributions defined in the short term, in order that the future contribution of wind energy might come to equal that of hydro-electricity before the end of the next century. (author)

Higher-order threshold resummation for semi-inclusive e+e- annihilation

International Nuclear Information System (INIS)

Moch, S.; Vogt, A.

2009-08-01

The complete soft-enhanced and virtual-gluon contributions are derived for the quark coefficient functions in semi-inclusive e + e - annihilation to the third order in massless perturbative QCD. These terms enable us to extend the soft-gluon resummation for the fragmentation functions by two orders to the next-to-next-to-next-to-leading logarithmic (N 3 LL) accuracy. The resummation exponent is found to be the same as for the structure functions in inclusive deep-inelastic scattering. This finding, together with known results on the higher-order quark form factor, facilitates the determination of all soft and virtual contributions of the fourth-order difference of the coefficient functions for these two processes. Unlike the previous (N 2 LL) order in the exponentiation, the numerical effect of the N 3 LL contributions turns out to be negligible at LEP energies. (orig.)

QCD analysis of first b cross section data at 1.96 TeV

International Nuclear Information System (INIS)

Cacciari, M.; Frixione, S.; Nason, P.; Ridolfi, G.; Mangano, M.L.

2004-01-01

The first data on bottom quark production in pp-bar collisions at 1.96 TeV have recently been obtained by the CDF collaboration. These data probe the region of p T ∼ 0, providing a new invaluable input on the issue of the compatibility between next-to-leading-order (NLO) QCD and data. We reconsider the evaluation of the b cross section, in view of recent theoretical developments, and of the latest inputs on structure function fits. We show that the new CDF measurements are in good agreement with NLO QCD. If CDF preliminary data are confirmed, a long-standing discrepancy between NLO QCD predictions and hadron-collider data can be settled. (author)

Spectator scattering at NLO in non-leptonic B decays: Leading penguin amplitudes

International Nuclear Information System (INIS)

Beneke, M.; Jaeger, S.

2007-01-01

We complete the computation of the 1-loop (α s 2 ) corrections to hard spectator scattering in non-leptonic B decays at leading power in Λ/m b by evaluating the penguin amplitudes. This extends the knowledge of these next-to-next-to-leading-order contributions in the QCD factorization formula for B decays to a much wider class of final states, including all pseudoscalar-pseudoscalar, pseudoscalar-vector, and longitudinally polarized vector-vector final states, except final states with η or η ' mesons. The new 1-loop correction is significant for the colour-suppressed amplitudes, but turns out to be strongly suppressed for the leading QCD penguin amplitude α 4 p . We provide numerical values of the phenomenological P/T and C/T amplitude ratios for the ππ, πρ and ρρ final states, and discuss corrections to several relations between electroweak penguin and tree amplitudes

Hard Quasi-real Photo-production of Charged Hadrons at COMPASS energies

CERN Document Server

Morréale, Astrid

2011-01-01

The Common Muon Proton Apparatus for Structure and Spectroscopy (COMPASS) at CERN with its use of beams of naturally polarized muons scattered of a polarized deuteron target, provides an environment of hard scattering between quasi-real photons and partons. Hard hadron quasi-real photo-production with polarized initial states is sensitive to the polarized gluon distribution $\\Delta$G through $\\gamma$-gluon($g$) direct channels as well as $q$-$g$ resolved processes. Comparisons of unpolarized differential cross section measurements to next-to-leading order (NLO) pQCD calculations are essential to develop our understanding of proton-proton and lepton-nucleon scattering at varying center of mass energies. These measurements are important to asses the applicability of NLO pQCD in interpreting polarized processes. In this talk we will discuss unidentified charged separated hadron production at low $Q^{2}$ (Q$^{2}1.0\\,GeV/c$). $$ spectra of charged hadrons at $Q^{2}>1 GeV^{2}/c^{2}$ will also be discussed.

Quark mass relations to four-loop order

International Nuclear Information System (INIS)

Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

2015-02-01

We present results for the relation between a heavy quark mass defined in the on-shell and MS scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS heavy quark masses.

Scaling violation in QCD

International Nuclear Information System (INIS)

Furmanski, W.

1981-08-01

The effects of scaling violation in QCD are discussed in the perturbative scheme, based on the factorization of mass singularities in the light-like gauge. Some recent applications including the next-to-leading corrections are presented (large psub(T) scattering, numerical analysis of the leptoproduction data). A proposal is made for extending the method on the higher twist sector. (author)

Associated production of a Higgs boson decaying into bottom quarks at the LHC in full NNLO QCD

Science.gov (United States)

Ferrera, Giancarlo; Somogyi, Gábor; Tramontano, Francesco

2018-05-01

We consider the production of a Standard Model Higgs boson decaying to bottom quarks in association with a vector boson W± / Z in hadron collisions. We present a fully exclusive calculation of QCD radiative corrections both for the production cross section and for the Higgs boson decay rate up to next-to-next-to-leading order (NNLO) accuracy. Our calculation also includes the leptonic decay of the vector boson with finite-width effects and spin correlations. We consider typical kinematical cuts applied in the experimental analyses at the Large Hadron Collider (LHC) and we find that the full NNLO QCD corrections significantly decrease the accepted cross section and have a substantial impact on the shape of distributions. We point out that these additional effects are essential to obtain precise theoretical predictions to be compared with the LHC data.

Fragmentation functions approach in pQCD fragmentation phenomena

International Nuclear Information System (INIS)

Rolli, S.

1996-07-01

Next-to-leading order parton fragmentation functions into light mesons are presented. They have been extracted from real and simulated e + e - data and used to predict inclusive single particle distributions at different machines

Charm production and QCD analysis at HERA and LHC

International Nuclear Information System (INIS)

Zenaiev, Oleksandr

2015-03-01

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 . Differential cross sections were measured as a function of virtuality Q 2 , inelasticity y, transverse momentum and pseudorapidity of the D + mesons. Lifetime information 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 production. 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 predictions in the fixed-flavour-number scheme. The combination method accounts for the correlations of the systematic uncertainties among the different datasets, thus allowing cross calibration of different measurements. The combined charm data were compared to QCD predictions in various heavy-flavour schemes and used together with the inclusive production data at HERA as input for QCD analyses to determine the charm running mass in the MS renormalisation scheme and the optimal values of the charm-quark mass parameters in other heavy-flavour schemes. An additional combination of the H1 and ZEUS D *+ visible cross sections was performed to provide the combined cross sections without theory-related uncertainties from the extrapolation procedure. This combination also provides differential cross sections as a function of the D *+ kinematic variables. Next-to-leading-order QCD predictions in the fixed-flavour-number scheme were compared to the combined D *+ cross

MoonNEXT: A European Mission to the Moon

Science.gov (United States)

Carpenter, J. D.; Koschny, D.; Crawford, I.; Falcke, H.; Kempf, S.; Lognonne, P.; Ricci, C.; Houdou, B.; Pradier, A.

2008-09-01

MoonNEXT is a mission currently being studied, under the direction of the European Space Agency, whose launch is foreseen between 2015 and 2018. MoonNEXT is intended to prepare the way for future exploration activities on the Moon, while addressing key science questions. Exploration Objectives The primary goal for the MoonNEXT mission is to demonstrate autonomous soft precision landing with hazard avoidance; a key capability for future exploration missions. The nominal landing site is at the South Pole of the Moon, at the edge of the Aitken basin and in the region of Shackleton crater, which has been identified as an optimal location for a future human outpost by the NASA lunar architecture team [1]. This landing site selection ensures a valuable contribution by MoonNEXT to the Global Exploration Strategy [2]. MoonNEXT will also prepare for future lunar exploration activities by characterising the environment at the lunar surface. The potentially hazardous radiation environment will me monitored while a dedicated instrument package will investigate the levitation and mobility of lunar dust. Experience on Apollo demonstrated the potentially hazardous effects of dust for surface operations and human activities and so an understanding of these processes is important for the future. Life sciences investigations will be carried out into the effects of the lunar environment (including radiation, gravity and illumination conditions) on a man made ecosystem analogous to future life support systems. In doing so MoonNEXT will demonstrate the first extraterrestrial man made ecosystem and develop valuable expertise for future missions. Geological and geochemical investigations will explore the possibilities for In Situ Resource Utilisation (ISRU), which will be essential for long term human habitation on the Moon and is of particular importance at the proposed landing site, given its potential as a future habitat location. Science Objectives In addition to providing extensive

Next Generation Sequencing of Ancient DNA: Requirements, Strategies and Perspectives

Directory of Open Access Journals (Sweden)

Michael Knapp

2010-07-01

Full Text Available The invention of next-generation-sequencing has revolutionized almost all fields of genetics, but few have profited from it as much as the field of ancient DNA research. From its beginnings as an interesting but rather marginal discipline, ancient DNA research is now on its way into the centre of evolutionary biology. In less than a year from its invention next-generation-sequencing had increased the amount of DNA sequence data available from extinct organisms by several orders of magnitude. Ancient DNA  research is now not only adding a temporal aspect to evolutionary studies and allowing for the observation of evolution in real time, it also provides important data to help understand the origins of our own species. Here we review progress that has been made in next-generation-sequencing of ancient DNA over the past five years and evaluate sequencing strategies and future directions.

Extension of the HAL QCD approach to inelastic and multi-particle scatterings in lattice QCD

Science.gov (United States)

Aoki, S.

We extend the HAL QCD approach, with which potentials between two hadrons can be obtained in QCD at energy below inelastic thresholds, to inelastic and multi-particle scatterings. We first derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave function at large space separations for systems with more than 2 particles, in terms of the one-shell $T$-matrix consrainted by the unitarity of quantum field theories. We show that its asymptotic behavior contains phase shifts and mixing angles of $n$ particle scatterings. This property is one of the essential ingredients of the HAL QCD scheme to define "potential" from the NBS wave function in quantum field theories such as QCD. We next construct energy independent but non-local potentials above inelastic thresholds, in terms of these NBS wave functions. We demonstrate an existence of energy-independent coupled channel potentials with a non-relativistic approximation, where momenta of all particles are small compared with their own masses. Combining these two results, we can employ the HAL QCD approach also to investigate inelastic and multi-particle scatterings.

The three-loop splitting functions in QCD. The helicity-dependent case

International Nuclear Information System (INIS)

Moch, S.; Vogt, A.

2014-09-01

We present the next-to-next-to-leading order (NNLO) contributions to the main splitting functions for the evolution of longitudinally polarized parton densities of hadrons in perturbative QCD. The quark-quark and gluon-quark splitting functions have been obtained by extending our previous all Mellin-N calculations to the structure function g 1 in electromagnetic deep-inelastic scattering (DIS). Their quark-gluon and gluon-gluon counterparts have been derived using third-order fixed-N calculations of structure functions in graviton-exchange DIS, relations to the unpolarized case and mathematical tools for systems of Diophantine equations. The NNLO corrections to the splitting functions are small outside the region of small momentum fractions x where they exhibit a large double-logarithmic enhancement, yet the corrections to the evolution of the parton densities can be unproblematic down to at least x∼10 -4 .

NextGen Future Safety Assessment Game

Science.gov (United States)

Ancel, Ersin; Gheorghe, Adrian; Jones, Sharon Monica

2011-01-01

The successful implementation of the next generation infrastructure systems requires solid understanding of their technical, social, political and economic aspects along with their interactions. The lack of historical data that relate to the long-term planning of complex systems introduces unique challenges for decision makers and involved stakeholders which in turn result in unsustainable systems. Also, the need to understand the infrastructure at the societal level and capture the interaction between multiple stakeholders becomes important. This paper proposes a methodology in order to develop a holistic approach aiming to provide an alternative subject-matter expert (SME) elicitation and data collection method for future sociotechnical systems. The methodology is adapted to Next Generation Air Transportation System (NextGen) decision making environment in order to demonstrate the benefits of this holistic approach.

A subtraction scheme for computing QCD jet cross sections at NNLO: integrating the subtraction terms I

Science.gov (United States)

Somogyi, Gábor; Trócsányi, Zoltán

2008-08-01

In previous articles we outlined a subtraction scheme for regularizing doubly-real emission and real-virtual emission in next-to-next-to-leading order (NNLO) calculations of jet cross sections in electron-positron annihilation. In order to find the NNLO correction these subtraction terms have to be integrated over the factorized unresolved phase space and combined with the two-loop corrections. In this paper we perform the integration of all one-parton unresolved subtraction terms.

QCD Analysis of Polarized Scattering Data and New Polarized Parton Distributions

International Nuclear Information System (INIS)

Bluemlein, J.; Boettcher, H.

2002-01-01

In this talk results from a new QCD analysis in Leading (LO) and Next-to-Leading (NLO) Order are presented. New parametrizations of the polarized quark and gluon densities are derived together with parametrizations of their fully correlated 1σ error bands. Furthermore the value of α s (M 2 Z ) is determined. Finally a number of low moments of the polarized parton densities are compared with results from lattice simulations. All details of the analysis are given in J. Bluemlein, H. Boettcher, Nucl. Phys. B636, 225 (2002). (author)

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

Electroweak production of top-quark pairs in e⁺e^- annihilation at NNLO in QCD: The vector current contributions

Energy Technology Data Exchange (ETDEWEB)

Gao, Jun [Southern Methodist Univ., Dallas, TX (United States); Zhu, Hua Xing [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2014-12-17

We report on a calculation of the vector current contributions to the 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 and can be used to calculate any infrared-safe observable. The real emission contributions are handled by a next-to-next-to-leading order generalization of the phase-space slicing method. As a result, we demonstrate the power of our technique by considering its application to various inclusive and exclusive observables.

A Search for Quark Compositeness with the CDF Detector at the Fermilab Collider

Energy Technology Data Exchange (ETDEWEB)

Hessing, Timothy Lee [Texas A & M Univ., College Station, TX (United States)

1990-12-01

The inclusive jet cross section in $p\\bar{p}$ collisions at $\\sqrt{s}$ 1.8 TeV has been measured using jet clustering cone sizes of 0.4, 0.7 and 1.0. The cone size, R, is defined to be, $R = \\sqrt{{\\Delta \\eta^2 + \\Delta \\phi^2}}$ where $\\eta$ = In tan 0/2, 0 represents the polar angle and represents the azimuthal angle. A lower limit on the value of the composite scale parameter, A was determined lo be 1100 GeV at 95% confidence level using the cone size 1.0. Comparisons to both lea.ding order Quantum Chromo Dyna.mies (QCD) and next-lo-leading order QCD calculations have been made and no significant deviations from QCD observed. The dependence of the inclusive jet cross section on cone size ha.s also been compared to next-to-leading order QCD. The measured cross section was found to grow larger with increasing cone size, more quickly than next-to-leading order QCD predicts.

Direct CP violation in KL→π0e+e- beyond leading logarithms

International Nuclear Information System (INIS)

Buras, A.J.; Lautenbacher, Markus E.; Misiak, Mikolaj; Muenz, Manfred

1994-01-01

We analyze the direct CP violation in the rare decay K L →π 0 e + e - with QCD effects taken into account consistently in the next-to-leading order. We calculate the two-loop mixing between the four-quark ΔS=1 operators and the operator Q 7V =(sd) V-A (ee) V in the NDR and HV renormalization schemes. Using the known two-loop anomalous dimension matrix of the four-quark operators, we find that the coefficient C 7V (μ) depends only very weakly on μ, renormalization scheme and Λ MS . The next-to-leading QCD corrections enhance the direct CP violating contribution over its leading order estimate so that it remains dominant in spite of the recent decrease of vertical stroke V ub /V cb vertical stroke and vertical stroke V cb vertical stroke . We expect typically BR(K L →π 0 e + e - ) dir ∼6x10 -12 , although values as high as 10 -11 are not yet excluded. ((orig.))

Small-x physics in perturbative QCD

International Nuclear Information System (INIS)

Lipatov, L.N.

1996-07-01

We review the parton model and the Regge approach to the QCD description of the deep-inelastic ep scattering at the small Bjorken variable x and demonstrate their relation with the DGLAP and BFKL evolution equations. It is shown, that in the leading logarithmic approximation the gluon is reggeized and the pomeron is a compound state of two reggeized gluons. The conformal invariance of the BFKL pomeron in the impact parameter space is used to investigate the scattering amplitudes at high energies and fixed momentum transfers. The remarkable properties of the Schroedinger equation for compound states of an arbitrary number of reggeized gluons in the multi-colour QCD are reviewed. The gauge-invariant effective action describing the gluon-Reggeon interactions is constructed. The known next-to-leading corrections to the QCD pomeron are discussed. (orig.)

Average gluon and quark jet multiplicities at higher orders

Energy Technology Data Exchange (ETDEWEB)

Bolzoni, Paolo; Kniehl, Bernd A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Kotikov, Anatoly V. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Joint Institute of Nuclear Research, Moscow (Russian Federation). Bogoliubov Lab. of Theoretical Physics

2013-05-15

We develop a new formalism for computing and including both the perturbative and nonperturbative QCD contributions to the scale evolution of average gluon and quark jet multiplicities. The new method is motivated by recent progress in timelike small-x resummation obtained in the MS factorization scheme. We obtain next-to-next-to-leading-logarithmic (NNLL) resummed expressions, which represent generalizations of previous analytic results. Our expressions depend on two nonperturbative parameters with clear and simple physical interpretations. A global fit of these two quantities to all available experimental data sets that are compatible with regard to the jet algorithms demonstrates by its goodness how our results solve a longstanding problem of QCD. We show that the statistical and theoretical uncertainties both do not exceed 5% for scales above 10 GeV. We finally propose to use the jet multiplicity data as a new way to extract the strong-coupling constant. Including all the available theoretical input within our approach, we obtain {alpha}{sub s}{sup (5)}(M{sub Z})=0.1199{+-}0.0026 in the MS scheme in an approximation equivalent to next-to-next-to-leading order enhanced by the resummations of ln(x) terms through the NNLL level and of ln Q{sup 2} terms by the renormalization group, in excellent agreement with the present world average.

Framework for Leading Next Generation Science Standards Implementation

Science.gov (United States)

Stiles, Katherine; Mundry, Susan; DiRanna, Kathy

2017-01-01

In response to the need to develop leaders to guide the implementation of the Next Generation Science Standards (NGSS), the Carnegie Corporation of New York provided funding to WestEd to develop a framework that defines the leadership knowledge and actions needed to effectively implement the NGSS. The development of the framework entailed…

Setting the renormalization scale in pQCD: Comparisons of the principle of maximum conformality with the sequential extended Brodsky-Lepage-Mackenzie approach

Energy Technology Data Exchange (ETDEWEB)

Ma, Hong -Hao [Chongqing Univ., Chongqing (People' s Republic of China); Wu, Xing -Gang [Chongqing Univ., Chongqing (People' s Republic of China); Ma, Yang [Chongqing Univ., Chongqing (People' s Republic of China); Brodsky, Stanley J. [Stanford Univ., Stanford, CA (United States); Mojaza, Matin [KTH Royal Inst. of Technology and Stockholm Univ., Stockholm (Sweden)

2015-05-26

A key problem in making precise perturbative QCD (pQCD) predictions is how to set the renormalization scale of the running coupling unambiguously at each finite order. The elimination of the uncertainty in setting the renormalization scale in pQCD will greatly increase the precision of collider tests of the Standard Model and the sensitivity to new phenomena. Renormalization group invariance requires that predictions for observables must also be independent on the choice of the renormalization scheme. The well-known Brodsky-Lepage-Mackenzie (BLM) approach cannot be easily extended beyond next-to-next-to-leading order of pQCD. Several suggestions have been proposed to extend the BLM approach to all orders. In this paper we discuss two distinct methods. One is based on the “Principle of Maximum Conformality” (PMC), which provides a systematic all-orders method to eliminate the scale and scheme ambiguities of pQCD. The PMC extends the BLM procedure to all orders using renormalization group methods; as an outcome, it significantly improves the pQCD convergence by eliminating renormalon divergences. An alternative method is the “sequential extended BLM” (seBLM) approach, which has been primarily designed to improve the convergence of pQCD series. The seBLM, as originally proposed, introduces auxiliary fields and follows the pattern of the β0-expansion to fix the renormalization scale. However, the seBLM requires a recomputation of pQCD amplitudes including the auxiliary fields; due to the limited availability of calculations using these auxiliary fields, the seBLM has only been applied to a few processes at low orders. In order to avoid the complications of adding extra fields, we propose a modified version of seBLM which allows us to apply this method to higher orders. As a result, we then perform detailed numerical comparisons of the two alternative scale-setting approaches by investigating their predictions for the annihilation cross section ratio R

QCD phenomenology of parton distribution functions at small x

International Nuclear Information System (INIS)

Tung, Wu-Ki

1990-09-01

The small x behavior of parton distributions is studied phenomenologically by examining in detail a series of QCD-evolved distribution sets obtained in a new global analysis of deep inelastic scattering and lepton-pair production experiments. The importance of 2-loop evolution is discussed. The main features and results of the global analysis are described. The range of small x behavior consistent with next-to-leading order QCD and current data is delineated. The extrapolated small x behavior is parameterized by effective Q-dependent power- and logarithmic-law parameters. Intriguing features of the evolution of these parameters with Q are presented. Alternative parametrizations based on the analytic solution for small x is also explored. 20 refs., 6 figs., 1 tab

Ethical challenges related to next of kin - nursing staffs' perspective.

Science.gov (United States)

Tønnessen, Siri; Solvoll, Betty-Ann; Brinchmann, Berit Støre

2016-11-01

Patients in clinical settings are not lonely islands; they have relatives who play a more or less active role in their lives. The purpose of this article is to elucidate the ethical challenges nursing staff encounter with patients' next of kin and to discuss how these challenges affect clinical practice. The study is based on data collected from ethical group discussions among nursing staff in a nursing home. The discussions took place in 2011 and 2012. The data were analysed and interpreted by using hermeneutic methodology. All the data have been anonymised and handled with confidentiality. Written informed consent was obtained from all participants. Ethical challenges relating to patients' next of kin were found to be an issue frequently discussed in the groups. Our findings indicate that next of kin have different characteristics, categorised as 'the professionals' and 'the shadows'. In this article, we will describe the next of kin's characteristics and the ethical challenges and practical implications that nursing staff experience in this connection. We will discuss the findings in the light of the four basic principles of medical ethics and propose interventions to help nurses manage ethical challenges related to next of kin. The study reveals the need to enhance nursing staffs' communicative and ethical skills on an individual level, but most importantly, to establish routines in clinical settings for informing and following up next of kin in a systematic and structured way. © The Author(s) 2015.

The three-loop splitting functions in QCD: The helicity-dependent case

Directory of Open Access Journals (Sweden)

S. Moch

2014-12-01

Full Text Available We present the next-to-next-to-leading order (NNLO contributions to the main splitting functions for the evolution of longitudinally polarized parton densities of hadrons in perturbative QCD. The quark–quark and gluon–quark splitting functions have been obtained by extending our previous all Mellin-N calculations to the structure function g1 in electromagnetic deep-inelastic scattering (DIS. Their quark–gluon and gluon–gluon counterparts have been derived using third-order fixed-N calculations of structure functions in graviton-exchange DIS, relations to the unpolarized case and mathematical tools for systems of Diophantine equations. The NNLO corrections to the splitting functions are small outside the region of small momentum fractions x where they exhibit a large double-logarithmic enhancement, yet the corrections to the evolution of the parton densities can be unproblematic down to at least x≈10−4.

AugerNext: innovative research studies for the next generation ground-based ultra-high energy cosmic ray experiment

Directory of Open Access Journals (Sweden)

Haungs Andreas

2013-06-01

Full Text Available The findings so far of the Pierre Auger Observatory and also of the Telescope Array define the requirements for a possible next generation experiment: it needs to be considerably increased in size, it needs a better sensitivity to composition, and it should cover the full sky. AugerNext aims to perform innovative research studies in order to prepare a proposal fulfilling these demands. Such R&D studies are primarily focused in the following areas iconsolidation of the detection of cosmic rays using MHz radio antennas; iiproof-of-principle of cosmic-ray microwave detection; iiitest of the large-scale application of a new generation photo-sensors; ivgeneralization of data communication techniques; vdevelopment of new ways of muon detection with surface arrays. These AugerNext studies on new innovative detection methods for a next generation cosmic-ray experiment are performed at the Pierre Auger Observatory. The AugerNext consortium consists presently of fourteen partner institutions from nine European countries supported by a network of European funding agencies and it is a principal element of the ASPERA/ApPEC strategic roadmaps.

Ian Ingram: Next Animals

DEFF Research Database (Denmark)

2015-01-01

Ian Ingram: Next Animals is an exhibition catalogue presenting research on the work by Ian Ingram in relation to his exhibition Next Animals at Nikolaj Kunsthal in 2015.......Ian Ingram: Next Animals is an exhibition catalogue presenting research on the work by Ian Ingram in relation to his exhibition Next Animals at Nikolaj Kunsthal in 2015....

Next-generation science information network for leading-edge applications

International Nuclear Information System (INIS)

Urushidani, S.; Matsukata, J.

2008-01-01

High-speed networks are definitely essential tools for leading-edge applications in many research areas, including nuclear fusion research. This paper describes a number of advanced features in the Japanese next-generation science information network, called SINET3, and gives researchers clues on the uses of advanced high-speed network for their applications. The network services have four categories, multiple layer transfer, enriched virtual private network, enhanced quality-of-service, and bandwidth on demand services, and comprise a versatile service platform. The paper also describes the network architecture and advanced networking capabilities that enable economical service accommodation and flexible network resource assignment as well as effective use of Japan's first 40-Gbps lines

Next-generation science information network for leading-edge applications

Energy Technology Data Exchange (ETDEWEB)

Urushidani, S. [National Institute of Informatics, 2-1-2 Hitotsubashi Chiyoda-ku, Tokyo 101-8430 (Japan)], E-mail: urushi@nii.ac.jp; Matsukata, J. [National Institute of Informatics, 2-1-2 Hitotsubashi Chiyoda-ku, Tokyo 101-8430 (Japan)

2008-04-15

High-speed networks are definitely essential tools for leading-edge applications in many research areas, including nuclear fusion research. This paper describes a number of advanced features in the Japanese next-generation science information network, called SINET3, and gives researchers clues on the uses of advanced high-speed network for their applications. The network services have four categories, multiple layer transfer, enriched virtual private network, enhanced quality-of-service, and bandwidth on demand services, and comprise a versatile service platform. The paper also describes the network architecture and advanced networking capabilities that enable economical service accommodation and flexible network resource assignment as well as effective use of Japan's first 40-Gbps lines.

Being next of kin to an elderly person with cancer

DEFF Research Database (Denmark)

Esbensen, Bente Appel

2010-01-01

Background: Being next of kin to an elderly person with cancer and its impact on everyday life has been sparsely researched. Such understanding is needed to support both the sufferers and their relatives in dealing with issues arising after a cancer diagnosis in old age. Aim: To illuminate...... the experience of life as next of kin to an elderly person with cancer. Method: A qualitative study was used to illuminate the experience of next of kin of elderly people with cancer. In total, 16 (mean age 61, range 42-80) persons were interviewed. Open-ended interviews were used to get closer...... to their experiences. Manifest and latent content analysis were used. Findings: Two main categories Transformations of roles and Changed frames of mind were identified, as well as four subcategories. The study showed that the cancer activated perceptions in the next of kin about aging and growing old. The onset...

Di-Jet Production in Photon-Photon Collisions at $\\sqrt{s}_{ee}$ = 161 and 172 GeV

CERN Document Server

Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barillari, T.; Barlow, Roger J.; Bartoldus, R.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bird, S.D.; Blobel, V.; Bloodworth, I.J.; Bobinski, M.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Burgard, C.; Burgin, R.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; del Pozo, L.A.; De Roeck, A.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Eatough, D.; Estabrooks, P.G.; Etzion, E.; Evans, H.G.; Fabbri, F.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Hargrove, C.K.; Hartmann, C.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hillier, S.J.; Hobson, P.R.; Hocker, James Andrew; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D.S.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lazic, D.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nellen, B.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schieck, J.; Schmitt, B.; Schmitt, S.; Schoning, A.; Schroder, Matthias; 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, R.; Soldner-Rembold, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Tanaka, S.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomson, M.A.; von Torne, E.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.

1999-01-01

Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies 161 and 172 GeV. The jets are reconstructed using a cone jet finding algorithm. The angular distributions of direct and double-resolved processes are measured and compared to the predictions of leading order and next-to-leading order perturbative QCD. The jet energy profiles are also studied. The inclusive two-jet cross-section is measured as a function of transverse energy and rapidity and compared to next-to-leading order perturbative QCD calculations. The inclusive two-jet cross-section as a function of rapidity is compared to the prediction of the leading order Monte Carlo generators PYTHIA and PHOJET. The Monte Carlo predictions are calculated with different parametrisations of the parton distributions of the photon. The influence of the `underlying event' has been studied to reduce the model dependence of the predicted jet cross-sections from the Monte Carlo generators.

Virtual photon interactions in high energy QCD

International Nuclear Information System (INIS)

Gieseke, S.

2001-07-01

We study the interactions of virtual photons in the high energy limit of quantum chromodynamics (QCD). The subject is discussed in terms of two closely linked applications: the calculation of the total cross section for γ * γ * -scattering and the description of DIS in the colour dipole model. We calculate virtual corrections in α s to the process γ * q → (qq)q and the tree level process γ * q → (qqg)q in the high energy limit. From this calculation we obtain one-loop corrections to the effective γ * -reggeon-qq-vertex in the helicity basis of the virtual photon and the qq-pair. The loop integrals for the virtual corrections have been performed and expressed in dimensional regularization in terms of logarithms and dilogarithms. We have convoluted the virtual one-loop matrix elements with tree level matrix elements and expressed the integrals over the phase space of the qq-pair explicitly in terms of a set of standard integrals. The real corrections have been calculated and, in case of the longitudinal polarization, expressed in factorized form. From these calculations, the impact factor of virtual photons will be determined, allowing for a first prediction of the total cross section for γ * γ * -scattering in the next-to-leading-log s approximation. The calculations in this thesis extend the photon wave function picture in the colour dipole model to next-to-leading order. For this purpose, the real corrections with a qqg final state are analyzed in transverse configuration space and interpreted as a first higher Fock component of the photon wave function. In addition, the matrix elements that have been calculated in this thesis are needed for the calculation of jet cross sections. (orig.)

Non-leading contributions in QCD: Summing the perturbative series

International Nuclear Information System (INIS)

Trentadue, L.

1984-01-01

This paper presents the results of a systematic analysis of the leading and non-leading contributions in perturbative QCD and addresses the question of logarithmic contributions to all orders of the perturbative series

QCD effects to Bjorken unpolarized sum rule for νN deep-inelastic scattering

International Nuclear Information System (INIS)

Alekhin, S I; Kataev, A L

2003-01-01

The possibility of the first measurement of Bjorken unpolarized sum rule for F 1 structure function of νN deep-inelastic scattering at neutrino factories is commented. The brief summary of various theoretical contributions to this sum rule is given. Using the next-to-leading set of parton distributions functions, we simulate the expected Q 2 -behaviour and emphasize that its measurement can allow us to determine the value of the QCD strong coupling constant α s with reasonable theoretical uncertainty, dominated by the ambiguity in the existing estimates of the twist-4 non-perturbative 1/Q 2 -effect

Color ordering in QCD

OpenAIRE

Schuster, Theodor

2013-01-01

We derive color decompositions of arbitrary tree and one-loop QCD amplitudes into color ordered objects called primitive amplitudes. Furthermore, we derive general fermion flip and reversion identities spanning the null space among the primitive amplitudes and use them to prove that all color ordered tree amplitudes of massless QCD can be written as linear combinations of color ordered tree amplitudes of $\\mathcal{N}=4$ super Yang-Mills theory.

Getting Ahead Three Steps to Take Your Career to the Next Level

CERN Document Server

Garfinkle, Joel A

2011-01-01

A leading executive coach pinpoints three vital traits necessary to advance your career In Getting Ahead, one of the top 50 executive coaches in the United States, Joel Garfinkle reveals his signature model for mastering three skills to take your career to the next level: Perception, Visibility, and Influence. The PVI-model of professional advancement will teach you to: (1) Actively promote yourself as an asset and valuable person inside the organization, (2) Increase your visibility to gain others' recognition and appreciation for your efforts and (3) Become a person of influence who makes ke

Phenomenology of QCD threshold resummation for gluino pair production at NNLL

Energy Technology Data Exchange (ETDEWEB)

Pfoh, Torsten

2013-02-15

We examine the impact of threshold resummation for the inclusive hadronic production cross section of gluino pairs at next-to-next-to-leading-logarithmic accuracy, compared to the exact next-to-leading- order cross section and the next-to-next-to-leading-order approximation. Here, we apply formulas derived recently in the classical Mellin-space formalism. Moreover, we give the analytic input for the alternative momentum-space formalism and discuss the crucial points of the numeric implementation. We find that soft resummation keeps the hadronic cross section close to the fixed next-to-leading-order result.

Implications of QCD radiative corrections on high-pT Higgs searches

International Nuclear Information System (INIS)

Banfi, Andrea; Cancino, Julián

2012-01-01

We discuss the effect of next-to-leading order (NLO) QCD corrections to the Higgsstrahlung process, where the Higgs boson decays to bottom quarks, using a partonic-level fully differential code. First we evaluate the impact of initial- and final-state gluon radiation on the reconstruction of a mass peak with the fat-jet analysis in the boosted regime at the LHC with √(s)=14 TeV as proposed in Butterworth et al. (2008). We then consider the current CMS search strategy for this channel and compare it to the fat-jet procedure at the LHC with √(s)=8 TeV. Both studies show that final-state QCD radiation has a sizeable effect and should be taken properly into account.

Next generation toroidal devices

International Nuclear Information System (INIS)

Yoshikawa, Shoichi

1998-10-01

A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one's view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)

Next generation toroidal devices

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, Shoichi [Princeton Plasma Physics Lab., Princeton Univ., NJ (United States)

1998-10-01

A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one`s view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)

A search for quark compositeness with the CDF detector at the Fermilab Collider

International Nuclear Information System (INIS)

Hessing, T.L.

1990-12-01

The inclusive jet cross section in p bar p collisions at √s = 1.8 TeV has been measured using jet clustering cone sizes of 0.4, 0.7 and 1.0. The cone size, R, is defined to be, R = √Δη 2 + Δφ 2 , where η = -ln tan θ/2, θ represents the polar angle and φ represents the azimuthal angle. A lower limit on the value of the composite scale parameter, Λ c , was determined to be 1100 GeV at the 95% confidence level using the cone size 1.0. Comparisons to both leading order Quantum Chromo Dynamics (QCD) and next-to-leading order QCD calculations have been made and no significant deviations from QCD observed. The dependence of the inclusive jet cross section on cone size has also been compared to next-to-leading order QCD. The measured cross section was found to grow larger with increasing cone size, more quickly than next-to-leading order QCD predicts. 89 refs., 61 figs., 44 tabs

Measurement of the differential cross sections for isolated direct photon pair production in pp¯ collisions at √(s)=1.96 TeV

International Nuclear Information System (INIS)

Abazov, V.M.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Anikeev, V.B.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D.V.; Banerjee, S.; Barberis, E.; Baringer, P.

2013-01-01

We present measurements of direct photon pair production cross sections using 8.5 fb −1 of data collected with the D0 detector at the Fermilab Tevatron pp ¯ collider. The results are presented as differential distributions of the photon pair invariant mass dσ/dM γγ , pair transverse momentum dσ/dp T γγ , azimuthal angle between the photons dσ/dΔϕ γγ , and polar scattering angle in the Collins–Soper frame dσ/d|cosθ ⁎ |. Measurements are performed for isolated photons with transverse momenta p T γ >18(17) GeV for the leading (next-to-leading) photon in p T , pseudorapidities |η γ | γγ >0.4. We present comparisons with the predictions from Monte Carlo event generators DIPHOX and RESBOS implementing QCD calculations at next-to-leading order, 2γNNLO at next-to-next-to-leading order, and SHERPA using matrix elements with higher-order real emissions matched to parton shower

Leading hadronic contributions to the running of the electroweak coupling constants from lattice QCD

International Nuclear Information System (INIS)

Burger, Florian; Jansen, Karl; Petschlies, Marcus; Pientka, Grit

2015-12-01

The quark-connected leading-order hadronic contributions to the running of the electromagnetic fine structure constant, α QED , and the weak mixing angle, θ W , are determined by a four-flavour lattice QCD computation with twisted mass fermions. Full agreement of the results with a phenomenological analysis is observed with an even comparable statistical uncertainty. We show that the uncertainty of the lattice calculation is dominated by systematic effects which then leads to significantly larger errors than obtained by the phenomenological analysis.

Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions

Science.gov (United States)

OPAL Collaboration; Ackerstaff, K.; et al.

Gluon jets are identified in e+e^- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the data compared to a next-to-leading order calculation without energy conservation. There is agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets.

Generation 'Next' and nuclear power

International Nuclear Information System (INIS)

Sergeev, A.A.

2001-01-01

My generation was labeled by Russian mass media as generation 'Next.' My technical education is above average. My current position is as a mechanical engineer in the leading research and development institute for Russian nuclear engineering for peaceful applications. It is noteworthy to point out that many of our developments were really first-of-a-kind in the history of engineering. However, it is difficult to grasp the importance of these accomplishments, especially since the progress of nuclear technologies is at a standstill. Can generation 'Next' be independent in their attitude towards nuclear power or shall we rely on the opinions of elder colleagues in our industry? (authors)

Achieving universal access to next generation networks

DEFF Research Database (Denmark)

Falch, Morten; Henten, Anders

The paper examines investment dimensions of next generation networks in a universal service perspective in a European context. The question is how new network infrastructures for getting access to communication, information and entertainment services in the present and future information society...

Next-generation wireless technologies 4G and beyond

CERN Document Server

Chilamkurti, Naveen; Chaouchi, Hakima

2013-01-01

This comprehensive text/reference examines the various challenges to secure, efficient and cost-effective next-generation wireless networking. Topics and features: presents the latest advances, standards and technical challenges in a broad range of emerging wireless technologies; discusses cooperative and mesh networks, delay tolerant networks, and other next-generation networks such as LTE; examines real-world applications of vehicular communications, broadband wireless technologies, RFID technology, and energy-efficient wireless communications; introduces developments towards the 'Internet o

Properties of three-body decay functions derived with time-like jet calculus beyond leading order

International Nuclear Information System (INIS)

Sugiura, Tetsuya

2002-01-01

Three-body decay functions in time-like parton branching are calculated using the jet calculus to the next-to-leading logarithmic (NLL) order in perturbative quantum chromodynamics (QCD). The phase space contributions from each of the ladder diagrams and interference diagrams are presented. We correct part of the results for the three-body decay functions calculated previously by two groups. Employing our new results, the properties of the three-body decay functions in the regions of soft partons are examined numerically. Furthermore, we examine the contribution of the three-body decay functions modified by the restriction resulting from the kinematical boundary of the phase space for two-body decay in the parton shower model. This restriction leads to some problems for the parton shower model. For this reason, we propose a new restriction introduced by the kinematical boundary of the phase space for two-body decay. (author)

Top quark mass effects in Higgs boson pair production up to NNLO

International Nuclear Information System (INIS)

Hoff, Jens

2016-09-01

We consider the production of pairs of Standard Model Higgs bosons via gluon fusion. Until recently the full dependence on the top quark mass M_t was not known at next-to-leading order. For this reason we apply an approximation based on the expansion for large top quark masses up to O(1/M"1"2_t). At next-to-next-to-leading order we avoid the calculation of real corrections via the soft-virtual approximation and obtain top quark mass corrections up to O(1/M"4_t). We use our results to estimate the residual uncertainty of the total cross section due to a finite top quark mass to be O(10%) at next-to-leading order and O(5%) at next-to-next-to-leading order.

Inspiring the Next Generation through Real Time Access to Ocean Exploration

Science.gov (United States)

Bell, K. L.; Ballard, R. D.; Witten, A. B.; O'Neal, A.; Argenta, J.

2011-12-01

Using live-access exposure to actual shipboard research activities where exciting discoveries are made can be a key contributor to engaging students and their families in learning about earth science and STEM subjects. The number of bachelor's degrees awarded annually in the Earth sciences peaked at nearly 8000 in 1984, and has since declined more than 50%; for the last several years, the number of bachelor's degrees issued in U.S. schools in the geosciences has hovered around 2500 (AGI, 2009). In 2008, the last year for which the data are published, only 533 Ph.D.s were awarded in Earth, Atmospheric and Ocean sciences (NSF, 2009). By 2030, the supply of geoscientists for the petroleum industry is expected to fall short of the demand by 30,000 scientists (AGI, 2009). The National Science Foundation (NSF) reports that minority students earn approximately 15% of all bachelor's degrees in science and engineering, but only 4.6% of degrees in the geosciences. Both of these percentages are very low in comparison to national and state populations, where Hispanics and African-Americans make up 29% of the U.S. overall. The Ocean Exploration Trust (OET) is a non-profit organization whose mission is to explore the world's ocean, and to capture the excitement of that exploration for audiences of all ages, but primarily to inspire and motivate the next generation of explorers. The flagship of OET's exploratory programs is the Exploration Vessel Nautilus, on which annual expeditions are carried out to support our mission. The ship is equipped with state of the art satellite telecommunications "telepresence" technology that enables 24/7 world-wide real time access to the data being collected by the ships remotely operated vehicles. It is this "live" access that affords OET and its partners the opportunity to engage and inspire audiences across the United States and abroad. OET has formed partnerships with a wide-range of educational organizations that collectively offer life

Next-Generation Pathology.