NNLO corrections for LHC processes
Caola, Fabrizio
2015-01-01
To fully profit from the remarkable achievements of the experimental program at the LHC, very precise theoretical predictions for signal and background processes are required. In this contribution, I will review some of the recent progress in fully exclusive next-to-next-toleading-order (NNLO) QCD computations. As an example of the phenomenological relevance of these results, I will present LHC predictions for t-channel single-top production and Higgs boson production in association with one hard jet.
NNLO corrections to the Higgs production cross section
Energy Technology Data Exchange (ETDEWEB)
Ravindran, V. [Harish-Chandra Research Institute, Chhatnag Road, Jhusii, Allahabad, 211019 (India); Smith, J. [C.N. Yang Institute for Theoretical Physics, State University of New York at Stony Brook, New York 11794-3840 (United States); Neerven, W.L. van [Instituut-Lorentz, Universiteit Leiden, PO Box 9506, 2300 RA Leiden (Netherlands)
2004-10-01
We discuss the next-to-next-to-leading order (NNLO) corrections to the total cross section for (pseudo-) scalar Higgs boson production. The computation is carried out in the e.ective Lagrangian approach which emerges from the standard model by taking the limit mt->{approx} where mt denotes the mass of the top quark.
NNLO corrections to the polarized Drell-Yan coefficient function
Energy Technology Data Exchange (ETDEWEB)
Ravindran, V. [Harish-Chandra Research Institute, Chhatnag Road, Jhusii, Allahabad, 211019 (India); Smith, J. [C.N. Yang Institute for Theoretical Physics, State University of New York at Stony Brook, New York 11794-3840 (United States); Neerven, W.L. van [Instituut-Lorentz, Universiteit Leiden, PO Box 9506, 2300 RA Leiden (Netherlands)
2004-10-01
We present the full next-to-next-to-leading order (NNLO) corrections to the coefficient function for the polarized cross section d{delta}{sigma}/dQ of the Drell-Yan process. We study the effect of these corrections on the process p+p->l+l-+'X' at an C.M. energy S=200GeV. All QCD partonic subprocesses have been included provided the lepton pair is created by a virtual photon, which is a valid approximation for a lepton pair invariant mass Q50GeV. For this reaction the dominant subprocess is given by q+q-bar ->{gamma}*+'X' and its higher order corrections so that it provides us with an excellent tool to measure the polarized sea-quark densities.
On the NNLO QCD corrections to single-top production at the LHC
Directory of Open Access Journals (Sweden)
Mathias Brucherseifer
2014-09-01
Full Text Available We present a fully-differential calculation of the NNLO QCD corrections to the t-channel mechanism for producing single top quarks at the LHC. We work in the structure function approximation, computing QCD corrections to the light- and heavy-quark lines separately and neglecting the dynamical cross-talk between the two. The neglected contribution, which appears at NNLO for the first time, is color-suppressed and is expected to be sub-dominant. Within this approximation, we find that, for the total cross section, NNLO QCD corrections are in the few percent range and, therefore, are comparable to NLO QCD corrections. We also find that the scale independence of the theoretical prediction for single-top production improves significantly once NNLO QCD corrections are included. Furthermore, we show how these results change if a cut on the transverse momentum of the top quark is applied and derive the NNLO QCD prediction for the ratio of single top and single anti-top production cross sections at the 8 TeV LHC.
arXiv Modeling NNLO jet corrections with neural networks
Carrazza, Stefano
2017-01-01
We present a preliminary strategy for modeling multidimensional distributions through neural networks. We study the efficiency of the proposed strategy by considering as input data the two-dimensional next-to-next leading order (NNLO) jet k-factors distribution for the ATLAS 7 TeV 2011 data. We then validate the neural network model in terms of interpolation and prediction quality by comparing its results to alternative models.
NNLO QCD corrections to $pp \\to \\gamma^* \\gamma^*$ in the large $N_F$ limit
Anastasiou, Charalampos; Chavez, Federico; Duhr, Claude; Lazopoulos, Achilleas; Mistlberger, Bernhard; Mueller, Romain
2014-01-01
We compute the NNLO QCD corrections for the hadroproduction of a pair of off-shell photons in the limit of a large number of quark flavors. We perform a reduction of the two-loop amplitude to master integrals and calculate the latter analytically as a Laurent series in the dimensional regulator using modern integration methods. Real radiation corrections are evaluated numerically with a direct subtraction of infrared limits which we cast in a simple factorized form. The results presented here constitute a gauge invariant part of the full NNLO corrections but are not necessarily dominant. We view this calculation as a step towards a complete computation. Our partial corrections to the total cross-section are about $1\\%-3\\%$ and vary with the virtuality of the two off-shell photons.
NNLO massive corrections to Bhabha scattering and theoretical precision of BabaYaga rate at NLO
Energy Technology Data Exchange (ETDEWEB)
Carloni Calame, C.M. [Southampton Univ. (United Kingdom). School of Physics; Czyz, H.; Gluza, J.; Gunia, M. [Silesia Univ., Katowice (Poland). Dept. of Field Theory and Particle Physics; Montagna, G. [Pavia Univ. (Italy). Dipt. di Fisica Nucleare e Teorica; INFN, Sezione di Pavia (Italy); Nicrosini, O.; Piccinini, F. [INFN, Sezione di Pavia (Italy); Riemann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Worek, M. [Bergische Univ., Wuppertal (Germany). Fachbereich Physik
2011-12-15
We provide an exact calculation of next-to-next-to-leading order (NNLO) massive corrections to Bhabha scattering in QED, relevant for precision luminosity monitoring at meson factories. Using realistic reference event selections, exact numerical results for leptonic and hadronic corrections are given and compared with the corresponding approximate predictions of the event generator BabaYaga rate at NLO. It is shown that the NNLO massive corrections are necessary for luminosity measurements with per mille precision. At the same time they are found to be well accounted for in the generator at an accuracy level below the one per mille. An update of the total theoretical precision of BabaYaga rate at NLO is presented and possible directions for a further error reduction are sketched. (orig.)
Calame, C. Carloni; Czyż, H.; Gluza, J.; Gunia, M.; Montagna, G.; Nicrosini, O.; Piccinini, F.; Riemann, T.; Worek, M.
2011-07-01
Virtual fermionic N f = 1 and N f = 2 contributions to Bhabha scattering are combined with realistic real corrections at next-to-next-to-leading order in QED. The virtual corrections are determined by the package bha_nnlo_hf, and real corrections with the Monte Carlo generators B hagen-1P h, H elac-P hegas and E khara. Numerical results are discussed at the energies of and with realistic cuts used at the Φ factory DANE, at the B factories PEP-II and KEK, and at the charm/τ factory BEPC II. We compare these complete calculations with the approximate ones realized in the generator B abaY aga@NLO used at meson factories to evaluate their luminosities. For realistic reference event selections we find agreement for the NNLO leptonic and hadronic corrections within 0.07% or better and conclude that they are well accounted for in the generator by comparison with the present experimental accuracy.
Energy Technology Data Exchange (ETDEWEB)
Carloni Calame, C. [Southampton Univ. (United Kingdom). School of Physics; Czyz, H.; Gluza, J.; Gunia, M. [Silesia Univ., Katowice (Poland). Dept. of Field Theory and Particle Physics; Montagna, G. [Pavia Univ. (Italy). Dipt. di Fisica Nucleare e Teorica; INFN, Sezione di Pavia (Italy); Nicrosini, O.; Piccinini, F. [INFN, Sezione di Pavia (Italy); Riemann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Worek, M. [Wuppertal Univ. (Germany). Fachbereich C Physik
2011-07-15
Virtual fermionic N{sub f}=1 and N{sub f}=2 contributions to Bhabha scattering are combined with realistic real corrections at next-to-next-to-leading order in QED. The virtual corrections are determined by the package BHANNLOHF, and real corrections with the Monte Carlo generators BHAGEN-1PH, HELAC-PHEGAS and EKHARA. Numerical results are discussed at the energies of and with realistic cuts used at the {phi} factory DA{phi}NE, at the B factories PEP-II and KEK, and at the charm/{tau} factory BEPC II. We compare these complete calculations with the approximate ones realized in the generator BABAYAGA rate at NLO used at meson factories to evaluate their luminosities. For realistic reference event selections we find agreement for the NNLO leptonic and hadronic corrections within 0.07% or better and conclude that they are well accounted for in the generator by comparison with the present experimental accuracy. (orig.)
NNLO QCD corrections to Higgs boson production at large transverse momentum
Chen, X; Gehrmann, T; Glover, E W N; Jaquier, M
2016-01-01
We derive the second-order QCD corrections to the production of a Higgs boson recoiling against a parton with finite transverse momentum, working in the effective field theory in which the top quark contributions are integrated out. To account for quark mass effects, we supplement the effective field theory result by the full quark mass dependence at leading order. Our calculation is fully differential in the final state kinematics and includes the decay of the Higgs boson to a photon pair. It allows one to make next-to-next-to-leading order (NNLO)-accurate theory predictions for Higgs-plus-jet final states and for the transverse momentum distribution of the Higgs boson, accounting for the experimental definition of the fiducial cross sections. The NNLO QCD corrections are found to be moderate and positive, they lead to a substantial reduction of the theory uncertainty on the predictions. We compare our results to 8 TeV LHC data from ATLAS and CMS. While the shape of the data is well-described for both experi...
NNLO QCD corrections to Higgs boson production at large transverse momentum
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.
NNLO QCD Corrections to the Drell-Yan Cross Section in Models of TeV-Scale Gravity
Ahmed, Taushif; Dhani, Prasanna K; Kumar, M C; Mathews, Prakash; Rana, Narayan; Ravindran, V
2016-01-01
The first results on the complete next-to-next-to-leading order (NNLO) Quantum Chromodynamic (QCD) corrections to the production of di-leptons at hadron colliders in large extra dimension models with spin-2 particles are reported in this article. In particular, we have computed these corrections to the invariant mass distribution of the di-leptons taking into account all the partonic subprocesses that contribute at NNLO. In these models, spin-2 particles couple through the energy-momentum tensor of the Standard Model (SM) with the universal coupling strength. The tensorial nature of the interaction and the presence of both quark annihilation and gluon fusion channels at the Born level make it challenging computationally and interesting phenomenologically. We have demonstrated numerically the importance of our results at the Large Hadron Collider (LHC) energies. The two loop corrections contribute an additional 10\\% to the total cross section. We find that the QCD corrections are not only large but also import...
Conservation laws, vertex corrections, and screening in Raman spectroscopy
Maiti, Saurabh; Chubukov, Andrey V.; Hirschfeld, P. J.
2017-07-01
We present a microscopic theory for the Raman response of a clean multiband superconductor, with emphasis on the effects of vertex corrections and long-range Coulomb interaction. The measured Raman intensity, R (Ω ) , is proportional to the imaginary part of the fully renormalized particle-hole correlator with Raman form factors γ (k ⃗) . In a BCS superconductor, a bare Raman bubble is nonzero for any γ (k ⃗) and diverges at Ω =2 Δmax , where Δmax is the largest gap along the Fermi surface. However, for γ (k ⃗) = constant, the full R (Ω ) is expected to vanish due to particle number conservation. It was sometimes stated that this vanishing is due to the singular screening by long-range Coulomb interaction. In our general approach, we show diagrammatically that this vanishing actually holds due to vertex corrections from the same short-range interaction that gives rise to superconductivity. We further argue that long-range Coulomb interaction does not affect the Raman signal for any γ (k ⃗) . We argue that vertex corrections eliminate the divergence at 2 Δmax . We also argue that vertex corrections give rise to sharp peaks in R (Ω ) at Ω <2 Δmin (the minimum gap along the Fermi surface), when Ω coincides with the frequency of one of the collective modes in a superconductor, e.g., Leggett and Bardasis-Schrieffer modes in the particle-particle channel, and an excitonic mode in the particle-hole channel.
Two-loop and n-loop eikonal vertex corrections
Kidonakis, Nikolaos
2003-01-01
I present calculations of two-loop vertex corrections with massive and massless partons in the eikonal approximation. I show that the $n$-loop result for the UV poles can be given in terms of the one-loop calculation.
String loop corrections from fusion of handles and vertex operators
Ooguri, H.; Sakai, N.
1987-10-01
Handle operators are introduced to describe nonlinear sigma models on higher genus surfaces by an operator formalism. Operator product expansions (fusions) among handle and vertex operators provide new sources of conformal symmetry breakings. Through the renormalization group equations, string-loop corrected equations of motion without one-particle reducible parts are derived to one-loop order. Work supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture (No. 61540200).
NNLO QCD corrections to the Drell-Yan cross section in models of TeV-scale gravity
Ahmed, Taushif; Banerjee, Pulak; Dhani, Prasanna K.; Kumar, M. C.; Mathews, Prakash; Rana, Narayan; Ravindran, V.
2017-01-01
The first results on the complete next-to-next-to-leading order (NNLO) Quantum Chromodynamic (QCD) corrections to the production of di-leptons at hadron colliders in large extra dimension models with spin-2 particles are reported in this article. In particular, we have computed these corrections to the invariant mass distribution of the di-leptons taking into account all the partonic sub-processes that contribute at NNLO. In these models, spin-2 particles couple through the energy-momentum tensor of the Standard Model with the universal coupling strength. The tensorial nature of the interaction and the presence of both quark annihilation and gluon fusion channels at the Born level make it challenging computationally and interesting phenomenologically. We have demonstrated numerically the importance of our results at Large Hadron Collider energies. The two-loop corrections contribute an additional 10% to the total cross section. We find that the QCD corrections are not only large but also important to make the predictions stable under renormalisation and factorisation scale variations, providing an opportunity to stringently constrain the parameters of the models with a spin-2 particle.
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.)
Ruiz-Femenia, Pedro
2014-01-01
We compute the dominant term in the expansion in rho=1-M_W/m_t of the unknown next-to-next-to-leading order (NNLO) nonresonant contributions to the e+ e- -> W+ W- b bbar total cross section at energies close to the top-antitop threshold. Our analytic result disagrees with a previous calculation by other authors [1]. We show that our determination has the correct infrared structure needed to cancel the divergences proportional to the top width arising in the resonant production of the same final state, and we point out to a missing contribution in the computation of [1] to explain the discrepancy.
NLO corrections to the gluon induced forward jet vertex from the high energy effective action
Chachamis, Grigorios; Madrigal, Jose Daniel; Vera, Agustin Sabio
2012-01-01
We determine both real and virtual next-to-leading order corrections to the gluon induced forward jet vertex, from the high energy effective action proposed by Lipatov. For these calculations we employ the same regularization and subtraction formalism developed in our previous work on the quark-initiated vertex. We find agreement with previous results in the literature.
Dominant NNLO corrections to four-fermion production near the W-pair production threshold
Actis, S; Falgari, P; Schwinn, C
2008-01-01
We calculate the parametrically dominant next-to-next-to-leading order corrections to four-fermion production e^- e^+ -> mu^- nubar_mu u dbar + X at centre-of-mass energies near the W-pair production threshold employing the method of unstable-particle effective theory. In total the correction is small, leading to a shift of 3 MeV in the W-mass measurement. We also discuss the implementation of realistic cuts and provide a result for the interference of single-Coulomb and soft radiative corrections that can easily be extended to include an arbitrary number of Coulomb photons.
Dominant NNLO Corrections to Four-Fermion Production at the WW Threshold
Actis, Stefano
2009-01-01
The recent evaluation of the parametrically dominant next-to-next-to-leading order corrections to four-fermion production near the W-pair threshold in the framework of unstable-particle effective theory is briefly summarized.
NNLO QCD corrections to t -channel single top quark production and decay
Berger, Edmond L.; Gao, Jun; Yuan, C.-P.; Zhu, Hua Xing
2016-10-01
We present a fully differential next-to-next-to-leading-order calculation of t -channel single top quark production and decay at the LHC under a narrow-width approximation and neglecting cross talk between incoming protons. We focus on the fiducial cross sections at 13 TeV, finding that the next-to-next-to-leading-order QCD corrections can reach the level of -6 %. The scale variations are reduced to the level of a percent. Our results can be used to improve experimental acceptance estimates and the measurements of the single top quark production cross section and the top quark electroweak couplings.
NNLO QCD corrections for Drell-Yan $p_T^Z$ and $\\phi^*$ observables at the LHC
Ridder, A Gehrmann-De; Glover, E W N; Huss, A; Morgan, T A
2016-01-01
Drell-Yan lepton pairs with finite transverse momentum are produced when the vector boson recoils against (multiple) parton emission(s), and is determined by QCD dynamics. At small transverse momentum, the fixed order predictions break down due to the emergence of large logarithmic contributions. This region can be studied via the $p_T^Z$ distribution constructed from the energies of the leptons, or through the $\\phi^*$ distribution that relies on the directions of the leptons. For sufficiently small transverse momentum, the $\\phi^*$ observable can be measured experimentally with better resolution. We study the small $p_T^Z$ and $\\phi^*$ distributions up to next-to-next-to-leading order (NNLO) in perturbative QCD. We compute the $\\phi^*$ distributions for the fully inclusive production of lepton pairs via $Z/\\gamma^*$ to NNLO and normalise them to the NNLO cross sections for inclusive $Z/\\gamma^*$ production. We compare our predictions with the $\\phi^*$ distribution measured by the ATLAS collaboration during ...
A spin-foam vertex amplitude with the correct semiclassical limit
Engle, Jonathan
2012-01-01
Spin-foam models are hoped to provide a dynamics for loop quantum gravity. All 4-d spin-foam models of gravity start from the Plebanski formulation, in which gravity is recovered from a topological field theory, BF theory, by the imposition of constraints, which, however, select not only the gravitational sector, but also unphysical sectors. We show that this is the root cause for terms beyond the required Feynman-prescribed exponential of i times the action in the semiclassical limit of the EPRL spin-foam vertex. By quantizing a condition isolating the gravitational sector, we modify the EPRL vertex, yielding what we call the proper EPRL vertex amplitude. This provides at last a vertex amplitude for loop quantum gravity with the correct semiclassical limit.
Vertex Corrections for Positive-Definite Spectral Functions of Simple Metals
Pavlyukh, Y.; Uimonen, A.-M.; Stefanucci, G.; van Leeuwen, R.
2016-11-01
We present a systematic study of vertex corrections in a homogeneous electron gas at metallic densities. The vertex diagrams are built using a recently proposed positive-definite diagrammatic expansion for the spectral function. The vertex function not only provides corrections to the well known plasmon and particle-hole scatterings, but also gives rise to new physical processes such as the generation of two plasmon excitations or the decay of the one-particle state into a two-particle-one-hole state. By an efficient Monte Carlo momentum integration we are able to show that the additional scattering channels are responsible for a reduction of the bandwidth, the appearance of a secondary plasmon satellite below the Fermi level, and a substantial redistribution of spectral weights. The feasibility of the approach for first-principles band-structure calculations is also discussed.
Perturbative Correction to Transverse Ward-Takahashi Relation for the Vector Vertex
Institute of Scientific and Technical Information of China (English)
HE Han-Xin; YU Hong-Wei
2003-01-01
We re-derive exactly the transverse Ward-Takahashi relation for the vector vertex in momentum space.The result shows that this transverse Ward-Takahashi relation in momentum space involves a perturbative correction term. We demonstrate explicitly that this transverse Ward-Takahashi relation is satisfied indeed at one-loop order.
Hague, J P
2003-01-01
I apply the newly developed dynamical cluster approximation (DCA) to the calculation of the electron and phonon dispersions in the two-dimensional Holstein model. In contrast to previous work, the DCA enables the effects of spatial fluctuations (non-local corrections) to be examined. Approximations neglecting and incorporating lowest-order vertex corrections are investigated. I calculate the phonon density of states, the renormalized phonon dispersion, the electron dispersion and electron spectral functions. I demonstrate how vertex corrections stabilize the solution, stopping a catastrophic softening of the (pi, pi) phonon mode. A kink in the electron dispersion is found in the normal state along the (zeta, zeta) symmetry direction in both the vertex- and non-vertex-corrected theories for low phonon frequencies, corresponding directly to the renormalized phonon frequency at the (pi, 0) point. This kink is accompanied by a sudden drop in the quasi-particle lifetime. Vertex and non-local corrections enhance th...
The staggered six-vertex model: Conformal invariance and corrections to scaling
Energy Technology Data Exchange (ETDEWEB)
Frahm, Holger [Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover (Germany); Seel, Alexander [Lehrstuhl für Theoretische Elektrotechnik und Photonik, Universität Siegen, Hölderlinstraße 3, 57068 Siegen (Germany)
2014-02-15
We study the emergence of non-compact degrees of freedom in the low energy effective theory for a class of Z{sub 2}-staggered six-vertex models. In the finite size spectrum of the vertex model this shows up through the appearance of a continuum of critical exponents. To analyze this part of the spectrum we derive a set of coupled nonlinear integral equations from the Bethe ansatz solution of the vertex model which allow to compute the energies of the system for a range of anisotropies and of the staggering parameter. The critical theory is found to be independent of the staggering. Its spectrum and density of states coincide with the SL(2,R)/U(1) Euclidean black hole conformal field theory which has been identified previously in the continuum limit of the vertex model for a particular ‘self-dual’ choice of the staggering. We also study the asymptotic behavior of subleading corrections to the finite size scaling and discuss our findings in the context of the conformal field theory.
The staggered six-vertex model: Conformal invariance and corrections to scaling
Frahm, Holger; Seel, Alexander
2014-02-01
We study the emergence of non-compact degrees of freedom in the low energy effective theory for a class of Z2-staggered six-vertex models. In the finite size spectrum of the vertex model this shows up through the appearance of a continuum of critical exponents. To analyze this part of the spectrum we derive a set of coupled nonlinear integral equations from the Bethe ansatz solution of the vertex model which allow to compute the energies of the system for a range of anisotropies and of the staggering parameter. The critical theory is found to be independent of the staggering. Its spectrum and density of states coincide with the SL(2,R)/U(1) Euclidean black hole conformal field theory which has been identified previously in the continuum limit of the vertex model for a particular ‘self-dual' choice of the staggering. We also study the asymptotic behavior of subleading corrections to the finite size scaling and discuss our findings in the context of the conformal field theory.
Color Singlet Production at NNLO in MCFM
Energy Technology Data Exchange (ETDEWEB)
Boughezal, Radja [Argonne; Campbell, John M. [Fermilab; Ellis, R. Keith [Durham U., IPPP; Focke, Christfried [Northwestern U.; Giele, Walter [Fermilab; Liu, Xiaohui [Maryland U.; Petriello, Frank [Northwestern U.; Williams, Ciaran [SUNY, Buffalo
2016-05-25
We present the implementation of several color-singlet final-state processes at Next-to-Next-to Leading Order (NNLO) accuracy in QCD to the publicly available parton-level Monte Carlo program MCFM. Specifically we discuss the processes $pp\\rightarrow H$, $pp\\rightarrow Z$, $pp\\rightarrow W$, $pp\\rightarrow HZ$, $pp\\rightarrow HW$ and $pp\\rightarrow\\gamma\\gamma$. Decays of the unstable bosons are fully included, resulting in a flexible fully differential Monte Carlo code. The NNLO corrections have been calculated using the non-local $N$-jettiness subtraction approach. Special attention is given to the numerical aspects of running MCFM for these processes at this order. We pay particular attention to the systematic uncertainties due to the power corrections induced by the $N$-jettiness regularization scheme and the evaluation time needed to run the hybrid openMP/MPI version of MCFM at NNLO on multi-processor systems.
Higgs production in gluon fusion beyond NNLO
Ball, Richard D; Forte, Stefano; Marzani, Simone; Ridolfi, Giovanni
2013-01-01
We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N3LO) in alpha_s with finite top mass. We argue that an accurate approximationcan be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N3LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.
Ridder, A Gehrmann-De; Glover, E W N; Huss, A; Morgan, T A
2016-01-01
We give a brief overview of our calculation of the next-to-next-to-leading order (NNLO) QCD corrections to Z+jet production in hadronic collisions. Phenomenological results are presented which comprise various differential distributions for 8 TeV proton-proton collisions. A significant reduction of the scale uncertainties is observed throughout as we move from NLO to NNLO. We further discuss how this calculation can be used to describe the inclusive Z-boson production at large transverse momentum. To this end, the theory prediction is compared to the measurements performed by the ATLAS and CMS collaborations at a centre-of-mass energy of 8 TeV. Here, the inclusion of NNLO QCD effects are found to result in a substantial improvement in the agreement between theory and data for the normalised distributions.
Two-body non-leptonic heavy-to-heavy decays at NNLO in QCD factorization
Huber, Tobias; Li, Xin-Qiang
2016-01-01
We evaluate in the framework of QCD factorization the two-loop vertex corrections to the decays $\\bar{B}_{(s)}\\to D_{(s)}^{(\\ast)+} \\, L^-$ and $\\Lambda_b \\to \\Lambda_c^+ \\, L^-$, where $L$ is a light meson from the set $\\{\\pi,\\rho,K^{(\\ast)},a_1\\}$. These decays are paradigms of the QCD factorization approach since only the colour-allowed tree amplitude contributes at leading power. Hence they are sensitive to the size of power corrections once their leading-power perturbative expansion is under control. Here we compute the two-loop ${\\cal O}(\\alpha_s^2)$ correction to the leading-power hard scattering kernels, and give the results for the convoluted kernels almost completely analytically. Our newly computed contribution amounts to a positive shift of the magnitude of the tree amplitude by $\\sim 2$\\%. We then perform an extensive phenomenological analysis to NNLO in QCD factorization, using the most recent values for non-perturbative input parameters. Given the fact that the NNLO perturbative correction and ...
Disorder Scattering in Magnetic Tunnel Junctions: Theory of Nonequilibrium Vertex Correction
Ke, Youqi; Xia, Ke; Guo, Hong
2008-04-01
We report a first principles formalism and its numerical implementation for treating quantum transport properties of nanoelectronic devices with atomistic disorder. We develop a nonequilibrium vertex correction (NVC) theory to handle the configurational average of random disorder at the density matrix level so that disorder effects to nonlinear and nonequilibrium quantum transport can be calculated from atomic first principles in a self-consistent and efficient manner. We implement the NVC into a Keldysh nonequilibrium Green’s function (NEGF) -based density functional theory (DFT) and apply the NEGF-DFT-NVC formalism to Fe/vacuum/Fe magnetic tunnel junctions with interface roughness disorder. Our results show that disorder has dramatic effects on the nonlinear spin injection and tunnel magnetoresistance ratio.
Yan, Jiawei; Ke, Youqi
2016-07-01
Electron transport properties of nanoelectronics can be significantly influenced by the inevitable and randomly distributed impurities/defects. For theoretical simulation of disordered nanoscale electronics, one is interested in both the configurationally averaged transport property and its statistical fluctuation that tells device-to-device variability induced by disorder. However, due to the lack of an effective method to do disorder averaging under the nonequilibrium condition, the important effects of disorders on electron transport remain largely unexplored or poorly understood. In this work, we report a general formalism of Green's function based nonequilibrium effective medium theory to calculate the disordered nanoelectronics. In this method, based on a generalized coherent potential approximation for the Keldysh nonequilibrium Green's function, we developed a generalized nonequilibrium vertex correction method to calculate the average of a two-Keldysh-Green's-function correlator. We obtain nine nonequilibrium vertex correction terms, as a complete family, to express the average of any two-Green's-function correlator and find they can be solved by a set of linear equations. As an important result, the averaged nonequilibrium density matrix, averaged current, disorder-induced current fluctuation, and averaged shot noise, which involve different two-Green's-function correlators, can all be derived and computed in an effective and unified way. To test the general applicability of this method, we applied it to compute the transmission coefficient and its fluctuation with a square-lattice tight-binding model and compared with the exact results and other previously proposed approximations. Our results show very good agreement with the exact results for a wide range of disorder concentrations and energies. In addition, to incorporate with density functional theory to realize first-principles quantum transport simulation, we have also derived a general form of
Khanpour, Hamzeh; Taheri Monfared, S.; Atashbar Tehrani, S.
2017-04-01
We extract polarized parton distribution functions (PPDFs), referred to as "KTA17," together with the highly correlated strong coupling αs from recent and up-to-date g1 and g2 polarized structure functions world data at next-to-next-to-leading order in perturbative QCD. The stability and reliability of the results are ensured by including nonperturbative target mass corrections as well as higher-twist terms which are particularly important at the large-x region at low Q2 . Their role in extracting the PPDFs in the nucleon is studied. Sum rules are discussed and compared with other results from the literature. This analysis is made by means of the Jacobi polynomials expansion technique to the DGLAP evolution. The uncertainties on the observables and on the PPDFs throughout this paper are computed using standard Hessian error propagation which served to provide a more realistic estimate of the PPDFs uncertainties.
Wγ and Zγ production at the LHC in NNLO QCD
Energy Technology Data Exchange (ETDEWEB)
Grazzini, Massimiliano [Physik-Institut, Universität Zürich,Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Kallweit, Stefan [PRISMA Cluster of Excellence, Institute of Physics, Johannes Gutenberg University,Staudingerweg 7, 55128 Mainz (Germany); Rathlev, Dirk [Physik-Institut, Universität Zürich,Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)
2015-07-16
We consider the production of Wγ and Zγ pairs at hadron colliders. We report on the complete fully differential computation of radiative corrections at next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation includes the leptonic decay of the vector boson with the corresponding spin correlations, off shell effects and final-state photon radiation. We present numerical results for pp collisions at 7 and 8 TeV and we compare them with available LHC data. In the case of Zγ production, the impact of NNLO corrections is generally moderate, ranging from 8% to 18%, depending on the applied cuts. In the case of Wγ production, the NNLO effects are more important, and range from 19% to 26%, thereby improving the agreement of the theoretical predictions with the data. As expected, the impact of QCD radiative corrections is significantly reduced when a jet veto is applied.
Wgamma and Zgamma production at the LHC in NNLO QCD
Grazzini, Massimiliano; Rathlev, Dirk
2016-01-01
We consider the production of Wgamma and Zgamma pairs at the LHC, and report on the fully differential computation of next-to-next-to-leading order (NNLO) corrections in QCD perturbation theory. The calculation includes leptonic vector-boson decays with the corresponding spin correlations, off-shell effects and final-state photon radiation. We present numerical results for pp collisions at 7 TeV, and compare them with available ATLAS data. In the case of Zgamma production, the impact of NNLO corrections is generally moderate, ranging from 8% to 17%, depending on the applied cuts. In the case of Wgamma production, the NNLO effects are more important, and range from 19% to 26%, thereby improving the agreement of the theoretical predictions with the data. As expected, a veto against jets significantly reduces the impact of QCD radiative corrections.
Top quark pair production at NNLO in the quark-antiquark channel
Abelof, Gabriel; Majer, Imre
2015-01-01
We present the derivation of the NNLO two-parton final state contributions to top pair production in the quark-antiquark channel proportionnal to the leading colour factor $N_c^2$. Together with the three and four-parton NNLO contributions derived in a previous publication, this enables us to complete the phenomenologically most important NNLO corrections to top pair hadro-production in this channel. We derive this two-parton contribution using the massive extension of the NNLO antenna subtraction formalism and implement those corrections in a parton-level event generator providing full kinematical information on all final state particles. Combining the new leading-colour contributions with the light quark contributions derived previously, we present NNLO differential distributions for LHC and Tevatron. We also compute the differential top quark forward-backward asymmetry at Tevatron and find that our results are in good agreement with the measurements by the D0 collaboration.
Kim, Taekwang; Kitazawa, Masakiyo
2016-01-01
We analyze the production rate of photons from the thermal medium above the deconfinement temperature with a quark propagator obtained from a lattice QCD numerical simulation. The photon-quark vertex is determined gauge-invariantly, so as to satisfy the Ward-Takahashi identity. The obtained photon production rate shows a suppression compared to perturbative results.
Jet production in the CoLoRFulNNLO method: event shapes in electron-positron collisions
Del Duca, Vittorio
2016-01-01
We present the CoLoRFulNNLO method to compute higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the computation of event shape observables in electron-positron collisions at NNLO accuracy and validate our code by comparing our predictions to previous results in the literature. We also calculate for the first time jet cone energy fraction at NNLO.
Towards NNLO accuracy for $\\varepsilon'/\\varepsilon$
Cerdà-Sevilla, M; Jäger, S; Kokulu, A
2016-01-01
The quantity $\\varepsilon'/\\varepsilon$ measures direct CP violation in Kaon decays. Recent SM predictions show a $2.9\\sigma$ tension with data, with the theoretical uncertainty dominating. As rapid progress on the lattice is bringing nonperturbative long-distance effects under control, a more precise knowledge of short-distance contributions is needed. We describe the first NNLO results for $\\varepsilon'/\\varepsilon$ and discuss future prospects, as well as issues of scheme dependence and the separation of perturbative and nonperturbative effects. Finally we also comment on the solution of the renormalisation-group evolution in one of the talks at this conference and present the correct solution.
Altmeyer, Michaela; Guterding, Daniel; Hirschfeld, P. J.; Maier, Thomas A.; Valentí, Roser; Scalapino, Douglas J.
2016-12-01
In the framework of a multiorbital Hubbard model description of superconductivity, a matrix formulation of the superconducting pairing interaction that has been widely used is designed to treat spin, charge, and orbital fluctuations within a random phase approximation (RPA). In terms of Feynman diagrams, this takes into account particle-hole ladder and bubble contributions as expected. It turns out, however, that this matrix formulation also generates additional terms which have the diagrammatic structure of vertex corrections. Here we examine these terms and discuss the relationship between the matrix-RPA superconducting pairing interaction and the Feynman diagrams that it sums.
Climbing NLO and NNLO Summits of Weak Decays
Buras, Andrzej J
2011-01-01
I describe the history of the calculations of NLO and NNLO QCD corrections to weak decays of mesons and particle-antiparticle mixing in the period 1988-2010. Also existing calculations of electroweak and QED corrections to these processes are included in this presentation. These efforts bear some analogies to the climbing of Himalayas and various expeditions by several teams of strongly motivated "climbers", acting mainly in Germany, Italy, Poland and Switzerland, allowed to move this field from the LO through the NLO to the NNLO level. The material is meant to be a guide to the rich literature on NLO and NNLO corrections in question and includes several anecdots related to the climbs that I was involved in. While, by no means this presentation should be regarded as a review of the size of NLO and NNLO corrections to weak decays, I hope that some of the comments made in the course of the presentation could turn out to be not only amusing but also instructive.
30 years, some 700 integrals, and 1 dessert, or: Electroweak two-loop corrections to the Zbb vertex
Dubovyk, I; Gluza, J; Riemann, T; Usovitsch, J
2016-01-01
The one-loop corrections to the weak mixing angle $\\sin^2\\theta_{eff}^b$ derived from the $Z{\\bar b}b$ vertex, are known since 1985. It took another 30 years to calculate the complete electroweak two-loop corrections to $\\sin^2\\theta_{eff}^b$. The main obstacle was the calculation of the O(700) bosonic two-loop vertex integrals with up to three mass scales, at $s=M_Z^2$. We did not perform the usual integral reduction and master evaluation, but chose a completely numerical approach, using two different calculational chains. One method relies on publicly available sector decomposition implementations. Further, we derived Mellin-Barnes (MB) representations, exploring the publicly available MB suite. We had to supplement the MB suite by two new packages: AMBRE~3, a Mathematica program, for the efficient treatment of non-planar integrals and MBnumerics for advanced numerics in the Minkowskian space-time. Our preliminary result for LL2016, the "dessert", for the electroweak bosonic two-loop contributions to $\\sin^...
Yan, Jiawei; Ke, Youqi
In realistic nanoelectronics, disordered impurities/defects are inevitable and play important roles in electron transport. However, due to the lack of effective quantum transport method, the important effects of disorders remain poorly understood. Here, we report a generalized non-equilibrium vertex correction (NVC) method with coherent potential approximation to treat the disorder effects in quantum transport simulation. With this generalized NVC method, any averaged product of two single-particle Green's functions can be obtained by solving a set of simple linear equations. As a result, the averaged non-equilibrium density matrix and various important transport properties, including averaged current, disordered induced current fluctuation and the averaged shot noise, can all be efficiently computed in a unified scheme. Moreover, a generalized form of conditionally averaged non-equilibrium Green's function is derived to incorporate with density functional theory to enable first-principles simulation. We prove the non-equilibrium coherent potential equals the non-equilibrium vertex correction. Our approach provides a unified, efficient and self-consistent method for simulating non-equilibrium quantum transport through disorder nanoelectronics. Shanghaitech start-up fund.
Drell-Yan Production at NNLL'+NNLO Matched to Parton Showers
Alioli, Simone; Berggren, Calvin; Tackmann, Frank J; Walsh, Jonathan R
2015-01-01
We present results for Drell-Yan production from the GENEVA Monte-Carlo framework. We combine the fully-differential NNLO calculation with higher-order resummation in the 0-jettiness resolution variable. The resulting parton-level events are further combined with parton showering and hadronization provided by PYTHIA8. The 0-jettiness resummation is carried out to NNLL', which consistently incorporates all singular virtual and real NNLO corrections. It thus provides a natural perturbative connection between the NNLO calculation and the parton shower regime, including a systematic assessment of perturbative uncertainties. In this way, inclusive observables are correct to NNLO, up to small power corrections in the resolution cutoff. Furthermore, the perturbative accuracy of 0-jet-like resummation variables is significantly improved beyond the parton shower approximation. We provide comparisons with LHC measurements of Drell-Yan production at 7 TeV from ATLAS, CMS, and LHCb. As already observed in $e^+e^-$ collis...
Higgs boson decay into b-quarks at NNLO accuracy
Del Duca, Vittorio; Somogyi, Gabor; Tramontano, Francesco; Trocsanyi, Zoltan
2015-01-01
We compute the fully differential decay rate of the Standard Model Higgs boson into b-quarks at next-to-next-to-leading order (NNLO) accuracy in alpha_S. We employ a general subtraction scheme developed for the calculation of higher order perturbative corrections to QCD jet cross sections, which is based on the universal infrared factorization properties of QCD squared matrix elements. We show that the subtractions render the various contributions to the NNLO correction finite. In particular, we demonstrate analytically that the sum of integrated subtraction terms correctly reproduces the infrared poles of the two-loop double virtual contribution to this process. We present illustrative differential distributions obtained by implementing the method in a parton level Monte Carlo program. The basic ingredients of our subtraction scheme, used here for the first time to compute a physical observable, are universal and can be employed for the computation of more involved processes.
Finite Size Vertex Correction to the Strong Decay of ηc and χc States and a Determination of αs(mc)
Institute of Scientific and Technical Information of China (English)
平荣刚; 姜焕清; 邹冰松
2002-01-01
We calculate the correction to the two-gluon decay width due to the finite extension of the vertex function. We obtain the corrected factor to the zero-range vertex γ=1.32,γ=1.45,γ=1.26 forηc,χc0,andχc2,respectively. With the decay width Г(ηc → 2g) we extract the value αs(mc) = 0.28 ± 0.05 which agrees with that calculated from the same correction to the process Г( J/ψ → 3g). This correction to the process Г(ηc → 2g) is not as large as that to the process Г(J/ψ → 3g).
W±Z production at hadron colliders in NNLO QCD
Directory of Open Access Journals (Sweden)
Massimiliano Grazzini
2016-10-01
Full Text Available We report on the first computation of the next-to-next-to-leading order (NNLO QCD corrections to W±Z production in proton collisions. We consider both the inclusive production of on-shell W±Z pairs at LHC energies and the total W±Z rates including off-shell effects of the W and Z bosons. In the off-shell computation, the invariant mass of the lepton pairs from the Z boson decay is required to be in a given mass window, and the results are compared with the corresponding measurements obtained by the ATLAS and CMS collaborations. The NNLO corrections range from 8% at s=7TeV to 11% at s=14TeV and significantly improve the agreement with the LHC data at s=7 and 8TeV.
W -boson plus jet differential distributions at NNLO in QCD
Boughezal, Radja; Liu, Xiaohui; Petriello, Frank
2016-12-01
We present a detailed phenomenological study of W -boson production in association with a jet through next-to-next-to-leading order (NNLO) in perturbative QCD. Fiducial cross sections and differential distributions for both 8 TeV and 13 TeV LHC collisions are presented, as are results for both the inclusive one-jet bin and the exclusive one-jet bin. Two different event selection criteria are considered: a general selection with standard cuts used in experimental analyses, and a boosted selection that focuses on high transverse momentum jets. We discuss the higher-order corrections in detail and identify for which observables and phase space regions the QCD perturbative expansion is under good theoretical control, and where additional work is needed. For most distributions and phase space regions the QCD perturbative expansion exhibits good convergence after the inclusion of the NNLO corrections.
Tazai, Rina; Yamakawa, Youichi; Tsuchiizu, Masahisa; Kontani, Hiroshi
2016-09-01
In various multiorbital systems, the emergence of the orbital fluctuations and their role on the pairing mechanism attract increasing attention. To achieve deep understanding on these issues, we perform a functional renormalization group (fRG) study for the two-orbital Hubbard model. The vertex corrections for the electron-boson coupling (U -VC), which are dropped in the Migdal-Eliashberg gap equation, are obtained by solving the RG equation. We reveal that the dressed electron-boson coupling for the charge channel Ûeffc becomes much larger than the bare Coulomb interaction Û 0 due to the U -VC in the presence of moderate spin fluctuations. For this reason, the attractive pairing interaction due to the charge or orbital fluctuations is enlarged by the factor (Ûeffc/Û0) 2≫1 . In contrast, the spin fluctuation pairing interaction is suppressed by the spin-channel U -VC, because of the relation Ûeffs≪Û 0 . The present study demonstrates that the orbital or charge fluctuation pairing mechanism can be realized in various multiorbital systems thanks to the U -VC, such as in Fe-based superconductors.
Driving Miss Data: Going Up a Gear to NNLO
Energy Technology Data Exchange (ETDEWEB)
Campbell, John M. [Fermilab; Ellis, R. Keith [Durham U., IPPP; Williams, Ciaran [SUNY, Buffalo
2017-03-29
In this paper we present a calculation of the $\\gamma+j$ process at next-to-next-to-leading order (NNLO) in QCD and compare the resulting predictions to 8 TeV CMS data. We find good agreement with the shape of the photon $p_T$ spectrum, particularly after the inclusion of additional electroweak corrections, but there is a tension between the overall normalization of the theoretical prediction and the measurement. We use our results to compute the ratio of $Z(\\to \\ell^+\\ell^-)+j$ to $\\gamma+j$ events as a function of the vector boson transverse momentum at NNLO, a quantity that is used to normalize $Z(\\rightarrow\
Energy Technology Data Exchange (ETDEWEB)
Goto, H. [Chiba Univ. (Japan). Graduate School of Science and Technology; Natsume, Y. [Department of Physics, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263 (Japan)
1996-01-01
Beyond Migdal`s theorem, a theoretical study on strong coupling superconductivity under quantizing magnetic fields in a system of an isotropic three-dimensional electron gas is reported. We consider the case of ultra-high magnetic fields, where electrons are confined only in the ground Landau level. Here, we treat the case in which the chemical potential becomes negative. The vertex correction is taken into account in the formulation, previously developed by the present authors in the expression of the Dyson-Eliashberg theory. A set of equations including the vertex correction up to infinite order is proposed under the condition that the Ward-Takahashi identity is exactly satisfied. Numerical results for demanded strength of the field H for a given concentration of the electron density N are also discussed in connection with the appearance of the Nambu-Goldstone mode with real velocity. (orig.).
A comparison of NNLO QCD predictions with 7 TeV ATLAS and CMS data for V+jet processes
Boughezal, Radja; Liu, Xiaohui; Petriello, Frank
2016-09-01
We perform a detailed comparison of next-to-next-to-leading order (NNLO) QCD predictions for the W+jet and Z+jet processes with 7 TeV experimental data from ATLAS and CMS. We observe excellent agreement between theory and data for most studied observables, which span several orders of magnitude in both cross section and energy. For some observables, such as the HT distribution, the NNLO QCD corrections are essential for resolving existing discrepancies between theory and data.
Universality of transverse-momentum resummation and hard factors at the NNLO
Energy Technology Data Exchange (ETDEWEB)
Catani, Stefano [INFN, Sezione di Firenze and Dipartimento di Fisica e Astronomia, Università di Firenze, I-50019 Sesto Fiorentino, Florence (Italy); Cieri, Leandro [Dipartimento di Fisica, Università di Roma “La Sapienza” and INFN, Sezione di Roma, I-00185 Rome (Italy); Florian, Daniel de [Departamento de Física, FCEYN, Universidad de Buenos Aires, (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Ferrera, Giancarlo [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, I-20133 Milan (Italy); Grazzini, Massimiliano [Institut für Theoretische Physik, Universität Zürich, CH-8057 Zürich (Switzerland)
2014-04-15
We consider QCD radiative corrections to the production of colorless high-mass systems in hadron collisions. The logarithmically-enhanced contributions at small transverse momentum are treated to all perturbative orders by a universal resummation formula that depends on a single process-dependent hard factor. We show that the hard factor is directly related to the all-order virtual amplitude of the corresponding partonic process. The direct relation is universal (process-independent), and it is expressed by an all-order factorization formula that we explicitly evaluate up to the next-to-next-to-leading order (NNLO) in QCD perturbation theory. Once the NNLO scattering amplitude is available, the corresponding hard factor is directly determined: it controls NNLO contributions in resummed calculations at full next-to-next-to-leading logarithmic accuracy, and it can be used in applications of the q{sub T} subtraction formalism to perform fully-exclusive perturbative calculations up to NNLO. The universality structure of the hard factor and its explicit NNLO form are also extended to the related formalism of threshold resummation.
Predictions for diphoton production at the LHC through NNLO in QCD
Campbell, John M; Li, Ye; Williams, Ciaran
2016-01-01
In this paper we present a next-to-next-to-leading order (NNLO) calculation of the process $pp\\rightarrow \\gamma\\gamma$ that we have implemented into the parton level Monte Carlo code MCFM. We do not find agreement with the previous calculation of this process in the literature. In addition to the $\\mathcal{O}(\\alpha_s^2)$ corrections present at NNLO, we include some effects arising at $\\mathcal{O}(\\alpha_s^3)$, namely those associated with gluon-initiated closed fermion loops. We investigate the role of this process in the context of studies of QCD at colliders and as a background for searches for new physics, paying particular attention to the diphoton invariant mass spectrum. We demonstrate that the NNLO QCD prediction for the shape of this spectrum agrees well with functional forms used in recent data-driven fits.
Drell-Yan production at NNLL'+NNLO matched to parton showers
Energy Technology Data Exchange (ETDEWEB)
Alioli, Simone [European Organization for Nuclear Research (CERN), Geneva (Switzerland). Theory Div.; Bauer, Christian W.; Walsh, Jonathan R. [California Univ., Berkeley (United States). Ernest Orlando Lawrence Berkeley National Laboratory; Berggren, Calvin [Texas Lutheran Univ., TX (United States); Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group
2015-08-15
We present results for Drell-Yan production from the GENEVA Monte-Carlo framework. We combine the fully-differential NNLO calculation with higher-order resummation in the 0-jettiness resolution variable. The resulting parton-level events are further combined with parton showering and hadronization provided by PYTHIA8. The 0-jettiness resummation is carried out to NNLL', which consistently incorporates all singular virtual and real NNLO corrections. It thus provides a natural perturbative connection between the NNLO calculation and the parton shower regime, including a systematic assessment of perturbative uncertainties. In this way, inclusive observables are correct to NNLO, up to small power corrections in the resolution cutoff. Furthermore, the perturbative accuracy of 0-jet-like resummation variables is significantly improved beyond the parton shower approximation. We provide comparisons with LHC measurements of Drell-Yan production at 7 TeV from ATLAS, CMS, and LHCb. As already observed in e{sup +}e{sup -} collisions, for resummation-sensitive observables, the agreement with data is noticeably improved by using a lower value of α{sub s}(M{sub Z})=0.1135.
Chang, Yao-Wen; Jin, Bih-Yaw
2012-01-14
Many-body perturbation theory is used to investigate the effect of π-electron correlations on the quasi-particle band structures of conjugated polymers at the level of the Pariser-Parr-Pople model. The self-consistent GW approximation with vertex corrections to both the self-energy and the polarization in Hedin's equations is employed in order to eliminate self-interaction errors and include the effects of electron-hole attraction in screening processes. The dynamic inverse dielectric function is constructed from the generalized plasmon-pole approximation with the static dressed polarization given by the coupled-perturbed Hartree-Fock equation. The bandgaps of trans-polyacetylene, trans-polyphenylenevinylene and poly(para)phenylene are calculated by both the Hartree-Fock and GW approximation, and a lowering of bandgaps due to electron correlations is found. We conclude that both dielectric screening and vertex corrections are important for calculating the quasi-particle bandgaps of conjugated polymers.
Nested soft-collinear subtractions in NNLO QCD computations
Energy Technology Data Exchange (ETDEWEB)
Caola, Fabrizio [CERN, Theoretical Physics Department, Geneva (Switzerland); IPPP, Durham University, Durham (United Kingdom); Melnikov, Kirill; Roentsch, Raoul [Institute for Theoretical Particle Physics, KIT, Karlsruhe (Germany)
2017-04-15
We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector where energies and angles of unresolved particles vanish in a correlated fashion is redundant and can be discarded. This simple observation allows us to formulate a transparent iterative subtraction procedure for double-real emission contributions, to demonstrate the cancellation of soft and collinear singularities in an explicit and (almost) process-independent way and to write the result of a NNLO calculation in terms of quantities that can be computed in four space-time dimensions. We illustrate this procedure explicitly in the simple case of O(α{sub s}{sup 2}) gluonic corrections to the Drell-Yan process of q anti q annihilation into a lepton pair. We show that this framework leads to fast and numerically stable computation of QCD corrections. (orig.)
Status Report of NNLO QCD Calculations
Klasen, M
2005-01-01
We review recent progress in next-to-next-to-leading order (NNLO) perturbative QCD calculations with special emphasis on results ready for phenomenological applications. Important examples are new results on structure functions and jet or Higgs boson production. In addition, we describe new calculational techniques based on twistors and their potential for efficient calculations of multiparticle amplitudes.
ZZ production at the LHC: Fiducial cross sections and distributions in NNLO QCD
Directory of Open Access Journals (Sweden)
Massimiliano Grazzini
2015-11-01
Full Text Available We consider QCD radiative corrections to the production of four charged leptons in the ZZ signal region at the LHC. We report on the complete calculation of the next-to-next-to-leading order (NNLO corrections to this process in QCD perturbation theory. Numerical results are presented for s=8 TeV, using typical selection cuts applied by the ATLAS and CMS Collaborations. The NNLO corrections increase the NLO fiducial cross section by about 15%, and they have a relatively small impact on the shape of the considered kinematical distributions. In the case of the ΔΦ distribution of the two Z candidates, the computed corrections improve the agreement of the theoretical prediction with the CMS data.
A Novel Vertex Affinity for Community Detection
Energy Technology Data Exchange (ETDEWEB)
Yoo, Andy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sanders, Geoffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henson, Van [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vassilevski, Panayot [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-10-05
We propose a novel vertex affinity measure in this paper. The new vertex affinity quantifies the proximity between two vertices in terms of their clustering strength and is ideal for such graph analytics applications as community detection. We also developed a framework that combines simple graph searches and resistance circuit formulas to compute the vertex affinity efficiently. We study the properties of the new affinity measure empirically in comparison to those of other popular vertex proximity metrics. Our results show that the existing metrics are ill-suited for community detection due to their lack of fundamental properties that are essential for correctly capturing inter- and intra-cluster vertex proximity.
Fully-differential NNLO predictions for vector-boson pair production with MATRIX
Wiesemann, Marius; Kallweit, Stefan; Rathlev, Dirk
2016-01-01
We review the computations of the next-to-next-to-leading order (NNLO) QCD corrections to vector-boson pair production processes in proton–proton collisions and their implementation in the numerical code MATRIX. Our calculations include the leptonic decays of W and Z bosons, consistently taking into account all spin correlations, off-shell effects and non-resonant contributions. For massive vector-boson pairs we show inclusive cross sections, applying the respective mass windows chosen by ATLAS and CMS to define Z bosons from their leptonic decay products, as well as total cross sections for stable bosons. Moreover, we provide samples of differential distributions in fiducial phase-space regions inspired by typical selection cuts used by the LHC experiments. For the vast majority of measurements, the inclusion of NNLO corrections significantly improves the agreement of the Standard Model predictions with data.
W-boson plus jet differential distributions at NNLO in QCD
Boughezal, Radja; Petriello, Frank
2016-01-01
We present a detailed phenomenological study of W-boson production in association with a jet through next-to-next-to-leading order (NNLO) in perturbative QCD. Fiducial cross sections and differential distributions for both 8 TeV and 13 TeV LHC collisions are presented, as are results for both the inclusive one-jet bin and the exclusive one-jet bin. Two different event selection criteria are considered: a general selection with standard cuts used in experimental analyses, and a boosted selection that focuses on high transverse momentum jets. We discuss the higher-order corrections in detail and identify for which observables and phase space regions the QCD perturbative expansion is under good theoretical control, and where additional work is needed. For most distributions and phase space regions the QCD perturbative expansion exhibits good convergence after the inclusion of the NNLO corrections.
W{sup ±}Z production at hadron colliders in NNLO QCD
Energy Technology Data Exchange (ETDEWEB)
Grazzini, Massimiliano; Wiesemann, Marius [Zuerich Univ. (Switzerland). Physik-Institut; Kallweit, Stefan [Mainz Univ. (Germany). PRISMA Cluster of Excellence, Inst. of Physics; California Univ., Santa Barbara, CA (United States). Kavli Inst. of Theoretical Physics; Rathlev, Dirk [DESY Hamburg (Germany). Theory Group
2016-04-15
We report on the first computation of the next-to-next-to-leading order (NNLO) QCD corrections to W{sup ±}Z production in proton collisions. We consider both the inclusive production of on-shell W{sup ±}Z pairs at LHC energies and the total W{sup ±}Z rates including off-shell effects of the W and Z bosons. In the off-shell computation, the invariant mass of the lepton pairs from the Z boson decay is required to be in a given mass window, and the results are compared with the corresponding measurements obtained by the ATLAS and CMS collaborations. The NNLO corrections range from 8% at √(s)=7 TeV to 11% at √(s)=14 TeV and significantly improve the agreement with the LHC data at √(s)=7 and 8 TeV.
Resummation of Jet Veto Logarithms at N$^3$LL$_a$ + NNLO for $W^+ W^-$ production at the LHC
Dawson, S; Li, Ye; Ramani, H; Zeng, Mao
2016-01-01
We compute the resummed on-shell $W^+ W^-$ production cross section under a jet-veto at the LHC at the approximate N$^3$LL+NNLO order. Differential NNLO cross sections are obtained from an implementation of $q_T$ subtraction in Sherpa. The two-loop virtual corrections to the $q \\bar q \\rightarrow W^+ W^-$ amplitude, used in both fixed order and resummation predictions, are extracted from the public code qqvvamp. We perform resummation using soft collinear effective theory (SCET), with approximate beam functions where only the logarithmic terms are included at two-loop. In addition to scale uncertainties from the hard matching scale and the factorization scale, rapidity scale variations are obtained within the analytic regulator approach. Our resummation results show a decrease in jet-veto cross-section compared to NNLO fixed order predictions, with reduced scale uncertainties compared to NNLL+NLO resummation predictions.
The global electroweak fit at NNLO and constraints on new physics
Baak, Max; Haller, Johannes; Hoecker, Andreas; Kogler, Roman; Mönig, K; Peiffer, Thomas; Schott, Matthias; Stelzer, Jörg
2015-01-01
We present an update of the global electroweak fit using electroweak next-to-next-to-leading order (NNLO) calculations for all precision observables that enter the fit. The availability of NNLO corrections allows for the first time the inclusion of realistic estimates of theoretical uncertainties due to missing higher order calculations. The knowledge of the mass of the Higgs boson improves the precision of the predictions in the global electroweak fit considerably and the global fits are used as powerful tools to assess the validity of the Standard Model and to constrain scenarios for new physics. We present updated constraints in a model with modified Higgs couplings to bosons and fermions, and two Higgs doublet models. We show that in many cases the Higgs signal strength measurements give complementary information to constraints obtained from electroweak precison observables. Future measurements at the LHC and an expected electron-positron collider promise to improve the experimental precision of key obser...
FDR, an easier way to NNLO calculations: a two-loop case study
Donati, Alice Maria
2013-01-01
In this paper we advertise the important simplifications produced by FDR in NNLO computations. We show that - due to its four-dimensionality - FDR does not require an order-by-order renormalization and that, unlike the one-loop case, FDR and dimensional regularization (DR) generate intermediate two-loop results which are no longer linked by a simple subtraction of the ultraviolet (UV) poles in epsilon. As an illustrative example, we re-derive the known two-loop result for H -> gamma gamma mediated by an infinitely heavy top loop in the presence of gluonic corrections. The calculation establishes FDR as a simpler and fully consistent approach to the UV problem at the two-loop level, that, in turn, is an essential ingredient toward purely numerical NNLO calculations.
Gluon induced contributions to WZ and W gamma production at NNLO
Adamson, K L; Signer, A
2002-01-01
We calculate the contribution of the partonic processes gg->WZ q\\bar{q} and gg -> W gamma q\\bar{q} to WZ and W gamma pair production at hadron colliders, including anomalous triple gauge-boson couplings. We use the helicity method and include the decay of the W and Z-boson into leptons in the narrow-width approximation. In order to integrate over the q\\bar{q} final state phase space we use an extended version of the subtraction method to NNLO and remove collinear singularities explicitly. Due to the large gluon density at low x, the gluon induced terms of vector-boson pair production are expected to be the dominant NNLO QCD correction, relevant at LHC energies. However, we show that due to a cancellation they turn out to provide a rather small contribution, anticipating good stability for the perturbative expansion.
Spinfoam Cosmology with the Proper Vertex
Vilensky, Ilya
2017-01-01
A modification of the EPRL vertex amplitude in the spin-foam framework of quantum gravity - so-called ``proper vertex amplitude'' - has been developed to enable correct semi-classical behavior to conform to the classical Regge calculus. The proper vertex amplitude is defined by projecting to the single gravitational sector. The amplitude is recast into an exponentiated form and we derive the asymptotic form of the projector part of the action. This enables us to study the asymptotics of the proper vertex by applying extended stationary phase methods. We use the proper vertex amplitude to investigate transition amplitudes between coherent quantum boundary states of cosmological geometries. In particular, Hartle-Hawking no-boundary states are computed in the proper vertex framework. We confirm that in the classical limit the Hartle-Hawking wavefunction satisfies the Hamiltonian constraint. Partly supported by NSF grants PHY-1205968 and PHY-1505490.
Virtual Hadronic Corrections to Massive Bhabha Scattering
Actis, Stefano; Riemann, Tord
2008-01-01
Virtual hadronic contributions to the Bhabha process at the NNLO level are discussed. They are substantial for predictions with per mil accuracy. The studies of heavy fermion and hadron corrections complete the calculation of Bhabha virtual effects at the NNLO level.
Charged Higgs production via vector-boson fusion at NNLO in QCD
Energy Technology Data Exchange (ETDEWEB)
Zaro, Marco; Maltoni, Fabio [Univ. Catholique de Louvain (Belgium). CP3; Bolzoni, Paolo [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2010-12-15
We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for single and double charged Higgs production via weak boson fusion. Results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses. (orig.)
Higgs production via vector-boson fusion at NNLO in QCD
Energy Technology Data Exchange (ETDEWEB)
Bolzoni, Paolo; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Maltoni, Fabio; Zaro, Marco [Catholique Univ. de Louvain, Louvain-la-Neuve (BE). Center for Particle Physics and Phenomenology (CP3)
2010-03-15
We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for Higgs production via weak boson fusion. Our results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses. (orig.)
Matching fully differential NNLO calculations and parton showers
Energy Technology Data Exchange (ETDEWEB)
Alioli, Simone; Bauer, Christian W.; Berggren, Calvin; Walsh, Jonathan R.; Zuberi, Saba [California Univ., Berkeley, CA (United States). Ernest Orlando Lawrence Berkeley National Laboratory; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-11-15
We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is based on consistently improving a given NNLO calculation with the leading-logarithmic (LL) resummation in a chosen jet resolution variable. The resulting NNLO+LL calculation is cast in the form of an event generator for physical events that can be directly interfaced with a parton shower routine, and we give an explicit construction of the input ''Monte Carlo cross sections'' satisfying all required criteria. We also show how other proposed approaches naturally arise as special cases in our method.
Matching Fully Differential NNLO Calculations and Parton Showers
Alioli, Simone; Berggren, Calvin; Tackmann, Frank J; Walsh, Jonathan R; Zuberi, Saba
2013-01-01
We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is based on consistently improving a given NNLO calculation with the leading-logarithmic (LL) resummation in a chosen jet resolution variable. The resulting NNLO$+$LL calculation is cast in the form of an event generator for physical events that can be directly interfaced with a parton shower routine, and we give an explicit construction of the input "Monte Carlo cross sections" satisfying all required criteria. We also show how other proposed approaches naturally arise as special cases in our method.
Chabanat, E; D'Hondt, J; Vanlaer, P; Prokofiev, K; Speer, T; Frühwirth, R; Waltenberger, W
2005-01-01
Because of the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ("vertex finding") and an estimation problem ("vertex fitting"). Starting from least-square methods, ways to render the classical algorithms more robust are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels.
Associated production of a Higgs boson at NNLO
Energy Technology Data Exchange (ETDEWEB)
Campbell, John M. [Fermi National Accelerator Laboratory,PO Box 500, Batavia, IL 60510 (United States); Ellis, R. Keith [Institute for Particle Physics Phenomenology,Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Williams, Ciaran [Department of Physics, University at Buffalo,The State University of New York, Buffalo 14260 (United States)
2016-06-30
In this paper we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all O(α{sub s}{sup 2}) contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the s-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. We study final states of interest for Run II phenomenology, namely H→bb̄, γγ and WW{sup ∗}. The treatment of the H→bb̄ decay includes QCD corrections at NLO. We use the recently developed N-jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying pp→V(H→WW{sup ∗})→ leptons.
Associated production of a Higgs boson at NNLO
Campbell, John M; Williams, Ciaran
2016-01-01
In this paper we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all $\\mathcal{O}(\\alpha_s^2)$ contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the $s$-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. We study final states of interest for Run II phenomenology, namely $H\\rightarrow b\\bar{b}$, $\\gamma\\gamma$ and $WW^*$. The treatment of the $H\\rightarrow b\\bar{b}$ decay includes QCD corrections at NLO. We use the recently developed $N$-jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying $pp\\rightarrow V(H\\rightarrow WW^*) \\rightarrow$ leptons.
NNLO QCD predictions for single jet inclusive production at the LHC
Currie, J; Pires, J
2016-01-01
We report the first calculation of fully differential jet production in all partonic channels at next-to-next-to leading order (NNLO) in perturbative QCD and compare to the available ATLAS 7 TeV data. We discuss the size and shape of the perturbative corrections along with their associated scale variation across a wide range in jet transverse momentum, $p_{T}$, and rapidity, $y$. We find significant effects, especially at low $p_{T}$, and discuss the possible implications for Parton Distribution Function fits.
Tensor structure function b{sub 1}{sup d}(x,Q{sup 2}) of the deuteron at NLO and NNLO at small-x
Energy Technology Data Exchange (ETDEWEB)
Islam, Saiful [R.G.I., Department of Physics, Assam, Guwahati (India); Choudhury, D.K. [Gauhati University, Department of Physics, Assam, Guwahati (India)
2012-12-15
The precision of the contemporary experimental data demands that the parton distribution functions (PDF's) should be corrected at least up to next-to-leading order (NLO) and preferably up to next-to-next-to-leading order (NNLO). A general form of tensor structure function b{sub 1}{sup d}(x,Q{sup 2}) of the deuteron at NLO and NNLO is obtained by using the solution of Dokshitzer, Gribov, Lipatov, Altarelli, Parisi (DGLAP) equation for singlet structure function at small-x. Results are compared with HERA Experiment data. (orig.)
Chen, Li; Shen, Cencheng; Vogelstein, Joshua; Priebe, Carey
2013-01-01
For random graphs distributed according to stochastic blockmodels, a special case of latent position graphs, adjacency spectral embedding followed by appropriate vertex classification is asymptotically Bayes optimal; but this approach requires knowledge of and critically depends on the model dimension. In this paper, we propose a sparse representation vertex classifier which does not require information about the model dimension. This classifier represents a test vertex as a sparse combinatio...
N-jettiness Subtractions for NNLO QCD Calculations
Gaunt, Jonathan; Tackmann, Frank J; Walsh, Jonathan R
2015-01-01
We present a subtraction method utilizing the N-jettiness observable, Tau_N, to perform QCD calculations for arbitrary processes at next-to-next-to-leading order (NNLO). Our method employs soft-collinear effective theory (SCET) to determine the IR singular contributions of N-jet cross sections for Tau_N -> 0, and uses these to construct suitable Tau_N-subtractions. The construction is systematic and economic, due to being based on a physical observable. The resulting NNLO calculation is fully differential and in a form directly suitable for combining with resummation and parton showers. We explain in detail the application to processes with an arbitrary number of massless partons at lepton and hadron colliders together with the required external inputs in the form of QCD amplitudes and lower-order calculations. We provide explicit expressions for the Tau_N-subtractions at NLO and NNLO. The required ingredients are fully known at NLO, and at NNLO for processes with two external QCD partons. The remaining NNLO ...
Soft factors for double parton scattering at NNLO
Vladimirov, Alexey
2016-01-01
We show at NNLO that the soft factors for double parton scattering (DPS) for both integrated and unintegrated kinematics, can be presented entirely in the terms of the soft factor for single Drell-Yan process, i.e. the transverse momentum dependent (TMD) soft factor. Using the linearity of logarithm of TMD soft factor in rapidity divergences, we decompose the DPS soft factor matrices into a product of matrices with rapidity divergences in given sectors, and thus, define individual double parton distributions at NNLO. The rapidity anomalous dimension matrices for double parton distributions are presented in terms of TMD rapidity anomalous dimension. The analysis is done using the generating function approach to web diagrams. Significant part of the result is obtained from the symmetry properties of web diagrams without referring to explicit expressions or a particular rapidity regularization scheme. Additionally we present NNLO expression for the web diagram generating function for Wilson lines with two light-...
Vector boson fusion NNLO in QCD. SM Higgs and beyond
Energy Technology Data Exchange (ETDEWEB)
Bolzoni, Paolo [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Maltoni, Fabio; Zaro, Marco [Catholique Univ. Louvain-la-Neuve (BE). Center for Cosmology, Particle Phyics and Phenomenology (CP3); Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2011-09-15
Weak vector boson fusion provides a unique channel to directly probe the mechanism of electroweak symmetry breaking at hadron colliders. We present a method that allows to calculate total cross sections to next-to-next-to-leading order (NNLO) in QCD for an arbitrary V{sup *}V{sup *}{yields}X process, the so-called structure function approach. By discussing the case of Higgs production in detail, we estimate several classes of previously neglected contributions and we argue that such method is accurate at a precision level well above the typical residual scale and PDF uncertainties at NNLO. Predictions for cross sections at the Tevatron and the LHC are presented for a variety of cases: the Standard Model Higgs (including anomalous couplings), neutral and charged scalars in extended Higgs sectors and (fermiophobic) vector resonance production. Further results can be easily obtained through the public use of the VBF rate at NNLO code. (orig.)
Soft factors for double parton scattering at NNLO
Energy Technology Data Exchange (ETDEWEB)
Vladimirov, Alexey [Institut für Theoretische Physik, Universität Regensburg,D-93040 Regensburg (Germany)
2016-12-13
We show at NNLO that the soft factors for double parton scattering (DPS) for both integrated and unintegrated kinematics, can be presented entirely in the terms of the soft factor for single Drell-Yan process, i.e. the transverse momentum dependent (TMD) soft factor. Using the linearity of the logarithm of TMD soft factor in rapidity divergences, we decompose the DPS soft factor matrices into a product of matrices with rapidity divergences in given sectors, and thus, define individual double parton distributions at NNLO. The rapidity anomalous dimension matrices for double parton distributions are presented in the terms of TMD rapidity anomalous dimension. The analysis is done using the generating function approach to web diagrams. Significant part of the result is obtained from the symmetry properties of web diagrams without referring to explicit expressions or a particular rapidity regularization scheme. Additionally, we present NNLO expression for the web diagram generating function for Wilson lines with two light-like directions.
Spinfoam cosmology with the proper vertex amplitude
Vilensky, Ilya
2016-01-01
The proper vertex amplitude is derived from the EPRL vertex by restricting to a single gravitational sector in order to achieve the correct semi-classical behaviour. We apply the proper vertex to calculate a cosmological transition amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform this calculation we deduce the integral form of the proper vertex and use extended stationary phase methods to estimate the large-volume limit. We show that the resulting amplitude satisfies an operator constraint whose classical analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker cosmology. We find that the constraint dynamically selects the relevant family of coherent states and demonstrate a similar dynamic selection in standard quantum mechanics.
Resummation of jet veto logarithms at N3LLa+NNLO for W+W- production at the LHC
Dawson, S.; Jaiswal, P.; Li, Ye; Ramani, Harikrishnan; Zeng, Mao
2016-12-01
We compute the resummed on-shell W+W- production cross section under a jet veto at the LHC to partial N3LL order matched to the fixed-order NNLO result. Differential NNLO cross sections are obtained from an implementation of qT subtraction in Sherpa. The two-loop virtual corrections to the q q ¯→W+W- amplitude, used in both fixed-order and resummation predictions, are extracted from the public code qqvvamp. We perform resummation using soft collinear effective theory, with approximate beam functions where only the logarithmic terms are included at two-loop. In addition to scale uncertainties from the hard matching scale and the factorization scale, rapidity scale variations are obtained within the analytic regulator approach. Our resummation results show a decrease in the jet veto cross section compared to NNLO fixed-order predictions, with reduced scale uncertainties compared to NNLL +NLO resummed predictions. We include the loop-induced g g contribution with jet veto resummation to NLL +LO . The prediction shows good agreement with recent LHC measurements.
Resummation of Jet Veto Logarithms at partial N$^3$LL + NNLO for $W^+W^-$ Production at the LHC
Energy Technology Data Exchange (ETDEWEB)
Dawson, S. [Brookhaven Natl. Lab.; Jaiswal, P. [Brown U.; Li, Ye [Fermilab; Ramani, H. [YITP, Stony Brook; Zeng, Mao [UCLA
2016-06-03
We compute the resummed on-shell $W^+ W^-$ production cross section under a jet-veto at the LHC to partial N$^3$LL order matched to the fixed order NNLO result. Differential NNLO cross sections are obtained from an implementation of $q_T$ subtraction in Sherpa. The two-loop virtual corrections to the $q \\bar q \\rightarrow W^+ W^-$ amplitude, used in both fixed order and resummation predictions, are extracted from the public code {\\tt qqvvamp}. We perform resummation using soft collinear effective theory (SCET), with approximate beam functions where only the logarithmic terms are included at two-loop. In addition to scale uncertainties from the hard matching scale and the factorization scale, rapidity scale variations are obtained within the analytic regulator approach. Our resummation results show a decrease in the jet-veto cross-section compared to NNLO fixed order predictions, with reduced scale uncertainties compared to NNLL+NLO resummed predictions. We include the loop-induced $gg$ contribution with jet veto resummation to NLL+LO. The prediction shows good agreement with recent LHC measurements.
Threshold pion production in proton-proton collisions at NNLO in chiral EFT
Baru, V.; Epelbaum, E.; Filin, A. A.; Hanhart, C.; Krebs, H.; Myhrer, F.
2016-05-01
The reaction NN → NN π offers a good testing ground for chiral effective field theory at intermediate energies. It challenges our understanding of the first inelastic channel in nucleon-nucleon scattering and of the charge symmetry breaking pattern in hadronic reactions. In our previous studies, we presented a complete calculation of the pion production operator for s -wave pions up-to-and-including next-to-next-to-leading order (NNLO) in the formulation of chiral effective field theory, which includes pions, nucleons and Δ(1232) degrees of freedom. In this paper we calculate the near-threshold cross section for the pp → d π+ reaction by performing the convolution of the obtained operators with nuclear wave functions based on modern phenomenological and chiral potentials. The available chiral NN wave functions are constructed with a cutoff comparable with the momentum transfer scale inherent in pion production reactions. Hence, a significant portion of the dynamical intermediate-range physics is thereby cut off by them. On the other hand, the NNLO amplitudes evaluated with phenomenological wave functions appear to be largely independent of the NN model used and give corrections to the dominant leading-order contributions as expected from dimensional analysis. The result gives support to the counting scheme used to classify the pion production operators, which is a precondition for a reliable investigation of the chirally suppressed neutral pion production. The explicit inclusion of the Δ(1232) is found to be important but smaller than expected due to cancellations.
Wermes, Norbert
2006-01-01
Pixel vertex detectors are THE instrument of choice for the tracking of charged particles close to the interaction point at the LHC. Hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as ...
Hung, Linda; da Jornada, Felipe H.; Souto-Casares, Jaime; Chelikowsky, James R.; Louie, Steven G.; Ã-ǧüt, Serdar
2016-08-01
We present first-principles calculations on the vertical ionization potentials (IPs), electron affinities (EAs), and singlet excitation energies on an aromatic-molecule test set (benzene, thiophene, 1,2,5-thiadiazole, naphthalene, benzothiazole, and tetrathiafulvalene) within the G W and Bethe-Salpeter equation (BSE) formalisms. Our computational framework, which employs a real-space basis for ground-state and a transition-space basis for excited-state calculations, is well suited for high-accuracy calculations on molecules, as we show by comparing against G0W0 calculations within a plane-wave-basis formalism. We then generalize our framework to test variants of the G W approximation that include a local density approximation (LDA)-derived vertex function (ΓLDA) and quasiparticle-self-consistent (QS) iterations. We find that ΓLDA and quasiparticle self-consistency shift IPs and EAs by roughly the same magnitude, but with opposite sign for IPs and the same sign for EAs. G0W0 and QS G W ΓLDA are more accurate for IPs, while G0W0ΓLDA and QS G W are best for EAs. For optical excitations, we find that perturbative G W -BSE underestimates the singlet excitation energy, while self-consistent G W -BSE results in good agreement with previous best-estimate values for both valence and Rydberg excitations. Finally, our work suggests that a hybrid approach, in which G0W0 energies are used for occupied orbitals and G0W0ΓLDA for unoccupied orbitals, also yields optical excitation energies in good agreement with experiment but at a smaller computational cost.
The Transverse Momentum Dependent Fragmentation Function at NNLO
Echevarria, Miguel G; Vladimirov, Alexey
2016-01-01
We calculate the unpolarized non-singlet transverse momentum dependent fragmentation function (TMDFF) at next-to-next-to-leading order (NNLO), evaluating separately TMD soft factor and TMD collinear correlator. For the first time the cancellation of spurious rapidity divergences in a properly defined individual TMD beyond the first non-trivial order is shown. This represents a strong check of the given TMD definition. We extract the matching coefficient necessary to perform the transverse momentum resummation at next-to-next-to-next-to-leading-logarithmic accuracy. The universal character of the soft function, which enters the definition of all (un)polarized TMD distribution/fragmentation functions, facilitates the future calculation of all the other TMDs and their coefficients at NNLO, pushing forward the accuracy of theoretical predictions for the current and next generation of high energy colliders.
The Orbifold Topological Vertex
Bryan, Jim; Young, Ben
2010-01-01
We define Donaldson-Thomas invariants of Calabi-Yau orbifolds and we develop a topological vertex formalism for computing them. The basic combinatorial object is the orbifold vertex, a generating function for the number of 3D partitions asymptotic to three given 2D partitions and colored by representations of a finite Abelian group G acting on C^3. In the case where G=Z_n acting on C^3 with transverse A_{n-1} quotient singularities, we give an explicit formula for the vertex in terms of Schur functions. We discuss applications of our formalism to the Donaldson-Thomas Crepant Resolution Conjecture and to the orbifold Donaldson-Thomas/Gromov-Witten correspondence. We also explicitly compute the Donaldson-Thomas partition function for some simple orbifold geometries: the local football and the local BZ_2 gerbe.
Cohomological vertex operators
Viña, Andrés
2016-01-01
Given a Calabi-Yau manifold and considering the $B$-branes on it as objects in the derived category of coherent sheaves, we identify the vertex operators for strings between two branes with elements of the cohomology groups of Ext sheaves. We define the correlation functions for these general vertex operators. Strings stretching between two coherent sheaves are studied as homological extensions of the corresponding branes. In this context, we relate strings between different pairs of branes when there are maps between these branes. We also interpret some strings with ghost number $k$ as obstructions for lifts or extensions of strings with ghost number $k-1$.
The Universal Transverse Momentum Dependent Soft Function at NNLO
Echevarria, Miguel G; Vladimirov, Alexey
2015-01-01
All (un)polarized transverse momentum dependent functions (TMDs), both distribution and fragmentation functions, are defined with the same universal soft function, which cancels spurious rapidity divergences within an individual TMD and renders them well-defined hadronic quantities. Moreover, it is independent of the kinematics, whether it is Drell-Yan ($e^+e^-\\rightarrow 2$ hadrons) or deep inelastic scattering. In this paper we provide this soft function at next-to-next-to-leading order (NNLO), necessary for the calculation of all TMDs at the same order, and to perform the resummation of large logarithms at next-to-next-to-next-to-leading-logarithmic accuracy. From the results we obtain the $D$ function at NNLO, which governs the evolution of all TMDs. This work represents the first independent and direct calculation of this quantity. Given the all order relation through a Casimir scaling between the soft function relevant for gluon TMDs and the one for quark TMDs, we also obtain the first at NNLO. The used...
On the plane-wave cubic vertex
Lucietti, J; Sinha, A K; Lucietti, James; Schäfer-Nameki, Sakura; Sinha, Aninda
2004-01-01
The exact bosonic Neumann matrices of the cubic vertex in plane-wave light-cone string field theory are derived using the contour integration techniques developed in our earlier paper. This simplifies the original derivation of the vertex. In particular, the Neumann matrices are written in terms of \\mu-deformed Gamma-functions, thus casting them into a form that elegantly generalizes the well-known flat-space solution. The asymptotics of the \\mu-deformed Gamma-functions allow one to determine the large-\\mu behaviour of the Neumann matrices including exponential corrections. We provide an explicit expression for the first exponential correction and make a conjecture for the subsequent exponential correction terms.
The fully differential hadronic production of a Higgs boson via bottom quark fusion at NNLO
Buehler, Stephan; Lazopoulos, Achilleas; Mueller, Romain
2012-01-01
The fully differential computation of the hadronic production cross section of a Higgs boson via bottom quarks is presented at NNLO in QCD. Several differential distributions with their corresponding scale uncertainties are presented for the 8 TeV LHC. This is the first application of the method of non-linear mappings for NNLO differential calculations at hadron colliders.
Threshold pion production in proton-proton collisions at NNLO in chiral EFT
Energy Technology Data Exchange (ETDEWEB)
Baru, V. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Epelbaum, E.; Filin, A.A.; Krebs, H. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Hanhart, C. [Forschungszentrum Juelich, Institut fuer Kernphysik, (Theorie) and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Myhrer, F. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States)
2016-05-15
The reaction NN→NNπ offers a good testing ground for chiral effective field theory at intermediate energies. It challenges our understanding of the first inelastic channel in nucleon-nucleon scattering and of the charge symmetry breaking pattern in hadronic reactions. In our previous studies, we presented a complete calculation of the pion production operator for s-wave pions up-to-and-including next-to-next-to-leading order (NNLO) in the formulation of chiral effective field theory, which includes pions, nucleons and Δ(1232) degrees of freedom. In this paper we calculate the near-threshold cross section for the pp → dπ{sup +} reaction by performing the convolution of the obtained operators with nuclear wave functions based on modern phenomenological and chiral potentials. The available chiral NN wave functions are constructed with a cutoff comparable with the momentum transfer scale inherent in pion production reactions. Hence, a significant portion of the dynamical intermediate-range physics is thereby cut off by them. On the other hand, the NNLO amplitudes evaluated with phenomenological wave functions appear to be largely independent of the NN model used and give corrections to the dominant leading-order contributions as expected from dimensional analysis. The result gives support to the counting scheme used to classify the pion production operators, which is a precondition for a reliable investigation of the chirally suppressed neutral pion production. The explicit inclusion of the Δ(1232) is found to be important but smaller than expected due to cancellations. (orig.)
Koch, N; Kolanoski, H; Siegmund, T; Bergter, J; Eckstein, P; Schubert, Klaus R; Waldi, R; Imhof, M; Ressing, D; Weiss, U; Weseler, S
1995-01-01
A fast second level trigger has been developed for the ARGUS experiment which recognizes tracks originating from the interaction region. The processor compares the hits in the ARGUS Micro Vertex Drift Chamber to 245760 masks stored in random access memories. The masks which are fully defined in three dimensions are able to reject tracks originating in the wall of the narrow beampipe of 10.5\\,mm radius.
Fermionic NNLO contributions to Bhabha scattering
Actis, S; Gluza, J; Riemann, T
2007-01-01
We derive the two-loop corrections to Bhabha scattering from heavy fermions using dispersion relations. The double-box contributions are expressed by three kernel functions. Convoluting the perturbative kernels with fermionic threshold functions or with hadronic data allows to determine numerical results for small electron mass m_e, combined with arbitrary values of the fermion mass m_f in the loop, $m_e^2<
Primary Vertex Reconstruction at the ATLAS Experiment
Grimm, Kathryn; The ATLAS collaboration
2016-01-01
Efficient and precise reconstruction of the primary vertex in an LHC collision is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. New methods have been developed by the ATLAS experiment to reconstruct vertices in such environments. Advances in vertex seeding include methods taken from medical imaging, which allow for reconstruction of multiple vertices with small spatial separation. The adoption of this new seeding algorithm within the ATLAS adaptive vertex finding and fitting procedure will be discussed, and the first results of the new techniques from Run-2 data will be presented. Additionally, data-driven methods to evaluate vertex resolution will be presented with special focus on correct methods to evaluate the effect of the beam spot constraint; results from these methods in Ru...
Jet p{sub T} resummation in Higgs production at NNLL'+NNLO
Energy Technology Data Exchange (ETDEWEB)
Stewart, Iain W. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Walsh, Jonathan R.; Zuberi, Saba [California Univ., Berkeley, CA (United States). Ernes Orlando Lawrence Berkeley National Laboratory
2013-07-15
We present predictions for Higgs production via gluon fusion with a p{sub T} veto on jets and with the resummation of jet-veto logarithms at NNLL'+NNLO order. These results incorporate explicit O({alpha}{sub s}{sup 2}) calculations of soft and beam functions, which include the dominant dependence on the jet radius R. In particular the NNLL' order accounts for the correct boundary conditions for the N{sup 3}LL resummation, for which the only unknown ingredients are higher-order anomalous dimensions. We use scale variations in a factorization theorem in both rapidity and virtuality space to estimate the perturbative uncertainties, accounting for both higher fixed-order corrections as well as higher-order towers of jet-p{sub T} logarithms. This formalism also predicts the correlations in the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At the values of R used experimentally, there are important corrections due to jet algorithm clustering that include logarithms of R. Although we do not sum logarithms of R, we do include an explicit contribution in our uncertainty estimate to account for higher-order jet clustering logarithms. Precision predictions for this H+0-jet cross section and its theoretical uncertainty are an integral part of Higgs analyses that employ jet binning.
Jet p_T Resummation in Higgs Production at NNLL'+NNLO
Stewart, Iain W; Walsh, Jonathan R; Zuberi, Saba
2013-01-01
We present predictions for Higgs production via gluon fusion with a p_T veto on jets and with the resummation of jet-veto logarithms at NNLL'+$NNLO order. These results incorporate explicit O(alphas^2) calculations of soft and beam functions, which include the dominant dependence on the jet radius R. In particular the NNLL' order accounts for the correct boundary conditions for the N3LL resummation, for which the only unknown ingredients are higher-order anomalous dimensions. We use scale variations in a factorization theorem in both rapidity and virtuality space to estimate the perturbative uncertainties, accounting for both higher fixed-order corrections as well as higher-order towers of jet-p_T logarithms. This formalism also predicts the correlations in the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At the values of R used experimentally, there are important corrections due to jet algorithm clustering that include logarithms of R. Although we do not sum logarithms of R, we do...
Frühwirth, R; Vanlaer, Pascal
2007-01-01
Vertex fitting frequently has to deal with both mis-associated tracks and mis-measured track errors. A robust, adaptive method is presented that is able to cope with contaminated data. The method is formulated as an iterative re-weighted Kalman filter. Annealing is introduced to avoid local minima in the optimization. For the initialization of the adaptive filter a robust algorithm is presented that turns out to perform well in a wide range of applications. The tuning of the annealing schedule and of the cut-off parameter is described, using simulated data from the CMS experiment. Finally, the adaptive property of the method is illustrated in two examples.
Dannheim, D
2015-01-01
The precision physics needs at TeV-scale linear electron-positron colliders (ILC and CLIC) require a vertex-detector system with excellent flavour-tagging capabilities through a meas- urement of displaced vertices. This is essential, for example, for an explicit measurement of the Higgs decays to pairs of b-quarks, c-quarks and gluons. Efficient identification of top quarks in the decay t → W b will give access to the ttH-coupling measurement. In addition to those requirements driven by physics arguments, the CLIC bunch structure calls for hit tim- ing at the few-ns level. As a result, the CLIC vertex-detector system needs to have excellent spatial resolution, full geometrical coverage extending to low polar angles, extremely low material budget, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations challenge current technological limits. A detector concept based on hybrid pixel-detector technology is under development for the CLIC ver- tex det...
A Mellin space program for W{sup {+-}} and Z{sup 0} production at NNLO
Energy Technology Data Exchange (ETDEWEB)
Kovacikova, Petra
2011-04-15
We present a program for the evaluation of full unpolarized cross sections for the W{sup {+-}} and Z{sup 0} production in the narrow width approximation at NNLO in perturbative QCD using Mellin space techniques. (orig.)
The Fully-Differential Quark Beam Function at NNLO
Gaunt, Jonathan R
2014-01-01
We present the first calculation of a fully-unintegrated parton distribution (beam function) at next-to-next-to-leading order (NNLO). We obtain the fully-differential beam function for quark-initiated processes by matching it onto standard parton distribution functions (PDFs) at two loops. The fully-differential beam function is a universal ingredient in resummed predictions of observables probing both the virtuality as well as the transverse momentum of the incoming quark in addition to its usual longitudinal momentum fraction. For such double-differential observables our result is an important contribution to the resummation of large logarithms related to collinear initial-state radiation (ISR) through N3LL.
ABM11 PDFs and the cross section benchmarks in NNLO
Alekhin, S; Moch, S -O
2013-01-01
We report an updated version of the ABKM09 NNLO PDF fit, which includes the most recent HERA collider data on the inclusive cross sections and an improved treatment of the heavy-quark contribution to deep-inelastic scattering using advantages of the running-mass definition for the heavy quarks. The ABM11 PDFs obtained from the updated fit are in a good agreement with the recent LHC data on the W- and Z-production within the experimental and PDF uncertainties. We also perform a determination of the strong coupling constant \\alpha_s in a variant of the ABM11 fit insensitive to the influence of the higher twist terms and find the value of \\alpha_s=0.1133(11) which is in good agreement with the nominal ABM11 one and our earlier determination.
Spin wave Feynman diagram vertex computation package
Price, Alexander; Javernick, Philip; Datta, Trinanjan
Spin wave theory is a well-established theoretical technique that can correctly predict the physical behavior of ordered magnetic states. However, computing the effects of an interacting spin wave theory incorporating magnons involve a laborious by hand derivation of Feynman diagram vertices. The process is tedious and time consuming. Hence, to improve productivity and have another means to check the analytical calculations, we have devised a Feynman Diagram Vertex Computation package. In this talk, we will describe our research group's effort to implement a Mathematica based symbolic Feynman diagram vertex computation package that computes spin wave vertices. Utilizing the non-commutative algebra package NCAlgebra as an add-on to Mathematica, symbolic expressions for the Feynman diagram vertices of a Heisenberg quantum antiferromagnet are obtained. Our existing code reproduces the well-known expressions of a nearest neighbor square lattice Heisenberg model. We also discuss the case of a triangular lattice Heisenberg model where non collinear terms contribute to the vertex interactions.
SusHi Bento: Beyond NNLO and the heavy-top limit
Harlander, Robert V; Mantler, Hendrik
2016-01-01
Version 1.6.0 of the code SusHi is presented. Concerning inclusive CP-even Higgs production in gluon fusion, the following new features with respect to previous versions have been implemented: expansion of the partonic cross section in the soft limit, i.e. around $x=M_H^2/\\hat{s}\\to 1$; N$^3$LO QCD corrections in terms of the soft expansion; top-quark mass suppressed terms through NNLO; matching to the cross section at $x\\to 0$ through N$^3$LO. For CP-even and -odd scalars, an efficient evaluation of the renormalization-scale dependence is included, and effects of dimension-5 operators can be studied, which we demonstrate for the SM Higgs boson and for a CP-even scalar with a mass of $750$ GeV. In addition, as a generalization of the previously available $b\\bar{b}\\to H$ cross section, SusHi 1.6.0 provides the cross section for charged and neutral Higgs production in the annihilation of arbitrary heavy quarks. At fixed order in perturbation theory, SusHi thus allows to obtain Higgs cross-section predictions in...
The STAR Vertex Position Detector
Llope, W J; Nussbaum, T; Hoffmann, G W; Asselta, K; Brandenburg, J D; Butterworth, J; Camarda, T; Christie, W; Crawford, H J; Dong, X; Engelage, J; Eppley, G; Geurts, F; Hammond, J; Judd, E; McDonald, D L; Perkins, C; Ruan, L; Scheblein, J; Schambach, J J; Soja, R; Xin, K; Yang, C
2014-01-01
The 2x3 channel pseudo Vertex Position Detector (pVPD) in the STAR experiment at RHIC has been upgraded to a 2x19 channel detector in the same acceptance, called the Vertex Position Detector (VPD). This detector is fully integrated into the STAR trigger system and provides the primary input to the minimum-bias trigger in Au+Au collisions. The information from the detector is used both in the STAR Level-0 trigger and offline to measure the location of the primary collision vertex along the beam pipe and the event "start time" needed by other fast-timing detectors in STAR. The offline timing resolution of single detector channels in full-energy Au+Au collisions is ~100 ps, resulting in a start time resolution of a few tens of picoseconds and a resolution on the primary vertex location of ~1 cm.
Extended technicolor contribution to the Zbb vertex
Hagiwara, K; Hagiwara, Kaoru; Kitazawa, Noriaki
1995-01-01
We show that the flavor-diagonal gauge boson of the extended technicolor theory contributes with opposite sign to the standard model correction for the Zbb vertex. This mechanism can naturally explain the deviation of the LEP result from the standard model prediction for the partial width \\Gamma(Z \\rightarrow b{\\bar b}). A smaller value of the QCD coupling, \\alpha_s(m_Z) \\simeq 0.115, is then preferred by the \\Gamma(Z \\rightarrow \\mbox{hadron}) data, which is consistent with both the recent Lattice-QCD estimate and the Particle Data Group average.
Some finite properties for vertex operator superalgebras
Dong, Chongying; Han, Jianzhi
2011-01-01
Vertex operator superalgebras are studied and various results on rational Vertex operator superalgebras are obtained. In particular, the vertex operator super subalgebras generated by the weight 1/2 and weight 1 subspaces are determined. It is also established that if the even part $V_{\\bar 0}$ of a vertex operator superalgebra $V$ is rational, so is $V.$
DEFF Research Database (Denmark)
Pinkevych, Mykola; Cromer, Deborah; Tolstrup, Martin
2016-01-01
[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.].......[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.]....
c, Aleksandar Ili\\'
2011-01-01
The vertex PI index is a distance--based molecular structure descriptor, that recently found numerous chemical applications. In order to increase diversity of this topological index for bipartite graphs, we introduce weighted version defined as $PI_w (G) = \\sum_{e = uv \\in E} (deg (u) + deg (v)) (n_u (e) + n_v (e))$, where $deg (u)$ denotes the vertex degree of $u$ and $n_u (e)$ denotes the number of vertices of $G$ whose distance to the vertex $u$ is smaller than the distance to the vertex $v$. We establish basic properties of $PI_w (G)$, and prove various lower and upper bounds. In particular, the path $P_n$ has minimal, while the complete tripartite graph $K_{n/3, n/3, n/3}$ has maximal weighed vertex $PI$ index among graphs with $n$ vertices. We also compute exact expressions for the weighted vertex PI index of the Cartesian product of graphs. Finally we present modifications of two inequalities and open new perspectives for the future research.
Mellin moments of heavy flavor contributions to F{sub 2}(x,Q{sup 2}) at NNLO
Energy Technology Data Exchange (ETDEWEB)
Klein, Sebastian Werner Gerhard
2009-10-15
The main parts of this thesis are the extension of the description of the contributions of heavy quark mass-effects to the deep-inelastic Wilson coefficients to NNLO. In course of that, we also obtain a first independent calculation of fixed moments of the fermionic parts of the NNLO anomalous dimensions. The calculation of the 3-loop heavy flavor Wilson coefficients in the whole Q{sup 2} region is currently not within reach. However, a very precise description of the heavy flavor Wilson coefficients contributing to the structure function F{sub 2}(x,Q{sup 2}) at NLO is obtained for Q{sup 2} >or similar 10 m{sub Q}{sup 2}, disregarding the power corrections {proportional_to}(m{sub Q}{sup 2}/Q{sup 2}){sup k}, k {>=} 1. If one considers the charm quark, this covers an important region for deep-inelastic physics at HERA. In this limit, the massive Wilson coefficients factorize into universal massive operator matrix elements (OMEs) A{sub ij}(x, {mu}{sup 2}/m{sub Q}{sup 2}) and the light flavor Wilson coefficients C{sub (q,g),(2,L)}(x,Q{sup 2}/{mu}{sup 2}). The former are process independent quantities and describe all quark mass effects. They are given by matrix elements of the leading twist local composite operators O{sub i} between partonic states j (i, j = q, g), including quark masses. The process dependence is described by the massless Wilson coefficients. (orig.)
NNLO QCD predictions for fully-differential top-quark pair production at the Tevatron
Czakon, Michal; Heymes, David; Mitov, Alexander
2016-01-01
We present a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks. All calculations are performed in NNLO QCD with the help of a fully differential partonic Monte-Carlo and are exact at this order in perturbation theory. We present predictions for all kinematic distributions for which data exists. Particular attention is paid on the top-quark forward-backward asymmetry which we study in detail. We compare the NNLO results with existing approximate NNLO predictions as well as differential distributions computed with different parton distribution sets. Theory errors are significantly smaller than current experimental ones with overall agreement between theory and data.
Belle II Silicon Vertex Detector
Mohanty, Gagan B
2015-01-01
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by a vertex detector, which comprises two layers of pixelated silicon detector and four layers of silicon vertex detector. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector that is aimed to be commissioned towards the middle of 2017.
NNLO contributions to inclusive-jet production in DIS and determination of \\alpha_s
Biekötter, T; Kramer, G
2015-01-01
We present the first calculation of inclusive jet production in deep-inelastic scattering with approximate next-to-next-to-leading order (aNNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients are computed analytically. We show that the aNNLO contributions reduce the theoretical prediction for jet production in deep-inelastic scattering, improve the description of the final HERA data in particular at high photon virtuality Q^2 and increase the central fit value of the strong coupling constant.
Hessian and graviton propagator of the proper vertex
Shirazi, Atousa Chaharsough; Vilensky, Ilya
2015-01-01
The proper spin-foam vertex amplitude is obtained from the EPRL vertex by projecting out all but a single gravitational sector, in order to achieve correct semi-classical behavior. In this paper we calculate the gravitational two-point function predicted by the proper spin-foam vertex to lowest order in the vertex expansion. We find the same answer as in the EPRL case in the `continuum spectrum' limit, so that the theory is consistent with the predictions of linearized gravity in the regime of small curvature. The method for calculating the two-point function is similar to that used in prior works: we cast it in terms of an action integral and to use stationary phase methods. Thus, the calculation of the Hessian matrix plays a key role. Once the Hessian is calculated, it is used not only to calculate the two-point function, but also to calculate the coefficient appearing in the semi-classical limit of the proper vertex amplitude itself. This coefficient is the effective discrete "measure factor" encoded in th...
SusHi bento. Beyond NNLO and the heavy-top limit
Energy Technology Data Exchange (ETDEWEB)
Harlander, Robert V. [RWTH Aachen Univ. (Germany). Inst. for Theoretical Particle Physics and Cosmology; Liebler, Stefan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mantler, Hendrik [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Physik; Karlsruher Institut fuer Technologie (KIT), Eggenstein-Leopoldshafen (Germany). Inst. fuer Experimentelle Kernphysik
2016-05-15
Version 1.6.0 of the code SusHi is presented. Concerning inclusive CP-even Higgs production in gluon fusion, the following new features with respect to previous versions have been implemented: expansion of the partonic cross section in the soft limit, i.e. around x=M{sup 2}{sub H}/s→1; N{sup 3}LO QCD corrections in terms of the soft expansion; top-quark mass suppressed terms through NNLO; matching to the cross section at x→0 through N{sup 3}LO. For CP-even and -odd scalars, an efficient evaluation of the renormalization-scale dependence is included, and effects of dimension-5 operators can be studied, which we demonstrate for the SM Higgs boson and for a CP-even scalar with a mass of 750 GeV. In addition, as a generalization of the previously available b anti b→H cross section, SusHi1.6.0 provides the cross section for charged and neutral Higgs production in the annihilation of arbitrary heavy quarks. At fixed order in perturbation theory, SusHi thus allows to obtain Higgs cross-section predictions in different models to the highest precision known today. For the SM Higgs boson of M{sub H}=125 GeV, SusHi yields 48.28 pb for the gluon-fusion cross section at the LHC at 13 TeV. Simultaneously, SusHi provides the renormalization-scale uncertainty of ±1.97 pb.
Energy Technology Data Exchange (ETDEWEB)
Abbiendi, G.; Braibant, S.; Capiluppi, P.; Ciocca, C.; Cuffiani, M.; Dallavalle, M.; Fabbri, F.; Giacomelli, G.; Giacomelli, P.; Mader, W.; Mes, H.; Renkel, P. [Univ. di Bologna (Italy); INFN, Bologna (Italy); Ainsley, C.; Batley, R.J.; Carter, J.R.; Hill, J.C.; Tasevsky, M.; Voss, H.; Vossebeld, J. [Cavendish Lab., Cambridge (United Kingdom); Aakesson, P.F.; Barberio, E.; Burckhart, H.J.; Roeck, A. de; Wolf, E.A. de; Ferrari, P.; Frey, A.; Gruwe, M.; Hauschild, M.; Hawkings, R.; Heuer, R.D.; McKenna, J.; Neal, H.A.; Pilcher, J.E.; Plane, D.E.; Przybycien, M.; Quadt, A.; Sachs, K.; Schaile, A.D.; Scharff-Hansen, P.; Schieck, J.; Schumacher, M.; Sherwood, P.; Stroehmer, R.; Torrence, E.; Vertesi, R.; Verzocchi, M.; Watson, A.T.; Watson, N.K. [European Organisation for Nuclear Research, CERN, Geneva 23 (Switzerland); Alexander, G.; Bella, G.; Etzion, E.; Grunhaus, J.; Trigger, I. [Tel Aviv Univ., Dept. of Physics and Astronomy, Tel Aviv (Israel); Anagnostou, G.; Bell, P.J.; Charlton, D.G.; Hawkes, C.M.; Jovanovic, P.; Nanjo, H.; Trocsanyi, Z.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Wermes, N. [Univ. of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Anderson, K.J.; Gupta, A.; Meijers, F.; O' Neale, S.W.; Pasztor, G.; Sobie, R.; Tarem, S. [Univ. of Chicago, Enrico Fermi Inst. and Dept. of Physics, Chicago, IL (United States); Asai, S.; Ishii, K.; Kanzaki, J.; Kawagoe, K.; Kawamoto, T.; Kobayashi, T.; Komamiya, S.; Martin, A.J.; Meyer, N.; Miller, D.J.; Mutter, A.; Nagai, K.; Oh, A.; Runge, K.; Thomson, M.A.; Tsur, E.; Wolf, G. [Univ. of Tokyo (Japan); Kobe Univ. (Japan); Axen, D.; Loebinger, F.K.; Mashimo, T. [Univ. of British Columbia, Dept. of Physics, Vancouver, BC (Canada); Bailey, I.; Karlen, D.; Keeler, R.K.; Maettig, P.; Rembser, C.; Skuja, A. [Univ. of Victoria (Canada); Barillari, T.; Bethke, S.; Kluth, S.; Oreglia, M.J.; Pooth, O.; Schaile, O. [Max-Planck-Inst. fuer Physik, Muenchen (Germany)] [and others
2011-09-15
Hadronic event shape distributions from e{sup +}e{sup -} annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong coupling {alpha}{sub S}. The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO + NLLA). The combined NNLO result from all variables and centre-of-mass energies is while the combined NNLO + NLLA result is The completeness of the NNLO and NNLO + NLLA results with respect to missing higher order contributions, studied by varying the renormalization scale, is improved compared to previous results based on NLO or NLO + NLLA predictions only. The observed energy dependence of {alpha}{sub S} agrees with the QCD prediction of asymptotic freedom and excludes the absence of running. (orig.)
Belle II silicon vertex detector
Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Enami, K.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.
2016-09-01
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.
Belle II silicon vertex detector
Energy Technology Data Exchange (ETDEWEB)
Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, Ti.; Baroncelli, To. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Università di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); and others
2016-09-21
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.
A cohomology theory of grading-restricted vertex algebras
Huang, Yi-Zhi
2010-01-01
We introduce a cohomology theory of grading-restricted vertex algebras. To construct the "correct" cohomologies, we consider linear maps from tensor powers of a grading-restricted vertex algebra to "rational functions valued in the algebraic completion of a module for the algebra," instead of linear maps from tensor powers of the algebra to a module for the algebra. One subtle complication arising from such "rational functions valued in the algebraic completion of a module" is that we have to carefully address the issue of convergence when we compose these linear maps with vertex operators. In particular, for each $n\\in \\N$, we have an inverse system $\\{H^{n}_{m}(V, W)\\}_{m\\in \\Z_{+}}$ of $n$-th cohomologies and an additional $n$-th cohomology $H_{\\infty}^{n}(V, W)$ of a grading-restricted vertex algebra $V$ with coefficients in a $V$-module $W$ such that $H_{\\infty}^{n}(V, W)$ is isomorphic to the inverse limit of the inverse system $\\{H^{n}_{m}(V, W)\\}_{m\\in \\Z_{+}}$. In the case of $n=2$, there is an addit...
Three-jet production in electron-positron collisions using the CoLoRFulNNLO method
Del Duca, Vittorio
2016-01-01
We introduce a subtraction method for jet cross sections at next-to-next-to-leading order (NNLO) accuracy in the strong coupling 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.
2002-01-01
Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.
The LHCb Vertex Locator performance and Vertex Locator upgrade
INSPIRE-00259789
2012-01-01
LHCb is an experiment dedicated to the study of new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is the silicon detector surrounding the LHCb interaction point. The detector operates in a severe and highly non-uniform radiation environment. The small pitch and analogue readout result in a best single hit precision of 4 $\\rm \\mu$m. The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz event rate. The vertex detector will have to cope with radiation levels up to 10$^{16}$ 1 MeV$\\rm n_{eq}/cm^2$, more than an order of magnitude higher than those expected at the current experiment. A solution is under development with a pixel detector, based on the Timepix/Medipix family of chips with 55 x 55 $\\rm \\mu m$ pixels. In addition a micro-strip solution is also under development, with finer pitch, higher granularity and lower mass than the current detector. The current...
AUTHOR|(SzGeCERN)734627
2015-01-01
A vertex-detector concept is under development for the proposed multi-TeV linear e+e- Compact Linear Collider (CLIC). To perform precision physics measurements in a chal- lenging environment, the CLIC vertex detector pushes the technological requirements to the limits. This paper reviews the requirements for the CLIC vertex detector and gives an over- view of recent R&D achievements in the domains of sensor, readout, powering and cooling.
Alipour Tehrani, Niloufar
2016-07-01
A vertex detector concept is under development for the proposed multi-TeV linear e+e- Compact Linear Collider (CLIC). To perform precision physics measurements in a challenging environment, the CLIC vertex detector pushes the technological requirements to the limits. This paper reviews the requirements for the CLIC vertex detector and gives an overview of recent R&D achievements in the domains of sensor, readout, powering and cooling.
The SUPERB silicon vertex tracker
Energy Technology Data Exchange (ETDEWEB)
Forti, F., E-mail: Francesco.Forti@pi.infn.it [INFN-Pisa and Universita di Pisa (Italy); Avanzini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Calderini, G.; Ceccanti, M.; Cenci, R.; Cervelli, A.; Crescioli, F.; Dell' Orso, M.; Giannetti, P.; Giorgi, M.A. [INFN-Pisa and Universita di Pisa (Italy); Lusiani, A. [Scuola Normale Superiore and INFN-Pisa (Italy); Gregucci, S.; Mammini, P.; Marchiori, G.; Massa, M.; Morsani, F.; Neri, N. [INFN-Pisa and Universita di Pisa (Italy)
2011-04-21
The SUPERB asymmetric e{sup +}e{sup -} collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10{sup 36} cm{sup -2} s{sup -1} with moderate beam currents, allowing precision measurements in the flavour sector sensitive to New Physics. The conceptual design of the Silicon Vertex Tracker for the SUPERB Detector is presented, based on double-sided silicon strip detectors for the outer layers, with the addition of an innermost Layer 0 close to the interaction point, with low material budget and capable of sustaining a background rate of several MHz/cm{sup 2}.
The CDF Silicon Vertex Detector
Energy Technology Data Exchange (ETDEWEB)
Tkaczyk, S.; Carter, H.; Flaugher, B. [and others
1993-09-01
A silicon strip vertex detector was designed, constructed and commissioned at the CDF experiment at the Tevatron collider at Fermilab. The mechanical design of the detector, its cooling and monitoring are presented. The front end electronics employing a custom VLSI chip, the readout electronics and various components of the SVX system are described. The system performance and the experience with the operation of the detector in the radiation environment are discussed. The device has been taking colliding beams data since May of 1992, performing at its best design specifications and enhancing the physics program of CDF.
A new construction for vertex decomposable graphs
Directory of Open Access Journals (Sweden)
Nasser Hajisharifi
2016-09-01
Full Text Available Let G be a finite simple graph on the vertex set V(G and let S⊆V(G. Adding a whisker to G at x means adding a new vertex y and edge xy to G where x∈V(G. The graph G∪W(S is obtained from G by adding a whisker to every vertex of S. We prove that if G∖S is either a graph with no chordless cycle of length other than 3 or 5, chordal graph or C5, then G∪W(S is a vertex decomposable graph.
NNLO contributions to jet photoproduction and determination of \\alpha_s
Klasen, M; Michael, M
2013-01-01
We present the first calculation of inclusive jet photoproduction with next-to-next-to-leading order (NNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved NNLO contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced.
NNLO contributions to jet photoproduction and determination of {alpha}{sub s}
Energy Technology Data Exchange (ETDEWEB)
Klasen, Michael; Michael, Markus [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2013-10-15
We present the first calculation of inclusive jet photoproduction with next-to-next-to-leading order (NNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved NNLO contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced.
Parton distribution functions at LO, NLO and NNLO with correlated uncertainties between orders
:,; Britzger, D; Camarda, S; Cooper-Sarkar, A M; Diaconu, C; Feltesse, J; Gizhko, A; Glazov, A; Kolesnikov, V; Lohwasser, K; Luszczak, A; Myronenko, V; Pirumov, H; Placakyte, R; Rabbertz, K; Radescu, V; Sapronov, A; Schoenig, A; Shushkevich, S; Slominski, W; Starovoitov, P; Sutton, M; Tomaszewska, J; Turkot, O; Watt, G; Wichmann, K; Lisovyi, M
2014-01-01
Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter program using the data from the HERA experiments and preserving correlations between uncertainties for the LO, NLO and NNLO PDF sets. The sets are used to study cross-section ratios and their uncertainties when calculated at different orders in QCD. A reduction of the overall theoretical uncertainty is observed if correlations between the PDF sets are taken into account for the ratio of $WW$ di-boson to $Z$ boson production cross sections at the LHC.
Proposed proper Engle-Pereira-Rovelli-Livine vertex amplitude
Engle, Jonathan
2013-04-01
As established in a prior work of the author, the linear simplicity constraints used in the construction of the so-called “new” spin-foam models mix three of the five sectors of Plebanski theory as well as two dynamical orientations, and this is the reason for multiple terms in the asymptotics of the Engle-Pereira-Rovelli-Livine vertex amplitude as calculated by Barrett et al. Specifically, the term equal to the usual exponential of i times the Regge action corresponds to configurations either in sector (II+) with positive orientation or sector (II-) with negative orientation. The presence of the other terms beyond this cause problems in the semiclassical limit of the spin-foam model when considering multiple 4-simplices due to the fact that the different terms for different 4-simplices mix in the semiclassical limit, leading in general to a non-Regge action and hence non-Regge and nongravitational configurations persisting in the semiclassical limit. To correct this problem, we propose to modify the vertex so its asymptotics include only the one term of the form eiSRegge. To do this, an explicit classical discrete condition is derived that isolates the desired gravitational sector corresponding to this one term. This condition is quantized and used to modify the vertex amplitude, yielding what we call the “proper Engle-Pereira-Rovelli-Livine vertex amplitude.” This vertex still depends only on standard SU(2) spin-network data on the boundary, is SU(2) gauge-invariant, and is linear in the boundary state, as required. In addition, the asymptotics now consist in the single desired term of the form eiSRegge, and all degenerate configurations are exponentially suppressed. A natural generalization to the Lorentzian signature is also presented.
2002-01-01
The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption. The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.
Directory of Open Access Journals (Sweden)
2012-01-01
Full Text Available Regarding Gorelik, G., & Shackelford, T.K. (2011. Human sexual conflict from molecules to culture. Evolutionary Psychology, 9, 564–587: The authors wish to correct an omission in citation to the existing literature. In the final paragraph on p. 570, we neglected to cite Burch and Gallup (2006 [Burch, R. L., & Gallup, G. G., Jr. (2006. The psychobiology of human semen. In S. M. Platek & T. K. Shackelford (Eds., Female infidelity and paternal uncertainty (pp. 141–172. New York: Cambridge University Press.]. Burch and Gallup (2006 reviewed the relevant literature on FSH and LH discussed in this paragraph, and should have been cited accordingly. In addition, Burch and Gallup (2006 should have been cited as the originators of the hypothesis regarding the role of FSH and LH in the semen of rapists. The authors apologize for this oversight.
Directory of Open Access Journals (Sweden)
2014-01-01
Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].
2015-10-01
In the article by Quintavalle et al (Quintavalle C, Anselmi CV, De Micco F, Roscigno G, Visconti G, Golia B, Focaccio A, Ricciardelli B, Perna E, Papa L, Donnarumma E, Condorelli G, Briguori C. Neutrophil gelatinase–associated lipocalin and contrast-induced acute kidney injury. Circ Cardiovasc Interv. 2015;8:e002673. DOI: 10.1161/CIRCINTERVENTIONS.115.002673.), which published online September 2, 2015, and appears in the September 2015 issue of the journal, a correction was needed. On page 1, the institutional affiliation for Elvira Donnarumma, PhD, “SDN Foundation,” has been changed to read, “IRCCS SDN, Naples, Italy.” The institutional affiliation for Laura Papa, PhD, “Institute for Endocrinology and Experimental Oncology, National Research Council, Naples, Italy,” has been changed to read, “Institute of Genetics and Biomedical Research, Milan Unit, Milan, Italy” and “Humanitas Research Hospital, Rozzano, Italy.” The authors regret this error.
Internal alignement of the BABAR silicon vertex tracking detector
Brown, D; Roberts, D
2007-01-01
The BABAR Silicon Vertex Tracker (SVT ) is a five-layer double-sided silicon detector designed to provide precise measurements of the position and direction of primary tracks, and to fully reconstruct low-momentum tracks produced in e+e¡ collisions at the PEP-II asymmetric collider at Stanford Linear Accelerator Center. This paper describes the design, implementation, performance and validation of the local alignment procedure used to determine the relative positions and orientations of the 340 Silicon Vertex Trackerwafers. This procedure uses a tuned mix of lab-bench measurements and complementary in-situ experimental data to control systematic distortions. Wafer positions and orientations are determined by minimizing a Â2 computed using these data for each wafer individually, iterating to account for between-wafer correlations. A correction for aplanar distortions of the silicon wafers is measured and applied. The net effect of residual mis-alignments on relevant physical variables evaluated in special co...
Quantum toroidal algebras and their vertex representations
Saitô, Y
1996-01-01
We construct the vertex representations of the quantum toroidal algebras $U_q({\\frak {sl}}_{n+1,tor})$. In the classical case the vertex representations are not irreducible. However in the quantum case they are irreducible. For n=1, we construct a set of finitely many generators of $U_q({\\frak {sl}}_{2,tor})$.
New vertex reconstruction algorithms for CMS
Frühwirth, R; Prokofiev, Kirill; Speer, T.; Vanlaer, P.; Chabanat, E.; Estre, N.
2003-01-01
The reconstruction of interaction vertices can be decomposed into a pattern recognition problem (``vertex finding'') and a statistical problem (``vertex fitting''). We briefly review classical methods. We introduce novel approaches and motivate them in the framework of high-luminosity experiments like at the LHC. We then show comparisons with the classical methods in relevant physics channels
Vertex Reconstruction in ATLAS Run II
Zhang, Matt; The ATLAS collaboration
2016-01-01
Vertex reconstruction is the process of taking reconstructed tracks and using them to determine the locations of proton collisions. In this poster we present the performance of our current vertex reconstruction algorithm, and look at investigations into potential improvements from a new seed finding method.
Dynamical Vertex Approximation for the Hubbard Model
Toschi, Alessandro
A full understanding of correlated electron systems in the physically relevant situations of three and two dimensions represents a challenge for the contemporary condensed matter theory. However, in the last years considerable progress has been achieved by means of increasingly more powerful quantum many-body algorithms, applied to the basic model for correlated electrons, the Hubbard Hamiltonian. Here, I will review the physics emerging from studies performed with the dynamical vertex approximation, which includes diagrammatic corrections to the local description of the dynamical mean field theory (DMFT). In particular, I will first discuss the phase diagram in three dimensions with a special focus on the commensurate and incommensurate magnetic phases, their (quantum) critical properties, and the impact of fluctuations on electronic lifetimes and spectral functions. In two dimensions, the effects of non-local fluctuations beyond DMFT grow enormously, determining the appearance of a low-temperature insulating behavior for all values of the interaction in the unfrustrated model: Here the prototypical features of the Mott-Hubbard metal-insulator transition, as well as the existence of magnetically ordered phases, are completely overwhelmed by antiferromagnetic fluctuations of exponentially large extension, in accordance with the Mermin-Wagner theorem. Eventually, by a fluctuation diagnostics analysis of cluster DMFT self-energies, the same magnetic fluctuations are identified as responsible for the pseudogap regime in the holed-doped frustrated case, with important implications for the theoretical modeling of the cuprate physics.
IR subtraction schemes. Integrating the counterterms at NNLO in QCD
Energy Technology Data Exchange (ETDEWEB)
Bolzoni, Paolo; Somogyi, Gabor
2010-06-15
We briefly review a subtraction scheme for computing radiative corrections to QCD jet cross sections that can be defined at any order in perturbation theory. Hereafter we discuss the computational methods used to evaluate analytically and numerically the integrated counterterms arising from such a subtraction scheme. Basically these methods the Mellin-Barnes (MB) representations technique together with the harmonic summation and the sector decomposition. (orig.)
Recursively arbitrarily vertex-decomposable suns
Directory of Open Access Journals (Sweden)
Olivier Baudon
2011-01-01
Full Text Available A graph \\(G = (V,E\\ is arbitrarily vertex decomposable if for any sequence \\(\\tau\\ of positive integers adding up to \\(|V|\\, there is a sequence of vertex-disjoint subsets of \\(V\\ whose orders are given by \\(\\tau\\, and which induce connected graphs. The aim of this paper is to study the recursive version of this problem on a special class of graphs called suns. This paper is a complement of [O. Baudon, F. Gilbert, M. Woźniak, Recursively arbitrarily vertex-decomposable graphs, research report, 2010].
DEPFET Vertex Detectors: Status and Plans
Simon, Frank
2010-01-01
DEPFET active pixel sensors are a well-developed technology for vertex detectors at future colliders. Extensive test beam campaigns have proven the excellent performance of these devices, and their radiation hardness has been thoroughly tested. For the Belle-II experiment at the SuperKEKB collider, a new vertex detector based on DEPFET technology is being developed, using sensors thinned down to 75 \\mu m. We give an overview over recent results with test devices using ILC pixel geometries as well as the concepts and challenges for the Belle-II pixel vertex tracker and discuss how the R&D for the ILC VXD can take advantage of these developments.
Vertex finding with deformable templates at LHC
Energy Technology Data Exchange (ETDEWEB)
Stepanov, N. [European Organization for Nuclear Research, Geneva (Switzerland); Khanov, A. [European Organization for Nuclear Research, Geneva (Switzerland)
1997-04-11
We present a novel vertex finding technique. The task is formulated as a discrete-continuous optimisation problem in a way similar to the deformable templates approach for the track finding. Unlike the track finding problem, ``elastic hedgehogs`` rather than elastic arms are used as deformable templates. They are initialised by a set of procedures which provide zero level approximation for vertex positions and track parameters at the vertex point. The algorithm was evaluated using the simulated events for the LHC CMS detector and demonstrated good performance. (orig.).
SIMP model at NNLO in chiral perturbation theory
DEFF Research Database (Denmark)
Hansen, Martin Rasmus Lundquist; Langaeble, K.; Sannino, F.
2015-01-01
We investigate the phenomenological viability of a recently proposed class of composite dark matter models where the relic density is determined by 3 to 2 number-changing processes in the dark sector. Here the pions of the strongly interacting field theory constitute the dark matter particles....... By performing a consistent next-to-leading and next-to-next-to-leading order chiral perturbative investigation we demonstrate that the leading order analysis cannot be used to draw conclusions about the viability of the model. We further show that higher order corrections substantially increase the tension...
Vertex-antimagic Labelings of Regular Graphs
Institute of Scientific and Technical Information of China (English)
Ali AHMAD; Kashif ALI; Martin BA(C)A; Petr KOV(A)(R); Andrea SEMANI(C)OV(A)-FE(N)OV(C)(I)KOV(A)
2012-01-01
Let G =(V,E) be a finite,simple and undirected graph with p vertices and q edges.An (a,d)-vertex-antimagic total labeling of G is a bijection f from V(G).∪E(G) onto the set of consecutive integers 1,2,...,p + q,such that the vertex-weights form an arithmetic progression with the initial term a and difference d,where the vertex-weight of x is the sum of the value f(x) assigned to the vertex x together with all values f(xy) assigned to edges xy incident to x.Such labeling is called super if the smallest possible labels appear on the vertices.In this paper,we study the properties of such labelings and examine their existence for 2r-regular graphs when the difference d is 0,1,...,r + 1.
The Perfect Quark-Gluon Vertex Function
Orginos, K; Brower, Richard C; Chandrasekharan, S; Wiese, U J
1998-01-01
We evaluate a perfect quark-gluon vertex function for QCD in coordinate space and truncate it to a short range. We present preliminary results for the charmonium spectrum using this quasi-perfect action.
Vertex occlusal radiography in localizing unerupted mesiodentes
Directory of Open Access Journals (Sweden)
P Chalakkal
2011-01-01
Full Text Available The aim was to compare the vertex occlusal projection with the anterior maxillary occlusal projection in localizing the position of mesiodentes. Mesiodentes were observed in an 8-year-old boy with an anterior maxillary occlusal radiograph. A vertex occlusal radiograph was taken to compare it with the former in terms of mesiodentes localization with respect to the maxillary central incisors. The vertex occlusal radiograph provided greater details of the position and proximity of mesiodentes with respect to the long axis of maxillary central incisors in comparison to the anterior maxillary occlusal radiograph. Vertex occlusal radiography is an important diagnostic tool in diagnosing the presence, position, and proximity of mesiodentes with respect to the long axis of normally aligned maxillary central incisors. However, it is not recommended for routine use in a patient as its radiation dose is higher than conventional intraoral radiographic methods.
Monitoring the stability of the ALEPH vertex detector
Energy Technology Data Exchange (ETDEWEB)
Sguazzoni, G.; Creanza, D.; De Palma, M.; Maggi, G.; Raso, G.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Burns, M.; Frank, M.; Maley, P.D.; Morel, M.; Wagner, A.; Focardi, E.; Parrini, G.; Scarlini, E.; Halley, A.; O' Shea, V.; Raine, C.; Barber, G.; Cameron, W.; Dornan, P.; Gentry, D.; Moutoussi, A.; Nash, J.; Price, D.; Stacey, A.; Toudup, L.W.; Williams, M.I.; Billault, M.; Blanc, P.E.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Coyle, P.; Curtil, C.; Destelle, J.J.; Diaconu, C.; Fouchez, D.; Karst, P.; Payre, P.; Rousseau, D.; Thulasidas, M.; Dietl, H.; Ganis, G.; Moser, H.G.; Settles, R.; Seywerd, H.; Waltermann, G.; Bosi, F.; Bozzi, C.; Dell' Orso, R.; Profeti, A.; Rizzo, G.; Verdini, P.G.; Bizzell, J.P.; Thompson, J.C.; Black, S.; Dann, J.; Kim, H.Y.; Konstantinidis, N.; Taylor, G.; Bosisio, L.; Rothberg, J.; Wasserbaech, S.; Armstrong, S.; Elmer, P.; Walsh, J
1999-08-01
The ALEPH Silicon Vertex Detector features an optical fibre laser system to monitor its mechanical stability. The operating principle and the general performance of the laser system are described. The experience obtained during 1997 and 1998 operations confirms the important role that such a system can have with respect to the detector alignment requirements. In particular, the laser system has been used to monitor short-term temperature-related effects and long-term movements. These results and a description of the laser-based alignment correction applied to the 1998 data are presented.
Monitoring the Stability of the ALEPH Vertex Detector
Sguazzoni, G; De Palma, M; Maggi, G; Raso, G; Selvaggi, G; Silvestris, L; Tempesta, P; Burns, M; Frank, M; Maley, P; Morel, M; Wagner, A; Focardi, E; Parrini, G; Scarlini, E; Halley, A W; O'Shea, V; Raine, C; Barber, G J; Cameron, W; Dornan, Peter J; Gentry, D; Moutoussi, A; Nash, J; Price, D; Stacey, A M; Toudup, L W; Williams, M I; Billault, M; Blanc, P E; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Curtil, C; Destelle, J J; Diaconu, C A; Fouchez, D; Karst, P; Payre, P; Rousseau, D; Thulasidas, M; Dietl, H; Ganis, G; Moser, H G; Settles, Ronald; Seywerd, H C J; Waltermann, G; Bosi, F; Bozzi, C; Dell'Orso, R; Profeti, A; Rizzo, G; Verdini, P G; Bizzell, J P; Thompson, J C; Black, S; Dann, J H; Kim, H Y; Konstantinidis, N P; Taylor, G; Bosisio, L; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Elmer, P; Walsh, J
1999-01-01
The ALEPH Silicon Vertex Detector features an optical fibre laser system to monitor its mechanical stability. The operating principle and the general performance of the laser system are described. The experience obtained during 1997 and 1998 operations confirms the important role that such a system can have with respect to the detector alignment requirements. In particular, the laser system has been used to monitor short-term temperature-related effects and long-term movements. These results and a description of the laser-based alignment correction applied to the 1998 data are presented.
A new tool for constrained vertex fitting in ATLAS
Colijn, Auke Pieter; Limper, Maaike; Prokofiev, Kirill
2009-01-01
The precise reconstruction of trajectories of charged and neutral particles and their decay vertices is crucial for many physics analyses. Studying the tracking performance on well known benchmark channels helps to understand the properties of the ATLAS detector during the initial phase of the LHC. In order to exploit the correlations between reconstructed parameters of final state tracks having the same mother particle, a new tool for vertex fitting with possibility of simultaneous application of kinematic constraints has been developed. Using this tool on a benchmark channel such as J/psi to μ+μ− helps to correct shifts in the reconstructed curvature induced by systematic deformations of the detector.
Recursively arbitrarily vertex-decomposable graphs
Directory of Open Access Journals (Sweden)
Olivier Baudon
2012-01-01
Full Text Available A graph \\(G = (V;E\\ is arbitrarily vertex decomposable if for any sequence \\(\\tau\\ of positive integers adding up to \\(|V|\\, there is a sequence of vertex-disjoint subsets of \\(V\\ whose orders are given by \\(\\tau\\, and which induce connected graphs. The main aim of this paper is to study the recursive version of this problem. We present a solution for trees, suns, and partially for a class of 2-connected graphs called balloons.
Track and Vertex Reconstruction in CMS
Adam, W
2006-01-01
The CMS experiment relies on a Silicon pixel and micro-strip tracker for the reconstruction of tracks and vertices of charged particles in the harsh environment of proton and heavy-ion collisions at the LHC at CERN. An outline of the basic track and vertex reconstruction algorithms used in CMS is given and their performance is described. Results of more advanced algorithms like the Gaussian Sum Filter for electron reconstruction and robust vertex fitters are shown.
Quadratic electroweak corrections for polarized Moller scattering
Energy Technology Data Exchange (ETDEWEB)
A. Aleksejevs, S. Barkanova, Y. Kolomensky, E. Kuraev, V. Zykunov
2012-01-01
The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.
Pinning down the large-x gluon with NNLO top-quark pair differential distributions
Czakon, Michał; Mitov, Alexander; Nocera, Emanuele R; Rojo, Juan
2016-01-01
Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at $\\sqrt{s}=8$ TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.
αs and |Vcs| determination, and CKM unitarity test, from W decays at NNLO
Directory of Open Access Journals (Sweden)
David d'Enterria
2016-12-01
Full Text Available The hadronic (ΓhadW and total (ΓtotW widths of the W boson, computed at least at next-to-next-to-leading-order (NNLO accuracy, are combined to derive a new precise prediction for the hadronic W branching ratio BhadW ≡ ΓhadW/ΓtotW=0.682±0.011par, using the experimental Cabibbo–Kobayashi–Maskawa (CKM matrix elements, with uncertainties dominated by the input parameters of the calculations, or BhadW=0.6742±0.0002th±0.0001par assuming CKM unitarity. Comparing the theoretical predictions and experimental measurements for various W decay observables, the NNLO strong coupling constant at the Z pole, αs(mZ2=0.117±0.042exp±0.004th±0.001par, as well as the charm-strange CKM element, |Vcs|=0.973±0.004exp±0.002par, can be extracted under different assumptions. We also show that W decays provide today the most precise test of CKM unitarity for the 5 quarks lighter than mW, ∑u,c,d,s,b|Vij|2=1.999±0.008exp±0.001th. Perspectives for αs and |Vcs| extractions from W decays measurements at the LHC and future e+e− colliders are presented.
αs and |Vcs| determination, and CKM unitarity test, from W decays at NNLO
d'Enterria, David; Srebre, Matej
2016-12-01
The hadronic (ΓhadW) and total (ΓtotW) widths of the W boson, computed at least at next-to-next-to-leading-order (NNLO) accuracy, are combined to derive a new precise prediction for the hadronic W branching ratio BhadW ≡ ΓhadW/ΓtotW = 0.682 ±0.011par, using the experimental Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, with uncertainties dominated by the input parameters of the calculations, or BhadW = 0.6742 ±0.0002th ±0.0001par assuming CKM unitarity. Comparing the theoretical predictions and experimental measurements for various W decay observables, the NNLO strong coupling constant at the Z pole, αs (mZ2) = 0.117 ±0.042exp ±0.004th ±0.001par, as well as the charm-strange CKM element, |Vcs | = 0.973 ±0.004exp ±0.002par, can be extracted under different assumptions. We also show that W decays provide today the most precise test of CKM unitarity for the 5 quarks lighter than mW, ∑u,c,d,s,b |Vij|2 = 1.999 ±0.008exp ±0.001th. Perspectives for αs and |Vcs | extractions from W decays measurements at the LHC and future e+e- colliders are presented.
Abbiendi, G; Akesson, P F; Alexander, G; Anagnostou, G; Anderson, K J; Asai, S; Axen, D; Bailey, I; Barberio, E; Barillari, T; Barlow, R J; Batley, R J; Bechtle, P; Behnke, T; Bell, K W; Bell, P J; Bella, G; Bellerive, A; Benelli, G; Bethke, S; Biebel, O; Boeriu, O; Bock, P; Boutemeur, M; Braibant, S; Brown, R M; Burckhart, H J; Campana, S; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Ciocca, C; Csilling, A; Cuffiani, M; Dado, S; Dallavalle, M; De Roeck, A; De Wolf, E A; Desch, K; Dienes, B; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Etzion, E; Fabbri, F; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Frey, A; Gagnon, P; Gary, J W; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giunta, M; Goldberg, J; Gross, E; Grunhaus, J; Gruwe, M; Gupta, A; Hajdu, C; Hamann, M; Hanson, G G; Harel, A; Hauschild, M; Hawkes, C M; Hawkings, R; Herten, G; Heuer, R D; Hill, J C; Horvath, D; Igo-Kemenes, P; Ishii, K; Jeremie, H; Jovanovic, P; Junk, T R; Kanzaki, J; Karlen, D; Kawagoe, K; Kawamoto, T; Keeler, R K; Kellogg, R G; Kennedy, B W; Kluth, S; Kobayashi, T; Kobel, M; Komamiya, S; Kramer, T; Krasznahorkay, Jr A; Krieger, P; von Krogh, J; Kuhl, T; Kupper, M; Lafferty, G D; Landsman, H; Lanske, D; Lellouch, D; Letts, J; Levinson, L; Lillich, J; Lloyd, S L; Loebinger, F K; Lu, J; Ludwig, A; Ludwig, J; Mader, W; Marcellini, S; Martin, A J; Mashimo, T; Mattig, P; McKenna, J; McPherson, R A; Meijers, F; Menges, W; Merritt, F S; Mes, H; Meyer, N; Michelini, A; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Mori, T; Mutter, A; Nagai, K; Nakamura, I; Nanjo, H; Neal, H A; O’Neale, S W; Oh, A; Oreglia, M J; Orito, S; Pahl, C; Pasztor, G; Pater, J R; Pilcher, J E; Pinfold, J; Plane, D E; Pooth, O; Przybycien, M; Quadt, A; Rabbertz, K; Rembser, C; Renkel, P; Roney, J M; Rossi, A M; Rozen, Y; Runge, K; Sachs, K; Saeki, T; Sarkisyan, E K G; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schorner-Sadenius, T; Schroder, M; Schumacher, M; Seuster, R; Shears, T G; Shen, B C; Sherwood, P; Skuja, A; Smith, A M; Sobie, R; Soldner-Rembold, S; Spano, F; Stahl, A; Strom, D; Strohmer, R; Tarem, S; Tasevsky, M; Teuscher, R; Thomson, M A; Torrence, E; Toya, D; Trigger, I; Trocsanyi, Z; Tsur, E; Turner-Watson, M F; Ueda, I; Ujvari, B; Vollmer, C F; Vannerem, P; Vertesi, R; Verzocchi, M; Voss, H; Vossebeld, J; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Zer-Zion, D; Zivkovic, L
2011-01-01
Hadronic event shape distributions from e+e− annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong coupling αS. The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is αS(mZ0) = 0.1201 ± 0.0008(stat.) ± 0.0013(exp.) ± 0.0010(had.) ± 0.0024(theo.). while the combined NNLO+NLLA result is αS(mZ0) = 0.1189 ± 0.0008(stat.) ± 0.0016(exp.) ± 0.0010(had.) ± 0.0036(theo.). The completeness of the NNLO and NNLO+NLLA results with respect to missing higher order contributions, studied by varying the renormalization scale, is improved compared to previous results based on NLO or NLO+NLLA predictions only. The observed energy dependence of αS agrees with the QCD prediction of asymptotic freedom and excludes the absence o...
Vertex stability and topological transitions in vertex models of foams and epithelia
Spencer, Meryl A; Lubensky, David K
2016-01-01
In computer simulations of dry foams and of epithelial tissues, vertex models are often used to describe the shape and motion of individual cells. Although these models have been widely adopted, relatively little is known about their basic theoretical properties. For example, while fourfold vertices in real foams are always unstable, it remains unclear whether a simplified vertex model description has the same behavior. Here, we study vertex stability and the dynamics of T1 topological transitions in vertex models. We show that, when all edges have the same tension, stationary fourfold vertices in these models do indeed always break up. In contrast, when tensions are allowed to depend on edge orientation, fourfold vertices can become stable, as is observed in some biological systems. More generally, our formulation of vertex stability leads to an improved treatment of T1 transitions in simulations and paves the way for studies of more biologically realistic models that couple topological transitions to the dy...
Effects of a dressed quark-gluon vertex in vector heavy-light mesons
Gomez-Rocha, M; Krassnigg, A
2016-01-01
We extend earlier investigations of heavy-light pseudoscalar mesons to the vector case, using a simple model in the context of the Dyson-Schwinger-Bethe-Salpeter approach. We investigate the effects of a dressed-quark-gluon vertex in a systematic fashion and illustrate and attempt to quantify corrections beyond the phenomenologically very useful and successful rainbow-ladder truncation. In particular we investigate dressed quark photon vertex in such a setup and make a prediction for the experimentally as yet unknown mass of the B_c*, which we obtain at 6.334 GeV well in line with predictions from other approaches.
Trace Identities for the Topological Vertex
Bryan, Jim; Young, Benjamin
2016-01-01
The topological vertex is a universal series which can be regarded as an object in combinatorics, representation theory, geometry, or physics. It encodes the combinatorics of 3D partitions, the action of vertex operators on Fock space, the Donaldson-Thomas theory of toric Calabi-Yau threefolds, or the open string partition function of $\\mathbb{C}^3$. We prove several identities in which a sum over terms involving the topological vertex is expressed as a closed formula, often a product of simple terms, closely related to Fourier expansions of Jacobi forms. We use purely combinatorial and representation theoretic methods to prove our formulas, but we discuss applications to the Donaldson-Thomas invariants of elliptically fibered Calabi-Yau threefolds at the end of the paper.
Open string amplitudes of closed topological vertex
Takasaki, Kanehisa
2016-01-01
The closed topological vertex is the simplest "off-strip" case of non-compact toric Calabi-Yau threefolds with acyclic web diagrams. By the diagrammatic method of topological vertex, open string amplitudes of topological string theory therein can be obtained by gluing a single topological vertex to an "on-strip" subdiagram of the tree-like web diagram. If non-trivial partitions are assigned to just two parallel external lines of the web diagram, the amplitudes can be calculated with the aid of techniques borrowed from the melting crystal models. These amplitudes are thereby expressed as matrix elements, modified by simple prefactors, of an operator product on the Fock space of 2D charged free fermions. This fermionic expression can be used to derive $q$-difference equations for generating functions of special subsets of the amplitudes. These $q$-difference equations may be interpreted as the defining equation of a quantum mirror curve.
Vertex Operators and Moduli Spaces of Sheaves
Carlsson, Erik
2009-01-01
The Nekrasov partition function in supersymmetric quantum gauge theory is mathematically formulated as an equivariant integral over certain moduli spaces of sheaves on a complex surface. In ``Seiberg-Witten Theory and Random Partitions'', Nekrasov and Okounkov studied these integrals using the representation theory of ``vertex operators'' and the infinite wedge representation. Many of these operators arise naturally from correspondences on the moduli spaces, such as Nakajima's Heisenberg operators, and Grojnowski's vertex operators. In this paper, we build a new vertex operator out of the Chern class of a vector bundle on a pair of moduli spaces. This operator has the advantage that it connects to the partition function by definition. It also incorporates the canonical class of the surface, whereas many other studies assume that the class vanishes. When the moduli space is the Hilbert scheme, we present an explicit expression in the Nakajima operators, and the resulting combinatorial identities. We then apply...
Primary Vertex Reconstruction at the ATLAS Experiment
Grimm, Kathryn; The ATLAS collaboration
2017-01-01
These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of $\\sqrt{s} = 8$ TeV, and during 2015-2016 at $\\sqrt{s} = 13$ TeV. Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.
The superB silicon vertex tracker
Energy Technology Data Exchange (ETDEWEB)
Rizzo, G., E-mail: giuliana.rizzo@pi.infn.i [INFN-Pisa and Universita di Pisa (Italy); Avanzini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Calderini, G.; Ceccanti, M.; Cenci, R.; Cervelli, A.; Crescioli, F.; Dell' Orso, M.; Forti, F.; Giannetti, P.; Giorgi, M.A. [INFN-Pisa and Universita di Pisa (Italy); Lusiani, A. [Scuola Normale Superiore and INFN-Pisa (Italy); Gregucci, S.; Mammini, P.; Marchiori, G.; Massa, M.; Morsani, F. [INFN-Pisa and Universita di Pisa (Italy)
2010-05-21
The SuperB asymmetric e{sup +}-e{sup -} collider has been designed to deliver a luminosity greater than 10{sup 36}cm{sup -2}s{sup -1} with moderate beam currents. Comparing to current B-Factories, the reduced center of mass boost of the SuperB machine requires improved vertex resolution to allow precision measurements sensitive to New Physics. We present the conceptual design of the silicon vertex tracker (SVT) for the SuperB detector with the present status of the R and D on the different options under study for its innermost Layer0.
Vertexing and Tracking Software at LHCb
Bowen, Espen Eie
2015-01-01
The LHCb experiment is a dedicated heavy flavour experiment at the LHC. Its primary goal is to search for indirect evidence of New Physics in CP violation and rare decays of beauty and charm hadrons. The detector includes a high granularity silicon-strip vertex detector, a silicon-strip detector upstream of the magnet and three stations of silicon-strip detectors and straw drift tubes downstream of the magnet. The software used to perform the track reconstruction and primary vertex reconstruction is described in detail along with a discussion of its performance.
On deformation theory of quantum vertex algebras
Grosse, H; Grosse, Harald; Schlesinger, Karl-Georg
2005-01-01
We study an algebraic deformation problem which captures the data of the general deformation problem for a quantum vertex algebra. We derive a system of coupled equations which is the counterpart of the Maurer-Cartan equation on the usual Hochschild complex of an assocative algebra. We show that this system of equations results from an action principle. This might be the starting point for a perturbative treatment of the deformation problem of quantum vertex algebras. Our action generalizes the action of the Kodaira-Spencer theory of gravity and might therefore also be of relevance for applications in string theory.
Vertex Reconstruction for AEGIS’ FACT Detector
Themistokleous, Neofytos
2017-01-01
My project dealt with the development of a vertex reconstruction technique to discriminate antihydrogen from background signals in the AEGIS apparatus. It involved the creation of a Toy Monte-Carlo to simulate particle annihilation events, and a vertex reconstruction utility based on the Bayesian theory of probability. The ﬁrst results based on 107 generated events with single track in the detector are encouraging. For such events, the algorithm can reconstruct the z-coordinate accurately , while for the r-coordinate the result is less accurate.
On spectral theory of quantum vertex operators
Etingof, P
1994-01-01
In this note we prove the Davies-Foda-Jimbo-Miwa-Nakayashiki conjecture on the asymptotics of the composition of n quantum vertex operators for the quantum affine algebra U_q(\\hat sl_2), as n goes to infinity. For this purpose we define and study the leading eigenvalue and eigenvector of the product of two components of the quantum vertex operator. This eigenvector and the corresponding eigenvalue were recently computed by M.Jimbo. The results of his computation are given in Section 4.
Vertex operators in solvable lattice models
Foda, O E; Miwa, T; Miki, K; Nakayashiki, A; Foda, Omar; Jimbo, Michio; Miwa, Tetsuji; Miki, Kei; Nakayashiki, Atsushi
1994-01-01
We formulate the basic properties of q-vertex operators in the context of the Andrews-Baxter-Forrester (ABF) series, as an example of face-interaction models, derive the q-difference equations satisfied by their correlation functions, and establish their connection with representation theory. We also discuss the q-difference equations of the Kashiwara-Miwa (KM) series, as an example of edge-interaction models. Next, the Ising model--the simplest special case of both ABF and KM series--is studied in more detail using the Jordan-Wigner fermions. In particular, all matrix elements of vertex operators are calculated.
Vertex Detector Performance for CLICdet, FCCee & FCChh.
Rasmussen, Peter Winkel
2017-01-01
The performance of the vertex detectors planned for CLICdet, FCCee & FCChh was tested in this project. This was done my studying the figure of merit for a vertex detector which is the transverse impact parameter resolution $\\sigma(d_0)$. This was carried out by simulating single $\\mu^-$ at different energies, polar angles, $\\theta$ with a uniform distribution in the azimuthal angle $\\phi$. The events were reconstructed and the distribution $\\Delta(d_0) = d_{0,reco}-d_{0,true}$ was fitted with a Gaussian function where the width of the function resulted in $\\sigma(d_0)$. The effect of material budget and fit function on this was also tested.
Thermo-magnetic behavior of the of the quark-gluon vertex
Ayala, Alejandro; Loewe, M; Tejeda-Yeomans, Maria Elena; Zamora, R
2015-01-01
The thermo-magnetic corrections to the quark-gluon vertex in the presence of a weak magnetic field are calculated in the frame of the Hard Thermal Loop approximation. The vertex satisfies a QED-like Ward identity with the quark self-energy calculated within the same approximation. It turns out that only the longitudinal vertex components get modified. The calculation provides a first principles result for the quark anomalous magnetic moment at high temperature in a weak magnetic field. The effective thermo-magnetic quark-gluon coupling shows a decreasing behavior as function of the field strength. This result supports the observation that the behavior of the effective quark-gluon coupling in the presence of a magnetic field is an important ingredient in order to understand the inverse magnetic catalysis phenomenon recently observed in the lattice QCD simulations.
A Cubic Kernel for Feedback Vertex Set
Bodlaender, H.L.
2006-01-01
The FEEDBACK VERTEX SET problem on unweighted, undirected graphs is considered. Improving upon a result by Burrage et al. [7], we show that this problem has a kernel with O(κ3) vertices, i.e., there is a polynomial time algorithm, that given a graph G and an integer κ, finds a graph G' and integer
Vertex Algebra Sheaf Structure on Torus
Institute of Scientific and Technical Information of China (English)
SUN Yuan-yuan
2016-01-01
In this paper, we first give a 1-1 corresponds between torus C/Λand cubic curve C in P2C. As complex manifold, they are isomorphic, therefore we can treat C/Λas a variety and construction a vertex algebra sheaf on it.
Redford, S
2014-01-01
In order to achieve its primary objectives of heavy-flavour tagging and tau lepton identification, the CLIC vertex detector must precisely reconstruct displaced vertices. This re- quires accurate determination of the impact parameter and charge of tracks originating from the secondary vertex. Excellent spatial resolution must therefore be provided down to low polar angles, whilst maintaining low occupancy, low mass and low power dissipation. These requirements chal- lenge current technological limits, and demand a broad programme of R&D. A detector concept is currently under development, comprising a hybrid pixel detector of small-pitch readout ASICs implemented in 65nm CMOS technology (CLICpix) combined with ultra-thin sensors. The read- out chips are low-power, and power-pulsing is used to reduce further their power dissipation. This enables a forced gas cooling system in the vertex detector region. In this paper, the CLIC vertex detector requirements are reviewed and the current status of R&D on se...
Energy Technology Data Exchange (ETDEWEB)
Battaglia, Marco; Bussat, Jean-Marie; Contarato, Devis; Denes,Peter; Glesener, Lindsay; Greiner, Leo; Hooberman, Benjamin; Shuman,Derek; Tompkins, Lauren; Vu, Chinh; Bisello, Dario; Giubilato, Piero; Pantano, Devis; Costa, Marco; La Rosa, Alessandro; Bolla, Gino; Bortoletto, Daniela; Children, Isaac
2007-10-01
This document summarizes past achievements, current activities and future goals of the R&D program aimed at the design, prototyping and characterization of a full detector module, equipped with monolithic pixel sensors, matching the requirements for the Vertex Tracker at the ILC. We provide a plan of activities to obtain a demonstrator multi-layered vertex tracker equipped with sensors matching the ILC requirements and realistic lightweight ladders in FY11, under the assumption that ILC detector proto-collaborations will be choosing technologies and designs for the Vertex Tracker by that time. The R&D program discussed here started at LBNL in 2004, supported by a Laboratory Directed R&D (LDRD) grant and by funding allocated from the core budget of the LBNL Physics Division and from the Department of Physics at UC Berkeley. Subsequently additional funding has been awarded under the NSF-DOE LCRD program and also personnel have become available through collaborative research with other groups. The aim of the R&D program carried out by our collaboration is to provide a well-integrated, inclusive research effort starting from physics requirements for the ILC Vertex Tracker and addressing Si sensor design and characterization, engineered ladder design, module system issues, tracking and vertex performances and beam test validation. The broad scope of this program is made possible by important synergies with existing know-how and concurrent programs both at LBNL and at the other collaborating institutions. In particular, significant overlaps with LHC detector design, SLHC R&D as well as prototyping for the STAR upgrade have been exploited to optimize the cost per deliverable of our program. This activity is carried out as a collaborative effort together with Accelerator and Fusion Research, the Engineering and the Nuclear Science Divisions at LBNL, INFN and the Department of Physics in Padova, Italy, INFN and the Department of Physics in Torino, Italy and the Department
$W^\\pm Z$ production at the LHC: fiducial cross sections and distributions in NNLO QCD arXiv
Grazzini, Massimiliano; Rathlev, Dirk; Wiesemann, Marius
We report on the first fully differential calculation for $W^\\pm Z$ production in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. Leptonic decays of the $W$ and $Z$ bosons are consistently taken into account, i.e. we include all resonant and non-resonant diagrams that contribute to the process $pp\\to \\ell^{'\\pm} \
CLIQUE IRREDUCIBILITY AND CLIQUE VERTEX IRREDUCIBILITY OF GRAPHS
Vijayakumar, A.; Aparna Lakshmanan S.
2009-01-01
A graphs G is clique irreducible if every clique in G of size at least two, has an edge which does not lie in any other clique of G and is clique reducible if it is not clique irreducible. A graph G is clique vertex irreducible if every clique in G has a vertex which does not lie in any other clique of G and clique vertex reducible if it is not clique vertex irreducible. The clique vertex irreducibility and clique irreducibility of graphs which are non-complete extended p-sums (NEPS) of two g...
Performance of the ALICE secondary vertex b-tagging algorithm
INSPIRE-00262232
2016-11-04
The identification of jets originating from beauty quarks in heavy-ion collisions is important to study the properties of the hot and dense matter produced in such collisions. A variety of algorithms for b-jet tagging was elaborated at the LHC experiments. They rely on the properties of B hadrons, i.e. their long lifetime, large mass and large multiplicity of decay products. In this work, the b-tagging algorithm based on displaced secondary-vertex topologies is described. We present Monte Carlo based performance studies of the algorithm for charged jets reconstructed with the ALICE tracking system in p-Pb collisions at $\\sqrt{s_\\text{NN}}$ = 5.02 TeV. The tagging efficiency, rejection rate and the correction of the smearing effects of non-ideal detector response are presented.
Optimized Vertex Method and Hybrid Reliability
Smith, Steven A.; Krishnamurthy, T.; Mason, B. H.
2002-01-01
A method of calculating the fuzzy response of a system is presented. This method, called the Optimized Vertex Method (OVM), is based upon the vertex method but requires considerably fewer function evaluations. The method is demonstrated by calculating the response membership function of strain-energy release rate for a bonded joint with a crack. The possibility of failure of the bonded joint was determined over a range of loads. After completing the possibilistic analysis, the possibilistic (fuzzy) membership functions were transformed to probability density functions and the probability of failure of the bonded joint was calculated. This approach is called a possibility-based hybrid reliability assessment. The possibility and probability of failure are presented and compared to a Monte Carlo Simulation (MCS) of the bonded joint.
Hypergraph Partitioning through Vertex Separators on Graphs
Kayaaslan, Enver; Catalyurek, Umit V; Aykanat, Cevdet
2011-01-01
The modeling flexibility provided by hypergraphs has drawn a lot of interest from the combinatorial scientific community, leading to novel models and algorithms, their applications, and development of associated tools. Hypergraphs are now a standard tool in combinatorial scientific computing. The modeling flexibility of hypergraphs however, comes at a cost: algorithms on hypergraphs are inherently more complicated than those on graphs, which sometimes translate to nontrivial increases in processing times. Neither the modeling flexibility of hypergraphs, nor the runtime efficiency of graph algorithms can be overlooked. Therefore, the new research thrust should be how to cleverly trade-off between the two. This work addresses one method for this trade-off by solving the hypergraph partitioning problem by finding vertex separators on graphs. Specifically, we investigate how to solve the hypergraph partitioning problem by seeking a vertex separator on its net intersection graph (NIG), where each net of the hyperg...
Vertex Reconstruction and Performance in ATLAS
Whitmore, Ben William; The ATLAS collaboration
2017-01-01
Efficient and precise reconstruction of the primary vertices in LHC collisions is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of the primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. The performance of the current vertexing algorithms using Run-2 data will be presented and compared to results from simulation. Additionally, data-driven methods to evaluate vertex resolution, and details of upgrades to the ATLAS inner detector will be presented.
Nonperturbative Aspects of Axial Vector Vertex
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
2002-01-01
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
The ZEUS vertex detector: Design and prototype
Energy Technology Data Exchange (ETDEWEB)
Alvisi, C.; Anzivino, G.; Arzarello, F.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, G.; Bruni, P.; Camerini, U.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; Costa, M.; D' Auria, S.; Del Papa, C.; De Pasquale, S.; Fiori, F.; Forte, A.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; O' Shea, V.; Palmonari, F.; Pelfer, P.; Pilastrini, R.; Qian, S.; Sartorelli, G.; Schioppa, M.; Susinno, G.; Timellini, R.; Zichichi, A. (European Organization for Nuclear Research, Geneva (Switzerland) Bologna Univ. (Italy). Dipt. di Fisica Cosenza Univ. (Italy). Dipt. di Fisica Florence Univ. (Italy). Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Bologna (Italy) Istituto Nazionale di Fisica Nucleare, Florence (Italy) Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati Consiglio Nazionale delle Ricerche, Flore
1991-07-10
A gas vertex detector, operated with dimethylether (DME) at atmospheric pressure, is presently being built for the ZEUS experiment at HERA. Its main design features, together with the performances of a prototype measured at various operating voltages, particle rates and geometrical conditions on a CERN Proton Synchrotron test beam, are presented. A spatial resolution down to 35 {mu}m and an average wire efficiency of 96% have been achieved, for a 3 mm gas gap relative to each sense wire. (orig.).
Bimodules associated to vertex operator superalgebras
Institute of Scientific and Technical Information of China (English)
2008-01-01
Let V be a vertex operator superalgebra and m,n ∈ 21Z+. We construct an An(V ) -Am(V )-bimodule An,m(V ) which characterizes the action of V from the level m subspace to level n subspace of an admissible V -module. We also construct the Verma type admissible V -module from an Am(V )-module by using bimodules
Primary vertex reconstruction with the ATLAS detector
Meloni, Federico; The ATLAS collaboration
2016-01-01
Efficient and precise reconstruction of the primary vertex in a LHC collision is essential for determining the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. The algorithms developed by the ATLAS experiments to reconstruct multiple vertices with small spatial separation are presented.
Silicon technologies for the CLIC vertex detector
Spannagel, S.
2017-06-01
CLIC is a proposed linear e+e- collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2% X0 per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50-150 μm, including different active edge designs, are evaluated using Timepix3 ASICs. First prototypes of the CLICpix readout ASIC, implemented in 65 nm CMOS technology and with a pixel size of 25×25μm 2, have been produced and tested in particle beams. An updated version of the ASIC with a larger pixel matrix and improved precision of the time-over-threshold and time-of-arrival measurements has been submitted. Different hybridization concepts have been developed for the interconnection between the sensor and readout ASIC, ranging from small-pitch bump bonding of planar sensors to capacitive coupling of active HV-CMOS sensors. Detector simulations based on Geant 4 and TCAD are compared with experimental results to assess and optimize the performance of the various designs. This contribution gives an overview of the R&D program undertaken for the CLIC vertex detector and presents performance measurements of the prototype detectors currently under investigation.
B Decay Charm Counting Via Topological Vertexing
Chou, Aaron Sze Ting
2002-01-01
We present a new and unique measurement of the branching fractions of b hadrons to states with 0, 1, and 2 open charm hadrons, using a sample of 350,000 hadronic Z0 decays collected during the SLD/SLC 97–98 run. The analysis takes advantage of the excellent vertexing resolution of the VXD3, a pixel-based CCD vertex detector, which allows the separation of B and cascade D decay vertices. A fit of the vertex count and the decay length distributions to distribution shapes predicted by Monte Carlo simulation allows the extraction of the inclusive branching fractions. We measure: BRB→0D X=3.7±1.1 stat±2.1 syst% BRB→2D X=17.9±1.4 stat±3.3 syst% where B, and D represent mixtures of open b and open c hadrons. The corresponding charm count, Nc = 1.188 ± 0.010 ± 0.040 ± 0.006 is consistent with previous measurement averages but slightly closer to theoretical expectations.
Nonperturbative study of the four gluon vertex
Binosi, D; Papavassiliou, J
2014-01-01
In this paper we study the nonperturbative structure of the SU(3) four-gluon vertex in the Landau gauge, concentrating on contributions quadratic in the metric. We employ an approximation scheme where "one-loop" diagrams are computed using fully dressed gluon and ghost propagators, and tree-level vertices. When a suitable kinematical configuration depending on a single momentum scale $p$ is chosen, only two structures emerge: the tree-level four-gluon vertex, and a tensor orthogonal to it. A detailed numerical analysis reveals that the form factor associated with this latter tensor displays a change of sign (zero-crossing) in the deep infrared, and finally diverges logarithmically. The origin of this characteristic behavior is proven to be entirely due to the masslessness of the ghost propagators forming the corresponding ghost-loop diagram, in close analogy to a similar effect established for the three-gluon vertex. However, in the case at hand, and under the approximations employed, this particular divergen...
B Decay Charm Counting via Topological Vertexing
Energy Technology Data Exchange (ETDEWEB)
Chou, Aaron S
2001-10-15
We present a new and unique measurement of the branching fractions of b hadrons to states with 0, 1, and 2 open charm hadrons, using a sample of 350,000 hadronic Z{sup 0} decays collected during the SLD/SLC 97-98 run. The method takes advantage of the excellent vertexing resolution of the VXD3, a pixel-based CCD vertex detector, which allows the separation of B and cascade D decay vertices. A fit of the vertex count and the decay length distributions to distribution shapes predicted by Monte Carlo simulation allows the extraction of the inclusive branching fractions. We measure: BR(B {yields} (0D)X) = (3.7{+-}1.1(stat) {+-} 2.1(syst))%; and BR(B {yields} (2D)X) = (17.9{+-}1.4(stat) {+-} 3.3(syst))% where B and D represent mixtures of open b and open c hadrons. The corresponding charm count, N{sub c} = 1.188 {+-} 0.010 {+-} 0.040 {+-} 0.006 is consistent with previous measurement averages but slightly closer to theoretical expectations.
Silicon Technologies for the CLIC Vertex Detector
Spannagel, Simon
2017-01-01
CLIC is a proposed linear e$^+$e$^−$ collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2%$~X_0$ per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50–150$~\\mu$m, including different active edge designs, are evaluated using Timepix3 A...
Heavy quark hadroproduction as a test of the effective BFKL quark-antiquark-vertex
Hagler, P; Schäfer, A; Szymanowski, L; Teryaev, O V; Hagler, Ph.
2000-01-01
We calculate heavy quark pair hadroproduction in the framework of thek_t-factorization approach. The quark pair production in the quasi multi Reggekinematics is described by an effective vertex which is a part of thenext-to-leading corrections to the BFKL kernel. We find very good agreement ofour results with the existing data for bottom-antibottom production. Inaddition we present predictions for LHC.
Threshold pion production in proton-proton collisions at NNLO in chiral EFT
Baru, V; Filin, A A; Hanhart, C; Krebs, H; Myhrer, F
2016-01-01
The reaction $NN \\to NN \\pi$ offers a good testing ground for chiral effective field theory at intermediate energies. It challenges our understanding of the first inelastic channel in nucleon-nucleon scattering and of the charge-symmetry breaking pattern in hadronic reactions. In our previous studies, we presented a complete calculation of the pion-production operator for s-wave pions up-to-and-including next-to-next-to-leading order (NNLO) in the formulation of chiral effective field theory, which includes pions, nucleons and $\\Delta(1232)$ degrees of freedom. In this paper we calculate the near threshold cross section for the $pp \\to d \\pi^{+}$ reaction by performing the convolution of the obtained operators with nuclear wave functions based on modern phenomenological and chiral potentials. The available chiral $NN$ wave functions are constructed with a cutoff comparable with the momentum transfer scale inherent in pion production reactions. Hence, a significant portion of the dynamical intermediate-range p...
The Belle II Silicon Vertex Detector
Energy Technology Data Exchange (ETDEWEB)
Friedl, M., E-mail: markus.friedl@oeaw.ac.at [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ackermann, K. [MPI Munich, Föhringer Ring 6, 80805 München (Germany); Aihara, H. [University of Tokyo, Department of Physics, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Aziz, T. [Tata Institute of Fundamental Research, Experimental High Energy Physics Group, Homi Bhabha Road, Mumbai 400 005 (India); Bergauer, T. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Bozek, A. [Institute of Nuclear Physics, Division of Particle Physics and Astrophysics, ul. Radzikowskiego 152, 31 342 Krakow (Poland); Campbell, A. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Dingfelder, J. [University of Bonn, Department of Physics and Astronomy, Nussallee 12, 53115 Bonn (Germany); Drasal, Z. [Charles University, Institute of Particle and Nuclear Physics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Frankenberger, A. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Gadow, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Gfall, I. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Haba, J.; Hara, K.; Hara, T. [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Higuchi, T. [University of Tokyo, Kavli Institute for Physics and Mathematics of the Universe, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Himori, S. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Irmler, C. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ishikawa, A. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Joo, C. [Seoul National University, High Energy Physics Laboratory, 25-107 Shinlim-dong, Kwanak-gu, Seoul 151-742 (Korea, Republic of); and others
2013-12-21
The KEKB machine and the Belle experiment in Tsukuba (Japan) are now undergoing an upgrade, leading to an ultimate luminosity of 8×10{sup 35}cm{sup −2}s{sup −1} in order to measure rare decays in the B system with high statistics. The previous vertex detector cannot cope with this 40-fold increase of luminosity and thus needs to be replaced. Belle II will be equipped with a two-layer Pixel Detector surrounding the beam pipe, and four layers of double-sided silicon strip sensors at higher radii than the old detector. The Silicon Vertex Detector (SVD) will have a total sensitive area of 1.13m{sup 2} and 223,744 channels—twice as many as its predecessor. All silicon sensors will be made from 150 mm wafers in order to maximize their size and thus to reduce the relative contribution of the support structure. The forward part has slanted sensors of trapezoidal shape to improve the measurement precision and to minimize the amount of material as seen by particles from the vertex. Fast-shaping front-end amplifiers will be used in conjunction with an online hit time reconstruction algorithm in order to reduce the occupancy to the level of a few percent at most. A novel “Origami” chip-on-sensor scheme is used to minimize both the distance between strips and amplifier (thus reducing the electronic noise) as well as the overall material budget. This report gives an overview on the status of the Belle II SVD and its components, including sensors, front-end detector ladders, mechanics, cooling and the readout electronics.
The Mark II Vertex Drift Chamber
Energy Technology Data Exchange (ETDEWEB)
Alexander, J.P.; Baggs, R.; Fujino, D.; Hayes, K.; Hoard, C.; Hower, N.; Hutchinson, D.; Jaros, J.A.; Koetke, D.; Kowalski, L.A.
1989-03-01
We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 {mu}m spatial resolution and <1000 {mu}m track-pair resolution in pressurized CO{sub 2} gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO{sub 2} mixtures are presented. 10 refs., 12 figs., 1 tab.
On the vertex index of convex bodies
Bezdek, Karoly
2011-01-01
We introduce the vertex index, vein(K), of a given centrally symmetric convex body K, which, in a sense, measures how well K can be inscribed into a convex polytope with small number of vertices. This index is closely connected to the illumination parameter of a body, introduced earlier by the first named author, and, thus, related to the famous conjecture in Convex Geometry about covering of a d-dimensional body by 2^d smaller positively homothetic copies. We provide asymptotically sharp estimates (up to a logarithmic term) of this index in the general case. Also, we provide sharp estimates in dimensions 2 and 3.
Radiation damage in the LHCb Vertex Locator
Affolder, A; Akiba, K.; Alexander, M.; Ali, S.; Artuso, M.; Benton, J.; van Beuzekom, M.; Bjørnstad, P M; Bogdanova, G; Borghi, S.; Bowcock, T. J. V.; Brown, H.; Buytaert, J.; Casse, G.; Collins, P.
2013-01-01
The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\\rm{45 \\times 10^{12}\\,1\\,MeV}$ neutron equivalent ($\\rm{1\\,MeV\\,n_{eq}}$). At the operational sensor temperature of approximately $-7\\,^{\\circ}\\rm{C}$, the average rate of sensor cu...
Performance of the LHCb Vertex Locator
Latham, T
2012-01-01
LHCb is a dedicated flavour physics experiment at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is an essential part of the LHCb detector, permitting precision measurements of the production and decay vertices of beauty and charm particles. The VELO consists of a series of silicon micro-strip detectors, arranged in two retractable halves. Positioned only 7 mm from the beam during normal operations, it must withstand very high levels of radiation. The performance of the LHCb VELO during the first year of LHC physics running is presented.
Quasi-lisse vertex algebras and modular linear differential equations
Arakawa, Tomoyuki
2016-01-01
We introduce a notion of quasi-lisse vertex algebras, which generalizes admissible affine vertex algebras. We show that the normalized character of an ordinary module over a quasi-lisse vertex operator algebra has a modular invariance property, in the sense that it satisfies a modular linear differential equation. As an application we obtain the explicit character formulas of simple affine vertex algebras associated with the Deligne exceptional series at level $-h^{\\vee}/6-1$, which expresses the homogeneous Schur limit of the superconformal index of 4d SCFTs studied by Beem, Lemos, Liendo, Peelaers, Rastelli and van Rees, as quasi-modular forms.
Energy Technology Data Exchange (ETDEWEB)
Marchesini, Ivan; Nowatschin, Dominik; Ott, Jochen; Schmidt, Alexander; Tholen, Heiner [University of Hamburg (Germany)
2015-07-01
In LHC Run II, CMS b-tagging algorithms will employ a new core algorithm, named Inclusive Vertex Finder (IVF). The IVF is designed to perform decay vertex reconstruction of long-lived particles, such as B hadrons. Using only tracks from the silicon tracker, it does not depend on jet clustering and allows for higher reconstruction efficiency of decay vertices, which particularly applies to topologies with two or more decay vertices at low distance. Thus, the IVF will offer increased sensitivity for SM measurements (e.g. angular correlations), but also for the search of BSM physics (e.g. final states with boosted Higgs bosons decaying into b-quarks). For the first time, the dependence of the IVF reconstruction efficiency on the distance of vertices in the η-φ plane is investigated with a data-driven approach. We use a clean set of top quark pair events, selected from data recorded in 2012 in pp-collisions at 8 TeV with the CMS detector, and perform a template fit to a 2D-distribution of the masses of the vertices in an event. Correction factors are derived for the application to simulated events. We conclude that our technique will enable precise calibration of double vertexing with the IVF in the LHC Run II.
Markov branching in the vertex splitting model
Stefansson, Sigurdur Orn
2011-01-01
We study a special case of the vertex splitting model which is a recent model of randomly growing trees. For any finite maximum vertex degree $D$, we find a one parameter model, with parameter $\\alpha \\in [0,1]$ which has a so--called Markov branching property. When $D=\\infty$ we find a two parameter model with an additional parameter $\\gamma \\in [0,1]$ which also has this feature. In the case $D = 3$, the model bears resemblance to Ford's $\\alpha$--model of phylogenetic trees and when $D=\\infty$ it is similar to its generalization, the $\\alpha\\gamma$--model. For $\\alpha = 0$, the model reduces to the well known model of preferential attachment. In the case $\\alpha > 0$, we prove convergence of the finite volume probability measures, generated by the growth rules, to a measure on infinite trees which is concentrated on the set of trees with a single spine. We show that the annealed Hausdorff dimension with respect to the infinite volume measure is $1/\\alpha$. When $\\gamma = 0$ the model reduces to a model of ...
The Construction of Spin Foam Vertex Amplitudes
Bianchi, Eugenio
2012-01-01
Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. They fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4 dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barret and Crane and Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.
The LHCb level 1 vertex trigger
Koratzinos, M
1999-01-01
Summary form only given. The Level 1 Vertex trigger of LHCb has certain features that make it unique amongst the LHC experiment trigger schemes: The problem it addresses is a reduction factor of 25 for minimum bias events while retaining good efficiency for signal B events. The best way to achieve such reduction factors is to rely on the most striking property of those B events, the long decay time of the B particles. The trigger therefore has to reconstruct the event around the interaction region and tag signal events using topological criteria. An accurate vertex detector is one of the key components of LHCb and a natural choice for providing the data for such a triggering scheme. The algorithm for the reconstruction of the event is complicated and not readily parallelisable in its totality. We are therefore proposing an architecture that resembles a high-level trigger architecture, where the event building function is performed by a switch network and each event is processed by a single processor, part of ...
First Results from the LHCb Vertex Locator
Borghi, S
2010-01-01
LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and offline physics analyses. The VELO is the silicon detector surrounding the interaction point, and is the closest LHC vertex detector to the interaction point, located only 7 mm from the LHC beam during normal operation. The detector will operate in an extreme and highly non-uniform radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 micron thick half disc sensors with R-measuring and Phi-measuring micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 $\\mu$m. The detector is also equipped with one n-on-p module. The detectors are operated in vacuum and a...
Vertexing and Tracking Software at Belle II
Schlüter, Tobias
2014-01-01
Belle II is a $B$ factory experiment aiming to start physics data taking in 2017. It is currently being set up at the SuperKEKB accelerator at the KEK facility in Tsukuba (Japan), an asymmetric $e^+e^-$ collider which aims to achieve an unprecedented instantaneous luminosity of $8\\cdot10^{35} \\textrm{Hz}/\\textrm{cm}^2$. This forty-fold increase over predecessor experiments is achieved by employing a novel nano-beam scheme. Originally developed for the now-defunct SuperB experiment, this scheme allows a significant increase in luminosity at only modest increases of beam currents. Challenges for the vertex detector result from increased data and background rates. At full luminosity, physics data will be recorded at a rate of $30\\,\\textrm{kHz}$. The radiation-hard DEPFET-sensors of the innermost layer of the vertex detector will be read out employing a novel data-reduction scheme using selective detector read out based on online reconstruction of event data. Belle II uses a software framework in which data handl...
The Construction of Spin Foam Vertex Amplitudes
Directory of Open Access Journals (Sweden)
Eugenio Bianchi
2013-01-01
Full Text Available Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.
Vertex Sparsifiers and Abstract Rounding Algorithms
Charikar, Moses; Li, Shi; Moitra, Ankur
2010-01-01
The notion of vertex sparsification is introduced in \\cite{M}, where it was shown that for any graph $G = (V, E)$ and a subset of $k$ terminals $K \\subset V$, there is a polynomial time algorithm to construct a graph $H = (K, E_H)$ on just the terminal set so that simultaneously for all cuts $(A, K-A)$, the value of the minimum cut in $G$ separating $A$ from $K -A$ is approximately the same as the value of the corresponding cut in $H$. We give the first super-constant lower bounds for how well a cut-sparsifier $H$ can simultaneously approximate all minimum cuts in $G$. We prove a lower bound of $\\Omega(\\log^{1/4} k)$ -- this is polynomially-related to the known upper bound of $O(\\log k/\\log \\log k)$. This is an exponential improvement on the $\\Omega(\\log \\log k)$ bound given in \\cite{LM} which in fact was for a stronger vertex sparsification guarantee, and did not apply to cut sparsifiers. Despite this negative result, we show that for many natural problems, we do not need to incur a multiplicative penalty fo...
Possible explanation of Zbb vertex anomaly in one-family technicolor models
Kitazawa, N
1996-01-01
In technicolor theories a large radiative correction to the Zbb vertex generally emerges, because of the large top quark mass and SU(2)_L gauge symmetry. The correction can give us an explanation for the deviation of the experimental value of R_b from the standard model prediction. However, generally the T parameter becomes unacceptably large. We show that in the one-family technicolor model recently proposed by the authors all the S, T, and U parameters can be consistent with the experimental bounds while the observed anomaly of R_b is naturally explained.
Internal Alignment of the SLD Vertex Detector using a Matrix Singular Value Decomposition Technique
Energy Technology Data Exchange (ETDEWEB)
Su, Dong
2002-01-03
The tracking resolution and vertex finding capabilities of the SLD experiment depend upon a precise knowledge of the location and orientation of the 96 elements of the SLD pixel vertex detector (VXD3) in 3D space. At the heart of the deterministic procedure described here to align the 96 CCDs is the matrix inversion technique of singular value decomposition (SVD). This tool is employed to unfold the detector geometry corrections from the track hit residual data in the VXD3. The algorithm is adapted to perform an optimal {chi}{sup 2} minimization by careful treatment of the errors and correlations in the residual measurements. The general form of the problems that might be solved with this technique is discussed. The tracking resolution obtained with the aligned geometry is compared with the starting point, based on an optical survey of the CCDs, and is shown to achieve the design performance.
Subgraphs in vertex neighborhoods of K-free graphs
DEFF Research Database (Denmark)
Bang-Jensen, J.; Brandt, Stephan
2004-01-01
In a K-free graph, the neighborhood of every vertex induces a K-free subgraph. The K-free graphs with the converse property that every induced K-free subgraph is contained in the neighborhood of a vertex are characterized, based on the characterization in the case r = 3 due to Pach [8]. © 2004...
Graphs with No Induced Five-Vertex Path or Antipath
DEFF Research Database (Denmark)
Chudnovsky, Maria; Esperet, Louis; Lemoine, Laetitia
2017-01-01
We prove that a graph G contains no induced five-vertex path and no induced complement of a five-vertex path if and only if G is obtained from 5-cycles and split graphs by repeatedly applying the following operations: substitution, split unification, and split unification in the complement, where...
Fermion-Boson Vertex at Finite Chemical Potential
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; FENG Hong-Tao; HOU Feng-Yao; SUN Wei-Min
2007-01-01
Based on the Ward-Takahashi identity at finite chemical potential and Lorentz structure analysis, we generalize the Ball-Chiu vertex to the case of nonzero chemical potential and obtain the general form of the fermionboson vertex in QED at finite chemical potential.
Unquenching the three-gluon vertex: A status report
Blum, Adrian L; Huber, Markus Q; Windisch, Andreas
2015-01-01
We discuss unquenching of the three-gluon vertex via its Dyson-Schwinger equation. We review the role of Furry's theorem and present first results for the quark triangle diagrams using non-perturbatively calculated dressing functions for the quark propagator and the quark-gluon vertex.
The SVX II silicon vertex detector at CDF
Energy Technology Data Exchange (ETDEWEB)
Worm, S. [New Mexico Univ., Albuquerque, NM (United States). New Mexico Center for Particle Physics; CDF Collaboration
1996-09-01
The CDF silicon vertex detector is being upgraded for use in Run II of the Fermilab collider. The increased luminosity in Run II, coupled with the desire for increased acceptance and secondary vertex triggering, necessitates a complete redesign of the previous generation tracker. Details of the design are described.
On-shell two-loop three-gluon vertex
Davydychev, A I
1999-01-01
The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when two of the gluons are on the mass shell. The corresponding two-loop results for the ghost-gluon vertex are also obtained. It is shown that the results are consistent with the Ward-Slavnov-Taylor identities.
Genus Ranges of 4-Regular Rigid Vertex Graphs.
Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin
2015-01-01
A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2n vertices (n > 1), we prove that all intervals [a, b] for all a genus ranges. For graphs with 2n - 1 vertices (n ≥ 1), we prove that all intervals [a, b] for all a genus ranges. We also provide constructions of graphs that realize these ranges.
Artificial Spin-Ice and Vertex Models
Cugliandolo, Leticia F.
2017-01-01
In classical and quantum frustrated magnets the interactions in combination with the lattice structure impede the spins to order in optimal configurations at zero temperature. The theoretical interest in their classical realisations has been boosted by the artificial manufacture of materials with these properties, that are of flexible design. This note summarises work on the use of vertex models to study bidimensional spin-ices samples, done in collaboration with R. A. Borzi, M. V. Ferreyra, L. Foini, G. Gonnella, S. A. Grigera, P. Guruciaga, D. Levis, A. Pelizzola and M. Tarzia, in recent years. It is an invited contribution to a J. Stat. Mech. special issue dedicated to the memory of Leo P. Kadanoff.
The Lorentzian proper vertex amplitude: Asymptotics
Engle, Jonathan; Zipfel, Antonia
2015-01-01
In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in the semi-classical limit. The starting point of the analysis is an expression for the amplitude as an action integral with action differing from that in the EPRL case by an extra `projector' term which scales linearly with spins only in the asymptotic limit. New tools are introduced to generalize stationary phase methods to this case. For the case of boundary data which can be glued to a non-degenerate Lorentzian 4-simplex, the asymptotic limit of the amplitude is shown to equal the single Feynman term, showing that the extra term in the asymptotics of the EPRL amplitude has been eliminated.
Weight Representations of Admissible Affine Vertex Algebras
Arakawa, Tomoyuki; Futorny, Vyacheslav; Ramirez, Luis Enrique
2017-08-01
For an admissible affine vertex algebra {V_k{(\\mathfrak{g})}} of type A, we describe a new family of relaxed highest weight representations of {V_k{(\\mathfrak{g})}}. They are simple quotients of representations of the affine Kac-Moody algebra {\\widehat{\\mathfrak{g}}} induced from the following {\\mathfrak{g}}-modules: (1) generic Gelfand-Tsetlin modules in the principal nilpotent orbit, in particular all such modules induced from {\\mathfrak{sl}_2}; (2) all Gelfand-Tsetlin modules in the principal nilpotent orbit that are induced from {\\mathfrak{sl}_3}; (3) all simple Gelfand-Tsetlin modules over {\\mathfrak{sl}_3}. This in particular gives the classification of all simple positive energy weight representations of {V_k{(\\mathfrak{g})}} with finite dimensional weight spaces for {\\mathfrak{g}=\\mathfrak{sl}_3}.
Vertex Nomination via Content and Context
Coppersmith, Glen A
2012-01-01
If I know of a few persons of interest, how can a combination of human language technology and graph theory help me find other people similarly interesting? If I know of a few people committing a crime, how can I determine their co-conspirators? Given a set of actors deemed interesting, we seek other actors who are similarly interesting. We use a collection of communications encoded as an attributed graph, where vertices represents actors and edges connect pairs of actors that communicate. Attached to each edge is the set of documents wherein that pair of actors communicate, providing content in context - the communication topic in the context of who communicates with whom. In these documents, our identified interesting actors communicate amongst each other and with other actors whose interestingness is unknown. Our objective is to nominate the most likely interesting vertex from all vertices with unknown interestingness. As an illustrative example, the Enron email corpus consists of communications between ac...
The upgrade of the LHCb Vertex Locator
Bird, T
2014-01-01
The LHCb experiment is set for a significant upgrade, which will be ready for Run~3 of the LHC in 2020. This upgrade will allow LHCb to run at a significantly higher instantaneous luminosity and collect an integrated luminosity of $50\\,\\text{fb}^{-1}$ by the end of Run~4. In this process the Vertex locator (VELO) detector will be upgraded to a pixel-based silicon detector. The upgraded VELO will improve upon the current detector by being closer to the beam and having lower material modules with microchannel cooling and a thinner RF-foil. Simulations have shown that it will maintain its excellent performance, even after the radiation damage caused by collecting an integrated luminosity of $50\\,\\text{fb}^{-1}$.
Primary Vertex Reconstruction for Upgrade at LHCb
Wanczyk, Joanna
2016-01-01
The aim of the LHCb experiment is the study of beauty and charm hadron decays with the main focus on CP violating phenomena and searches for physics beyond the Standard Model through rare decays. At the present, the second data taking period is ongoing, which is called Run II. After 2018 during the long shutdown, the replacement of signicant parts of the LHCb detector is planned. One of main changes is upgrade of the present software and hardware trigger to a more rapid full software trigger. Primary Vertex (PV) is a basis for the further tracking and it is sensitive to the LHC running conditions, which are going to change for the Upgrade. In particular, the center-of-mass collision energy should reach the maximum value of 14 TeV. As a result the quality of the reconstruction has to be studied and the reconstruction algorithms have to be optimized.
NLO Corrections to Hard Process in Parton Shower MC - KrkNLO Method
Jadach, S; Sapeta, S; Siódmok, A; Skrzypek, M
2015-01-01
A new method of combining an NLO-corrected hard process with an LO parton shower Monte Carlo, nicknamed {\\sf KrkNLO}, was proposed recently. It is simpler than well-established two other methods: {\\sf MC@NLO} and {\\sf POWHEG}. In this contribution, we present some results of extensive numerical tests of the new method for single $Z$-boson production at hadron colliders and numerical comparisons with two other methods as well as with NNLO calculations.
$\\alpha_s$ and |$\\rm V_{cs}$| determination, and CKM unitarity test, from W decays at NNLO
d'Enterria, David
2016-01-01
The hadronic ($\\Gamma^{\\rm W}_{\\rm had}$) and total ($\\Gamma^{\\rm W}_{\\rm tot}$) widths of the W boson, computed at least at next-to-next-to-leading-order (NNLO) accuracy, are combined to derive a new precise prediction for the hadronic W branching ratio ${\\cal B}^{\\rm W}_{\\rm had} \\equiv \\Gamma^{\\rm W}_{\\rm had}/\\Gamma^{\\rm W}_{\\rm tot}$ = $0.682 \\pm 0.011_{\\rm par}$, using the experimental Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, or ${\\cal B}^{\\rm W}_{\\rm had} = 0.6742 \\pm 0.0002_{\\rm th} \\pm 0.0001_{\\rm par}$ assuming CKM unitarity, with uncertainties dominated by the input parameters of the calculations. Comparing the theoretical predictions and experimental measurements for various W decay observables, the NNLO strong coupling constant at the Z pole, $\\alpha_s(\\rm m_Z) = 0.117 \\pm 0.030_{\\rm exp} \\pm 0.003_{\\rm th} \\pm 0.001_{\\rm par}$, as well as the charm-strange CKM element, $\\rm V_{cs} = 0.973 \\pm 0.003_{\\rm exp} \\pm 0.001_{\\rm par}$, can be extracted under different assumptions. We also show...
Two-loop corrections to Higgs boson production
Energy Technology Data Exchange (ETDEWEB)
Ravindran, V. [Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211019 (India); Smith, J. [C.N. Yang Institute for Theoretical Physics, State University of New York, Stony Brook, NY 11794-3840 (United States); Neerven, W.L. van [Instituut-Lorentz, University of Leiden, PO Box 9506, 2300 RA Leiden (Netherlands)]. E-mail: neerven@lorentz.leidenuniv.nl
2005-01-03
In this paper we present the complete two-loop vertex corrections to scalar and pseudo-scalar Higgs boson production for general colour factors for the gauge group SU(N) in the limit where the top quark mass gets infinite. We derive a general formula for the vertex correction which holds for conserved and non-conserved operators. For the conserved operator we take the electromagnetic vertex correction as an example whereas for the non-conserved operators we take the two vertex corrections above. Our observations for the structure of the pole terms 1/-bar 4, 1/-bar 3 and 1/-bar 2 in two loop order are the same as made earlier in the literature for electromagnetism. However, we also elucidate the origin of the second order single pole term which is equal to the second order singular part of the anomalous dimension plus a universal function which is the same for the quark and the gluon.
19-vertex version of the fully frustrated XY model
Knops, Yolanda M. M.; Nienhuis, Bernard; Knops, Hubert J. F.; Blöte, Henk W. J.
1994-07-01
We investigate a 19-vertex version of the two-dimensional fully frustrated XY (FFXY) model. We construct Yang-Baxter equations for this model and show that there is no solution. Therefore we have chosen a numerical approach based on the transfer matrix. The results show that a coupled XY Ising model is in the same universality class as the FFXY model. We find that the phase coupling over an Ising wall is irrelevant at criticality. This leads to a correction of earlier determinations of the dimension x*h,Is of the Ising disorder operator. We find x*h,Is=0.123(5) and a conformal anomaly c=1.55(5). These results are consistent with the hypothesis that the FFXY model behaves as a superposition of an Ising model and an XY model. However, the dimensions associated with the energy, xt=0.77(3), and with the XY magnetization xh,XY~=0.17, refute this hypothesis.
Novel integrated CMOS pixel structures for vertex detectors
Energy Technology Data Exchange (ETDEWEB)
Kleinfelder, Stuart; Bieser, Fred; Chen, Yandong; Gareus, Robin; Matis, Howard S.; Oldenburg, Markus; Retiere, Fabrice; Ritter, Hans Georg; Wieman, Howard H.; Yamamoto, Eugene
2003-10-29
Novel CMOS active pixel structures for vertex detector applications have been designed and tested. The overriding goal of this work is to increase the signal to noise ratio of the sensors and readout circuits. A large-area native epitaxial silicon photogate was designed with the aim of increasing the charge collected per struck pixel and to reduce charge diffusion to neighboring pixels. The photogate then transfers the charge to a low capacitance readout node to maintain a high charge to voltage conversion gain. Two techniques for noise reduction are also presented. The first is a per-pixel kT/C noise reduction circuit that produces results similar to traditional correlated double sampling (CDS). It has the advantage of requiring only one read, as compared to two for CDS, and no external storage or subtraction is needed. The technique reduced input-referred temporal noise by a factor of 2.5, to 12.8 e{sup -}. Finally, a column-level active reset technique is explored that suppresses kT/C noise during pixel reset. In tests, noise was reduced by a factor of 7.6 times, to an estimated 5.1 e{sup -} input-referred noise. The technique also dramatically reduces fixed pattern (pedestal) noise, by up to a factor of 21 in our tests. The latter feature may possibly reduce pixel-by-pixel pedestal differences to levels low enough to permit sparse data scan without per-pixel offset corrections.
Radiative corrections to electron-proton scattering
Maximon, LC; Tjon, JA
2000-01-01
The radiative corrections to elastic electron-proton scattering are analyzed in a hadronic model including the finite size of the nucleon. For initial electron energies above 8 GeV and large scattering angles, the proton vertex correction in this model increases by at least 2% of the overall factor
Locking mechanisms in degree-4 vertex origami structures
Fang, Hongbin; Li, Suyi; Xu, Jian; Wang, K. W.
2016-04-01
Origami has emerged as a potential tool for the design of mechanical metamaterials and metastructures whose novel properties originate from their crease patterns. Most of the attention in origami engineering has focused on the wellknown Miura-Ori, a folded tessellation that is flat-foldable for folded sheet and stacked blocks. This study advances the state of the art and expands the research field to investigate generic degree-4 vertex (4-vertex) origami, with a focus on facet-binding. In order to understand how facet-binding attributes to the mechanical properties of 4-vertex origami structures, geometries of the 4-vertex origami cells are analyzed and analytically expressed. Through repeating and stacking 4-vertex cells, origami sheets and stacked origami blocks can be constructed. Geometry analyses discover four mechanisms that will lead to the self-locking of 4-vertex origami cells, sheets, and stacked blocks: in-cell facet-binding, inlayer facet-binding, inter-layer facet binding, and in-layer and inter-layer facet-bindings. These mechanisms and the predicted self-locking phenomena are verified through 3D simulations and prototype experiments. Finally, this paper briefly introduces the unusual mechanical properties caused by the locking of 4-vertex origami structures. The research reported in this paper could foster a new breed of self-locking structures with various engineering applications.
Measurement of $R_{b}$ using a Vertex Mass Tag
Abe, K; Akagi, T; Allen, N J; Ash, W W; Aston, D; Baird, K G; Baltay, C; Band, H R; Barakat, M B; Baranko, G; Bardon, O; Barklow, T L; Bashindzhagian, G L; Bazarko, A O; Ben-David, R; Benvenuti, Alberto C; Bilei, G M; Bisello, D; Blaylock, G; Bogart, J R; Bolen, B; Bolton, T; Bower, G R; Brau, J E; Breidenbach, M; Bugg, W M; Burke, D; Burnett, T H; Burrows, P N; Busza, W; Calcaterra, A; Caldwell, D O; Calloway, D; Camanzi, B; Carpinelli, M; Cassell, R; Castaldi, R; Castro, A; Cavalli-Sforza, M; Chou, A; Church, E; Cohn, H O; Coller, J A; Cook, V; Cotton, R; Cowan, R F; Coyne, D G; Crawford, G; de Oliveira, A; Damerell, C J S; Daoudi, M; De Groot, N; De Sangro, R; Dell'Orso, R; Dervan, P J; Dima, M; Dong, D N; Du, P Y C; Dubois, R; Eisenstein, B I; Elia, R; Etzion, E; Fahey, S; Falciai, D; Fan, C; Fernández, J P; Fero, M J; Frey, R; Gillman, T; Gladding, G; González, S; Hart, E L; Harton, J L; Hasan, A; Hasegawa, Y; Hasuko, K; Hedges, S J; Hertzbach, S S; Hildreth, M D; Huber, J; Huffer, M E; Hughes, E W; Hwang, H; Iwasaki, Y; Jackson, D J; Jacques, P; Jaros, J A; Jiang, Z Y; Johnson, A S; Johnson, J R; Johnson, R A; Junk, T R; Kajikawa, R; Kalelkar, M; Kang, H J; Karliner, I; Kawahara, H; Kendall, H W; Kim, Y D; King, M E; King, R; Kofler, R R; Krishna, N M; Kroeger, R S; Labs, J F; Langston, M; Lath, A; Lauber, J A; Leith, D W G S; Lia, V; Liu, M X; Liu, X; Loreti, M; Lu, A; Lynch, H L; Ma, J; Mancinelli, G; Manly, S; Mantovani, G C; Markiewicz, T W; Maruyama, T; Masuda, H; Mazzucato, E; McKemey, A K; Meadows, B T; Messner, R; Mockett, P M; Moffeit, K C; Moore, T B; Müller, D; Nagamine, T; Narita, S; Nauenberg, U; Neal, H; Nussbaum, M; Ohnishi, Y; Oishi, N; Onoprienko, D; Osborne, L S; Panvini, R S; Park, C H; Park, H; Pavel, T J; Peruzzi, I; Piccolo, M; Piemontese, L; Pieroni, E; Pitts, K T; Plano, R J; Prepost, R; Prescott, C Y; Punkar, G D; Quigley, J; Ratcliff, B N; Reeves, T W; Reidy, J; Reinertsen, P L; Rensing, P E; Rochester, L S; Rowson, P C; Russell, J J; Saxton, O H; Schalk, T; Schindler, R H; Schumm, B A; Schwiening, J; Sen, S; Serbo, V V; Shaevitz, M H; Shank, J T; Shapiro, G; Sherden, D J; Shmakov, K D; Simopoulos, C; Sinev, N B; Smith, S R; Smy, M B; Snyder, J A; Stängle, H; Stamer, P; Steiner, H; Steiner, R; Strauss, M G; Su, D; Suekane, F; Sugiyama, A; Suzuki, S; Swartz, M; Szumilo, A; Takahashi, T; Taylor, F E; Torrence, E; Trandafir, A I; Turk, J D; Usher, T; Vavra, J; Vannini, C; Vella, E; Venuti, J P; Verdier, R; Verdini, P G; Wagner, D L; Wagner, S R; Waite, A P; Watts, S J; Weidemann, A W; Weiss, E R; Whitaker, J S; White, S L; Wickens, F J; Williams, D C; Williams, S H; Willocq, S; Wilson, R J; Wisniewski, W J; Woods, M; Word, G B; Wyss, J; Yamamoto, R K; Yamartino, J M; Yang, X; Yashima, J; Yellin, S J; Young, C C; Yuta, H; Zapalac, G; Zdarko, R W; Zhou, J
1998-01-01
We report a new measurement of Rb = Gamma(Z0->b-bbar) / Gamma(Z0->hadrons) using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130k hadronic Z0 events, collected with the SLD at the SLC. The method utilizes the 3-D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b-tagging efficiency and purity. We obtain Rb=0.2142+/-0.0034(stat.)+/-0.0015(syst.)+/-0.0002(R_c).
Quark-gluon vertex in arbitrary gauge and dimension
Davydychev, A I; Saks, L
2001-01-01
One-loop off-shell contributions to the quark-gluon vertex are calculated, in an arbitrary covariant gauge and in arbitrary space-time dimension, including quark-mass effects. It is shown how one can get results for all on-shell limits of interest directly from the off-shell expressions. In order to demonstrate that the Ward-Slavnov-Taylor identity for the quark-gluon vertex is satisfied, we have also calculated the corresponding one-loop contribution involving the quark-quark-ghost-ghost vertex.
Animation Visualization for Vertex Coloring of Polyhedral Graphs
Directory of Open Access Journals (Sweden)
Hidetoshi Nonaka
2013-12-01
Full Text Available Vertex coloring of a graph is the assignment of labels to the vertices of the graph so that adjacent vertices have different labels. In the case of polyhedral graphs, the chromatic number is 2, 3, or 4. Edge coloring problem and face coloring problem can be converted to vertex coloring problem for appropriate polyhedral graphs. We have been developed an interactive learning system of polyhedra, based on graph operations and simulated elasticity potential method, mainly for educational purpose. In this paper, we introduce a learning subsystem of vertex coloring, edge coloring and face coloring, based on minimum spanning tree and degenerated polyhedron, which is introduced in this paper.
Performance of the LHCb Vertex Locator
Aaij, R; Akiba, K; Alexander, M; Ali, S; Appleby, R B; Artuso, M; Bates, A; Bay, A; Behrendt, O; Benton, J; van Beuzekom, M; Bjornstad, P M; Bogdanova, G; Borghi, S; Borgia, A; Bowcock, T J V; van den Brand, J; Brown, H; Buytaert, J; Callot, O; Carroll, J; Casse, G; Collins, P; De Capua, S; Doets, M; Donleavy, S; Dossett, D; Dumps, R; Eckstein, D; Eklund, L; Farinelli, C; Farry, S; Ferro-Luzzi, M; Frei, R; Garofoli, J; Gersabeck, M; Gershon, T; Gong, A; Gong, H; Gordon, H; Haefeli, G; Harrison, J; Heijne, V; Hennessy, K; Hulsbergen, W; Huse, T; Hutchcroft, D; Jaeger, A; Jalocha, P; Jans, E; John, M; Keaveney, J; Ketel, T; Korolev, M; Kraan, M; Lastovicka, T; Laﬀerty, G; Latham, T; Lefeuvre, G; Leﬂat, A; Liles, M; van Lysebetten, A; MacGregor, G; Marinho, F; McNulty, R; Merkin, M; Moran, D; Mountain, R; Mous, I; Mylroie-Smith, J; Needham, M; Nikitin, N; Noor, A; Oblakowska-Mucha, A; Papadelis, A; Pappagallo, M; Parkes, C; Patel, G D; Rakotomiaramanana, B; Redford, S; Reid, M; Rinnert, K; Rodrigues, E; Saavedra, A F; Schiller, M; Schneider, O; Shears, T; Silva Coutinho, R; Smith, N A; Szumlak, T; Thomas, C; van Tilburg, J; Tobin, M; Velthuis, J; Verlaat, B; Viret, S; Volkov, V; Wallace, C; Wang, J; Webber, A; Whitehead, M; Zverev, E
2014-01-01
The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 microns is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means ...
The PHENIX Forward Silicon Vertex Detector
Aidala, C; Anderssen, LE; Bambaugh, A; Barron, A; Boissevain, J G; Bok, J; Boose, S; Brooks, M L; Butsyk, S; Cepeda, LM; Chacon, P; Chacon, S; Chavez, L; Cote, T; D'Agostino, C; Datta, A; DeBlasio, K; DelMonte, L; Desmond, E J; Durham, J M; Fields, D; Finger, M; Gingu, C; Gonzales, B; Haggerty, J S; Hawke, T; van Hecke, H W; Herron, M; Hoff, J; Huang, J; Jiang, X; Johnson, LT; Jonas, M; Kapustinsky, J; Key, A; Kunde, G J; LaBounty, J; Lee, D M; Lee, K B; Leitch, M J; Lenz, M; Lenz, W; Liu, M X; Lynch, D; Mannel, E; McGaughey, P L; Meles, A; Meredith, B; Nguyen, H; O'Brien, E; Pak, R; Papavassiliou, V; Pate, S; Pereira, H; Perera, G D N; Phillips, M; Pisani, R; Polizzo, S; Poncione, R J; Popule, J; Prokop, M; Purschke, M L; Purwar, A K; Ronzhina, N; Silva, C L; Slunecka, M; Smith, R; Sondheim, W E; Spendier, K; Stoffer, M; Tennant, E; Thomas, D; Tomasek, M; Veicht, A; Vrba, V; Wang, X R; Wei, F; Winter, D; Yarema, R; You, Z; Zimmerman, A; Zimmerman, T
2013-01-01
A new silicon detector has been developed to provide the PHENIX experiment with precise charged particle tracking at forward and backward rapidity. The Forward Silicon Vertex Tracker (FVTX) was installed in PHENIX prior to the 2012 run period of the Relativistic Heavy Ion Collider (RHIC). The FVTX is composed of two annular endcaps, each with four stations of silicon mini-strip sensors, covering a rapidity range of $1.2<|\\eta|<2.2$ that closely matches the two existing PHENIX muon arms. Each station consists of 48 individual silicon sensors, each of which contains two columns of mini-strips with 75 $\\mu$m pitch in the radial direction and lengths in the $\\phi$ direction varying from 3.4 mm at the inner radius to 11.5 mm at the outer radius. The FVTX has approximately 0.54 million strips in each endcap. These are read out with FPHX chips, developed in collaboration with Fermilab, which are wire bonded directly to the mini-strips. The maximum strip occupancy reached in central Au-Au collisions is approxim...
Vertex micromagnetic energy in artificial square ice
Perrin, Yann; Canals, Benjamin; Rougemaille, Nicolas
2016-10-01
Artificial arrays of interacting magnetic elements provide an uncharted arena in which the physics of magnetic frustration and magnetic monopoles can be observed in real space and in real time. These systems offer the formidable opportunity to investigate a wide range of collective magnetic phenomena with a lab-on-chip approach and to explore various theoretical predictions from spin models. Here, we study artificial square ice systems numerically and use micromagnetic simulations to understand how the geometrical parameters of the individual magnetic elements affect the energy levels of an isolated square vertex. More specifically, we address the question of whether the celebrated square ice model could be made relevant for artificial square ice systems. Our work reveals that tuning the geometry alone should not allow the experimental realization of the square ice model when using nanomagnets coupled through the magnetostatic interaction. However, low-aspect ratios combined with small gaps separating neighboring magnetic elements of moderated thickness might permit approaching the ideal case where the degeneracy of the ice rule states is recovered.
Radiation damage in the LHCb Vertex Locator
Affolder, A; Alexander, M; Ali, S; Artuso, M; Benton, J; van Beuzekom, M; Bjørnstad, P M; Bogdanova, G; Borghi, S; Bowcock, T J V; Brown, H; Buytaert, J; Casse, G; Collins, P; De Capua, S; Dossett, D; Eklund, L; Farinelli, C; Garofoli, J; Gersabeck, M; Gershon, T; Gordon, H; Harrison, J; Heijne, V; Hennessy, K; Hutchcroft, D; Jans, E; John, M; Ketel, T; Lafferty, G; Latham, T; Leflat, A; Liles, M; Moran, D; Mous, I; Oblakowska-Mucha, A; Parkes, C; Patel, G D; Redford, S; Reid, M M; Rinnert, K; Rodrigues, E; Schiller, M; Szumlak, T; Thomas, C; Velthuis, J; Volkov, V; Webber, A D; Whitehead, M; Zverev, E
2013-01-01
The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\\rm{45 \\times 10^{12}\\,1\\,MeV}$ neutron equivalent ($\\rm{1\\,MeV\\,n_{eq}}$). At the operational sensor temperature of approximately $-7\\,^{\\circ}\\rm{C}$, the average rate of sensor current increase is 18$\\mu$ A per $\\rm{fb^{-1}}$, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of $E_{g}=1.16\\pm0.03\\pm0.04\\,\\rm{eV}$ obtained. The first observation of n-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around $15 \\times 10 ^{12}$ of $1\\,\\rm{MeV\\,n_{eq}}$. The only n-on-p sensors in use at the LHC have also been studied. With an initial fluence of ap...
Torus Knots and the Topological Vertex
Jockers, Hans; Soroush, Masoud
2012-01-01
We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S^3. The key role is played by the SL(2,Z) transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Marino. Comparing to the recent proposal by Aganagic and Vafa for knots on S^3, we demonstrate that the disk amplitude of the A-brane associated to any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.
Status of the LHCb VErtex LOcator
Palacios, J P
2003-01-01
LHCb is a single arm spectrometer at the LHC. It is dedicated to the study of CP violation in the B-hadron system. The VErtex LOcator (VELO) is a silicon microstrip detector providing accurate measurements of event primary and secondary vertices, impact parameters, and tracks. The second level trigger decision of LHCb is mainly based on information from a full readout of the VELO. This document gives a general introduction to LHCb as a context for a more extensive description of the VELO. The VELO design emphasises the need for precise reconstruction of tracks down to momenta of a few GeV. The VELO operates inside the LHC beam-pipe, and the sensors, the hybrids, and the foil separating the primary and secondary vacuua must be built with the minimum possible material. The R-$\\phi$ strip layout is optimised for efficient trigger operation and precise measurements at the smallest radii. The performance must be maintained in the harsh radiation environment close to the LHC beams. These issues have led to a choice...
On vertex-coloring edge-weighting of graphs
Institute of Scientific and Technical Information of China (English)
Honglian LU; Xu YANG; Qinglin YU
2009-01-01
A k-edge-weighting w of a graph G is an assignment of an integer weight, w(e) ∈ {1,..., k}, to each edge e. An edge-weighting naturally induces a vertex coloring c by defining e(u) = ∑eЭuw(e) for every u ∈ V(G). A k-edge-weighting of a graph G is vertex-coloring if the induced coloring c is proper, I.e., c(u)≠c(v) for any edge uv ∈ E(G). When k ≡ 2 (mod 4)and k≥ 6, we prove that if G is k-colorable and 2-connected, δ(G) ≥ k - 1, then G admits a vertex-coloring k-edge-weighting. We also obtain several sufficient conditions for graphs to be vertex-coloring k-edge-weighting.
The $\\omega DD$ vertex in a Sum Rule approach
Holanda, L B; Mihara, A
2007-01-01
The study of charmonium dissociation in heavy ion collisions is generally performed in the framework of effective Lagrangians with meson exchange. Some studies are also developed with the intention of calculate form factors and coupling constants related with charmed and light mesons. These quantities are important in the evaluation of charmonium cross sections. In this paper we present a calculation of the $\\omega DD$ vertex that is a possible interaction vertex in some meson-exchange models spread in the literature. We used the standard method of QCD Sum Rules in order to obtain the vertex form factor as a function of the transferred momentum. Our results are compatible with the value of this vertex form factor (at zero momentum transfer) obtained in the vector-meson dominance model.
A new method for counting trees with vertex partition
Institute of Scientific and Technical Information of China (English)
2008-01-01
A direct and elementary method is provided in this paper for counting trees with vertex partition instead of recursion, generating function, functional equation, Lagrange inversion, and matrix methods used before.
Assembling the last module of the vertex locator for LHCb
Maximilien Brice
2007-01-01
The 42nd and final vertex locator module is assembled in the LHCb clean room. This will be used to measure the point at which two protons in the beam collide from the tracks of particles produced in the collision.
Vertex models: from cell mechanics to tissue morphogenesis
Alt, Silvanus; Ganguly, Poulami
2017-01-01
Tissue morphogenesis requires the collective, coordinated motion and deformation of a large number of cells. Vertex model simulations for tissue mechanics have been developed to bridge the scales between force generation at the cellular level and tissue deformation and flows. We review here various formulations of vertex models that have been proposed for describing tissues in two and three dimensions. We discuss a generic formulation using a virtual work differential, and we review applications of vertex models to biological morphogenetic processes. We also highlight recent efforts to obtain continuum theories of tissue mechanics, which are effective, coarse-grained descriptions of vertex models. This article is part of the themed issue ‘Systems morphodynamics: understanding the development of tissue hardware’. PMID:28348254
Factorial Schur functions via the six vertex model
McNamara, Peter J
2009-01-01
For a particular set of Boltzmann weights and a particular boundary condition for the six vertex model in statistical mechanics, we compute explicitly the partition function and show it to be equal to a factorial Schur function.
Vertex Reconstruction in the ATLAS Experiment at the LHC
Bouhova-Thacker, E; The ATLAS collaboration; Kostyukhin, V; Liebig, W; Limper, M; Piacquadio, G; Lichard, P; Weiser, C; Wildauer, A
2009-01-01
In the harsh environment of the Large Hadron Collider at CERN (design luminosity of $10^{34}$ cm$^{-2}$ s$^{-1}$) efficient reconstruction of vertices is crucial for many physics analyses. Described in this paper are the strategies for vertex reconstruction used in the ATLAS experiment and their implementation in the software framework Athena. The algorithms for the reconstruction of primary and secondary vertices as well as for finding of photon conversions and vertex reconstruction in jets are described. A special emphasis is made on the vertex fitting with application of additional constraints. The implementation of mentioned algorithms follows a very modular design based on object-oriented C++ and use of abstract interfaces. The user-friendly concept allows event reconstruction and physics analyses to compare and optimize their choice among different vertex reconstruction strategies. The performance of implemented algorithms has been studied on a variety of Monte Carlo samples and results are presented.
Mirror of the refined topological vertex from a matrix model
Eynard, B
2011-01-01
We find an explicit matrix model computing the refined topological vertex, starting from its representation in terms of plane partitions. We then find the spectral curve of that matrix model, and thus the mirror symmetry of the refined vertex. With the same method we also find a matrix model for the strip geometry, and we find its mirror curve. The fact that there is a matrix model shows that the refined topological string amplitudes also satisfy the remodeling the B-model construction.
The vertex detector for the Lepton/Photon collaboration
Energy Technology Data Exchange (ETDEWEB)
Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)
1991-12-31
The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.
R&D Challenges of a CLIC Vertex Detector
van der Kraaij, E
2010-01-01
The Compact Linear Collider (CLIC) is a concept for an electron-positron collider with a center- of-mass energy of up to 3 TeV. Given the unprecedented experimental conditions at CLIC none of the technologies available today can fulfill all requirements set for the vertex detector. At the conference these conditions and the challenges they pose for the R&D of a CLIC vertex detector were presented.
The vertex detector for the Lepton/Photon collaboration
Energy Technology Data Exchange (ETDEWEB)
Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)
1991-12-31
The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.
Performance of the ATLAS primary vertex reconstruction algorithms
Zhang, Matt
2017-01-01
The reconstruction of primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. Such advances in vertex seeding include methods taken from medical imagining, which allow for reconstruction of very nearby vertices will be highlighted. The performance of the current vertexing algorithms using early Run-2 data will be presented and compared to results from simulation.
DISTRIBUTED VERTEX COVER ALGORITHMS FOR WIRELESS SENSOR NETWORKS
Directory of Open Access Journals (Sweden)
Vedat Kavalci
2014-01-01
Full Text Available Vertex covering has important applications for wireless sensor networks such as monitoring link failures, facility location, clustering, and data aggregation. In this study, we designed three algorithms for constructing vertex cover in wireless sensor networks. The first algorithm, which is an adaption of the Parnas & Ron’s algorithm, is a greedy approach that finds a vertex cover by using the degrees of the nodes. The second algorithm finds a vertex cover from graph matching where Hoepman’s weighted matching algorithm is used. The third algorithm firstly forms a breadth-first search tree and then constructs a vertex cover by selecting nodes with predefined levels from breadth-first tree. We show the operation of the designed algorithms, analyze them, and provide the simulation results in the TOSSIM environment. Finally we have implemented, compared and assessed all these approaches. The transmitted message count of the first algorithm is smallest among other algorithms where the third algorithm has turned out to be presenting the best results in vertex cover approximation ratio.
Energy Technology Data Exchange (ETDEWEB)
Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics, Protvino (Russian Federation); Bluemlein, J.; Klein, S.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2009-08-15
We determine the parton distribution functions (PDFs) in a next-to-next-to-leading order (NNLO) QCD-analysis of the inclusive neutral-current deep-inelastic-scattering (DIS) world data combined with the neutrino-nucleon DIS di-muon data and the fixed-target Drell-Yan data. The PDF-evolution is performed in the N{sub f} = 3 fixed-flavor scheme and supplementary sets of PDFs in the 4- and 5-flavor schemes are derived from the results in the 3-flavor scheme using matching conditions. The charm-quark DIS contribution is calculated in a general-mass variable-flavor-number (GMVFN) scheme interpolating between the zero mass 4-flavor scheme at asymptotically large values of momentum transfer Q{sup 2} and the 3-flavor scheme prescription of Buza-Matiounine-Smith-van Neerven (BMSN) at the value of Q{sup 2} = m{sub c}{sup 2}. The results in the GMVFN scheme are compared with those of the fixed-flavor scheme and other prescriptions used in global fits of PDFs. The strong coupling constant is measured at an accuracy of {approx} 1.5%. We obtain at NNLO {alpha}{sub s}(M{sub Z}{sup 2})=0.1135{+-}0.0014 in the fixed-flavor scheme and {alpha}{sub s}(M{sub Z}{sup 2})=0.1129{+-}0.0014 applying the BMSN-prescription. The implications for important standard candle and hard scattering processes at hadron colliders are illustrated. Predictions for cross sections of W{sup {+-}}- and Z-boson, the top-quark pair- and Higgs-boson production at the Tevatron and the LHC based on the 5-flavor PDFs of the present analysis are provided. (orig.)
Connecting dark matter annihilation to the vertex functions of Standard Model fermions
Kumar, Jason; Light, Christopher
2017-07-01
We consider scenarios in which dark matter is a Majorana fermion which couples to Standard Model fermions through the exchange of charged mediating particles. The matrix elements for various dark matter annihilation processes are then related to one-loop corrections to the fermion-photon vertex, where dark matter and the charged mediators run in the loop. In particular, in the limit where Standard Model fermion helicity mixing is suppressed, the cross section for dark matter annihilation to various final states is related to corrections to the Standard Model fermion charge form factor. These corrections can be extracted in a gauge-invariant manner from collider cross sections. Although current measurements from colliders are not precise enough to provide useful constraints on dark matter annihilation, improved measurements at future experiments, such as the International Linear Collider, could improve these constraints by several orders of magnitude, allowing them to surpass the limits obtainable by direct observation.
The high energy behavior of QCD. The effective action and the triple-Pomeron-vertex
Energy Technology Data Exchange (ETDEWEB)
Hentschinski, Martin
2009-07-15
We study integrations over light-cone momenta in the high energy effective action of QCD. After a brief review of the effective action, we arrive on a regularization mechanism from matching of effective action diagrams with QCD diagrams, which we apply to a re-derivation of the reggeized gluon and of the BFKL-equation. We study consequences of the proposed regularization on the analytic structure of 2{yields}3 and 2{yields}4 production amplitudes in the Multi-Regge-Kinematics. We derive a certain part of the 1-loop corrections to the production vertex and demonstrate that they yield the on-set of corrections demanded by the Steinmann-relations. The Reggeon-Particle-2-Reggeon vertex is determined and applied to the construction of various signature configurations of the production amplitudes. We extend the proposed regularization method to states of three and four reggeized gluons and propose a supplement to the effective Lagrangian. We derive vertices for the 1-3 and 2-4 reggeized-gluon-transition inside the elastic amplitude and verify that signature conservation is obeyed. Integral equations for the state of three and four reggeized gluons are formulated and shown to be in accordance with a result by Bartels and Wuesthoff. In a second part we investigate the high-energy behavior of QCD for different surface topologies of color graphs. After a brief review of the planar limit (bootstrap and gluon reggeization) and of the cylinder topology (BFKL) we investigate the 3{yields}3 scattering in the triple Regge limit which belongs to the pair-of-pants topology. We re-derive the triple Pomeron vertex function and show that it belongs to a specific set of graphs in color space which we identify as the analog of the Mandelstam diagram. We then extend the study to the high-energy behavior of N=4 SYM where we find a new class of color graphs not present in QCD. (orig.)
Childers, Annie Burns; Vidakovic, Draga
2014-01-01
This paper explores sixty-six students' personal meaning and interpretation of the vertex of a quadratic function in relation to their understanding of quadratic functions in two different representations, algebraic and word problem. Several categories emerged from students' personal meaning of the vertex including vertex as maximum or minimum…
VERTEX: manganese transport through oxygen minima
Martin, John H.; Knauer, George A.
1984-01-01
Manganese transport through a well-developed oxygen minimum was studied off central Mexico (18°N, 108°W) in October-November 1981 as part of the VERTEX (Vertical Transport and Exchange) research program. Refractory, leachable and dissolved Mn fractions associated with particulates caught in traps set at eight depths (120-1950 m) were analyzed. Particles entering the oxygen minimum had relatively large Mn loads; however, as the particulates sank further into the minimum, total Mn fluxes steadily decreased from 190 nmol m -2 day -1 at 120 m to 36 nmol m -2 day -1 at 400 m. Manganese fluxes then steadily increased in the remaining 800-1950 m, reaching rates of up to 230 nmol m -2 day -1 at 1950 m. Manganese concentrations were also measured in the water column. Dissolved Mn levels Rate-of-change estimates based on trap flux data yield regeneration rates of up to 0.44 nmol kg -1 yr -1 in the upper oxygen minimum (120-200 m). However, only 30% of the dissolved Mn in the oxygen minimum appears to be from sinking particulate regeneration; the other 70% probably results from continental-slope-release-horizontal-transport processes. Dissolved Mn scavenges back onto particles as oxygen levels begin to increase with depth. Scavenging rates ranging from -0.03 to -0.09 nmol kg -1 yr -1 were observed at depths from 700 to 1950 m. These scavenging rates result in Mn residence times of 16-19 years, and scavenging rate constants on the order of 0.057 yr -1. Manganese removal via scavenging on sinking particles below the oxygen minimum is balanced by Mn released along continental boundaries and transported horizontally via advective-diffusive processes. Manganese appears to be very weakly associated with particulates. Nevertheless, the amounts of Mn involved with sinking biogenic particles are large, and the resulting fluxes are on the same order of magnitude as those necessary to explain the excess Mn accumulating on the sea floor. The overall behavior of Mn observed in this, and
Electron-phonon vertex in the two-dimensional one-band Hubbard model
Huang, Z. B.; Hanke, W.; Arrigoni, E.; Scalapino, D. J.
2003-12-01
Using quantum Monte Carlo techniques, we study the effects of electronic correlations on the effective electron-phonon (el-ph) coupling in a two-dimensional one-band Hubbard model. We consider a momentum-independent bare ionic el-ph coupling. In the weak- and intermediate-correlation regimes, we find that the on-site Coulomb interaction U acts to effectively suppress the ionic el-ph coupling at all electron and phonon momenta. In this regime, our numerical simulations are in good agreement with the results of perturbation theory to order U2. However, entering the strong-correlation regime, we find that the forward-scattering process stops decreasing and begins to substantially increase as a function of U, leading to an effective el-ph coupling which is peaked in the forward direction. Whereas at weak and intermediate Coulomb interactions, screening is the dominant correlation effect suppressing the el-ph coupling, at larger U values irreducible vertex corrections become more important and give rise to this increase. These vertex corrections depend crucially on the renormalized electronic structure of the strongly correlated system.
A covariant representation of the Ball–Chiu vertex
Energy Technology Data Exchange (ETDEWEB)
Ahmadiniaz, Naser, E-mail: naser@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Schubert, Christian, E-mail: schubert@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Mühlenberg 1, D-14476 Potsdam (Germany)
2013-04-21
In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger–Dyson equations. Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches. Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases. The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations. We find that the Bern–Kosower loop replacement rules, originally derived for the on-shell case, hold off-shell as well. We explain the relation of the structure of this representation to the low-energy effective action, and establish the precise connection with the standard Ball–Chiu decomposition of the vertex. This allows us also to predict that the vanishing of the completely antisymmetric coefficient function S of this decomposition is not a one-loop accident, but persists at higher-loop orders. The sum rule found by Binger and Brodsky, which leads to the vanishing of the one-loop vertex in N=4 SYM theory, in the present approach relates to worldline supersymmetry.
Directed Subset Feedback Vertex Set is Fixed-Parameter Tractable
Chitnis, Rajesh; Hajiaghayi, MohammadTaghi; Marx, Dániel
2012-01-01
Given a graph $G$ and an integer $k$, the \\textsc{Feedback Vertex Set} (\\textsc{FVS}) problem asks if there is a vertex set $T$ of size at most $k$ that hits all cycles in the graph. Bodlaender (WG '91) gave the first fixed-parameter algorithm for \\textsc{FVS} in undirected graphs. The fixed-parameter tractability status of \\textsc{FVS} in directed graphs was a long-standing open problem until Chen et al. (STOC '08) showed that it is fixed-parameter tractable by giving an $4^{k}k!n^{O(1)}$ algorithm. In the subset versions of this problems, we are given an additional subset $S$ of vertices (resp. edges) and we want to hit all cycles passing through a vertex of $S$ (resp. an edge of $S$). Indeed both the edge and vertex versions are known to be equivalent in the parameterized sense. Recently the \\textsc{Subset Feedback Vertex Set} in undirected graphs was shown to be FPT by Cygan et al. (ICALP '11) and Kakimura et al. (SODA '12). We generalize the result of Chen et al. (STOC '08) by showing that \\textsc{Subset...
On trees with total domination number equal to edge-vertex domination number plus one
Indian Academy of Sciences (India)
B Krishnakumari; Y B Venkatakrishnan; Marcin Krzywkowski
2016-05-01
An edge $e \\in E(G)$ dominates a vertex $v \\in V(G)$ if $e$ is incident with $v$ or $e$ is incident with a vertex adjacent to $v$. An edge-vertex dominating set of a graph $G$ is a set $D$ of edges of $G$ such that every vertex of $G$ is edge-vertex dominated by an edge of $D$. The edge-vertex domination number of a graph $G$ is the minimum cardinality of an edge-vertex dominating set of $G$. A subset $D \\subseteq V(G)$ is a total dominating set of $G$ if every vertex of $G$ has a neighbor in $D$. The total domination number of $G$ is the minimum cardinality of a total dominating set of $G$. We characterize all trees with total domination number equal to edge-vertex domination number plus one.
On the uniqueness of d-vertex magic constant
Directory of Open Access Journals (Sweden)
Arumugam S.
2014-05-01
Full Text Available Let G = (V,E be a graph of order n and let D ⊆ {0, 1, 2, 3, . . .}. For v ∈ V, let ND(v = {u ∈ V : d(u, v ∈ D}. The graph G is said to be D-vertex magic if there exists a bijection f : V (G → {1, 2, . . . , n} such that for all v ∈ V, ∑uv∈ND(v f(u is a constant, called D-vertex magic constant. O’Neal and Slater have proved the uniqueness of the D-vertex magic constant by showing that it can be determined by the D-neighborhood fractional domination number of the graph. In this paper we give a simple and elegant proof of this result. Using this result, we investigate the existence of distance magic labelings of complete r-partite graphs where r ≥ 4.
Plethystic Vertex Operators and Boson-Fermion Correspondences
Fauser, Bertfried; King, Ronald C
2016-01-01
We study the algebraic properties of plethystic vertex operators, introduced in J. Phys. A: Math. Theor. 43 405202 (2010), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape \\pi. Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each \\pi, the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms.
Plethystic vertex operators and boson-fermion correspondences
Fauser, Bertfried; Jarvis, Peter D.; King, Ronald C.
2016-10-01
We study the algebraic properties of plethystic vertex operators, introduced in (2010 J. Phys. A: Math. Theor. 43 405202), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape π. Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each π, the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms.
Fatigue crack shape prediction based on vertex singularity
Directory of Open Access Journals (Sweden)
Hutař P.
2008-11-01
Full Text Available Due to the existence of vertex singularity at the point where the crack intersects the free surface, stress distribution around the crack tip and the type of the singularity is changed. In the interior of the specimen the classical singular behaviour of the crack is dominant and can be described using analytic equations. Contrary to this, at the free surface or in the boundary layer close to free surface the vertex singularity is significant. The influence of vertex singularity on crack behaviour and a crack shape for a three-dimensional structure is described in this paper. The results presented make it possible to estimate fatigue crack growth rate and crack shape using the concept of the generalized stress intensity factor. The estimated fatigue crack shape can help to provide a more reliable estimation of the fatigue life of the structures considered.
Vertex-centred Method to Detect Communities in Evolving Networks
Canu, Maël; d'Allonnes, Adrien Revault
2016-01-01
Finding communities in evolving networks is a difficult task and raises issues different from the classic static detection case. We introduce an approach based on the recent vertex-centred paradigm. The proposed algorithm, named DynLOCNeSs, detects communities by scanning and evaluating each vertex neighbourhood, which can be done independently in a parallel way. It is done by means of a preference measure, using these preferences to handle community changes. We also introduce a new vertex neighbourhood preference measure, CWCN, more efficient than current existing ones in the considered context. Experimental results show the relevance of this measure and the ability of the proposed approach to detect classical community evolution patterns such as grow-shrink and merge-split.
Nath, N. M.; Mukharjee, A.; Das, M. K.; Sarma, J. K.
2016-12-01
We present an analysis of the xF3(x,Q2) structure function and Gross-Llewellyn Smith(GLS) sum rule taking into account the nuclear effects and higher twist correction. This analysis is based on the results presented in [N.M. Nath, et al, Indian J. Phys. 90 (2016) 117]. The corrections due to nuclear effects predicted in several earlier analysis are incorporated to our results of xF3(x,Q2) structure function and GLS sum rule for free nucleon, corrected upto next-next-to-leading order (NNLO) perturbative order and calculate the nuclear structure function as well as sum rule for nuclei. In addition, by means of a simple model we have extracted the higher twist contributions to the non-singlet structure function xF3(x,Q2) and GLS sum rule in NNLO perturbative orders and then incorporated them to our results. Our NNLO results along with nuclear effect and higher twist corrections are observed to be compatible with corresponding experimental data and other phenomenological analysis. Support from DAE-BRNS, India, as Major Research Project under Sanction No. 2012/37P/36/BRNS/2018 dated 24 Nov. 2012
Semiclassical correlation functions of Wilson loops and local vertex operators
Hernandez, Rafael
2012-01-01
We analyze correlation functions of Wilson loop observables and local vertex operators within the strong-coupling regime of the AdS/CFT correspondence. When the local operator corresponds to a light string state with finite conserved charges the correlation function can be evaluated in the semiclassical approximation of large string tension, where the contribution from the light vertex can be neglected. We consider the cases where the Wilson loops are described by two concentric surfaces and the local vertices are the superconformal chiral primary scalar or a singlet massive scalar operator.
Simulations of silicon vertex tracker for star experiment at RHIC
Energy Technology Data Exchange (ETDEWEB)
Odyniec, G.; Cebra, D.; Christie, W.; Naudet, C.; Schroeder, L.; Wilson, W. [Lawrence Berkeley Lab., CA (United States); Liko, D. [Institut fur Hochenenergiephysik, Vienna, (Austria); Cramer, J.; Prindle, D.; Trainor, T. [Univ. of Washington, Seattle (United States); Braithwaite, W. [Univ. of Arkansas, Little Rock (United States)
1991-12-31
The first computer simulations to optimize the Silicon Vertex Tracker (SVT) designed for the STAR experiment at RHIC are presented. The physics goals and the expected complexity of the events at RHIC dictate the design of a tracking system for the STAR experiment. The proposed tracking system will consist of a silicon vertex tracker (SVT) to locate the primary interaction and secondary decay vertices and to improve the momentum resolution, and a time projection chamber (TPC), positioned inside a solenoidal magnet, for continuous tracking.
The RAVE/VERTIGO vertex reconstruction toolkit and framework
Waltenberger, W.; Mitaroff, W.; Moser, F.; Pflugfelder, B.; Riedel, H. V.
2008-07-01
A detector-independent toolkit for vertex reconstruction (RAVE1) is being developed, along with a standalone framework (VERTIGO2) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
RAVE-a Detector-independent vertex reconstruction toolkit
Energy Technology Data Exchange (ETDEWEB)
Waltenberger, Wolfgang [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at; Mitaroff, Winfried; Moser, Fabian [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)
2007-10-21
A detector-independent toolkit for vertex reconstruction (RAVE) is being developed, along with a standalone framework (VERTIGO) for testing, analyzing and debugging. The core algorithms represent state of the art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
The RAVE/VERTIGO vertex reconstruction toolkit and framework
Energy Technology Data Exchange (ETDEWEB)
Waltenberger, W; Mitaroff, W; Moser, F; Pflugfelder, B; Riedel, H V [Austrian Academy of Sciences, Institute of High Energy Physics, A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at
2008-07-15
A detector-independent toolkit for vertex reconstruction (RAVE{sup 1}) is being developed, along with a standalone framework (VERTIGO{sup 2}) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.
Simulations with the PANDA micro-vertex-detector
Energy Technology Data Exchange (ETDEWEB)
Kliemt, Ralf
2013-07-17
The PANDA experiment will be built at the upcoming FAIR facility at GSI in Darmstadt, featuring antiproton-proton reactions hadron physics in a medium energy range. Charm physics will play an important role and therefore secondary decays relatively close to the interaction zone as well. The MVD will be the detector closest to these and will provide high-quality vertex position measurements. Alongside the detector layout and hardware development a detailed detector simulation and reconstruction software is required. This work contains the detailed description and the performance studies of the software developed for the MVD. Furthermore, vertexing tools are introduced and their performance is studied for the MVD.
Simulations of silicon vertex tracker for star experiment at RHIC
Energy Technology Data Exchange (ETDEWEB)
Odyniec, G.; Cebra, D.; Christie, W.; Naudet, C.; Schroeder, L.; Wilson, W. [Lawrence Berkeley Lab., CA (United States); Liko, D. [Institut fur Hochenenergiephysik, Vienna, (Austria); Cramer, J.; Prindle, D.; Trainor, T. [Univ. of Washington, Seattle (United States); Braithwaite, W. [Univ. of Arkansas, Little Rock (United States)
1991-12-31
The first computer simulations to optimize the Silicon Vertex Tracker (SVT) designed for the STAR experiment at RHIC are presented. The physics goals and the expected complexity of the events at RHIC dictate the design of a tracking system for the STAR experiment. The proposed tracking system will consist of a silicon vertex tracker (SVT) to locate the primary interaction and secondary decay vertices and to improve the momentum resolution, and a time projection chamber (TPC), positioned inside a solenoidal magnet, for continuous tracking.
On vertex-coloring 13-edge-weighting
Institute of Scientific and Technical Information of China (English)
Tao WANG; Qinglin YU
2008-01-01
L. Addario-Berry et al. [Discrete Appl. Math., 2008, 156:1168-1174] have shown that there exists a 16-edge-weighting such that the induced vertex coloring is proper. In this note, we improve their result and prove that there exists a 13-edge-weighting of a graph G, such that itsinduced vertex coloring of G is proper. This result is one step close to the original conjecture posed by M. Karofiski et al. [J. Combin. Theory, Set. B, 2004, 91: 151-157].
Preliminary studies for the LHCb vertex detector vacuum system
Doets, M; Van Bakel, N; Van den Brand, J F J; van den Brand, Jo
2000-01-01
We lay down some general considerations which will serve as a starting point for design studies of a realistic LHCb vertex detector vacuum system. Based on these considerations, we propose a design strategy and identify issues to be further studied. In particular we try to outline some boundary conditions imposed by LHC and LHCb on the vacuum system. We discuss two possibilities for the LHCb vertex detector vacuum system. The preferred strategy uses a differentially pumped vacuum system with the silicon detectors separated from the beam line vacuum. Some estimations on static vacuum pressures and gas flows are presented.
The Virasoro vertex algebra and factorization algebras on Riemann surfaces
Williams, Brian
2017-08-01
This paper focuses on the connection of holomorphic two-dimensional factorization algebras and vertex algebras which has been made precise in the forthcoming book of Costello-Gwilliam. We provide a construction of the Virasoro vertex algebra starting from a local Lie algebra on the complex plane. Moreover, we discuss an extension of this factorization algebra to a factorization algebra on the category of Riemann surfaces. The factorization homology of this factorization algebra is computed as the correlation functions. We provide an example of how the Virasoro factorization algebra implements conformal symmetry of the beta-gamma system using the method of effective BV quantization.
Dannheim, D
2014-01-01
A detector concept based on hybrid planar pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. In this paper the CLIC vertex-detector requirements are reviewed and the current status of R&D on sensors, readout and detector integration is presented.
Dannheim, D
2014-01-01
A detector concept based on hybrid pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors (planar or active HV-CMOS) via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced air flow. In this contribution the CLIC vertex-detector requirements are reviewed and the current status of R&D on readout and sensors is presented.
The VELO (VErtex LOcator) at the LHCb experiment
De Capua, S.
2008-01-01
The LHCb silicon vertex locator (VELO) is an array of silicon planes installed in a retractable roman pot system, which will enable the LHCb experiment to reconstruct and trigger on b-hadrons produced in collisions at the LHC. The VELO will be also used to attempt measuring the absolute luminosity with a novel method based on vertex reconstruction of beam gas interactions. In this paper the VELO system, its construction and the results from the commissioning phase are presented. The options for a possible upgraded detector are also discussed.
Charm-quark production in deep-inelastic neutrino scattering at NNLO in QCD
Berger, Edmond L; Li, Chong Sheng; Liu, Ze Long; Zhu, Hua Xing
2016-01-01
We present a fully differential next-to-next-to-leading order calculation of charm quark production in charged-current deep-inelastic scattering, with full charm-quark mass dependence. The next-to-next-to-leading order corrections in perturbative quantum chromodynamics are found to be comparable in size to the next-to-leading order corrections in certain kinematic regions. We compare our predictions with data on dimuon production in (anti-)neutrino scattering from a heavy nucleus. Our results can be used to improve the extraction of the parton distribution function of a strange quark in the nucleon.
Chiral symmetry breaking with the Curtis-Pennington vertex
Atkinson, D.; Gusynin, V. P.; Maris, P.
1992-01-01
Published in: Phys. Lett. B 303 (1993) 157-162 citations recorded in [Science Citation Index] Abstract: We study chiral symmetry breaking in quenched QED$_4$, using a vertex Ansatz recently proposed by Curtis and Pennington. Bifurcation analysis is employed to establish the existence of a critical c
Track and vertex finding performance with the CMS inner tracker
Caner, A; Khanov, A I; Stepanov, N
1999-01-01
The Compact Muon Solenoid (CMS) Tracker Collaboration has recently finalised the design of the tracking detector. After characterising the detector layout, we review in detail the algorithms developed for track and vertex reconstruction. We discuss the reconstruction capability for several benchmark event topologies and assess the projected performance of the CMS tracking detector. (12 refs).
Approximation Algorithms for Edge Partitioned Vertex Cover Problems
Bera, Suman Kalyan; Kumar, Amit; Roy, Sambuddha
2011-01-01
In the Partial Vertex Cover (PVC) problem we are given an undirected graph G = (V, E), a positive cost associated with each vertex and a positive integer k and the goal is to find a minimum cost subset of vertices S such that atleast k edges of the graph are covered. In this paper we consider two new generalization of the PVC problem. In the first variation which we call Partition Vertex Cover (Partition-VC) problem, the edges of the graph G are divided into n disjoint partitions $P_1, P_2... P_n$ and we have to select a minimum cost subset of vertices S such that atleast $k_i$ edges are covered from partition $P_i$. In the second variation which we call Knapsack Partition Vertex Cover (KPVC) problem, in addition to the previous conditions, each edge e has a profit $\\pi_{e}$ associated with it and we have an added knapsack constraint that the total profit of the covered edges in partition $P_i$ should be atleast $\\Pi_i$. We give an $O(log n)$ approximation for both the problems using a combination of determin...
One vertex spin-foams with the Dipole Cosmology boundary
Kisielowski, Marcin; Puchta, Jacek
2012-01-01
We find all the spin-foams contributing in the first order of the vertex expansion to the transition amplitude of the Bianchi-Rovelli-Vidotto Dipole Cosmology model. Our algorithm is general and provides spin-foams of arbitrarily given, fixed: boundary and, respectively, a number of internal vertices. We use the recently introduced Operator Spin-Network Diagrams framework.
A Remark on Newest Vertex Bisection in Any Space Dimension
D. Gallistl; M. Schedensack; R.P. Stevenson
2014-01-01
With newest vertex bisection, there is no uniform bound on the number of n-simplices that need to be refined to arrive at the smallest conforming refinement T′ of a conforming partition T in which one simplex has been bisected. In this note, we show that the difference in levels between any T′∈T′ an
Vertex deviation maps to bracked the Milky Way resonant radius
Roca-Fàbrega, S.; Antoja, T.; Figueras, F.; Valenzuela, O.; Romero-Gómez, M.; Pichardo, B.
2015-05-01
We map the kinematics of stars in simulated galaxy disks with spiral arms using the velocity ellipsoid vertex deviation (l_v). We use test particle simulations, and for the first time, fully self-consistent high resolution N-body models. We compare our maps with the Tight Winding Approximation model analytical predictions. We see that for all barred models spiral arms rotate closely to a rigid body manner and the vertex deviation values correlate with the density peaks position bounded by overdense and underdense regions. In such cases, vertex deviation sign changes from negative to positive when crossing the spiral arms in the direction of disk rotation, in regions where the spiral arms are in between corotation (CR) and the Outer Lindblad Resonance (OLR). By contrast, when the arm sections are inside the CR and outside the OLR, l_v changes from negative to positive.We propose that measurements of the vertex deviations pattern can be used to trace the position of the main resonances of the spiral arms. We propose that this technique might exploit future data from Gaia and APOGEE surveys. For unbarred N-body simulations with spiral arms corotating with disk material at all radii, our analysis suggests that no clear correlation exists between l_v and density structures.
Random matrices and the six-vertex model
Bleher, Pavel
2013-01-01
This book provides a detailed description of the Riemann-Hilbert approach (RH approach) to the asymptotic analysis of both continuous and discrete orthogonal polynomials, and applications to random matrix models as well as to the six-vertex model. The RH approach was an important ingredient in the proofs of universality in unitary matrix models. This book gives an introduction to the unitary matrix models and discusses bulk and edge universality. The six-vertex model is an exactly solvable two-dimensional model in statistical physics, and thanks to the Izergin-Korepin formula for the model with domain wall boundary conditions, its partition function matches that of a unitary matrix model with nonpolynomial interaction. The authors introduce in this book the six-vertex model and include a proof of the Izergin-Korepin formula. Using the RH approach, they explicitly calculate the leading and subleading terms in the thermodynamic asymptotic behavior of the partition function of the six-vertex model with domain wa...
A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems
Ciftci, B.B.; Tijs, S.H.
2007-01-01
In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari
Self-locking degree-4 vertex origami structures
Fang, Hongbin; Li, Suyi; Wang, K. W.
2016-11-01
A generic degree-4 vertex (4-vertex) origami possesses one continuous degree-of-freedom for rigid folding, and this folding process can be stopped when two of its facets bind together. Such facet-binding will induce self-locking so that the overall structure stays at a pre-specified configuration without additional locking elements or actuators. Self-locking offers many promising properties, such as programmable deformation ranges and piecewise stiffness jumps, that could significantly advance many adaptive structural systems. However, despite its excellent potential, the origami self-locking features have not been well studied, understood, and used. To advance the state of the art, this research conducts a comprehensive investigation on the principles of achieving and harnessing self-locking in 4-vertex origami structures. Especially, for the first time, this study expands the 4-vertex structure construction from single-component to dual-component designs and investigates their self-locking behaviours. By exploiting various tessellation designs, this research discovers that the dual-component designs offer the origami structures with extraordinary attributes that the single-component structures do not have, which include the existence of flat-folded locking planes, programmable locking points and deformability. Finally, proof-of-concept experiments investigate how self-locking can effectively induce piecewise stiffness jumps. The results of this research provide new scientific knowledge and a systematic framework for the design, analysis and utilization of self-locking origami structures for many potential engineering applications.
The role of geometry in 4-vertex origami mechanics
Waitukaitis, Scott; Dieleman, Peter; van Hecke, Martin
Origami offers an interesting design platform metamaterials because it strongly couples mechanics with geometry. Even so, most research carried out so far has been limited to one or two particular patterns. I will discuss the full geometrical space of the most common origami building block, the 4-vertex, and show how exotic geometries can have dramatic effects on the mechanics.
Redford, S
2015-01-01
The Compact Linear Collider is a candidate to be the next high-energy particle physics collider. Using a novel acceleration technique, electrons and positrons would be brought into collision with a centre-of-mass energy of up to 3 TeV. Despite challenging levels of beam-induced background, this would provide a relatively clean environment in which to perform precision physics measurements. The vertex detector would be crucial in achieving this, and would need to provide accurate particle tracking information to facilitate secondary vertex reconstruction and jet flavour-tagging. With this goal in mind, current technological limits are being stretched to design a low occupancy, low mass and low-power dissipation vertex detector for CLIC. A concept comprising thin hybrid pixel detectors coupled to high- performance readout ASICs, power-pulsing and air-flow cooling is under development. In this paper, the CLIC vertex detector requirements are reviewed and the current status of R&D on sensors, readout, powerin...
Anomalous $\\omega$-$Z$-$\\gamma$ Vertex from Hidden Local Symmetry
Harada, Masayasu; Yamawaki, Koichi
2011-01-01
We formulate the general form of omega-Z-gamma vertex in the framework based on the hidden local symmetry (HLS), which arises from the gauge invariant terms for intrinsic parity-odd (IP-odd) part of the effective action. Those terms are given as the homogeneous part of the general solution (having free parameters) to the Wess-Zumino (WZ) anomaly equation and hence are not determined by the anomaly, in sharp contrast to the Harvey-Hill-Hill (HHH) action where the relevant vertex is claimed to be uniquely determined by the anomaly. We show that, even in the framework that HHH was based on, the omega-Z-gamma vertex is actually not determined by the anomaly but by the homogeneous (anomaly-free) part of the general solution to the WZ anomaly equation having free parameters in the same way as in the HLS formulation: The HHH action is just a particular choice of the free parameters in the general solution. We further show that the omega-Z-gamma vertex related to the neutrino (nu) - nucleon (N) scattering cross secti...
W. K. H. Panofsky Prize Talk: The Silicon Vertex Trigger
Ristori, Luciano
2009-05-01
I will discuss the importance of real-time selection of events at a hadron collider, the ideas that led to the conception of the Silicon Vertex Trigger (SVT) and some historical notes on its construction and commissioning. I will also highlight some remarkable results obtained by CDF with the data selected by the SVT.
A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems
Ciftci, B.B.; Tijs, S.H.
2007-01-01
In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari
Energy Technology Data Exchange (ETDEWEB)
Deptuch, Grzegorz; Christian, David; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab
2008-12-01
3D-Integrated Circuit technology enables higher densities of electronic circuitry per unit area without the use of nanoscale processes. It is advantageous for mixed mode design with precise analog circuitry because processes with conservative feature sizes typically present lower process dispersions and tolerate higher power supply voltages, resulting in larger separation of a signal from the noise floor. Heterogeneous wafers (different foundries or different process families) may be combined with some 3D integration methods, leading to the optimization of each tier in the 3D stack. Tracking and vertexing in future High-Energy Physics (HEP) experiments involves construction of detectors composed of up to a few billions of channels. Readout electronics must record the position and time of each measurement with the highest achievable precision. This paper reviews a prototype of the first 3D readout chip for HEP, designed for a vertex detector at the International Linear Collider. The prototype features 20 x 20 {micro}m{sup 2} pixels, laid out in an array of 64 x 64 elements and was fabricated in a 3-tier 0.18 {micro}m Fully Depleted SOI CMOS process at MIT-Lincoln Laboratory. The tests showed correct functional operation of the structure. The chip performs a zero-suppressed readout. Successive submissions are planned in a commercial 3D bulk 0.13 {micro}m CMOS process to overcome some of the disadvantages of an FDSOI process.
An upwind vertex centred Finite Volume solver for Lagrangian solid dynamics
Aguirre, Miquel; Gil, Antonio J.; Bonet, Javier; Lee, Chun Hean
2015-11-01
A vertex centred Jameson-Schmidt-Turkel (JST) finite volume algorithm was recently introduced by the authors (Aguirre et al., 2014 [1]) in the context of fast solid isothermal dynamics. The spatial discretisation scheme was constructed upon a Lagrangian two-field mixed (linear momentum and the deformation gradient) formulation presented as a system of conservation laws [2-4]. In this paper, the formulation is further enhanced by introducing a novel upwind vertex centred finite volume algorithm with three key novelties. First, a conservation law for the volume map is incorporated into the existing two-field system to extend the range of applications towards the incompressibility limit (Gil et al., 2014 [5]). Second, the use of a linearised Riemann solver and reconstruction limiters is derived for the stabilisation of the scheme together with an efficient edge-based implementation. Third, the treatment of thermo-mechanical processes through a Mie-Grüneisen equation of state is incorporated in the proposed formulation. For completeness, the study of the eigenvalue structure of the resulting system of conservation laws is carried out to demonstrate hyperbolicity and obtain the correct time step bounds for non-isothermal processes. A series of numerical examples are presented in order to assess the robustness of the proposed methodology. The overall scheme shows excellent behaviour in shock and bending dominated nearly incompressible scenarios without spurious pressure oscillations, yielding second order of convergence for both velocities and stresses.
Domination parameters of a graph with added vertex
Directory of Open Access Journals (Sweden)
Maciej Zwierzchowski
2004-01-01
Full Text Available Let \\(G=(V,E\\ be a graph. A subset \\(D\\subseteq V\\ is a total dominating set of \\(G\\ if for every vertex \\(y\\in V\\ there is a vertex \\(x\\in D\\ with \\(xy\\in E\\. A subset \\(D\\subseteq V\\ is a strong dominating set of \\(G\\ if for every vertex \\(y\\in V-D\\ there is a vertex \\(x\\in D\\ with \\(xy\\in E\\ and \\(\\deg _{G}(x\\geq\\deg _{G}(y\\. The total domination number \\(\\gamma _{t}(G\\ (the strong domination number \\(\\gamma_{S}(G\\ is defined as the minimum cardinality of a total dominating set (a strong dominating set of \\(G\\. The concept of total domination was first defined by Cockayne, Dawes and Hedetniemi in 1980 [Cockayne E. J., Dawes R. M., Hedetniemi S. T.: Total domination in graphs. Networks 10 (1980, 211–219], while the strong domination was introduced by Sampathkumar and Pushpa Latha in 1996 [Pushpa Latha L., Sampathkumar E.: Strong weak domination and domination balance in a graph. Discrete Mathematics 161 (1996, 235–242]. By a subdivision of an edge \\(uv\\in E\\ we mean removing edge \\(uv\\, adding a new vertex \\(x\\, and adding edges \\(ux\\ and \\(vx\\. A graph obtained from \\(G\\ by subdivision an edge \\(uv\\in E\\ is denoted by \\(G\\oplus u_{x}v_{x}\\. The behaviour of the total domination number and the strong domination number of a graph \\(G\\oplus u_{x}v_{x}\\ is developed.
Limit theorems for vertex-reinforced jump processes on regular trees
Collevecchio, Andrea
2009-01-01
Consider a vertex-reinforced jump process defined on a regular tree, where each vertex has exactly $b$ children, with $b \\ge 3$. We prove the strong law of large numbers and the central limit theorem for the distance of the process from the root. Notice that it is still unknown if vertex-reinforced jump process is transient on the binary tree.
A quantum hybrid with a thin antenna at the vertex of a wedge
Carlone, Raffaele; Posilicano, Andrea
2017-03-01
We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a "hybrid surface" consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex.
Campbell, John M.; Wackeroth, Doreen; Zhou, Jia
2016-11-01
Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real W and Z bosons that result in Sudakov-like corrections of the form αWllogn(Q2/MW,Z 2) , where αW=α /(4 π sin2θW) and n ≤2 l -1 . The inclusion of EW corrections in predictions for hadron colliders is, therefore, especially important when searching for signals of possible new physics in distributions probing the kinematic regime Q2≫MV2. Next-to-leading order (NLO) EW corrections should also be taken into account when their size [O (α )] is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) [O (αs2)]. To this end, we have implemented the NLO weak corrections to the neutral-current Drell-Yan process, top-quark pair production and dijet production in the parton-level Monte Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide both the full NLO weak corrections and their Sudakov approximation since the latter is often used for a fast evaluation of weak effects at high energies and can be extended to higher orders. With both the exact and approximate results at hand, the validity of the Sudakov approximation can be readily quantified.
Top quark mass effects in Higgs boson pair production up to NNLO
Hoff, Jens
2016-01-01
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 $\\mathcal{O}(1/M_t^{12})$. 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 $\\mathcal{O}(1/M_t^4)$. We use our results to estimate the residual uncertainty of the total cross section due to a finite top quark mass to be $\\mathcal{O}(10\\%)$ at next-to-leading order and $\\mathcal{O}(5\\%)$ at next-to-next-to-leading order.
Charm and Beauty Production from Secondary Vertexing at HERA
Energy Technology Data Exchange (ETDEWEB)
Thompson, Paul [University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom)
2010-07-01
Measurement of the Charm and Beauty Structure Functions using the H1 Vertex Detector at HERA Inclusive charm and beauty cross sections are measured in e{sup -} p and e{sup +}p neutral current collisions at HERA in the kinematic region of photon virtuality 5 < Q{sup 2} < 2000 GeV{sup 2} and Bjorken scaling variable 0.0002 < x < 0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions. Measurement of Charm and Beauty Jets in Deep Inelastic Scattering at HERA Measurements of the charm and beauty jet cross sections have been made in deep inelastic scattering at HERA for the kinematic region of photon virtuality Q{sup 2} > 6 GeV{sup 2} and elasticity variable 0.07 < y < 0.625 for jets in the laboratory frame with transverse energy E{sub T}{sup jet} > 6 GeV and pseudorapidity -1.0 < {eta}{sup jet} < 1.5. Measurements are also made requiring a jet in the Breit frame with E{sub T}{sup jet} > 6 GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The number of charm and beauty jets are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are compared with QCD predictions and with previous measurements obtained using muon tagging. Charm and beauty production in deep inelastic scattering from inclusive secondary vertexing at ZEUS Charm and beauty production in deep inelastic scattering has been measured with the ZEUS detector using the full HERA II data set. The charm and beauty contents
Parameter Vertex Color Pada Animation Procedural 3D Model Vegetasi Musaceae
Directory of Open Access Journals (Sweden)
I Gede Ngurah Arya Indrayasa
2017-02-01
Full Text Available Penggunaan vegetasi untuk industri film, video game, simulasi, dan arsitektur visualisas merupakan faktor penting untuk menghasilkan adegan pemandangan alam lebih hidup. Penelitian ini bertujuan untuk mengetahui pengaruh dari vertex color terhadap efek angin pada animasi prosedural 3d model vegetasi musaceae serta parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi musaceae realistis. Hasil akhir yang di capai adalah meneliti apakah perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta pengaruh dari vertex color terhadap efek angin pada animasi prosedural 3d model vegetasi Musaceae. Berdasarkan pengamat dan perbandingan pada pengujian 5 sample vertex color diperoleh hasil bahwa perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta di peroleh kesimpulan Sample No.5 merupakan parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi Musaceae yang realistis. Kata kunci—3D, Animasi Prosedural, Vegetation
Worldline calculation of the three-gluon vertex
Energy Technology Data Exchange (ETDEWEB)
Ahmadiniaz, N.; Schubert, C. [Dipartimento di Fisica, Universita di Bologna and INFN Sezione di Bologna Via Irnerio 46, I-40126 Bologna (Italy); Instituto de Fisica y Matematicas Universidad Michoacana de San Nicolas de Hidalgo Apdo. Postal 2-82 C.P. 58040, Morelia, Michoacan (Mexico)
2012-10-23
The three-gluon vertex is a basic object of interest in nonabelian gauge theory. At the one-loop level, it has been calculated and analyzed by a number of authors. Here we use the worldline formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in terms of field strength tensors. We verify its equivalence with previously obtained representations, and explain the relation of its structure to the low-energy effective action. The sum rule found by Binger and Brodsky for the scalar, spinor and gluon loop contributions in the present approach relates to worldline supersymmetry.
Six-vertex models and the GUE-corners process
Dimitrov, Evgeni
2016-01-01
In this paper we consider a class of probability distributions on the six-vertex model from statistical mechanics, which originate from the higher spin vertex models of https://arxiv.org/abs/1601.05770. We define operators, inspired by the Macdonald difference operators, which extract various correlation functions, measuring the probability of observing different arrow configurations. The development of our operators is largely based on the properties of a remarkable family of symmetric rational functions, which were previously studied in https://arxiv.org/abs/1410.0976. For the class of models we consider, the correlation functions can be expressed in terms of multiple contour integrals, which are suitable for asymptotic analysis. For a particular choice of parameters we analyze the limit of the correlation functions through a steepest descent method. Combining this asymptotic statement with some new results about Gibbs measures on Gelfand-Tsetlin cones and patterns, we show that the asymptotic behavior of o...
The design and performance of the ZEUS micro vertex detector
Energy Technology Data Exchange (ETDEWEB)
Polini, A. [Bologna Univ. (Italy)]|[INFN Bologna (Italy); Brock, I.; Goers, S. [Bonn Univ. (DE). Physikalisches Institut] (and others)
2007-08-15
In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9 m{sup 2} of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed. (orig.)
K-vertex-connectivity minimum augmentation for undirected unweighted graphs
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
For an undirected unweighted graph G0＝(V0,E0) and a positive integer K, the K-vertex-connectivity minimum augmentation problem (K-VCMAP) is to find a minimum set of edges Emin such that the graph H0＝(V0,E0∪Emin) is K-vertex-connected. Results in the literature have given polynomial time algorithms for K-VCMAP in several special cases such as where k≤3, or G0 is a tree. However, it still remains open whether or not there exist polynomial time algorithms for K-VCMAP for any graph G0 and any integer K. In this paper, we settle the problem by describing an efficient algorithm (KUCA) with time-complexity of O(K|V(G0)|5) for the K-VCMAP for any G0 and any positive integer K.
The silicon vertex locator for the LHCb upgrade
Head, Tim
2014-01-01
The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a triggerless system being read out at 40 MHz. The upgraded silicon vertex detector (VELO) must be light weight, radiation hard, and compatible with LHC vacuum requirements. It must be capable of fast pattern recognition, fast track reconstruction and high precision vertexing. This challenge is being met with a new VELO design based on hybrid pixel detectors positioned to within 5 mm of the LHC colliding beams. The detector will be shielded from the beam by a View the MathML source~300μm thick aluminium foil. Evaporative CO2 coolant circulating in micro-channels embedded in a thin silicon substrate will be used for cooling.
Exploratory study of the 3-gluon vertex on the lattice
Parrinello, C
1994-01-01
We define and evaluate on the lattice the amputated 3-gluon vertex function in momentum space. We give numerical results for 16^3 \\times 40 and 24^3 \\times 40 quenched lattices at \\beta=6.0. A good numerical signal is obtained, at the price of enforcing the gauge-fixing condition with high accuracy. By comparing results from two different lattice volumes, we try to investigate the crucial issue of finite volume effects. We also outline a method for the lattice evaluation of the QCD running coupling constant as defined from the 3-gluon vertex, while being aware that a realistic calculation will require larger \\beta values and very high statistics.
On the zero crossing of the three-gluon vertex
Directory of Open Access Journals (Sweden)
A. Athenodorou
2016-10-01
Full Text Available We report on new results on the infrared behavior of the three-gluon vertex in quenched Quantum Chromodynamics, obtained from large-volume lattice simulations. The main focus of our study is the appearance of the characteristic infrared feature known as ‘zero crossing’, the origin of which is intimately connected with the nonperturbative masslessness of the Faddeev–Popov ghost. The appearance of this effect is clearly visible in one of the two kinematic configurations analyzed, and its theoretical origin is discussed in the framework of Schwinger–Dyson equations. The effective coupling in the momentum subtraction scheme that corresponds to the three-gluon vertex is constructed, revealing the vanishing of the effective interaction at the exact location of the zero crossing.
On the zero crossing of the three-gluon vertex
Athenodorou, A.; Binosi, D.; Boucaud, Ph.; De Soto, F.; Papavassiliou, J.; Rodríguez-Quintero, J.; Zafeiropoulos, S.
2016-10-01
We report on new results on the infrared behavior of the three-gluon vertex in quenched Quantum Chromodynamics, obtained from large-volume lattice simulations. The main focus of our study is the appearance of the characteristic infrared feature known as 'zero crossing', the origin of which is intimately connected with the nonperturbative masslessness of the Faddeev-Popov ghost. The appearance of this effect is clearly visible in one of the two kinematic configurations analyzed, and its theoretical origin is discussed in the framework of Schwinger-Dyson equations. The effective coupling in the momentum subtraction scheme that corresponds to the three-gluon vertex is constructed, revealing the vanishing of the effective interaction at the exact location of the zero crossing.
Integrable mixing of A_{n-1} type vertex models
Grillo, S
2002-01-01
Given a family of monodromy matrices {T_u; u=1,...,K} corresponding to integrable anisotropic vertex models of A_{n_u-1}-type, we build up a related mixed vertex model by means of gluing the lattices on which they are defined, in such a way that integrability property is preserved. Algebraically, the gluing process is implemented through one dimensional representations of rectangular matrix algebras A(R_p,R_q), where R_n indicates the R-matrix associated to the standard Hopf algebra deformation of the simple Lie algebra A_{n-1}. We show that algebraic Bethe ansatz can be applied, and the resulting nested equations are identical to the ones corresponding to an A_{n-1} quasi- periodic model with n=min{n_u; u=1,...,K}.
3-state Hamiltonians associated to solvable 33-vertex models
Crampé, N.; Frappat, L.; Ragoucy, E.; Vanicat, M.
2016-09-01
Using the nested coordinate Bethe ansatz, we study 3-state Hamiltonians with 33 non-vanishing entries, or 33-vertex models, where only one global charge with degenerate eigenvalues exists and each site possesses three internal degrees of freedom. In the context of Markovian processes, they correspond to diffusing particles with two possible internal states which may be exchanged during the diffusion (transmutation). The first step of the nested coordinate Bethe ansatz is performed providing the eigenvalues in terms of rapidities. We give the constraints ensuring the consistency of the computations. These rapidities also satisfy Bethe equations involving 4 × 4 R-matrices, solutions of the Yang-Baxter equation which implies new constraints on the models. We solve them allowing us to list all the solvable 33-vertex models.
On the zero crossing of the three-gluon vertex
Athenodorou, A; Boucaud, Ph; De Soto, F; Papavassiliou, J; Rodriguez-Quintero, J; Zafeiropoulos, S
2016-01-01
We report on new results on the infrared behaviour of the three-gluon vertex in quenched Quantum Chormodynamics, obtained from large-volume lattice simulations. The main focus of our study is the appearance of the characteristic infrared feature known as 'zero crossing', the origin of which is intimately connected with the nonperturbative masslessness of the Faddeev-Popov ghost. The appearance of this effect is clearly visible in one of the two kinematic configurations analyzed, and its theoretical origin is discussed in the framework of Schwinger-Dyson equations. The effective coupling in the momentum subtraction scheme that corresponds to the three-gluon vertex is constructed, revealing the vanishing of the effective interaction at the exact location of the zero crossing.
Diagonalization of the XXZ Hamiltonian by Vertex Operators
Davies, B; Jimbo, M; Miwa, T; Nakayashiki, A; Davies, Brian; Foda, Omar; Jimbo, Michio; Miwa, Tetsuji; Nakayashiki, Atsushi
1993-01-01
We diagonalize the anti-ferroelectric XXZ-Hamiltonian directly in the thermodynamic limit, where the model becomes invariant under the action of affine U_q( sl(2) ). Our method is based on the representation theory of quantum affine algebras, the related vertex operators and KZ equation, and thereby bypasses the usual process of starting from a finite lattice, taking the thermodynamic limit and filling the Dirac sea. From recent results on the algebraic structure of the corner transfer matrix of the model, we obtain the vacuum vector of the Hamiltonian. The rest of the eigenvectors are obtained by applying the vertex operators, which act as particle creation operators in the space of eigenvectors. We check the agreement of our results with those obtained using the Bethe Ansatz in a number of cases, and with others obtained in the scaling limit --- the $su(2)$-invariant Thirring model.
The secondary vertex finding algorithm with the ATLAS detector
Heer, Sebastian; The ATLAS collaboration
2017-01-01
A high performance identification of jets, produced via fragmentation of bottom quarks, is crucial for the ATLAS physics program. These jets can be identified by exploiting the presence of cascade decay vertices from bottom hadrons. A general vertex-finding algorithm is introduced and its ap- plication to the search for secondary vertices inside jets is described. Kinematic properties of the reconstructed vertices are used to construct several b-jet identification algorithms. The features and performance of the secondary vertex finding algorithm in a jet, as well as the performance of the jet tagging algorithms, are studied using simulated $pp$ -> $t\\bar{t}$ events at a centre-of-mass energy of 13 TeV.
OPAL Central Detector (Including vertex, jet and Z chambers)
OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. OPAL's central tracking system consists of (in order of increasing radius) a silicon microvertex detector, a vertex detector, a jet chamber, and z-chambers. All the tracking detectors work by observing the ionization of atoms by charged particles passing by: when the atoms are ionized, electrons are knocked out of their atomic orbitals, and are then able to move freely in the detector. These ionization electrons are detected in the different parts of the tracking system. (This piece includes the vertex, jet and Z chambers) In the picture above, the central detector is the piece being removed to the right.
Vertex detectors: The state of the art and future prospects
Energy Technology Data Exchange (ETDEWEB)
Damerell, C.J.S. [Rutherford Appleton Laboratory, Didcot (United Kingdom)
1997-01-01
We review the current status of vertex detectors (tracking microscopes for the recognition of charm and bottom particle decays). The reasons why silicon has become the dominant detector medium are explained. Energy loss mechanisms are reviewed, as well as the physics and technology of semiconductor devices, emphasizing the areas of most relevance for detectors. The main design options (microstrips and pixel devices, both CCD`s and APS`s) are discussed, as well as the issue of radiation damage, which probably implies the need to change to detector media beyond silicon for some vertexing applications. Finally, the evolution of key performance parameters over the past 15 years is reviewed, and an attempt is made to extrapolate to the likely performance of detectors working at the energy frontier ten years from now.
Higgs boson pair production: Top quark mass effects at NLO and NNLO
Directory of Open Access Journals (Sweden)
Jonathan Grigo
2015-11-01
Full Text Available We compute next-to-next-to-leading order QCD corrections to the gluon-induced production cross section of Higgs boson pairs in the large top quark mass limit using the soft-virtual approximation. In the limit of infinitely-heavy top quark we confirm the results in the literature. We add two more expansion terms in the inverse top quark mass to the Mt→∞ result. Since the 1/Mt expansion converges poorly, we try to improve on it by factorizing the exact leading order cross section. We discuss two ways of doing that and conclude that the finite top quark mass effects shift the cross section at most by about 10% at next-to-leading order and by about 5% at next-to-next-to-leading order.
Technical Design Report for the: PANDA Micro Vertex Detector
Erni, W; Krusche, B; Steinacher, M; Heng, Y; Liu, Z; Liu, H; Shen, X; Wang, Q; Xu, H; Albrecht, M; Becker, J; Eickel, K; Feldbauer, F; Fink, M; Friedel, P; Heinsius, F H; Held, T; Koch, H; Kopf, B; Leyhe, M; Motzko, C; Pelizäus, M; Pychy, J; Roth, B; Schröder, T; Schulze, J; Steinke, M; Trifterer, T; Wiedner, U; Zhong, J; Beck, R; Becker, M; Bianco, S; Brinkmann, K -Th; Hammann, C; Hinterberger, F; Jäkel, R; Kaiser, D; Kliemt, R; Koop, K; Schmidt, C; Schnell, R; Thoma, U; Vlasov, P; Wendel, C; Winnebeck, A; Würschig, Th; Zaunick, H -G; Bianconi, A; Bragadireanu, M; Caprini, M; Ciubancan, M; Pantea, D; Tarta, P -D; De Napoli, M; Giacoppo, F; Rapisarda, E; Sfienti, C; Fiutowski, T; Idzik, N; Mindur, B; Przyborowski, D; Swientek, K; Bialkowski, E; Budzanowski, A; Czech, B; Kliczewski, S; Kozela, A; Kulessa, P; Lebiedowicz, P; Malgorzata, K; Pysz, K; Schäfer, W; Siudak, R; Szczurek, A; Brandys, P; Czyzewski, T; Czyzycki, W; Domagala, M; Hawryluk, M; Filo, G; Kwiatkowski, D; Lisowski, E; Lisowski, F; Bardan, W; Gil, D; Kamys, B; Kistryn, St; Korcyl, K; Krzemieñ, W; Magiera, A; Moskal, P; Rudy, Z; Salabura, P; Smyrski, J; Wroñska, A; Al-Turany, M; Arora, R; Augustin, I; Deppe, H; Dutta, D; Flemming, H; Götzen, K; Hohler, G; Karabowicz, R; Lehmann, D; Lewandowski, B; Lühning, J; Maas, F; Orth, H; Peters, K; Saito, T; Schepers, G; Schmidt, C J; Schmitt, L; Schwarz, C; Schwiening, J; Voss, B; Wieczorek, P; Wilms, A; Abazov, V M; Alexeev, G D; Arefiev, V A; Astakhov, V I; Barabanov, M Yu; Batyunya, B V; Davydov, Yu I; Dodokhov, V Kh; Efremov, A A; Fedunov, A G; Feshchenko, A A; Galoyan, A S; Grigoryan, S; Karmokov, A; Koshurnikov, E K; Lobanov, V I; Lobanov, Yu Yu; Makarov, A F; Malinina, L V; Malyshev, V L; Mustafaev, G A; Olshevski, A G; Pasyuk, M A; Perevalova, E A; Piskun, A A; Pocheptsov, T A; Pontecorvo, G; Rodionov, V K; Rogov, Yu N; Salmin, R A; Samartsev, A G; Sapozhnikov, M G; Shabratova, G S; Skachkova, A N; Skachkov, N B; Strokovsky, E A; Suleimanov, M K; Teshev, R Sh; Tokmenin, V V; Uzhinsky, V V; Vodopyanov, A S; Zaporozhets, S A; Zhuravlev, N I; Zorin, A G; Branford, D; Glazier, D; Watts, D; Woods, P; Britting, A; Eyrich, W; Lehmann, A; Uhlig, F; Dobbs, S; Metreveli, Z; Seth, K; Tann, B; Tomaradze, A; Bettoni, D; Carassiti, V; Dalpiaz, P; Drago, A; Fioravanti, E; Garzia, I; Negrini, M; Savriè, M; Stancari, G; Dulach, B; Gianotti, P; Guaraldo, C; Lucherini, V; Pace, E; Bersani, A; Macri, M; Marinelli, M; Parodi, R F; Dormenev, V; Drexler, P; Düren, M; Eisner, T; Foehl, K; Hayrapetyan, A; Koch, P; Krïoch, B; Kühn, W; Lange, S; Liang, Y; Liu, M; Merle, O; Metag, V; Moritz, M; Nanova, M; Novotny, R; Spruck, B; Stenzel, H; Strackbein, C; Thiel, M; Wang, Q; Clarkson, T; Euan, C; Hill, G; Hoek, M; Ireland, D; Kaiser, R; Keri, T; Lehmann, I; Livingston, K; Lumsden, P; MacGregor, D; McKinnon, B; Montgomery, R; Murray, M; Protopopescu, D; Rosner, G; Seitz, B; Yang, G; Babai, M; Biegun, A K; Glazenborg-Kluttig, A; Guliyev, E; Jothi, V S; Kavatsyuk, M; Lemmens, P; Löhner, H; Messchendorp, J; Poelman, T; Smit, H; van der Weele, J C; Sohlbach, H; Büscher, M; Dosdall, R; Dzhygadlo, R; Esch, S; Gillitzer, A; Goldenbaum, F; Grunwald, D; Jha, V; Kemmerling, G; Kleines, H; Lehrach, A; Maier, R; Mertens, M; Ohm, H; Pohl, D L; Prasuhn, D; Randriamalala, T; Ritman, J; Roeder, M; Sterzenbach, G; Stockmanns, T; Wintz, P; Wüstner, P; Xu, H; Kisiel, J; Li, S; Li, Z; Sun, Z; Xu, H; Fissum, K; Hansen, K; Isaksson, L; Lundin, M; Schröder, B; Achenbach, P; Denig, A; Distler, M; Fritsch, M; Kangh, D; Karavdina, A; Lauth, W; Michel, M; Espi, M C Mora; Pochodzalla, J; Sanchez, S; Sanchez-Lorente, A; Sfienti, C; Weber, T; Dormenev, V I; Fedorov, A A; Korzhik, M V; Missevitch, O V; Boukharov, A; Malyshev, O; Marishev, I; Semenov, A; Varma, R; Höppner, C; Ketzer, B; Konorov, I; Mann, A; Neubert, S; Paul, S; Vandenbroucke, M; Zhang, Q; Khoukaz, A; Rausmann, T; Täschner, A; Wessels, J; Baldin, E; Kotov, K; Peleganchuk, S; Tikhonov, Yu; Hennino, T; Imre, M; Kunne, R; Galliard, C Le; Normand, J P Le; Marchand, D; Maroni, A; Ong, S; Pouthas, J; Ramstein, B; Rosier, P; Sudol, M; Theneau, C; Tomasi-Gustafsson, E; Van de Wiele, J; Zerguerras, T; Boca, G; Braghieri, A; Costanza, S; Fontana, A; Genova, P; Lavezzi, L; Montagna, P; Rotondi, A; Buda, V; Abramov, V V; Davidenko, A M; Derevschikov, A A; Goncharenko, Y M; Grishin, V N; Kachanov, V A; Konstantinov, D A; Kormilitsin, V A; Matulenko, Y A; Melnik, Y M; Meschanin, A P; Minaev, N G; Mochalov, V V; Morozov, D A; Nogach, L V; Nurushev, S B; Ryazantsev, A V; Semenov, P A; Soloviev, L F; Uzunian, A V; Vasiliev, A N; Yakutin, A E; Belostotski, S; Gavrilov, G; Itzotov, A; Kisselev, A; Kravchenko, P; Manaenkov, S; Miklukho, O; Naryshkin, Y; Veretennikov, D; Vikhrov, V; Zhadanov, A; Bäck, T; Cederwall, B; Bargholtz, C; Gerén, L; Tegnér, P E
2012-01-01
This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined.
The LHCb Vertex Locator – Performance and Radiation Damage
Oblakowska-Mucha, A
2014-01-01
LHCb is a dedicated flavour physics experiment at the Large Hadron Collider at CERN. The Vertex Locator (VELO) is an important part of a LHCb tracking system, enabling precision measurement of beauty and charm mesons’ flight distance. The VELO consist of a set of silicon micro-strip detectors, arranged in two retractable halves, operating only 7 mm from the interac- tion region. In these proceedings the VELO performance during the Run 1 is summarised and radiation damage studies are presented.
Silicon vertex detector upgrade in the ALPHA experiment
Amole, C; Ashkezari, M.D; Baquero-Ruiz, M; Bertsche, W; Burrows, C; Butler, E; Capra, A; Cesar, C.L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M.C; Gill, D.R; Gutierrez, A; Hangst, J.S; Hardy, W.N; Hayden, M.E; Humphries, A.J; Isaac, C.A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J.T.K; Menary, S; Napoli, S.C; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Rasmussen, C.Ø; Robicheaux, F; Sacramento, R.L; Sampson, J.A; Sarid, E; Seddon, D; Silveira, D.M; So, C; Stracka, S; Tharp, T; Thompson, R.I; Thornhill, J; Tooley, M.P; Van Der Werf, D.P; Wells, D
2013-01-01
The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA ' s analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA ' s new neutral atom trap.
Silicon vertex detector upgrade in the ALPHA experiment
Amole, C.; Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Burrows, C.; Butler, E.; Capra, A.; Cesar, C. L.; Chapman, S.; Charlton, M.; Deller, A.; Eriksson, S.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Gutierrez, A.; Hangst, J. S.; Hardy, W. N.; Hayden, M. E.; Humphries, A. J.; Isaac, C. A.; Jonsell, S.; Kurchaninov, L.; Little, A.; Madsen, N.; McKenna, J. T. K.; Menary, S.; Napoli, S. C.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Rasmussen, C. Ø.; Robicheaux, F.; Sacramento, R. L.; Stracka, S.; Sampson, J. A.; Sarid, E.; Seddon, D.; Silveira, D. M.; So, C.; Thompson, R. I.; Tharp, T.; Thornhill, J.; Tooley, M. P.; van der Werf, D. P.; Wells, D.
2013-12-01
The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA's analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA's new neutral atom trap.
Vertex-based diffusion for 3-D mesh denoising.
Zhang, Ying; Ben Hamza, A
2007-04-01
We present a vertex-based diffusion for 3-D mesh denoising by solving a nonlinear discrete partial differential equation. The core idea behind our proposed technique is to use geometric insight in helping construct an efficient and fast 3-D mesh smoothing strategy to fully preserve the geometric structure of the data. Illustrating experimental results demonstrate a much improved performance of the proposed approach in comparison with existing methods currently used in 3-D mesh smoothing.
Vertex Operators for Irregular Conformal Blocks: Supersymmetric Case
Polyakov, Dimitri
2016-01-01
We construct supersymmetric irregular vertex operators of arbitrary rank, appearing in the colliding limit of primary fields. We find that the structure of the supersymmetric irregular vertices differs significantly from the bosonic case: upon supersymmetrization, the irregular operators are no longer the eigenstates of positive Virasoro and $W_N$ generators but block-diagonalize them. We relate the block-diagonal structure of the irregular vertices to contributions of the Ramond sector to the colliding limit.
Recent status of FPCCD vertex detector R&D
Murai, S; Sanuki, T; Miyamoto, A; Sugimoto, Y; Constantino, C; Sato, H; Ikeda, H; Hitoshi, H
2016-01-01
The Fine Pixel CCD (FPCCD) is one of the candidate sensor technologies for the ILC vertex detector. It will be located near interaction point and require high radiation tolerance. It will thus be operated at -40 degree C to improve radiation tolerance. In this paper, we report on the status of neutron radiation tests, on a cooling system using two-phase CO2 with a gas compressor for circulation, and on the mechanical structure of the FPCCD ladders.
Q-operators in the six-vertex model
Directory of Open Access Journals (Sweden)
Vladimir V. Mangazeev
2014-09-01
Here we use a different strategy and construct Q-operators as integral operators with factorized kernels based on the original Baxter's method used in the solution of the eight-vertex model. We compare this approach with the method developed in [1] and find the explicit connection between two constructions. We also discuss a reduction to the case of finite-dimensional representations with (half-integer spins.
Silicon vertex detector upgrade in the ALPHA experiment
Energy Technology Data Exchange (ETDEWEB)
Amole, C. [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada); Andresen, G.B. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M.D. [Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6 (Canada); Baquero-Ruiz, M. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Bertsche, W. [School of Physics and Astronomy, University of Manchester, M13 9PL Manchester (United Kingdom); The Cockcroft Institute, Daresbury Laboratory, WA4 4AD Warrington (United Kingdom); Burrows, C. [Department of Physics, College of Science, Swansea University, Swansea SA2 8PP (United Kingdom); Butler, E. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Capra, A. [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada); Cesar, C.L. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Chapman, S. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Charlton, M.; Deller, A.; Eriksson, S. [Department of Physics, College of Science, Swansea University, Swansea SA2 8PP (United Kingdom); Fajans, J. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Friesen, T. [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Fujiwara, M.C. [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Gill, D.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Gutierrez, A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4 (Canada); and others
2013-12-21
The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA's analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA's new neutral atom trap.
General Vertex-Distinguishing Total Coloring of Graphs
Directory of Open Access Journals (Sweden)
Chanjuan Liu
2014-01-01
Full Text Available The general vertex-distinguishing total chromatic number of a graph G is the minimum integer k, for which the vertices and edges of G are colored using k colors such that any two vertices have distinct sets of colors of them and their incident edges. In this paper, we figure out the exact value of this chromatic number of some special graphs and propose a conjecture on the upper bound of this chromatic number.
Factorized domain wall partition functions in trigonometric vertex models
Foda, O; Zuparic, M
2007-01-01
We obtain factorized domain wall partition functions for two sets of trigonometric vertex models: 1. The N-state Deguchi-Akutsu models, for N = {2, 3, 4} (and conjecture the result for all N >= 5), and 2. The sl(r+1|s+1) Perk-Schultz models, for {r, s = \\N}, where (given the symmetries of these models) the result is independent of {r, s}.
A neural network z-vertex trigger for Belle II
Neuhaus, Sara; Abudinén, Fernando; Chen, Yang; Feindt, Michael; Frühwirth, Rudolf; Heck, Martin; Kiesling, Christian; Knoll, Alois; Paul, Stephan; Schieck, Jochen
2014-01-01
We present the concept of a track trigger for the Belle II experiment, based on a neural network approach, that is able to reconstruct the z (longitudinal) position of the event vertex within the latency of the first level trigger. The trigger will thus be able to suppress a large fraction of the dominating background from events outside of the interaction region. The trigger uses the drift time information of the hits from the Central Drift Chamber (CDC) of Belle II within narrow cones in polar and azimuthal angle as well as in transverse momentum (sectors), and estimates the z-vertex without explicit track reconstruction. The preprocessing for the track trigger is based on the track information provided by the standard CDC trigger. It takes input from the 2D ($r - \\varphi$) track finder, adds information from the stereo wires of the CDC, and finds the appropriate sectors in the CDC for each track in a given event. Within each sector, the z-vertex of the associated track is estimated by a specialized neural ...
Flattening single-vertex origami: the non-expansive case
Panina, Gaiane
2010-01-01
A single-vertex origami is a piece of paper with straight-line rays called creases emanating from a fold vertex placed in its interior or on its boundary. The Single-Vertex Origami Flattening problem asks whether it is always possible to reconfigure the creased paper from any configuration compatible with the metric, to a flat, non-overlapping position, in such a way that the paper is not torn, stretched and, for rigid origami, not bent anywhere except along the given creases. Streinu and Whiteley showed how to reduce the problem to the carpenter's rule problem for spherical polygons. Using spherical expansive motions, they solved the cases of open < \\pi and closed <= 2\\pi spherical polygons. Here, we solve the case of open polygons with total length between [\\pi, 2\\pi), which requires non-expansive motions. Our motion planning algorithm works in a finite number of discrete steps, for which we give precise bounds depending on both the number of links and the angle deficit.
Colour-independent partition functions in coloured vertex models
Energy Technology Data Exchange (ETDEWEB)
Foda, O., E-mail: omar.foda@unimelb.edu.au [Dept. of Mathematics and Statistics, University of Melbourne, Parkville, VIC 3010 (Australia); Wheeler, M., E-mail: mwheeler@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies, CNRS UMR 7589 (France); Université Pierre et Marie Curie – Paris 6, 4 place Jussieu, 75252 Paris cedex 05 (France)
2013-06-11
We study lattice configurations related to S{sub n}, the scalar product of an off-shell state and an on-shell state in rational A{sub n} integrable vertex models, n∈{1,2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A{sub n} models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S{sub 2} (Caetano and Vieira, 2012, [1], Wheeler, (arXiv:1204.2089), [2]). Namely, 1.S{sub 2}, which depends on two sets of Bethe roots, {b_1} and {b_2}, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit {b_1}→∞, and/or {b_2}→∞, into a product of determinants, 2. Each of the latter determinants is an A{sub 1} vertex-model partition function.
NLO Electroweak Corrections to Higgs Boson Production at Hadron Colliders
Actis, S; Sturm, C; Uccirati, S
2008-01-01
Results for the complete NLO electroweak corrections to Standard Model Higgs production via gluon fusion are included in the total cross section for hadronic collisions. Artificially large threshold effects are avoided working in the complex-mass scheme. The numerical impact at LHC (Tevatron) energies is explored for Higgs mass values up to 500 GeV (200 GeV). Assuming a complete factorization of the electroweak corrections, one finds a +5 % shift with respect to the NNLO QCD cross section for a Higgs mass of 120 GeV both at the LHC and the Tevatron. Adopting two different factorization schemes for the electroweak effects, an estimate of the corresponding total theoretical uncertainty is computed.
Mellin moments of heavy flavor contributions to F_2(x,Q^2) at NNLO
Klein, Sebastian
2009-01-01
This thesis is concerned with the calculation of fixed moments of the O(a_s^3) heavy flavor contributions to the Wilson coefficients of the structure function F_2(x,Q^2) in the limit Q^2 >> m^2, neglecting power corrections. The massive Wilson coefficients in the asymptotic region are given as convolutions of massive operator matrix elements (OMEs) and the known light flavor Wilson coefficients. The former derive from the twist--2 operators emerging in the light--cone--expansion and are calculated at the 3--loop level for fixed moments. We also compute the massive OMEs which are needed to evaluate heavy flavor parton distributions in the variable flavor number scheme to the same order. All contributions to the Wilson coefficients and OMEs but the genuine constant terms at O(a_s^3) of the OMEs are derived in terms of quantities, which are known for general values in the Mellin variable N. For the OMEs A_{Qg}^(3), A_{qg,Q}^(3) and A_{gg,Q}^(3) the moments N = 2 to 10, for A_{Qq}^{(3), PS} to N = 12, and for A_{...
Updated NNLO QCD predictions for the weak radiative B-meson decays
Misiak, M; Boughezal, R; Czakon, M; Ewerth, T; Ferroglia, A; Fiedler, P; Gambino, P; Greub, C; Haisch, U; Huber, T; Kaminski, M; Ossola, G; Poradzinski, M; Rehman, A; Schutzmeier, T; Steinhauser, M; Virto, J
2015-01-01
We perform an updated analysis of the inclusive weak radiative B-meson decays in the standard model, incorporating all our results for the O(alpha_s^2) and lower-order perturbative corrections that have been calculated after 2006. New estimates of non-perturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find B_{s gamma} = (3.36 +_ 0.23) * 10^-4 and B_{d gamma} = 1.73^{+0.12}_{-0.22} * 10^-5, for E_gamma > 1.6 GeV. These results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_gamma = ( B_{s gamma} + B_{d gamma})/B_{c l nu} = (3.31 +_ 0.22) * 10^-3. A new bound from B_{s gamma} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^+} > 480 GeV at 95%C.L.
NNLO Computational Techniques: the Cases H -> gamma gamma and H -> g g
Actis, S; Sturm, C; Uccirati, S
2008-01-01
A large set of techniques needed to compute decay rates at the two-loop level are derived and systematized. The main emphasis of the paper is on the two Standard Model decays H -> gamma gamma and H -> g g. The techniques, however, have a much wider range of application: they give practical examples of general rules for two-loop renormalization; they introduce simple recipes for handling internal unstable particles in two-loop processes; they illustrate simple procedures for the extraction of collinear logarithms from the amplitude. The latter is particularly relevant to show cancellations, e.g. cancellation of collinear divergencies. Furthermore, the paper deals with the proper treatment of non-enhanced two-loop QCD and electroweak contributions to different physical (pseudo-)observables, showing how they can be transformed in a way that allows for a stable numerical integration. Numerical results for the two-loop percentage corrections to H -> gamma gamma, g g are presented and discussed. When applied to the...
cellGPU: Massively parallel simulations of dynamic vertex models
Sussman, Daniel M.
2017-10-01
Vertex models represent confluent tissue by polygonal or polyhedral tilings of space, with the individual cells interacting via force laws that depend on both the geometry of the cells and the topology of the tessellation. This dependence on the connectivity of the cellular network introduces several complications to performing molecular-dynamics-like simulations of vertex models, and in particular makes parallelizing the simulations difficult. cellGPU addresses this difficulty and lays the foundation for massively parallelized, GPU-based simulations of these models. This article discusses its implementation for a pair of two-dimensional models, and compares the typical performance that can be expected between running cellGPU entirely on the CPU versus its performance when running on a range of commercial and server-grade graphics cards. By implementing the calculation of topological changes and forces on cells in a highly parallelizable fashion, cellGPU enables researchers to simulate time- and length-scales previously inaccessible via existing single-threaded CPU implementations. Program Files doi:http://dx.doi.org/10.17632/6j2cj29t3r.1 Licensing provisions: MIT Programming language: CUDA/C++ Nature of problem: Simulations of off-lattice "vertex models" of cells, in which the interaction forces depend on both the geometry and the topology of the cellular aggregate. Solution method: Highly parallelized GPU-accelerated dynamical simulations in which the force calculations and the topological features can be handled on either the CPU or GPU. Additional comments: The code is hosted at https://gitlab.com/dmsussman/cellGPU, with documentation additionally maintained at http://dmsussman.gitlab.io/cellGPUdocumentation
Transverse Ward-Takahashi Relation for the Vector Vertex in Quantum Field Theory
Institute of Scientific and Technical Information of China (English)
HE Han-Xin
2001-01-01
The transverse Ward-Takahashi (W-T) relation for the vector vertex in quantum field theory is derived by calculating the curl of the time-ordered product of the three-point function including the vector current operator. This provides the constraint on the transverse part of the vertex. By combining the transverse and normal (longitudinal)W-T identities, we obtain the expression for the full vector vertex function.``
Freely generated vertex algebras and non-linear Lie conformal algebras
De Sole, Alberto; Kac, Victor
2003-01-01
We introduce the notion of a non--linear Lie conformal superalgebra and prove a PBW theorem for its universal enveloping vertex algebra. We also show that conversely any graded freely generated vertex algebra is the universal enveloping algebra of a non--linear Lie conformal superalgebra. This correspondence will be applied in the subsequent work to the problem of classification of finitely generated simple graded vertex algebras.
2008-01-01
We discuss approximations of vertex couplings of quantum graphs using families of thin branched manifolds. We show that if a Neumann type Laplacian on such manifolds is amended by suitable potentials, the resulting Schr\\"odinger operators can approximate non-trivial vertex couplings. The latter include not only the delta-couplings but also those with wavefunctions discontinuous at the vertex. We work out the example of the symmetric delta'-couplings and conjecture that the same method can be ...
Vertex Operators Arising from Jacobi-Trudi Identities
Jing, Naihuan; Rozhkovskaya, Natasha
2016-09-01
We give an interpretation of the boson-fermion correspondence as a direct consequence of the Jacobi-Trudi identity. This viewpoint enables us to construct from a generalized version of the Jacobi-Trudi identity the action of a Clifford algebra on the polynomial algebras that arrive as analogues of the algebra of symmetric functions. A generalized Giambelli identity is also proved to follow from that identity. As applications, we obtain explicit formulas for vertex operators corresponding to characters of the classical Lie algebras, shifted Schur functions, and generalized Schur symmetric functions associated to linear recurrence relations.
Vertex Normals and Face Curvatures of Triangle Meshes
Sun, Xiang
2016-08-12
This study contributes to the discrete differential geometry of triangle meshes, in combination with discrete line congruences associated with such meshes. In particular we discuss when a congruence defined by linear interpolation of vertex normals deserves to be called a ŉormal’ congruence. Our main results are a discussion of various definitions of normality, a detailed study of the geometry of such congruences, and a concept of curvatures and shape operators associated with the faces of a triangle mesh. These curvatures are compatible with both normal congruences and the Steiner formula.
Movable radiation shields for the CLEO II silicon vertex detector
Energy Technology Data Exchange (ETDEWEB)
Dumas, D.J.; Ward, C.W.; Alexander, J.; Cherwinka, J.; Henderson, S. [Cornell Univ., Ithaca, NY (United States); Cinabro, D. [Harvard University, Cambridge, MA 02138 (United States); Fast, J. [Purdue University, Lafayette, IN 47907 (United States); Morrison, R. [University of California at Santa Barbara, Santa Barbara, CA 93106 (United States); O`Neill, M. [CRPP, Carleton University, Ottawa, Ont. (Canada)
1998-02-11
Two movable tungsten radiation shields were installed on the beam pipe during the upgrade of the CLEO II detector, operating at the Cornell electron storage ring (CESR). This upgrade included the installation of a silicon vertex detector (SVX) and the purpose of the shields is to protect the SVX readout electronics from synchrotron radiation produced during injection and non-high-energy physics operation of CESR. Shield motion is controlled remotely by cables, keeping the associated motors and controls outside the detection volume. We discuss the design and performance of the radiation shields and the associated control system. (orig.). 8 refs.
New Hybrid Genetic Algorithm for Vertex Cover Problems
Institute of Scientific and Technical Information of China (English)
霍红卫; 许进
2003-01-01
This paper presents a new hybrid genetic algorithm for the vertex cover problems in which scan-repair and local improvement techniques are used for local optimization. With the hybrid approach, genetic algorithms are used to perform global exploration in a population, while neighborhood search methods are used to perform local exploitation around the chromosomes. The experimental results indicate that hybrid genetic algorithms can obtain solutions of excellent quality to the problem instances with different sizes. The pure genetic algorithms are outperformed by the neighborhood search heuristics procedures combined with genetic algorithms.
The vacuum system of the LHCb vertex detector
Van den Brand, J F J; Kraan, M G; Klous, S; Kaan, A P
2002-01-01
An overview of the design of the vertex detector of the LHCb experiment in the future Large Hadron Collider at CERN will be given. The application of silicon detectors close to the beam implies the isolation of the materials with a high desorption rate from the accelerator vacuum. The aluminium containment has a complicated shape and a thickness of 250 mu m in order to minimize the multiple scattering. Alignment, safety and precision problems have been solved in the design and are being tested. (1 refs).
A DNA computer model for solving vertex coloring problem
Institute of Scientific and Technical Information of China (English)
XU Jin; QIANG Xiaoli; FANG Gang; ZHOU Kang
2006-01-01
A special DNA computer was designed to solve the vertex coloring problem. The main body of this kind of DNA computer was polyacrylamide gel electrophoresis which could be classified into three parts: melting region, unsatisfied solution region and solution region. This polyacrylamide gel was connected with a controllable temperature device, and the relevant temperature was Tm1, Tm2 and Tm3, respectively. Furthermore, with emphasis on the encoding way, we succeeded in performing the experiment of a graph with 5 vertices. In this paper we introduce the basic structure, the principle and the method of forming the library DNA sequences.
W-symmetry, topological vertex and affine Yangian
Procházka, Tomáš
2015-01-01
We discuss the representation theory of non-linear chiral algebra $\\mathcal{W}_{1+\\infty}$ of Gaberdiel and Gopakumar and its connection to Yangian of $\\hat{\\mathfrak{u}(1)}$ whose presentation was given by Tsymbaliuk. The characters of completely degenerate representations of $\\mathcal{W}_{1+\\infty}$ are for generic values of parameters given by the topological vertex. The Yangian picture provides an infinite number of commuting charges which can be explicitly diagonalized in $\\mathcal{W}_{1+\\infty}$ highest weight representations. Many properties that are difficult to study in $\\mathcal{W}_{1+\\infty}$ picture turn out to have a simple combinatorial interpretation.
EMC studies for the vertex detector of the Belle II experiment
Thalmeier, R.; Iglesias, M.; Arteche, F.; Echeverria, I.; Friedl, M.; Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, T.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Cervenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Forti, F.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kiesling, C.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnicka, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Moser, H. G.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rao, K. K.; Rashevskaia, I.; Rizzo, G.; Rozanska, M.; Rummel, S.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.
2016-01-01
The upgrade of the Belle II experiment plans to use a vertex detector based on two different technologies, DEPFET pixel (PXD) technology and double side silicon microstrip (SVD) technology. The vertex electronics are characterized by the topology of SVD bias that forces to design a sophisticated grounding because of the floating power scheme. The complex topology of the PXD power cable bundle may introduce some noise inside the vertex area. This paper presents a general overview of the EMC issues present in the vertex system, based on EMC tests on an SVD prototype and a study of noise propagation in the PXD cable bundle based on Multi-conductor transmission line theory.
Effects of Vertex Activity and Self-organized Criticality Behavior on a Weighted Evolving Network
Institute of Scientific and Technical Information of China (English)
ZHANG Gui-Qing; YANG Qiu-Ying; CHEN Tian-Lun
2008-01-01
Effects of vertex activity have been analyzed on a weighted evolving network. The network is characterized by the probability distribution of vertex strength, each edge weight and evolution of the strength of vertices with different vertex activities. The model exhibits self-organized criticality behavior. The probability distribution of avalanche size for different network sizes is also shown. In addition, there is a power law relation between the size and the duration of an avalanche and the average of avalanche size has been studied for different vertex activities.
Spontaneous polarization of spin 1 analogue of the eight-vertex model
Quano, Yas-Hiro
2013-01-01
The spin 1 analogue of the eight-vertex model is considered on the basis of free field representations of vertex operators in the $2\\times 2$-fold fusion SOS model and vertex-face transformation. The spontaneous polarization of the model is obtained in terms of one-fold integral formula. Some limiting cases are discussed in order to examine the validity of the formula. Furthermore, we also present the integral formulae of the one-point function for the inhomogeneous twenty-one-vertex model.
Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge
Blum, Adrian L; Huber, Markus Q; Windisch, Andreas
2016-01-01
Solutions for the three-gluon and quark-gluon vertices from Dyson-Schwinger equations and the three-particle irreducible formalism are discussed. Dynamical quarks (``unquenching'') change the three-gluon vertex via the quark-triangle diagrams which themselves include fully dressed quark-gluon vertex functions. On the other hand, the quark-swordfish diagram is, at least with the model used for the two-quark-two-gluon vertex employed here, of minor importance. For the leading tensor structure of the three-gluon vertex the "unquenching" effect can be summarized for the nonperturbative part as a shift of the related dressing function towards the infrared.
Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge
Blum, Adrian L.; Alkofer, Reinhard; Huber, Markus Q.; Windisch, Andreas
2017-03-01
Solutions for the three-gluon and quark-gluon vertices from Dyson-Schwinger equations and the three-particle irreducible formalism are discussed. Dynamical quarks ("unquenching") change the three-gluon vertex via the quark-triangle diagrams which themselves include fully dressed quark-gluon vertex functions. On the other hand, the quark-swordfish diagram is, at least with the model used for the two-quark-two-gluon vertex employed here, of minor importance. For the leading tensor structure of the threegluon vertex the "unquenching" effect can be summarized for the nonperturbative part as a shift of the related dressing function towards the infrared.
National Research Council Canada - National Science Library
Yarash K. Abuev; Albert B. Babaev; Pharkhat E. Esetov
2017-01-01
Objectives A computer simulation of the antiferromagnetic structures described by the three-vertex Potts model on a triangular lattice is performed, taking into account the antiferromagnetic exchange...
Campbell, John M; Zhou, Jia
2016-01-01
Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real $W$ and $Z$ bosons that result in Sudakov-like corrections of the form $\\alpha_W^l\\log^n(Q^2/M_{W,Z}^2)$, where $\\alpha_W =\\alpha/(4\\pi\\sin^2\\theta_W)$ and $n\\le 2l-1$. The inclusion of EW corrections in predictions for hadron colliders is therefore especially important when searching for signals of possible new physics in distributions probing the kinematic regime $Q^2 \\gg M_V^2$. Next-to-leading order (NLO) EW corrections should also be taken into account when their size ($\\mathcal{O}(\\alpha)$) is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) ($\\mathcal{O}(\\alpha_s^2)$). To this end we have implemented the NLO weak corrections to the Neutral-Current Drell-Yan process, top-quark pair production and di-jet production in the parton-level Monte-Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide b...
The Bondi-Sachs metric at the vertex of a null cone: axially symmetric vacuum solutions
Mädler, Thomas
2012-01-01
In the Bondi-Sachs formulation of General Relativity space-time is foliated via a family of null cones. If these null cones are defined such that their vertices are traced by a regular world-line then the metric tensor has to obey regularity conditions at the vertices. We explore these regularity conditions when the world line is a time-like geodesic. In particular, we solve the Einstein equations for the Bondi-Sachs metric near the vertices for axially symmetric vacuum space- times. The metric is calculated up to third order corrections with respect to a flat metric along the time-like geodesic, as this is the lowest order where non- linear coupling of the metric coefficients occurs. We also determine the boundary conditions of the metric to arbitrary order of these corrections when a linearized and axially symmetric vacuum space-time is assumed. In both cases we find that (i) the initial data on the null cone must have a very rigid angular structure for the vertex to be a regular point, and (ii) the initial...
The Vertex-Rainbow Index of A Graph
Directory of Open Access Journals (Sweden)
Mao Yaping
2016-08-01
Full Text Available The k-rainbow index rxk(G of a connected graph G was introduced by Chartrand, Okamoto and Zhang in 2010. As a natural counterpart of the k-rainbow index, we introduce the concept of k-vertex-rainbow index rvxk(G in this paper. In this paper, sharp upper and lower bounds of rvxk(G are given for a connected graph G of order n, that is, 0 ≤ rvxk(G ≤ n − 2. We obtain Nordhaus-Gaddum results for 3-vertex-rainbow index of a graph G of order n, and show that rvx3(G + rvx3(Ḡ = 4 for n = 4 and 2 ≤ rvx3(G + rvx3(Ḡ ≤ n − 1 for n ≥ 5. Let t(n, k, ℓ denote the minimal size of a connected graph G of order n with rvxk(G ≤ ℓ, where 2 ≤ ℓ ≤ n − 2 and 2 ≤ k ≤ n. Upper and lower bounds on t(n, k, ℓ are also obtained.
Electronics cooling of Phenix multiplicity and vertex detector
Energy Technology Data Exchange (ETDEWEB)
Chen, Z.; Gregory, W.S.
1996-08-01
The Multiplicity and Vertex Detector (MVD) uses silicon strip sensors arranged in two concentric barrels around the beam pipe of the PHENIX detector that will be installed at Brookhaven National Laboratory. Each silicon sensor is connected by a flexible kapton cable to its own front-end electronics printed circuit board that is a multi-chip module or MCM. The MCMs are the main heat source in the system. To maintain the MVD at optimized operational status, the maximum temperature of the multi-chip modules must be below 40 C. Using COSMOS/M HSTAR for the Heat Transfer analysis, a finite element model of a typical MCM plate was created to simulate a 9m/s airflow and 9m/s mixed flow composed of 50% helium and 50% air respectively, with convective heat transfer on both sides of the plate. The results using a mixed flow of helium and air show that the average maximum temperature reached by the MCMs is 37.5 C. The maximum temperature which is represented by the hot spots on the MCM is 39.43 C for the helium and air mixture which meets the design temperature requirement 40 C. To maintain the Multiplicity and Vertex Detector at optimized operational status, the configuration of the plenum chamber, the power dissipated by the silicon chips, the fluid flow velocity and comparison on the MCM design parameters will be discussed.
Quark-gluon vertex: A perturbation theory primer and beyond
Bermudez, R.; Albino, L.; Gutiérrez-Guerrero, L. X.; Tejeda-Yeomans, M. E.; Bashir, A.
2017-02-01
There has been growing evidence that the infrared enhancement of the form factors defining the full quark-gluon vertex plays an important role in realizing a dynamical breakdown of chiral symmetry in quantum chromodynamics, leading to the observed spectrum and properties of hadrons. Both the lattice and the Schwinger-Dyson communities have begun to calculate these form factors in various kinematical regimes of momenta involved. A natural consistency check for these studies is that they should match onto the perturbative predictions in the ultraviolet, where nonperturbative effects mellow down. In this article, we carry out a numerical analysis of the one-loop result for all the form factors of the quark-gluon vertex. Interestingly, even the one-loop results qualitatively encode most of the infrared enhancement features expected of their nonperturbative counter parts. We analyze various kinematical configurations of momenta: symmetric, on shell, and asymptotic. The on-shell limit enables us to compute anomalous chromomagnetic moment of quarks. The asymptotic results have implications for the multiplicative renormalizability of the quark propagator and its connection with the Landau-Khalatnikov-Fradkin transformations, allowing us to analyze and compare various Ansätze proposed so far.
A $z$-Vertex Trigger for Belle II
Skambraks, Sebastian; Chen, Yang; Feindt, Michael; Frühwirth, Rudolf; Heck, Martin; Kiesling, Christian; Knoll, Alois; Neuhaus, Sara; Paul, Stephan; Schieck, Jochen
2014-01-01
The Belle II experiment will go into operation at the upgraded SuperKEKB collider in 2016. SuperKEKB is designed to deliver an instantaneous luminosity $\\mathcal{L}=8\\times10^{35}\\,\\mathrm{cm}^{-2}\\,\\mathrm{s}^{-1}$. The experiment will therefore have to cope with a much larger machine background than its predecessor Belle, in particular from events outside of the interaction region. We present the concept of a track trigger, based on a neural network approach, that is able to suppress a large fraction of this background by reconstructing the $z$ (longitudinal) position of the event vertex within the latency of the first level trigger. The trigger uses the hit information from the Central Drift Chamber (CDC) of Belle II within narrow cones in polar and azimuthal angle as well as in transverse momentum ("sectors"), and estimates the $z$-vertex without explicit track reconstruction. The preprocessing for the track trigger is based on the track information provided by the standard CDC trigger. It takes input fro...
SPARTex: A Vertex-Centric Framework for RDF Data Analytics
Abdelaziz, Ibrahim
2015-08-31
A growing number of applications require combining SPARQL queries with generic graph search on RDF data. However, the lack of procedural capabilities in SPARQL makes it inappropriate for graph analytics. Moreover, RDF engines focus on SPARQL query evaluation whereas graph management frameworks perform only generic graph computations. In this work, we bridge the gap by introducing SPARTex, an RDF analytics framework based on the vertex-centric computation model. In SPARTex, user-defined vertex centric programs can be invoked from SPARQL as stored procedures. SPARTex allows the execution of a pipeline of graph algorithms without the need for multiple reads/writes of input data and intermediate results. We use a cost-based optimizer for minimizing the communication cost. SPARTex evaluates queries that combine SPARQL and generic graph computations orders of magnitude faster than existing RDF engines. We demonstrate a real system prototype of SPARTex running on a local cluster using real and synthetic datasets. SPARTex has a real-time graphical user interface that allows the participants to write regular SPARQL queries, use our proposed SPARQL extension to declaratively invoke graph algorithms or combine/pipeline both SPARQL querying and generic graph analytics.
Guarding curvilinear art galleries with vertex or point guards
Karavelas, Menelaos I
2008-01-01
One of the earliest and most well known problems in computational geometry is the so-called art gallery problem. The goal is to compute the minimum possible number guards placed on the vertices of a simple polygon in such a way that they cover the interior of the polygon. In this paper we consider the problem of guarding an art gallery which is modeled as a polygon with curvilinear walls. Our main focus is on polygons the edges of which are convex arcs pointing towards the exterior or interior of the polygon (but not both), named piecewise-convex and piecewise-concave polygons. We prove that, in the case of piecewise-convex polygons, if we only allow vertex guards, $\\lfloor\\frac{4n}{7}\\rfloor-1$ guards are sometimes necessary, and $\\lfloor\\frac{2n}{3}\\rfloor$ guards are always sufficient. Moreover, an $O(n\\log{}n)$ time and $O(n)$ space algorithm is described that produces a vertex guarding set of size at most $\\lfloor\\frac{2n}{3}\\rfloor$. When we allow point guards the afore-mentioned lower bound drops down ...
The Lorentzian proper vertex amplitude: Classical analysis and quantum derivation
Engle, Jonathan
2015-01-01
Spin foam models, an approach to defining the dynamics of loop quantum gravity, make use of the Plebanski formulation of gravity, in which gravity is recovered from a topological field theory via certain constraints called simplicity constraints. However, the simplicity constraints in their usual form select more than just one gravitational sector as well as a degenerate sector. This was shown, in previous work, to be the reason for the "extra" terms appearing in the semiclassical limit of the Euclidean EPRL amplitude. In this previous work, a way to eliminate the extra sectors, and hence terms, was developed, leading to the what was called the Euclidean proper vertex amplitude. In the present work, these results are extended to the Lorentzian signature, establishing what is called the Lorentzian proper vertex amplitude. This extension is non-trivial and involves a number of new elements since, for Lorentzian bivectors, the split into self-dual and anti-self-dual parts, on which the Euclidean derivation was b...
First results with prototype ISIS devices for ILC vertex detector
Energy Technology Data Exchange (ETDEWEB)
Damerell, C., E-mail: c.damerell@rl.ac.u [RAL, Oxon OX11 0QX (United Kingdom); Zhang, Z. [RAL, Oxon OX11 0QX (United Kingdom); Gao, R.; John John, Jaya; Li, Y.; Nomerotski, A. [Oxford U (United Kingdom); Holland, A.; Seabroke, G. [Centre for Electronic Imaging, Open U (United Kingdom); Havranek, M. [Czech Technical University in Prague (Czech Republic); Stefanov, K. [Sentec Ltd, Cambridge (United Kingdom); Kar-Roy, A. [Jazz Semiconductors, California (United States); Bell, R.; Burt, D.; Pool, P. [e2V Technologies, Chelmsford (United Kingdom)
2010-12-11
The vertex detectors at the International Linear Collider (ILC) (there will be two of them, one for each of two general purpose detectors) will certainly be built with silicon pixel detectors, either monolithic or perhaps vertically integrated. However, beyond this general statement, there is a wide range of options supported by active R and D programmes all over the world. Pixel-based vertex detectors build on the experience at the SLAC large detector (SLD) operating at the SLAC linear collider (SLC), where a 307 Mpixel detector permitted the highest physics performance at LEP or SLC. For ILC, machine conditions demand much faster readout than at SLC, something like 20 time slices during the 1 ms bunch train. The approach of the image sensor with in-situ storage (ISIS) is unique in offering this capability while avoiding the undesirable requirement of 'pulsed power'. First results from a prototype device that approaches the pixel size of 20 {mu}m square, needed for physics, are reported. The dimensional challenge is met by using a 0.18 {mu}m imaging CMOS process, instead of a conventional CCD process.
Natural constraints on the gluon-quark vertex
Binosi, Daniele; Papavassiliou, Joannis; Qin, Si-Xue; Roberts, Craig D
2016-01-01
In principle, the strong-interaction sector of the Standard Model is characterised by a unique renormalisation-group-invariant (RGI) running interaction and a unique form for the dressed--gluon-quark vertex, $\\Gamma_\\mu$; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles both top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansaetze for $\\Gamma_\\mu$. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Plainly, therefore, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansaetze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.
Natural constraints on the gluon-quark vertex
Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Qin, Si-Xue; Roberts, Craig D.
2017-02-01
In principle, the strong-interaction sector of the standard model is characterized by a unique renormalization-group-invariant (RGI) running interaction and a unique form for the dressed-gluon-quark vertex, Γμ; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansätze for Γμ. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Evidently, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansätze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.
Performance of the CLAS12 Silicon Vertex Tracker modules
Energy Technology Data Exchange (ETDEWEB)
Antonioli, M.A.; Boiarinov, S.; Bonneau, P.; Elouadrhiri, L.; Eng, B. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Gotra, Y., E-mail: gotra@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Kurbatov, E. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Leffel, M.; Mandal, S.; McMullen, M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Merkin, M. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Raydo, B.; Teachey, W. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Tucker, R. [Arizona State University, Tempe, AZ (United States); Ungaro, M.; Yegneswaran, A.; Ziegler, V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2013-12-21
For the 12 GeV upgrade, the CLAS12 experiment has designed a Silicon Vertex Tracker (SVT) using single sided microstrip sensors fabricated by Hamamatsu. The sensors have graded angle design to minimize dead areas and a readout pitch of 156μm, with intermediate strip. Double sided SVT module hosts three daisy-chained sensors on each side with a full strip length of 33 cm. There are 512 channels per module read out by four Fermilab Silicon Strip Readout (FSSR2) chips featuring data driven architecture, mounted on a rigid-flex hybrid. Modules are assembled on the barrel using unique cantilevered geometry to minimize the amount of material in the tracking volume. Design and performance of the SVT modules are presented, focusing on results of electrical measurements. -- Highlights: •A Silicon Vertex Tracker has been designed for the central tracker of the CLAS12 experiment. •Using cantilevered module geometry allows minimizing amount of material in the tracking volume. •A dedicated Hybrid Flex Circuit Board has been developed to read out double sided module. •Module performance meets design goals of the CLAS12 Central Tracker.
[Posterior atlantoaxial fixation using vertex multiaxial screw system].
Zhong, Dejun; Song, Yueming
2007-06-01
This study aims to assess the effectiveness and advantages of Vertex multiaxial screw system in use for stabilizing the atlanto-axial junction. The entry point of the atlas was located 18-20 mm lateral to the midline and 2.0 mm superior to the inferior border of posterior arch, and the direction of screw was chosen to be about 10 degrees medial to the sagittal plane and about 5 degrees cephalad to the transverse plane. In odontoid vertebra (C2), the direction of the drill bit was guided directly by the medial and superior aspect of the individual C2 pedicle. All screws were placed properly without incidence of nerve or blood vessel injury, and no complication appeared in operation and after surgery. All cases were followed up for an average of 9 months, all cases achieved well reposition and fixation of atlantoaxial joint, average JOA grade was 9.6 before preoperation and 15.9 after operation. Fixation of the atlantoaxial complex using Vertex multiaxial screw system seemed to be a reliable technique and should be considered a good alternative in atlantoaxial fusion. The technique could be used in young patiens.
Colour-independent partition functions in coloured vertex models
Foda, O
2013-01-01
We study lattice configurations related to S_n, the scalar product of an off-shell state and an on-shell state in rational A_n integrable vertex models, n = {1, 2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A_n models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S_2 [1, 2]. Namely, 1. S_2 which depends on two sets of Bethe roots, b_1 and b_2, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit b_1 -> infinity, and/or b_2 -> infinity, into a product of determinants, 2. Each of the la...
On the path-avoidance vertex-coloring game
Mütze, Torsten
2011-01-01
For any graph $F$ and any integer $r\\geq 2$, the \\emph{online vertex-Ramsey density of $F$ and $r$}, denoted $m^*(F,r)$, is a parameter defined via a deterministic two-player Ramsey-type game (Painter vs.\\ Builder). This parameter was introduced in a recent paper \\cite{mrs11}, where it was shown that the online vertex-Ramsey density determines the threshold of a similar probabilistic one-player game (Painter vs.\\ the binomial random graph $G_{n,p}$). For a large class of graphs $F$, including cliques, cycles, complete bipartite graphs, hypercubes, wheels, and stars of arbitrary size, a simple greedy strategy is optimal for Painter and closed formulas for $m^*(F,r)$ are known. In this work we show that for the case where $F=P_\\ell$ is a (long) path, the picture is very different. It is not hard to see that $m^*(P_\\ell,r)= 1-1/k^*(P_\\ell,r)$ for an appropriately defined integer $k^*(P_\\ell,r)$, and that the greedy strategy gives a lower bound of $k^*(P_\\ell,r)\\geq \\ell^r$. We construct and analyze Painter strat...
The Belle II silicon vertex detector assembly and mechanics
Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Bulla, L.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Lueck, T.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.
2017-02-01
The Belle II experiment at the asymmetric SuperKEKB collider in Japan will operate at an instantaneous luminosity approximately 50 times greater than its predecessor (Belle). The central feature of the experiment is a vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is CP violation asymmetry in the decays of beauty and charm hadrons, which hinges on a precise charged-track vertex determination and low-momentum track measurement. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision 3D coordinate measurements of the final SVD modules. Finally, some results from the latest test-beam are reported.
Adjacent Vertex Distinguishing Incidence Coloring of the Cartesian Product of Some Graphs
Institute of Scientific and Technical Information of China (English)
Qian WANG; Shuang Liang TIAN
2011-01-01
An adjacent vertex distinguishing incidence coloring of graph G is an incidence coloring of G such that no pair of adjacent vertices meets the same set of colors. We obtain the adjacent vertex distinguishing incidence chromatic number of the Cartesian product of a path and a path, a path and a wheel, a path and a fan, and a path and a star.
Instanton-induced Effective Vertex in the Seiberg-Witten Theory with Matter
Lee, B K; Lee, ByungKoo; Nam, Soonkeon
1997-01-01
The instanton-induced effective vertex is derived for N=2 supersymmetric QCD (SQCD) with arbitrary mass matter hypermultiplets for the case of SU(2). The leading term of the low energy effective lagrangian obtained from this vertex agrees with one-instanton effective term of the Seiberg-Witten result.
Lambda: A Mathematica-package for operator product expansions in vertex algebras
Ekstrand, Joel
2010-01-01
We give an introduction to the Mathematica package Lambda, designed for calculating {\\lambda}-brackets in both vertex algebras, and in SUSY vertex algebras. This is equivalent to calculating operator product expansions in two-dimensional conformal field theory. The syntax of {\\lambda}-brackets is reviewed, and some simple examples are shown, both in component notation, and in N=1 superfield notation.
On the Relation between Edge and Vertex Modelling in Shape Analysis
DEFF Research Database (Denmark)
Hobolth, Asger; Kent, John Thomas; Dryden, Ian L.
2002-01-01
circulant covariance matrix to model the edge transformation vector. This type of model is also feasible for the vertex transformation vector and in certain cases the free parameters of the two models match up in a simple way. A vertex model and an edge model are applied to a data set of sand particles...
On the Relation between Edge and Vertex Modelling in Shape Analysis
DEFF Research Database (Denmark)
Hobolth, Asger; Kent, John Thomas; Dryden, Ian L.
2002-01-01
circulant covariance matrix to model the edge transformation vector. This type of model is also feasible for the vertex transformation vector and in certain cases the free parameters of the two models match up in a simple way. A vertex model and an edge model are applied to a data set of sand particles...
Consistent off-shell pi NN vertex and nucleon self-energy
Kondratyuk, S; Scholten, O
1999-01-01
We present a consistent calculation of half-off-shell form factors in the pion-nucleon vertex and the nucleon self-energy. Numerical results are presented. Near the on-shell point the pion-nucleon vertex is dominated by the pseudovector coupling, while at large nucleon invariant masses we find a siz
Consistent off-shell πNN vertex and nucleon self-energy
Kondratyuk, S.; Scholten, O.
1999-01-01
We present a consistent calculation of half-off-shell form factors in the pion-nucleon vertex and the nucleon self-energy. Numerical results are presented. Near the on-shell point the pion-nucleon vertex is dominated by the pseudovector coupling, while at large nucleon invariant masses we find a siz
Non-perturbative model for the half-off-shell $gamma N N$ vertex
Kondratyuk, S.; Scholten, O.
1999-01-01
Submitted to: Phys. Rev. C Abstract: Form factors in the nucleon-photon vertex with one off-shell nucleon are calculated by dressing the vertex with pion loops up to infinite order. Cutting rules and dispersion relations are implemented in the model. Using the prescription of minimal substitution we
Non-oblique Correction in Extenden Technicolor Theory
Kitazawa, N
1993-01-01
We study radiative corrections on $Zb{\\bar b}$ vertex generated by the ETC gauge bosons, ``diagonal'' as well as sideways. Although the oblique corrections due to the ETC bosons are small in comparison with the oblique correction due to the technicolor dynamics, the non-oblique corrections result in substantial shift of contour plot in the $S$-$T$ plane. We show that such a shift due to the non-oblique corrections is actually important for discussing $S$ and $T$ values in the technicolor models.
Constructing Scalar-Photon Three Point Vertex in Massless Quenched Scalar QED
Fernandez-Rangel, L Albino; Gutierrez-Guerrero, L X; Concha-Sanchez, Y
2016-01-01
Non perturbative studies of Schwinger-Dyson equations (SDEs) require their infnite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the three point scalar-photon vertex can be expressed in terms of only two independent form factors, a longitudinal and a transverse one. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green-Takahashi identity (WFGTI), while the transverse vertex remains undetermined. In massless quenched sQED, we construct the transverse part of the non perturbative scalar-photon vertex. This construction (i) ensures multiplicative renormalizability (MR) of the scalar propagator in keeping with the Landau-Khalatnikov-Fradkin transformations (LKFTs), (ii) has the same transformatio...
The scalar-photon 3-point vertex in massless quenched scalar QED
Concha-Sánchez, Y.; Gutiérrez-Guerrero, L. X.; Fernández-Rangel, L. A.
2016-10-01
Non perturbative studies of Schwinger-Dyson equations (SDEs) require their infinite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the scalar-photon three point vertex can be expressed in terms of only two independent form factors, longitudinal and transverse. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green- Takahashi identity (WFGTI), while the transverse vertex remains undetermined. In massless quenched sQED, we propose the transverse part of the non perturbative scalar-photon vertex.
A quantum hybrid with a thin antenna at the vertex of a wedge
Energy Technology Data Exchange (ETDEWEB)
Carlone, Raffaele, E-mail: raffaele.carlone@unina.it [Università “Federico II” di Napoli, Dipartimento di Matematica e Applicazioni “R. Caccioppoli”, MSA, via Cinthia, I-80126, Napoli (Italy); Posilicano, Andrea, E-mail: andrea.posilicano@uninsubria.it [DiSAT, Università dell' Insubria, via Valleggio 11, I-22100, Como (Italy)
2017-03-26
We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a “hybrid surface” consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex. - Highlights: • Spectral characterization of a quantum Hamiltonian on “hybrid surface” consisting of a halfline attached to the vertex of a concave planar wedge. • The system is tunable by varying the measure of the angle at the vertex. • Relation between the conduction properties inside the hybrid and formation of resonances. • Easy generalization of the results to more complicated structures.
Mixed electroweak-QCD corrections to e+e-→H Z at Higgs factories
Sun, Qing-Feng; Feng, Feng; Jia, Yu; Sang, Wen-Long
2017-09-01
The prospective Higgs factories, exemplified by ILC, FCC-ee and CEPC, plan to conduct precision Higgs measurements at the e+e- center-of-mass energy around 250 GeV. The cross sections for the dominant Higgs production channel, the Higgsstrahlung process, can be measured to a (sub)percent accuracy. Merely incorporating the well-known next-to-leading-order (NLO) electroweak corrections appears to be far from sufficient to match the unprecedented experimental precision. In this work, we make an important advancement toward this direction by investigating the mixed electroweak-QCD corrections to e+e-→H Z at next-to-next-to-leading order (NNLO) for both unpolarized and polarized Z bosons. The corrections turn out to reach the 1% level of the Born order results, and thereby must be incorporated in future confrontations with the data.
Balanced vertex decomposable simplicial complexes and their h-vectors
Biermann, Jennifer
2012-01-01
Given any finite simplicial complex \\Delta, we show how to construct a new simplicial complex \\Delta_{\\chi} that is balanced and vertex decomposable. Moreover, we show that the h-vector of the simplicial complex \\Delta_{\\chi} is precisely the f-vector, denoted f(\\Delta), of the original complex \\Delta. We deduce this result by relating f(\\Delta) with the graded Betti numbers of the Alexander dual of \\Delta_{\\chi}. Our construction generalizes the "whiskering" construction of Villarreal, and Cook and Nagel. As a corollary of our work, we add a new equivalent statement to a theorem of Bj\\"orner, Frankl, and Stanley that classifies the f-vectors of simplicial complexes. We also prove a special case of a conjecture of Cook and Nagel, and Constantinescu and Varbaro on the h-vectors of flag complexes.
Performance of the CLAS12 Silicon Vertex Tracker modules
Energy Technology Data Exchange (ETDEWEB)
Antonioli, Mary Ann [JLAB; Boiarinov, Serguie; Bonneau, Peter R. [JLAB; Elouadrhiri, Latifa [JLAB; Eng, Brian J. [JLAB; Gotra, Yuri N. [JLAB; Kurbatov, Evgeny O. [Moscow State U.; Leffel, Mindy A. [JLAB; Mandal, Saptarshi [JLAB; McMullen, Marc E. [JLAB; Merkin, Mikhail M. [Moscow State U.; Raydo, Benjamin J. [JLAB; Teachey, Robert W, [JLAB; Tucker, Ross J. [Arizona State U.; Ungaro, Maurizio [JLAB; Yegneswaran, Amrit S. [JLAB; Ziegler, Veronique [JLAB
2013-12-01
For the 12 GeV upgrade, the CLAS12 experiment has designed a Silicon Vertex Tracker (SVT) using single sided microstrip sensors fabricated by Hamamatsu. The sensors have graded angle design to minimize dead areas and a readout pitch of 156{micro}m, with intermediate strip. Double sided SVT module hosts three daisy-chained sensors on each side with a full strip length of 33 cm. There are 512 channels per module read out by four Fermilab Silicon Strip Readout (FSSR2) chips featuring data driven architecture, mounted on a rigid-flex hybrid. Modules are assembled on the barrel using unique cantilevered geometry to minimize the amount of material in the tracking volume. Design and performance of the SVT modules are presented, focusing on results of electrical measurements.
Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector
AUTHOR|(SzGeCERN)734627; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo
2016-01-01
The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.
D. phi. vertex drift chamber construction and test results
Energy Technology Data Exchange (ETDEWEB)
Clark, A.R.; Goozen, F.; Grudberg, P.; Klopfenstein, C.; Kerth, L.T.; Loken, S.C.; Oltman, E.; Strovink, M.; Trippe, T.G.
1991-05-01
A jet-cell based vertex chamber has been built for the D{O} experiment at Fermilab and operated in a test beam there. Low drift velocity and diffusion properties were achieved using CO{sub 2}(95%)-ethane(5%) at atmospheric pressure. The drift velocity is found to be consistent with (9.74+8.68( E -1.25)) {mu}m/nsec where E is the electric field strength in (kV/cm < E z 1.6 kV/cm.) An intrinsic spatial resolution of 60 {mu}m or better for drift distances greater than 2 mm is measured. The track pair efficiency is estimated to be better than 90% for separations greater than 630 {mu}m. 8 refs., 6 figs., 1 tab.
A vertex similarity index for better personalized recommendation
Chen, Ling-Jiao; Zhang, Zi-Ke; Liu, Jin-Hu; Gao, Jian; Zhou, Tao
2017-01-01
Recommender systems benefit us in tackling the problem of information overload by predicting our potential choices among diverse niche objects. So far, a variety of personalized recommendation algorithms have been proposed and most of them are based on similarities, such as collaborative filtering and mass diffusion. Here, we propose a novel vertex similarity index named CosRA, which combines advantages of both the cosine index and the resource-allocation (RA) index. By applying the CosRA index to real recommender systems including MovieLens, Netflix and RYM, we show that the CosRA-based method has better performance in accuracy, diversity and novelty than some benchmark methods. Moreover, the CosRA index is free of parameters, which is a significant advantage in real applications. Further experiments show that the introduction of two turnable parameters cannot remarkably improve the overall performance of the CosRA index.
Solving Vertex Cover Problem Using DNA Tile Assembly Model
Directory of Open Access Journals (Sweden)
Zhihua Chen
2013-01-01
Full Text Available DNA tile assembly models are a class of mathematically distributed and parallel biocomputing models in DNA tiles. In previous works, tile assembly models have been proved be Turing-universal; that is, the system can do what Turing machine can do. In this paper, we use tile systems to solve computational hard problem. Mathematically, we construct three tile subsystems, which can be combined together to solve vertex cover problem. As a result, each of the proposed tile subsystems consists of Θ(1 types of tiles, and the assembly process is executed in a parallel way (like DNA’s biological function in cells; thus the systems can generate the solution of the problem in linear time with respect to the size of the graph.
A dynamical system connected with inhomogeneous 6-vertex model
Korepanov, I G
1994-01-01
A completely integrable dynamical system in discrete time is studied by means of algebraic geometry. The system is associated with factorization of a linear operator acting in a direct sum of three linear spaces into a product of three operators, each acting nontrivially only in a direct sum of two spaces, and the following reversing of the order of factors. There exists a reduction of the system interpreted as a classical field theory in 2+1-dimensional space-time, the integrals of motion coinciding, in essence, with the statistical sum of an inhomogeneous 6-vertex free-fermion model on the 2-dimensional Kagomé lattice (here the statistical sum is a function of two parameters). Thus, a connection with the "local", or "generalized", quantum Yang-Baxter equation is revealed.
New limits on anomalous contributions to the $Wtb$ vertex
Birman, J L; Fiolhais, M C N; Onofre, A; Pease, C M
2016-01-01
The latest and most precise top quark measurements at the LHC and Tevatron are used to establish new limits on the $Wtb$ vertex. Recent results on the measurements of the $W$-boson helicity fractions and single top quark production cross section are combined in order to establish new limits at 95% CL (confidence level). The allowed regions for these limits are presented, for the first time, in three-dimensional graphics, for both real and imaginary components of the different anomalous couplings, providing a new perspective on the impact of the combination of different physics observables. These results are also combined with the prospected future measurement of the single top quark production cross section and $W$-boson helicity fractions at the LHC.
Studying the $Wtb$ vertex structure using recent LHC results
Bernardo, César; Fiolhais, Miguel C N; Gonçalves, Hugo; Guerra, André G C; Oliveira, Miguel; Onofre, A
2014-01-01
The $Wtb$ vertex structure and the search for new anomalous couplings is studied using top quark measurements obtained at the LHC, for a centre-of-mass energy of 8 TeV. By combining the latest and most precise results on the single top quark production cross section and the measurements of the $W$-boson helicity fractions ($F_0$ and $F_L$), it is possible to set new limits, at 95% CL (confidence level), on the real and imaginary components of the new couplings. The combination of the LHC observables clearly improves the limits obtained when using the individual results alone. The updated measurements of the $W$-boson helicity fractions and the $s+t$-channels electroweak single top quark production, at the Tevatron, improve the LHC limits, when a world combination of all observables (LHC+Tevatron) is performed.
The silicon vertex detector of the Belle II experiment
Energy Technology Data Exchange (ETDEWEB)
Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, T. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Universitá di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); Bozek, A. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); and others
2016-07-11
The silicon vertex detector of the Belle II experiment, structured in a lantern shape, consists of four layers of ladders, fabricated from two to five silicon sensors. The APV25 readout ASIC chips are mounted on one side of the ladder to minimize the signal path for reducing the capacitive noise; signals from the sensor backside are transmitted to the chip by bent flexible fan-out circuits. The ladder is assembled using several dedicated jigs. Sensor motion on the jig is minimized by vacuum chucking. The gluing procedure provides such a rigid foundation that later leads to the desired wire bonding performance. The full ladder with electrically functional sensors is consistently completed with a fully developed assembly procedure, and its sensor offsets from the design values are found to be less than 200 μm. The potential functionality of the ladder is also demonstrated by the radioactive source test.
The LHCb Vertex Locator (VELO) Pixel Detector Upgrade
Buchanan, Emma
2017-01-01
The LHCb experiment is designed to perform high-precision measurements of CP violation and the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. There is a planned upgrade during Long Shutdown 2 (LS2), expected in 2019, which will allow the detector to run at higher luminosities by transforming the entire readout to a trigger-less system. This will include a substantial upgrade of the Vertex Locator (VELO), the silicon tracker that surrounds the LHCb interaction region. The VELO is moving from silicon strip technology to hybrid pixel sensors, where silicon sensors are bonded to VeloPix ASICs. Sensor prototypes have undergone rigorous testing using the Timepix3 Telescope at the SPS, CERN. The main components of the upgrade are summarised and testbeam results presented.
An integrable nineteen vertex model lying on a hypersurface
Directory of Open Access Journals (Sweden)
M.J. Martins
2015-03-01
Full Text Available We have found a family of solvable nineteen vertex model with statistical configurations invariant by the time reversal symmetry within a systematic study of the respective Yang–Baxter relation. The Boltzmann weights sit on a degree seven algebraic threefold which is shown birationally equivalent to the three-dimensional projective space. This permits to write parameterized expressions for both the transition operator and the R-matrix depending on three independent affine spectral parameters. The Hamiltonian limit tells us that the azimuthal magnetic field term is connected with the asymmetry among two types of spectral variables. The absence of magnetic field defines a physical submanifold whose geometrical properties are remarkably shown to be governed by a quartic K3 surface. This expands considerably the class of irrational manifolds that could emerge in the theory of quantum integrable models.
The FIRST experiment: interaction region and MAPS vertex detector
Energy Technology Data Exchange (ETDEWEB)
Spiriti, E. [INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); De Napoli, M.; Romano, F. [INFN, Laboratori Nazionali del Sud, Via S. Sofia 62, I-95125 Catania (Italy)
2011-06-15
The improvement of the precision of the measurement of the nuclear cross-section, in order to fulfill the requirements of the actual Monte Carlo simulations for hadrontherapy and space radioprotection, is the main goal of the FIRST experiment. After a brief introduction on the treatment planning in hadrontherapy, this paper describes main characteristics and components of the experiment. The features of the interaction region detectors and their main needs (low material budget, high angular coverage, two tracks resolution and large trigger rate) are discussed. Special emphasis is devoted in discussing the new silicon pixel vertex detector, in particular its new developed data acquisition and its characterization with the first test results obtained with a prototype of the detector.
The FIRST experiment: interaction region and MAPS vertex detector
Spiriti, E.; de Napoli, M.; Romano, F.; FIRST Collaboration
2011-06-01
The improvement of the precision of the measurement of the nuclear cross-section, in order to fulfill the requirements of the actual Monte Carlo simulations for hadrontherapy and space radioprotection, is the main goal of the FIRST experiment. After a brief introduction on the treatment planning in hadrontherapy, this paper describes main characteristics and components of the experiment. The features of the interaction region detectors and their main needs (low material budget, high angular coverage, two tracks resolution and large trigger rate) are discussed. Special emphasis is devoted in discussing the new silicon pixel vertex detector, in particular its new developed data acquisition and its characterization with the first test results obtained with a prototype of the detector.
The silicon vertex detector of the Belle II experiment
Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, T.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rao, K. K.; Rashevskaya, I.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.
2016-07-01
The silicon vertex detector of the Belle II experiment, structured in a lantern shape, consists of four layers of ladders, fabricated from two to five silicon sensors. The APV25 readout ASIC chips are mounted on one side of the ladder to minimize the signal path for reducing the capacitive noise; signals from the sensor backside are transmitted to the chip by bent flexible fan-out circuits. The ladder is assembled using several dedicated jigs. Sensor motion on the jig is minimized by vacuum chucking. The gluing procedure provides such a rigid foundation that later leads to the desired wire bonding performance. The full ladder with electrically functional sensors is consistently completed with a fully developed assembly procedure, and its sensor offsets from the design values are found to be less than 200 μm. The potential functionality of the ladder is also demonstrated by the radioactive source test.
Cutaneous paraganglioma of the vertex in a child.
Kim; Lee, Il Jae; Park, Myong Chul; Kim, Joo Hyoung; Lim, Hyoseob
2012-07-01
Paraganglioma is a neuroendocrine neoplasm that may develop at various body sites, including the head, neck, thorax, and abdomen. Approximately 85% of paragangliomas develop on the abdomen, 12% develop on the chest, and only 3% develop on the head and neck. These tumors are found in locations that parallel the sympathetic chain ganglion in the thoracolumbar regions and parasympathetic nervous system in craniosacral regions, and all head and neck paragangliomas arise from the parasympathetic nervous system. Although the skin has a rich neural network, it is devoid of ganglia. There has been only 1 report of a paraganglioma on the scalp of a child. We describe a 3-year-old child with a primary cutaneous paraganglioma of the vertex scalp and review the literature on paragangliomas.
Vertex partitions of r-edge-colored graphs
Institute of Scientific and Technical Information of China (English)
JIN Ze-min; LI Xue-liang
2008-01-01
Let G be an edge-colored graph. The monochromatic tree partition problem is to find the minimum number of vertex disjoint monochromatic trees to cover the all vertices of G. In the authors' previous work,it has been proved that the problem is NP-complete and there does not exist any constant factor approximation algorithm for it unless P = NP. In this paper the authors show that for any fixed integer r ≥ 5,if the edges of a graph G are colored by r colors,called an r-edge-colored graph,the problem remains NP-complete. Similar result holds for the monochromatic path (cycle) partition problem. Therefore,to find some classes of interesting graphs for which the problem can be solved in polynomial time seems interesting.A linear time algorithm for the monochromatic path partition problem for edge-colored trees is given.
The top quark right coupling in the tbW-vertex
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Sprinberg, Gabriel A. [Universidad de la Republica, Facultad de Ciencias, Instituto de Fisica, Montevideo (Uruguay); Vidal, Jordi [Universitat de Valencia, y Instituto de Fisica Corpuscular (IFIC), Centro Mixto Universitat de Valencia-CSIC, Departament de Fisica Teorica, Valencia (Spain)
2015-12-15
The most general parametrization of the tbW vertex includes a right coupling V{sub R} that is zero at tree level in the standard model. This quantity may be measured at the Large Hadron Collider where the physics of the top decay is currently investigated. This coupling is present in new physics models at tree level and/or through radiative corrections, so its measurement can be sensitive to non-standard physics. In this paper we compute the leading electroweak and QCD contributions to the top V{sub R} coupling in the standard model. This value is the starting point in order to separate the standard model effects and, then, search for new physics. We also propose observables that can be addressed at the LHC in order to measure this coupling. These observables are defined in such a way that they do not receive tree level contributions from the standard model and are directly proportional to the right coupling. Bounds on new physics models can be obtained through the measurements of these observables. (orig.)
The top quark right coupling in the tbW-vertex
Energy Technology Data Exchange (ETDEWEB)
González-Sprinberg, Gabriel A., E-mail: gabrielg@fisica.edu.uy [Facultad de Ciencias, Instituto de Física, Universidad de la República, Iguá 4225, 11600, Montevideo (Uruguay); Vidal, Jordi, E-mail: vidal@uv.es [Departament de Física Teòrica, Universitat de València, and Instituto de Física Corpuscular (IFIC), Centro Mixto Universitat de València-CSIC, Burjassot, 46100, València (Spain)
2015-12-26
The most general parametrization of the tbW vertex includes a right coupling V{sub R} that is zero at tree level in the standard model. This quantity may be measured at the Large Hadron Collider where the physics of the top decay is currently investigated. This coupling is present in new physics models at tree level and/or through radiative corrections, so its measurement can be sensitive to non-standard physics. In this paper we compute the leading electroweak and QCD contributions to the top V{sub R} coupling in the standard model. This value is the starting point in order to separate the standard model effects and, then, search for new physics. We also propose observables that can be addressed at the LHC in order to measure this coupling. These observables are defined in such a way that they do not receive tree level contributions from the standard model and are directly proportional to the right coupling. Bounds on new physics models can be obtained through the measurements of these observables.
Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
Energy Technology Data Exchange (ETDEWEB)
Hrayr Matevosyan; Anthony Thomas; Peter Tandy
2007-04-01
We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. With the more consistent vertex used here, the error in ladder-rainbow truncation for vector mesons is never more than 10% as the current quark mass is varied from the u/d region to the b region.
Progress toward the Determination of Complete Vertex Operators for The IIB Matrix Model
Kitazawa, Y; Saito, O; Kitazawa, Yoshihisa; Mizoguchi, Shun'ya; Saito, Osamu
2006-01-01
We report on progress in determining the complete form of vertex operators for the IIB matrix model. The exact expressions are obtained for those emitting massless IIB supergravity fields up to sixth order in the light-cone superfield, in which the conjugate gravitino and conjugate two-form vertex operators are newly determined. We also provide a consistency check by computing the kinematical factor of a four-point graviton amplitude in a D-instanton background. We conjecture that the low-energy effective action of the IIB matrix model at large N is given by tree-level supergravity coupled to the vertex operators.
Transverse Vector Vertex Function and Transverse Ward-Takahashi Relations in QED
Institute of Scientific and Technical Information of China (English)
HE Han-Xin
2006-01-01
The transverse vector vertex function in momentum space in four-dimensional QED is derived in terms of a set of transverse Ward-Takahashi relations for the vector and the axial-vector vertices in the case of massless fermion.It is demonstrated explicitly that the transverse vector vertex function derived this way to one-loop order leads to the same result as one obtained in perturbation theory. This provides a basic approach to determine the transverse part of basic vertex function from the symmetry relations of the system.
The method of regions and next-to-soft corrections in Drell–Yan production
Directory of Open Access Journals (Sweden)
D. Bonocore
2015-03-01
Full Text Available We perform a case study of the behaviour of gluon radiation beyond the soft approximation, using as an example the Drell–Yan production cross section at NNLO. We draw a careful distinction between the eikonal expansion, which is in powers of the soft gluon energies, and the expansion in powers of the threshold variable 1−z, which involves important hard-collinear effects. Focusing on the contribution to the NNLO Drell–Yan K-factor arising from real–virtual interference, we use the method of regions to classify all relevant contributions up to next-to-leading power in the threshold expansion. With this method, we reproduce the exact two-loop result to the required accuracy, including z-independent non-logarithmic contributions, and we precisely identify the origin of the soft-collinear interference which breaks simple soft-gluon factorisation at next-to-eikonal level. Our results pave the way for the development of a general factorisation formula for next-to-leading-power threshold logarithms, and clarify the nature of loop corrections to a set of recently proposed next-to-soft theorems.
QED radiative corrections to parity nonconservation in heavy atoms.
Kuchiev, M Yu; Flambaum, V V
2002-12-31
The self-energy and vertex QED radiative corrections [approximately Zalpha2f(Zalpha)] are shown to give a large negative contribution to the parity nonconserving (PNC) amplitude in heavy atoms. The correction -0.73(20)% found for the 6s-7s PNC amplitude in 133Cs brings the experimental result for this transition into agreement with the standard model. The calculations are based on a new relation that expresses the radiative corrections to the PNC matrix element via corrections to the energy shifts induced by the finite nuclear size.
The silicon vertex detector of the Belle II experiment
Energy Technology Data Exchange (ETDEWEB)
Friedl, Markus, E-mail: friedl@hephy.a [Institute of High Energy Physics, Nikolsdorfergasse 18, A-1050 Vienna (Austria); Bergauer, Thomas; Gfall, Immanuel; Irmler, Christian; Valentan, Manfred [Institute of High Energy Physics, Nikolsdorfergasse 18, A-1050 Vienna (Austria)
2011-02-01
After 10 years of successful operation, the Belle experiment at KEK (Tsukuba, Japan) will be completed in 2010. Thereafter, a major upgrade of the KEK-B machine is foreseen until 2014, aiming at a final luminosity of 8x10{sup 35} cm{sup -2} s{sup -1}, which is about 40 times higher than the present peak value. Consequently, also the Belle experiment needs to be changed and the Silicon Vertex Detector (SVD) in particular will be completely replaced as it already operates close to its limits in the present system. The future SVD (a.k.a. SuperSVD) will consist of four layers of double-sided silicon strip detectors like the present one, but at larger radii, because it will be complemented by a two-layer pixel detector as the innermost sensing device. The SuperSVD will be entirely composed of silicon sensors made from 6 in. wafers read out by APV25 front-end chips that were originally developed for the CMS experiment at the LHC. Several years of R and D effort led to innovations such as the Origami chip-on-sensor concept and readout electronics with hit time finding which were successfully demonstrated on prototypes. These features will be included in the final system which is presently being designed. This paper will give an overview of the SuperSVD and present results from prototype tests ranging from detector modules to back-end electronics.
The upgrade of the LHCb Vertex Locator (VELO)
van Beuzekom, M
2014-01-01
The upgrade of the LHCb experiment, planned for 2018, will enable the detector to run at a luminosity of 2 x 10$^{33}$ cm$^{-22}$s$^{-1}$ and explore New Physics effects in the beauty and charm sector with unprecedented precision. To achieve this, the entire readout will be transformed into a triggerless system operating at 40 MHz, where the event selection algorithms will be executed by high-level software in the CPU farm. The upgraded silicon vertex detector (VELO) must be lightweight, radiation hard, vacuum compatible, and has to drive data to the data acquisition system at speeds of up to 3 Tbit/s. This challenge will be met with a new VELO design based on hybrid pixel detectors, positioned to within 5 mm of the LHC colliding beams. The sensors have 55 x 55 $\\mu$m$^2$ square pixels and the VeloPix ASIC, which is being developed for the readout, is based on the Timepix/Medipix family of chips. The hottest ASIC will have to cope with integrated hit rates of up to 900 MHz which translates to a bandwidth of m...
A dynamic cellular vertex model of growing epithelial tissues
Lin, Shao-Zhen; Li, Bo; Feng, Xi-Qiao
2017-04-01
Intercellular interactions play a significant role in a wide range of biological functions and processes at both the cellular and tissue scales, for example, embryogenesis, organogenesis, and cancer invasion. In this paper, a dynamic cellular vertex model is presented to study the morphomechanics of a growing epithelial monolayer. The regulating role of stresses in soft tissue growth is revealed. It is found that the cells originating from the same parent cell in the monolayer can orchestrate into clustering patterns as the tissue grows. Collective cell migration exhibits a feature of spatial correlation across multiple cells. Dynamic intercellular interactions can engender a variety of distinct tissue behaviors in a social context. Uniform cell proliferation may render high and heterogeneous residual compressive stresses, while stress-regulated proliferation can effectively release the stresses, reducing the stress heterogeneity in the tissue. The results highlight the critical role of mechanical factors in the growth and morphogenesis of epithelial tissues and help understand the development and invasion of epithelial tumors.
CDF Run II Silicon Vertex Detector Annealing Study
Stancari, M; Behari, S; Christian, D; Di Ruzza, B; Jindariani, S; Junk, T R; Mattson, M; Mitra, A; Mondragon, M N; Sukhanov, A
2013-01-01
Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron collider delivered 12~fb$^{-1}$ of $p\\bar{p}$ collisions at $\\sqrt{s}=1.96$ TeV to the Collider Detector at Fermilab (CDF). During that time, the CDF silicon vertex detector was subject to radiation doses of up to 12 Mrad. After the end of operations, the silicon detector was annealed for 24 days at $18^{\\circ}$C. In this paper, we present a measurement of the change in the bias currents for a subset of sensors during the annealing period. We also introduce a novel method for monitoring the depletion voltage throughout the annealing period. The observed bias current evolution can be characterized by a falling exponential term with time constant $\\tau_I=17.88\\pm0.36$(stat.)$\\pm0.25$(syst.) days. We observe an average decrease of $(27\\pm3)\\%$ in the depletion voltage, whose evolution can similarly be described by an exponential time constant of $\\tau_V=6.21\\pm0.21$ days. These results are consistent with the Ham...
The micro vertex detector for the anti PANDA experiment
Energy Technology Data Exchange (ETDEWEB)
Esch, Simone [Forschungszentrum Juelich (Germany); Collaboration: PANDA-Collaboration
2015-07-01
The anti PANDA detector is one of the main experiments at the upcoming Facility for Antiproton and Ion Research (FAIR), which is under construction in Darmstadt, Germany. The fixed-target experiment will explore anti pp annihilations with intense, phase space-cooled beams with momenta between 1.5 and 15 GeV/c. One aim of the detector is to perform high precision measurements of particles like excited charmonium and D mesons. Essential for background suppression is the tagging of D mesons by measuring their decay point. Therefore, a Micro Vertex Detector (MVD) is planned at anti PANDA as the innermost tracking detector. The MVD aims to reconstruct vertices with a resolution better than 100 μm to cope with the decay length of the D{sup ±} mesons (cτ=315 μm) produced with a mean βγ=2. The detector consists of silicon pixel and double-sided silicon strip detectors, arranged in four barrel layers and six disk layers. An overview of the MVD is given in this talk. Recent developments like laboratory and testbeam results of the current pixel front-end ASIC prototype ToPix 4 are shown. The concept of the newly developed strip front-end ASIC PASTA is presented.
CDF Run IIb Silicon Vertex Detector DAQ Upgrade
Energy Technology Data Exchange (ETDEWEB)
S. Behari et al.
2003-12-18
The CDF particle detector operates in the beamline of the Tevatron proton-antiproton collider at Fermilab, Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of CDF's silicon vertex detector (SVX) subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand and operated successfully using an adapted version of CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. In this paper they present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards, and discuss a PCI-based DAQ system developed to facilitate production tests.
From vertex detectors to inner trackers with CMOS pixel sensors
Besson, A.; Pérez, A. Pérez; Spiriti, E.; Baudot, J.; Claus, G.; Goffe, M.; Winter, M.
2017-02-01
The use of CMOS Pixel Sensors (CPS) for high resolution and low material vertex detectors has been validated with the 2014 and 2015 physics runs of the STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner tracking devices, with 10-100 times larger sensitive area, which require therefore a sensor design privileging power saving, response uniformity and robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was considered as too poorly suited to upcoming applications like the upgraded ALICE Inner Tracking System (ITS), which requires sensors with one order of magnitude improvement on readout speed and improved radiation tolerance. This triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz 180 nm, for the design of a CPS well adapted for the new ALICE-ITS running conditions. This paper reports the R & D results for the conception of a CPS well adapted for the ALICE-ITS.
Automatised Data Quality Monitoring of the LHCb Vertex Locator
Szumlak, Tomasz
2016-01-01
The LHCb Vertex Locator (VELO) is a silicon strip semiconductor detector operating at just 8mm distance to the LHC beams. Its 172,000 strips are read at a frequency of 1 MHz and processed by off-detector FPGAs followed by a PC cluster that reduces the event rate to about 10 kHz. During the second run of the LHC, which lasts from 2015 until 2018, the detector performance will undergo continued change due to radiation damage effects. This necessitates a detailed monitoring of the data quality to avoid adverse effects on the physics analysis performance. The VELO monitoring infrastructure has been re-designed compared to the first run of the LHC when it was based on manual checks. The new system is based around an automatic analysis framework, which monitors the performance of new data as well as long-term trends and flags issues whenever they arise. An unbiased subset of the detector data are processed about once per hour by monitoring algorithms. The new analysis framework then analyses the plots that are prod...
Performance of the Aleph Upgraded Silicon Vertex Detector
Energy Technology Data Exchange (ETDEWEB)
Creanza, D.; De Palma, M.; Girone, M.; Maggi, G.; Selvaggi, G.; Silvestris, L.; Raso, G.; Tempesta, P.; Burns, M.; Coyle, P.; Engster, C.; Frank, M.; Moneta, L.; Wachnik, M.; Wagner, A.; Zaslavsky, J.; Focardi, E.; Sguazzoni, G.; Parrini, G.; Scarlini, E.; Halley, A.; O`Shea, V.; Raine, C.; Barber, G.; Cameron, W.; Dornan, P.; Gentry, D.; Konstantinidis, N.; Moutoussi, A.; Nash, J.; Price, D.; Stacey, A.; Toudup, L.W.; Williams, M.I.; Billault, M.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Blanc, P.E.; Destelle, J.J.; Karst, P.; Payre, P.; Rousseau, D.; Thulasidas, M.; Dietl, H.; Moser, H.-G.; Settles, R.; Seywerd, H.; Waltermann, G.; Bettarini, S.; Bosi, F.; Dell`Orso, R.; Messineo, A.; Profeti, A.; Rizzo, G.; Verdini, P.G.; Walsh, J.; Bizzell, J.P.; Maley, P.D.; Thompson, J.C.; Wright, A.E.; Black, S.; Kim, H.Y.; Bosisio, L.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Elmer, P. [Bari Univ. (Italy). Dipt. di Fisica]|[INFN, Bari (Italy)]|[European Laboratory for Particle Physics (CERN), 1211 Geneva 23 (Switzerland)]|[Dipartimento di Fisica, Universita di Firenze, INFN Sezione di Firenze, 50125 Firenze (Italy)]|[Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)]|[Department of Physics, Imperial College, London SW7 2BZ (United Kingdom)]|[Department of Physics, University of Lancaster, Lancaster LA1 4YB (United Kingdom)]|[Centre de Physique des Particules, Faculte des Sciences de Luminy, IN2P3-CNRS, 13288 Marseille (France)]|[Max-Planck-Institut fuer Physik, Werner-Heisenberg-Institut, 80805 Muenchen (Germany)]|[Dipartimento di Fisica dell`Universita e INFN Sezione di Pisa, 56010 Pisa (Italy)]|[Particle Physics Dept., Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)]|[Institute for Particle Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)
1997-03-01
The ALEPH Vertex Detector (VDET) has been upgraded for the second phase of LEP running. The new version still uses double sided silicon strip detectors, fabricated with the same technology as the previous one, but the upgraded one is twice as long and has about half passive material in the tracking volume. Furthermore the readout electronics is now radiation hard (MX7-RH chips). An almost complete version of the upgraded VDET was installed in ALEPH during a three week LEP technical stop and took data in November 1995 during the LEP run at 130 GeV. The new detector worked well showing high signal over noise ratio and good efficiency. The point resolution measured during this run, using high momentum muons, 13 {mu}m in the r-{phi} view and 21 {mu}m in the r-z view, is dominated by the alignment precision, due to the low statistics available for this short LEP run. This result is however acceptable, since for lower momentum charged particle, the multiple scattering gives a significant contribution to the final impact parameter resolution. A better resolution has been achieved in the next run, when an initial period at the Z peak has been foreseen to calibrate and align the whole detector. (orig.).
CDF Run IIb Silicon Vertex Detector DAQ Upgrade
Energy Technology Data Exchange (ETDEWEB)
S. Behari et al.
2003-12-18
The CDF particle detector operates in the beamline of the Tevatron proton-antiproton collider at Fermilab, Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of CDF's silicon vertex detector (SVX) subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand and operated successfully using an adapted version of CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. In this paper they present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards, and discuss a PCI-based DAQ system developed to facilitate production tests.
Performance of the ALEPH upgraded silicon vertex detector
Creanza, D; Girone, M.; Maggi, G.; Selvaggi, G.; Silvestris, L.; Raso, G.; Tempesta, P.; Burns, M.; Coyle, P.; Engster, C.; Frank, M.; Moneta, L.; Wachnik, M.; Wagner, A.; Zaslavsky, J.; Focardi, E.; Sguazzoni, G.; Parrini, G.; Scarlini, E.; Halley, A.; O'Shea, V.; Raine, C.; Barber, G.; Cameron, W.; Dornan, P.; Gentry, D.; Konstantinidis, N.; Moutoussi, A.; Nash, J.; Price, D.; Stacey, A.; Toudup, L.W.; Williams, M.I.; Billault, M.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Blanc, P.E.; Destelle, J.J.; Karst, P.; Payre, P.; Rousseau, D.; Thulasidas, M.; Dietl, H.; Moser, H.G.; Settles, R.; Seywerd, H.; Waltermann, G.; Bettarini, S.; Bosi, F.; Dell'Orso, R.; Messineo, A.; Profeti, A.; Rizzo, G.; Verdini, P.G.; Walsh, J.; Bizzell, J.P.; Maley, P.D.; Thompson, J.C.; Wright, A.E.; Black, S.; Kim, H.Y.; Bosisio, L.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Elmer, P.
1997-01-01
The ALEPH Vertex Detector (VDET) has been upgraded for the second phase of LEP running. The new version still uses double sided silicon strip detectors, fabricated with the same technology as the previous one, but the upgraded one is twice as long and has about half passive material in the tracking volume. Furthermore the readout electronics is now radiation hard (MX7-RH chips). An almost complete version of the upgraded VDET was installed in ALEPH during a three week LEP technical stop and took data in November 1995 during the LEP run at 130 GeV. The new detector worked well showing high signal over noise ratio and good efficiency. The point resolution measured during this run, using high momentum muons, 13 μm in the τ - φ view and 21 μm in the τ - z view, is dominated by the alignment precision, due to the low statistics available for this short LEP run. This result is however acceptable, since for lower momentum charged particle, the multiple scattering gives a significant contribution to the final im...
On the complexity of the balanced vertex ordering problem
Directory of Open Access Journals (Sweden)
Jan Kara
2007-01-01
Full Text Available We consider the problem of finding a balanced ordering of the vertices of a graph. More precisely, we want to minimise the sum, taken over all vertices v, of the difference between the number of neighbours to the left and right of v. This problem, which has applications in graph drawing, was recently introduced by Biedl et al. [Discrete Applied Math. 148:27--48, 2005]. They proved that the problem is solvable in polynomial time for graphs with maximum degree three, but NP-hard for graphs with maximum degree six. One of our main results is to close the gap in these results, by proving NP-hardness for graphs with maximum degree four. Furthermore, we prove that the problem remains NP-hard for planar graphs with maximum degree four and for 5-regular graphs. On the other hand, we introduce a polynomial time algorithm that determines whetherthere is a vertex ordering with total imbalance smaller than a fixed constant, and a polynomial time algorithm that determines whether a given multigraph with even degrees has an `almost balanced' ordering.
Towards Petaflops Capability of the VERTEX Supernova Code
Marek, Andreas; Hanke, Florian; Janka, Hans-Thomas
2014-01-01
The VERTEX code is employed for multi-dimensional neutrino-radiation hydrodynamics simulations of core-collapse supernova explosions from first principles. The code is considered state-of-the-art in supernova research and it has been used for modeling for more than a decade, resulting in numerous scientific publications. The computational performance of the code, which is currently deployed on several high-performance computing (HPC) systems up to the Tier-0 class (e.g. in the framework of the European PRACE initiative and the German GAUSS program), however, has so far not been extensively documented. This paper presents a high-level overview of the relevant algorithms and parallelization strategies and outlines the technical challenges and achievements encountered along the evolution of the code from the gigaflops scale with the first, serial simulations in 2000, up to almost petaflops capabilities, as demonstrated lately on the SuperMUC system of the Leibniz Supercomputing Centre (LRZ). In particular, we sh...
A neural network z-vertex trigger for Belle II
Energy Technology Data Exchange (ETDEWEB)
Neuhaus, Sara; Skambraks, Sebastian; Chen, Yang [Technische Universitaet Muenchen (Germany); Abudinen, Fernando; Kiesling, Christian [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: Belle II-Collaboration
2015-07-01
In the Belle II experiment the efficiency of the track trigger could be increased by reconstructing the z-coordinate of track vertices at the first trigger level and rejecting tracks not coming from the interaction region, which form a large part of the machine background. The presented method employs neural networks to estimate the z-vertex without explicit track reconstruction. Input data is taken from the central drift chamber, using both the wire coordinates and the drift times for each hit. Neural networks are general function approximators that can learn nonlinear dependencies from real data without the need of an explicit model. However, using a priori knowledge about the track in a meaningful way can help to train more efficient networks, in terms of both prediction quality and network size. Such input information is provided by the Belle II 2D track trigger and is used explicitly in the calculation of the input values for the neural network. The algorithms for the input representation are presented together with estimations for the trigger efficiency and the rejection capability.
Metric Extension Operators, Vertex Sparsifiers and Lipschitz Extendability
Makarychev, Konstantin
2010-01-01
We study vertex cut and flow sparsifiers that were recently introduced by Moitra, and Leighton and Moitra. We improve and generalize their results. We give a new polynomial-time algorithm for constructing O(log k / log log k) cut and flow sparsifiers, matching the best existential upper bound on the quality of a sparsifier, and improving the previous algorithmic upper bound of O(log^2 k / log log k). We show that flow sparsifiers can be obtained from linear operators approximating minimum metric extensions. We introduce the notion of (linear) metric extension operators, prove that they exist, and give an exact polynomial-time algorithm for finding optimal operators. We then establish a direct connection between flow and cut sparsifiers and Lipschitz extendability of maps in Banach spaces, a notion studied in functional analysis since 1950s. Using this connection, we prove a lower bound of \\Omega(\\sqrt{log k/log log k}) for flow sparsifiers and a lower bound of \\Omega(\\sqrt[4]{log k/log log k}) for cut sparsif...
Jet Vertex Charge Reconstruction Poster for LHCP 2015
Nektarijevic, Snezana; The ATLAS collaboration
2015-01-01
B-jet reconstruction algorithms used so far in ATLAS data analyses do not provide the b-jet charge information, which could potentially play a major role in reducing the combinatorial backgrounds in final states with multiple b-jets. This missing point is addressed by the newly developed JetVertexCharge (JVC) algorithm presented in this poster. Inspired by the decay chain of B-hadrons, the JVC algorithm provides a multi-variate b-jet charge estimate relying on tracks, displaced vertices and muons contained in the jet. In this algorithm, the established concept of estimating jet charge as a transverse momentum weighted sum of track charges is used to reconstruct the charge of the jet as whole, as well as the charges of up to two displaced vertices in the jet, using the corresponding sets of associated tracks. The charge of the associated muon is interpreted as the same-sign or opposite-sign relative to the b-jet charge, according to its transverse momentum and geometrical match to vertices. Jets are divided in...
A DEPFET pixel system for the ILC vertex detector
Trimpl, M; Kohrs, R; Krüger, H; Lodomez, P; Reuen, L; Sandow, C; Toerne, E; Velthuis, J J; Wermes, N; Andricek, L; Moser, H G; Richter, R H; Lutz, Gerhard; Giesen, F; Fischer, P; Peric, I
2006-01-01
We have developed a prototype system for the ILC vertex detector based on DEPFET pixels. The system operates a 128x64 pixel matrix and uses two dedicated microchips, the SWITCHER II chip for matrix steering and the CURO II chip for readout. The system development has been driven by the final ILC requirements which above all demand a detector thinned to 50 micron and a row wise read out with line rates of 20MHz and more. The targeted noise performance for the DEPFET technology is in the range of ENC=100e-. The functionality of the system has been demonstrated using different radioactive sources in an energy range from 6keV to 60keV. In recent test beam experiments using 6GeV electrons, a signal-to-noise ratio of S/N~120 has been achieved with present sensors being 450 micron thick. For improved DEPFET systems using 50 micron thin sensors in future, a signal-to-noise of 40 is expected.
Error handling for the CDF Silicon Vertex Tracker
Belforte, S; Dell'Orso, Mauro; Donati, S; Galeotti, S; Giannetti, P; Morsani, F; Punzi, G; Ristori, L; Spinella, F; Zanetti, A M
2000-01-01
The SVT online tracker for the CDF upgrade reconstructs two- dimensional tracks using information from the Silicon Vertex detector (SVXII) and the Central Outer Tracker (COT). The SVT has an event rate of 100 kHz and a latency time of 10 mu s. The system is composed of 104 VME 9U digital boards (of 8 different types) and it is implemented as a data driven architecture. Each board runs on its own 30 MHz clock. Since the data output from the SVT (few Mbytes/sec) are a small fraction of the input data (200 Mbytes/sec), it is extremely difficult to track possible internal errors by using only the output stream. For this reason several diagnostic tools have been implemented: local error registers, error bits propagated through the data streams and the Spy Buffer system. Data flowing through each input and output stream of every board are continuously copied to memory banks named Spy Buffers which act as built in logic state analyzers hooked continuously to internal data streams. The contents of all buffers can be ...
Error handling for the CDF online silicon vertex tracker
Bari, M; Cerri, A; Dell'Orso, Mauro; Donati, S; Galeotti, S; Giannetti, P; Morsani, F; Punzi, G; Ristori, L; Spinella, F; Zanetti, A M
2001-01-01
The online silicon vertex tracker (SVT) is composed of 104 VME 9U digital boards (of eight different types). Since the data output from the SVT (few MB/s) are a small fraction of the input data (200 MB/s), it is extremely difficult to track possible internal errors by using only the output stream. For this reason, several diagnostic tools have been implemented: local error registers, error bits propagated through the data streams, and the Spy Buffer system. Data flowing through each input and output stream of every board are continuously copied to memory banks named spy buffers, which act as built-in logic state analyzers hooked continuously to internal data streams. The contents of all buffers can be frozen at any time (e.g., on error detection) to take a snapshot of all data flowing through each SVT board. The spy buffers are coordinated at system level by the Spy Control Board. The architecture, design, and implementation of this system are described. (4 refs).
A dynamic cellular vertex model of growing epithelial tissues
Lin, Shao-Zhen; Li, Bo; Feng, Xi-Qiao
2017-03-01
Intercellular interactions play a significant role in a wide range of biological functions and processes at both the cellular and tissue scales, for example, embryogenesis, organogenesis, and cancer invasion. In this paper, a dynamic cellular vertex model is presented to study the morphomechanics of a growing epithelial monolayer. The regulating role of stresses in soft tissue growth is revealed. It is found that the cells originating from the same parent cell in the monolayer can orchestrate into clustering patterns as the tissue grows. Collective cell migration exhibits a feature of spatial correlation across multiple cells. Dynamic intercellular interactions can engender a variety of distinct tissue behaviors in a social context. Uniform cell proliferation may render high and heterogeneous residual compressive stresses, while stress-regulated proliferation can effectively release the stresses, reducing the stress heterogeneity in the tissue. The results highlight the critical role of mechanical factors in the growth and morphogenesis of epithelial tissues and help understand the development and invasion of epithelial tumors.
From vertex detectors to inner trackers with CMOS pixel sensors
Besson, A; Spiriti, E.; Baudot, J.; Claus, G.; Goffe, M.; Winter, M.
2016-01-01
The use of CMOS Pixel Sensors (CPS) for high resolution and low material vertex detectors has been validated with the 2014 and 2015 physics runs of the STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner tracking devices, with 10-100 times larger sensitive area, which require therefore a sensor design privileging power saving, response uniformity and robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was considered as too poorly suited to upcoming applications like the upgraded ALICE Inner Tracking System (ITS), which requires sensors with one order of magnitude improvement on readout speed and improved radiation tolerance. This triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz 180 nm, for the design of a CPS well adapted for the new ALICE-ITS running conditions. This paper reports the R&D results for the conception of a CPS well adapted for the ALICE-ITS.
The quark-gluon vertex in Landau gauge bound-state studies
Williams, Richard
2015-05-01
We present a practical method for the solution of the quark-gluon vertex for use in Bethe-Salpeter and Dyson-Schwinger calculations. The efficient decomposition into the necessary covariants is detailed, with the numerical algorithm outlined for both real and complex Euclidean momenta. A truncation of the quark-gluon vertex, that neglects explicit back-coupling to enable the application to bound-state calculations, is given together with results for the quark propagator and quark-gluon vertex for different quark flavours. The relative impact of the various components of the quark-gluon vertex is highlighted with the flavour dependence of the effective quark-gluon interaction obtained, thus providing insight for the construction of phenomenological models within the rainbow ladder. Finally, we solve the corresponding Green's functions for complex Euclidean momenta as required in future bound-state calculations.
Lattice Landau gauge quark propagator and the quark-gluon vertex
Oliveira, Orlando; Silva, Paulo J; Skullerud, Jon-Ivar; Sternbeck, Andre; Williams, Anthony G
2016-01-01
We report preliminary results of our ongoing lattice computation of the Landau gauge quark propagator and the soft gluon limit of the quark-gluon vertex with 2 flavors of dynamical O(a) improved Wilson fermions.
Asymmetric 6-vertex model and classical Ruijsenaars-Schneider system of particles
Liashyk, A; Zabrodin, A; Zotov, A
2016-01-01
We discuss the correspondence between models solved by Bethe ansatz and classical integrable systems of Calogero type. We illustrate the correspondence by the simplest example of the inhomogeneous asymmetric 6-vertex model parametrized by trigonometric (hyperbolic) functions.
Experimental study of heat generation at the vertex of a fatigue crack
Terekhina, A. I.; Bannikov, M. V.; Plekhov, O. A.; Plekhova, E. V.
2012-08-01
The process of heat generation at the vertex of a fatigue crack in VT-6 titanium alloy under conditions of cyclic loading has been studied by infrared thermography. The spatial and temporal variations of temperature at the crack vertex have been measured, the shape of the zone of heat evolution has been determined, and the intensity of heat generation has been evaluated. Comparison of the obtained experimental data to the relations of the linear theory of elasticity shows that neither the observed shape of the plastic deformation zone nor the measured dynamics of heat evolution at the crack vertex is consistent with predictions of the linear theoretical models. The experimental results revealed a time delay between the moments of maximum applied stress and maximum intensity of heat evolution at the vertex of a fatigue crack.
The quark-gluon vertex in Landau gauge bound-state studies
Energy Technology Data Exchange (ETDEWEB)
Williams, Richard [Justus-Liebig University of Giessen, Institute of Theoretical Physics, Giessen (Germany)
2015-05-15
We present a practical method for the solution of the quark-gluon vertex for use in Bethe-Salpeter and Dyson-Schwinger calculations. The efficient decomposition into the necessary covariants is detailed, with the numerical algorithm outlined for both real and complex Euclidean momenta. A truncation of the quark-gluon vertex, that neglects explicit back-coupling to enable the application to bound-state calculations, is given together with results for the quark propagator and quark-gluon vertex for different quark flavours. The relative impact of the various components of the quark-gluon vertex is highlighted with the flavour dependence of the effective quark-gluon interaction obtained, thus providing insight for the construction of phenomenological models within the rainbow ladder. Finally, we solve the corresponding Green's functions for complex Euclidean momenta as required in future bound-state calculations. (orig.)
Calculating the vertex unknowns of nine point scheme on quadrilateral meshes for diffusion equation
Institute of Scientific and Technical Information of China (English)
YUAN GuangWei; SHENG ZhiQiang
2008-01-01
In the construction of nine point scheme, both vertex unknowns and cell-centered unknowns are introduced, and the vertex unknowns are usually eliminated by using the interpolation of neighboring cell-centered unknowns, which often leads to lose accuracy. Instead of using interpolation,here we propose a different method of calculating the vertex unknowns of nine point scheme, which are solved independently on a new generated mesh. This new mesh is a Voronoi mesh based on the vertexes of primary mesh and some additional points on the interface. The advantage of this method is that it is particularly suitable for solving diffusion problems with discontinuous coefficients on highly distorted meshes, and it leads to a symmetric positive definite matrix. We prove that the method has first-order convergence on distorted meshes. Numerical experiments show that the method obtains nearly second-order accuracy on distorted meshes.
Non-Abelian Ball-Chiu vertex for arbitrary Euclidean momenta
Aguilar, A C; Ferreira, M N; Papavassiliou, J
2016-01-01
We determine the non-Abelian version of the four longitudinal form factors of the quark-gluon vertex, using exact expressions derived from the Slavnov-Taylor identity that this vertex satisfies. In addition to the quark and ghost propagators, a key ingredient of the present approach is the quark-ghost scattering kernel, which is computed within the one-loop dressed approximation. The vertex form factors obtained from this procedure are evaluated for arbitrary Euclidean momenta, and display features not captured by the well-known Ball-Chiu vertex, deduced from the Abelian (ghost-free) Ward identity. The potential phenomenological impact of these results is evaluated through the study of special renormalization-point-independent combinations, which quantify the strength of the interaction kernels appearing in the standard quark gap and Bethe-Salpeter equations.
Explicit Exact Formulas for the 3-D Tetrahedron Inertia Tensor in Terms of its Vertex Coordinates
Directory of Open Access Journals (Sweden)
F. Tonon
2005-01-01
Full Text Available The inertia tensor of a tetrahedron is composed of its moments of inertia. This study presents explicit exact formulas for the moments of inertia of a 3-D tetrahedron as simple polynomials of its vertex coordinates.
Calculating the vertex unknowns of nine point scheme on quadrilateral meshes for diffusion equation
Institute of Scientific and Technical Information of China (English)
2008-01-01
In the construction of nine point scheme,both vertex unknowns and cell-centered unknowns are introduced,and the vertex unknowns are usually eliminated by using the interpolation of neighboring cell-centered unknowns,which often leads to lose accuracy.Instead of using interpolation,here we propose a different method of calculating the vertex unknowns of nine point scheme,which are solved independently on a new generated mesh.This new mesh is a Vorono¨i mesh based on the vertexes of primary mesh and some additional points on the interface.The advantage of this method is that it is particularly suitable for solving diffusion problems with discontinuous coeffcients on highly distorted meshes,and it leads to a symmetric positive definite matrix.We prove that the method has first-order convergence on distorted meshes.Numerical experiments show that the method obtains nearly second-order accuracy on distorted meshes.
Twist Field as Three String Interaction Vertex in Light Cone String Field Theory
Kishimoto, Isao; Moriyama, Sanefumi; Teraguchi, Shunsuke
2006-01-01
It has been suggested that matrix string theory and light-cone string field theory are closely related. In this paper, we investigate the relation between the twist field, which represents string interactions in matrix string theory, and the three-string interaction vertex in light-cone string field theory carefully. We find that the three-string interaction vertex can reproduce some of the most important OPEs satisfied by the twist field.
Gornushkin, Yu. A.; Dmitrievsky, S. G.; Chukanov, A. V.
2015-01-01
The OPERA experiment is designed for the direct observation of the appearance of ντ from νμ → ντ oscillation in a νμ beam. A description of the procedure of neutrino interaction vertex localization (Brick Finding) by electronic detectors of a hybrid OPERA setup is presented. The procedure includes muon track and hadronic shower axis reconstruction and a determination of the target bricks with the highest probability to contain the vertex.
Precise Numerical Results of IR-vertex and box integration with Extrapolation Method
Yuasa, F; Fujimoro, J; Hamaguchi, N; Ishikawa, T; Shimizu, Y
2007-01-01
We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision library, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as $10^{-150}$ GeV in the infrared vertex diagram.
NLO vertex for a forward jet plus a rapidity gap at high energies
Hentschinski, Martin; Madrigal Martínez, José Daniel; Murdaca, Beatrice; Vera, Agustín Sabio
2015-04-01
We present the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the BFKL formalism at next-to-leading order (NLO). Real emission contributions are computed via Lipatov's effective action. The NLO jet vertex turns out to be finite within collinear factorization and allows, together with the NLO non-forward gluon Green's function, to perform NLO studies of jet production in diffractive events (e.g. Mueller-Tang dijets).
Wake fields in the LHCb vertex detector : alternative designs for the wake field suppressor
Van Bakel, N; Ferro-Luzzi, M
2000-01-01
Two previous LHCb notes showed that wake field suppressors are needed to prevent dissipating excessive power in resonating modes of the vertex detector components. This note concentrates on two different designs of the encapsulations of the silicon detectors which can serve as an alternative to the design which uses long thin strips spanned throughout the vertex detector near the beam axis. The quality of wake field suppression with respect to the depth of a corrugated structure is simulated.
NLO Vertex for a Forward Jet plus a Rapidity Gap at High Energies
Hentschinski, Martin; Murdaca, Beatrice; Vera, Agustín Sabio
2015-01-01
We present the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the BFKL formalism at next-to-leading order (NLO). Real emission contributions are computed via Lipatov's effective action. The NLO jet vertex turns out to be finite within collinear factorization and allows, together with the NLO non-forward gluon Green's function, to perform NLO studies of jet production in diffractive events (e.g. Mueller-Tang dijets).
Twist Field as Three String Interaction Vertex in Light Cone String Field Theory
Kishimoto, Isao; Moriyama, Sanefumi; Teraguchi, Shunsuke
2006-01-01
It has been suggested that matrix string theory and light-cone string field theory are closely related. In this paper, we investigate the relation between the twist field, which represents string interactions in matrix string theory, and the three-string interaction vertex in light-cone string field theory carefully. We find that the three-string interaction vertex can reproduce some of the most important OPEs satisfied by the twist field.
Tracking and Vertexing with the ATLAS Inner Detector in the LHC Run-2
Choi, Kyungeon; The ATLAS collaboration
2017-01-01
Run-2 of the Large Hadron Collider (LHC) has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity envi- ronments, boosted, and highly-collimated physics objects. We present an overview of the ATLAS Inner Detector tracker in Run-2 including the track reconstruction algorithm, time-dependent alignment, tracking and vertexing performance.
DFT Predictions on Structures and Stabilities of Eleven-vertex nido-and cioso-Heteroboranes
Institute of Scientific and Technical Information of China (English)
LI Ping
2009-01-01
Based on the octadecahedron of eleven-vertex closo-borane,the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron,and the stabilities were predicted at G96PW91/6-31+G(3d,2p) level.The small heteroatoms,C,N,O,preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes.They cap four-membered rings to satisfy the geometrical demand of short B-Z bonds.The electron attractions from the vicinal boron atoms make the frameworks shrink.Differently,Si and Ge preferentially substitute for boron at vertex 1 with six tight B-Z bonds and form stabilized molecules.P,As,S,and Se tend to occupy vertex 4 and the optimized structures belong to the nido configurations,in contrast to high electronegative heteroatoms,S and Se transfer less negative charges to framework and the electropositive heteroatoms,Si and Ge transfer more negative charges to framework to form the delocalization structures.The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities.The substitutions of heteroatoms for boron atoms in eleven-vertex closo-hcteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.
TECHNICAL DESIGN REPORT OF THE FORWARD SILICON VERTEX (FVTX)
Energy Technology Data Exchange (ETDEWEB)
PHENIX EXPERIMENT; OBRIEN,E.; PAK, R.; DREES, K.A.; (PHENIX EXPERIMENT COLLABORATORS)
2007-08-01
The main goal of the RHIC heavy ion program is the discovery of the novel ultra-hot high-density state of matter predicted by the fundamental theory of strong interactions and created in collisions of heavy nuclei, the Quark-Gluon Plasma (QGP). From measurements of the large elliptic flow of light mesons and baryons and their large suppression at high transverse momentum pT that have been made at RHIC, there is evidence that new degrees of freedom, characteristic of a deconfined QCD medium, drive the dynamics of nucleus-nucleus collisions. It has been recognized, however, that the potential of light quarks and gluons to characterize the properties of the QGP medium is limited and the next phase of the RHIC program calls for the precise determination of its density, temperature, opacity and viscosity using qualitatively new probes, such as heavy quarks. We propose the construction of two Forward Silicon Vertex Trackers (FVTX) for the PHENIX experiment that will directly identify and distinguish charm and beauty decays within the acceptance of the muon spectrometers. The FVTX will provide this essential coverage over a range of forward and backward rapidities (1.2 < |y| < 2.4)--a rapidity range coverage which not only brings significantly larger acceptance to PHENIX but which is critical for separating cold nuclear matter effects from QGP effects and is critical for measuring the proton spin contributions over a significant fraction of the kinematic range of interest. In addition, the FVTX will provide greatly reduced background and improved mass resolution for dimuon events, culminating in the first measurements of the {upsilon}{prime} and Drell-Yan at RHIC. These same heavy flavor and dimuon measurements in p+p collisions will allow us to place significant constraints on the gluon and sea quark contributions to the proton's spin and to make fundamentally new tests of the Sivers function universality.
VERTEX: Manganese transport with CaCO 3
Martin, John H.; Knauer, George A.
1983-04-01
Manganese transport was studied off central California in August and September 1981 as part of the VERTEX (Vertica l Transport and Exchange) research program. Refractory, leachable, and dissolved Mn fractions associated with particles caught in traps set at 11 depths (50 to 2000 m) were analyzed. Through intentional and unintentional CaCO 3 dissolution 'experiments', it was learned that the weakly leachable Mn was originally in association with the carbonate phase. Adsorption on surfaces rather than absorption in CaCO 3 matrices was indicated by the finding that Mn was not released in proportion to the CaCo 3 dissolved, instead it appeared to keep readsorbing to the dissolving surface. Ultimately, Mn went into solution when the particulate CaCO 3 was essentially depleted, suggesting that sufficient sites for adsorption were no longer available. Manganese fluxes with CaCO 3 were low near the surface (0.1 mg cm -2 ky -1), but increased rapidly in the 50 to 200-m depth interval, and then became more or less constant (1.3 mg cm -2 ky -1 for the remainder of the water column (300 to 2000 m). Rate-of-change estimates indicate that Mn is rapidly scavenged in near-surface waters (-130 ng 1 -1 y -1) and slowly regenerated at depth (2.7 ng 1 -1 y -1) in our near-shore study area. Residence times for dissolved Mn were estimated at 1.2 y for surface waters and 17 y at depth. The implications of Mn transport with CaCO 3 in relation to open-ocean sediment excess Mn are discussed.
A vertex model of Drosophila ventral furrow formation.
Directory of Open Access Journals (Sweden)
Philipp Spahn
Full Text Available Ventral furrow formation in Drosophila is an outstanding model system to study the mechanisms involved in large-scale tissue rearrangements. Ventral cells accumulate myosin at their apical sides and, while being tightly coupled to each other via apical adherens junctions, execute actomyosin contractions that lead to reduction of their apical cell surface. Thereby, a band of constricted cells along the ventral epithelium emerges which will form a tissue indentation along the ventral midline (the ventral furrow. Here we adopt a 2D vertex model to simulate ventral furrow formation in a surface view allowing easy comparison with confocal live-recordings. We show that in order to reproduce furrow morphology seen in vivo, a gradient of contractility must be assumed in the ventral epithelium which renders cells more contractile the closer they lie to the ventral midline. The model predicts previous experimental findings, such as the gain of eccentric morphology of constricting cells and an incremental fashion of apical cell area reduction. Analysis of the model suggests that this incremental area reduction is caused by the dynamical interplay of cell elasticity and stochastic contractility as well as by the opposing forces from contracting neighbour cells. We underpin results from the model through in vivo analysis of ventral furrow formation in wildtype and twi mutant embryos. Our results show that ventral furrow formation can be accomplished as a "tug-of-war" between stochastically contracting, mechanically coupled cells and may require less rigorous regulation than previously thought.For the developmental biologist it is a fascinating question how cells can coordinate major tissue movements during embryonic development. The so-called ventral furrow of the Drosophila embryo is a well-studied example of such a process when cells from a ventral band, spanning nearly the entire length of the embryo, undergo dramatic shape change by contracting their
Domain wall partition function of the eight-vertex model with a non-diagonal reflecting end
Yang, Wen-Li; Feng, Jun; Hao, Kun; Shi, Kang-Jie; Sun, Cheng-Yi; Yang, Zhan-Ying; Zhang, Yao-Zhong
2011-01-01
With the help of the Drinfeld twist or factorizing F-matrix for the eight-vertex SOS model, we obtain the explicit determinant expression of the partition function of the eight-vertex model with a generic non-diagonal reflecting end and domain wall boundary condition. Our result shows that, contrary to the eight-vertex model without a reflection end, the partition function can be expressed as a single determinant.
Higher order QCD corrections in exclusive charmless B decays
Energy Technology Data Exchange (ETDEWEB)
Bell, G.
2006-10-15
We discuss exclusive charmless B decays within the Standard Model of particle physics. These decays play a central role in the on-going process to constrain the parameters of the CKM matrix and to clarify the nature of CP violation. In order to exploit the rich source of data that is currently being collected at the experiments, a systematic theoretical treatment of the complicated hadronic dynamics is strongly desired. QCD Factorization represents a model-independent framework to compute hadronic matrix elements from first principles. It is based on a power expansion in {lambda}{sub QCD}/m{sub b} and allows for the systematic implementation of perturbative corrections. In particular, we consider hadronic two-body decays as B {yields} {pi}{pi} and perform a conceptual analysis of heavy-to-light form factors which encode the strong interaction effects in semi-leptonic decays as B {yields} {pi}l{nu}. Concerning the hadronic decays we compute NNLO QCD corrections which are particularly important with respect to strong interaction phases and hence direct CP asymmetries. On the technical level, we perform a 2-loop calculation which is based on an automatized reduction algorithm and apply sophisticated techniques for the calculation of loop-integrals. We indeed find that the considered quantities are well-defined as predicted by QCD Factorization, which is the result of a highly complicated subtraction procedure. We present results for the imaginary part of the topological tree amplitudes and observe that the considered corrections are substantial. The calculation of the real part of the amplitudes is far more complicated and we present a preliminary result which is based on certain simplifications. Our calculation is one part of the full NNLO analysis of nonleptonic B decays within QCD Factorization which is currently pursued by various groups. In our conceptual analysis of the QCD dynamics in heavy-to-light transitions we consider form factors between non
QCD radiative corrections for $h\\to b\\bar b$ in the Standard Model Dimension-6 EFT
Gauld, Rhorry; Scott, Darren J
2016-01-01
We calculate the $\\mathcal{O}(\\alpha_s)$ QCD corrections to the inclusive $h\\to b\\bar b$ decay rate in the dimension-6 Standard Model Effective Field Theory (SMEFT). The QCD corrections multiplying the dimension-6 Wilson coefficients which alter the $hb\\bar b$-vertex at tree-level are proportional to the Standard Model (SM) ones, so next-to-leading order results can be obtained through a simple rescaling of the tree-level decay rate. On the other hand, contributions from the operators $Q_{bG}$ and $Q_{HG}$, which alter the $gb\\bar b$-vertex and introduce a $hgg$-vertex respectively, enter at $\\mathcal{O}(\\alpha_s)$ and induce sizeable corrections which are unrelated to the SM ones and cannot be anticipated through a renormalisation-group analysis. We present compact analytic results for these contributions, which we recommend to be included in future phenomenological studies.
The eta'g sup * g sup ( sup * sup ) vertex including the eta'-meson mass
Ali, A
2003-01-01
The eta'g sup * g sup ( sup * sup ) effective vertex function is calculated in the QCD hard-scattering approach, taking into account the eta'-meson mass. We work in the approximation in which only one non-leading Gegenbauer moment for both the quark-antiquark and the gluonic light-cone distribution amplitudes for the eta'-meson is kept. The vertex function with one off-shell gluon is shown to have the form (valid for vertical stroke q sub 1 sup 2 vertical stroke >m subeta sub ' sup 2) F subeta sub ' sub g sub sup * sub g (q sub 1 sup 2 ,0,m subeta sub ' sup 2)=m subeta sub ' sup 2 H(q sub 1 sup 2)/(q sub 1 sup 2 -m subeta sub ' sup 2), where H(q sub 1 sup 2) is a slowly varying function, derived analytically in this paper. The resulting vertex function is in agreement with the phenomenologically inferred form of this vertex obtained from an analysis of the CLEO data on the eta'-meson energy spectrum in the decay UPSILON(1S)-> eta'X. We also present an interpolating formula for the vertex function F subeta sub...
The $\\eta^{'} g^{*} g^{(*)}$ Vertex Including the $\\eta^{'}$-Meson Mass
Ali, A
2003-01-01
The $eta^prime g^* g^{(*)}$ effective vertex function is calculated in the QCD hard-scattering approach, taking into account the $eta^prime$-meson mass. We work in the approximation in which only one non-leading Gegenbauer moment for both the quark-antiquark and the gluonic light-cone distribution amplitudes for the $eta^prime$-meson is kept. The vertex function with one off-shell gluon is shown to have the form (valid for $| q_1^2 | > m_{eta^prime}^2$) $F_{eta^prime g^* g} (q_1^2, 0, m_{eta^prime}^2) = m_{eta^prime}^2 H(q_1^2)/(q_1^2 - m_{eta^prime}^2)$, where $H(q_1^2)$ is a slowly varying function, derived analytically in this paper. The resulting vertex function is in agreement with the phenomenologically inferred form of this vertex obtained from an analysis of the CLEO data on the $eta^prime$-meson energy spectrum in the decay $Upsilon(1S) to eta^prime X$. We also present an interpolating formula for the vertex function $F_{eta^prime g^* g} (q_1^2, 0, m_{eta^prime}^2)$ for the space-like region of the v...
Vertex ﬁnding performance studies for the Phase II CMS Level-1 Trigger
Udrescu, Silviu Marian
2017-01-01
At the HL-LHC, a signiﬁcant increase in the luminosity delivered to CMS will result in a pileup per bunch crossing of 140-200. This provides a diﬃcult environment to obtain reliable physics results and keep trigger rates manageable. In order to mitigate this problem, tracker information will be used, for the ﬁrst time, at the Level-1 (L1) trigger. This will allow the primary vertex reconstruction at L1. In this report, an investigation into the vertex ﬁnding performance of a potential algorithm is presented. The vertex ﬁnding eﬃciency was measured as a function of several variables, such as the percentage of tracks associated to the primary vertex within the barrel and the pT of the tracks. The eﬃciency was found to not depend signiﬁcantly on the pileup for the samples analyzed, however, a strong dependence was observed on the number of tracks associated with the primary vertex.
Dominant mixed QCD-electroweak O(αsα corrections to Drell–Yan processes in the resonance region
Directory of Open Access Journals (Sweden)
Stefan Dittmaier
2016-03-01
Full Text Available A precise theoretical description of W- and Z-boson production in the resonance region is essential for the correct interpretation of high-precision measurements of the W-boson mass and the effective weak mixing angle. Currently, the largest unknown fixed-order contribution is given by the mixed QCD-electroweak corrections of O(αsα. We argue, using the framework of the pole expansion for the NNLO QCD-electroweak corrections established in a previous paper, that the numerically dominant corrections arise from the combination of large QCD corrections to the production with the large electroweak corrections to the decay of the W/Z boson. We calculate these so-called factorizable corrections of “initial–final” type and estimate the impact on the W-boson mass extraction. We compare our results to simpler approximate combinations of electroweak and QCD corrections in terms of naive products of NLO QCD and electroweak correction factors and using leading-logarithmic approximations for QED final-state radiation as provided by the structure-function approach or QED parton-shower programs. We also compute corrections of “final–final” type, which are given by finite counterterms to the leptonic vector-boson decays and are found to be numerically negligible.
Mass-corrections to double-Higgs production & TopoID
Grigo, Jonathan
2014-01-01
We consider power corrections due to a finite top quark mass M_t to the production of a Higgs boson pair within the Standard Model at next-to-leading order (NLO) in QCD. Previous calculations for this process and at this precision were done in the limit of an inifinitely heavy top quark. Our results for the inclusive production cross section at NLO include terms up to O(1/M_t^12). We present the Mathematica package TopoID which for arbitrary processes aims to perform the necessary steps from Feynman diagrams to unrenormalized results expressed in terms of master integrals. We employ it for advancing in this process towards next-to-next-to-leading order (NNLO) where further automatization is needed.
The quark-gluon vertex in Landau gauge bound-state studies
Williams, Richard
2014-01-01
We present a practical method for the solution of the quark-gluon vertex for use in Bethe--Salpeter and Dyson--Schwinger calculations. The efficient decomposition into the necessary covariants is detailed, with the numerical algorithm outlined for both real and complex Euclidean momenta. A model suitable for bound-state calculations is given together with results for the quark propagator and quark-gluon vertex for different quark flavours. The relative impact of the various components of the quark-gluon vertex is highlighted with the flavour dependence of the effective quark-gluon interaction obtained, thus providing insight for the construction of phenomenological models within Rainbow-Ladder. Finally, we solve the corresponding Green's functions for complex Euclidean momenta as required for practical calculations.
Modeling & Informatics at Vertex Pharmaceuticals Incorporated: our philosophy for sustained impact
McGaughey, Georgia; Patrick Walters, W.
2016-11-01
Molecular modelers and informaticians have the unique opportunity to integrate cross-functional data using a myriad of tools, methods and visuals to generate information. Using their drug discovery expertise, information is transformed to knowledge that impacts drug discovery. These insights are often times formulated locally and then applied more broadly, which influence the discovery of new medicines. This is particularly true in an organization where the members are exposed to projects throughout an organization, such as in the case of the global Modeling & Informatics group at Vertex Pharmaceuticals. From its inception, Vertex has been a leader in the development and use of computational methods for drug discovery. In this paper, we describe the Modeling & Informatics group at Vertex and the underlying philosophy, which has driven this team to sustain impact on the discovery of first-in-class transformative medicines.
A new efficient RLF-like algorithm for the vertex coloring problem
Directory of Open Access Journals (Sweden)
Adegbindin Mourchid
2016-01-01
Full Text Available The Recursive Largest First (RLF algorithm is one of the most popular greedy heuristics for the vertex coloring problem. It sequentially builds color classes on the basis of greedy choices. In particular, the first vertex placed in a color class C is one with a maximum number of uncolored neighbors, and the next vertices placed in C are chosen so that they have as many uncolored neighbors which cannot be placed in C. These greedy choices can have a significant impact on the performance of the algorithm, which explains why we propose alternative selection rules. Computational experiments on 63 difficult DIMACS instances show that the resulting new RLF-like algorithm, when compared with the standard RLF, allows to obtain a reduction of more than 50% of the gap between the number of colors used and the best known upper bound on the chromatic number. The new greedy algorithm even competes with basic metaheuristics for the vertex coloring problem.
Measurement of the Charm and Beauty Structure Functions using the H1 Vertex Detector at HERA
Aaron, FD; Alexa, C; Alimujiang, K; Andreev, V; Antunovic, B; Asmone, A; Backovic, S; Baghdasaryan, A; Barrelet, E; Bartel, W; Begzsuren, K; Belousov, A; Bizot, J C; Boudry, V; Bozovic-Jelisavcic, I; Bracinik, J; Brandt, G; Brinkmann, M; Brisson, V; Bruncko, D; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Cantun Avila, K B; Cassol-Brunner, F; Cerny, K; Cerny, V; Chekelian, V; Cholewa, A; Contreras, J G; Coughlan, J A; Cozzika, G; Cvach, J; Dainton, J B; Daum, K; Deak, M; de Boer, Y; Delcourt, B; Del Degan, M; Delvax, J; De Wolf, E A; Diaconu, C; Dodonov, V; Dossanov, A; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eliseev, A; Elsen, E; Falkiewicz, A; Favart, L; Fedotov, A; Felst, R; Feltesse, J; Ferencei, J; Fischer, D -J; Fleischer, M; Fomenko, A; Gabathuler, E; Gayler, J; Ghazaryan, Samvel; Glazov, A; Glushkov, I; Goerlich, L; Gogitidze, N; Gouzevitch, M; Grab, C; Greenshaw, T; Grell, B R; Grindhammer, G; Habib, S; Haidt, D; Helebrant, C; Henderson, R C W; Hennekemper, E; Henschel, H; Herbst, M; Herrera, G; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R; Hreus, T; Jacquet, M; Janssen, M E; Janssen, X; Jonsson, L; Jung, Andreas Werner; Jung, H; Kapichine, M; Katzy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Kluge, T; Knutsson, A; Kogler, R; Kostka, P; Kraemer, M; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Kruger, K; Kutak, K; Landon, M P J; Lange, W; Lastovicka-Medin, G; Laycock, P; Lebedev, A; Leibenguth, G; Lendermann, V; Levonian, S; Li, G; Lipka, K; Liptaj, A; List, B; List, J; Loktionova, N; Lopez-Fernandez, R; Lubimov, V; Lytkin, L; Makankine, A; Malinovski, E; Marage, P; Marti, Ll; Martyn, H -U; Maxfield, S J; Mehta, A; Meyer, A B; Meyer, H; Meyer, H; Meyer, J; Michels, V; Mikocki, S; Milcewicz-Mika, I; Moreau, F; Morozov, A; Morris, J V; Mozer, Matthias Ulrich; Mudrinic, M; Muller, K; Murin, P; Naumann, Th; Newman, P R; Niebuhr, C; Nikiforov, A; Nowak, G; Nowak, K; Nozicka, M; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Palichik, V; Panagoulias, I; Pandurovic, M; Papadopoulou, Th; Pascaud, C; Patel, G D; Pejchal, O; Perez, E; Petrukhin, A; Picuric, I; Piec, S; Pitzl, D; Placakyte, R; Pokorny, B; Polifka, R; Povh, B; Preda, T; Radescu, V; Rahmat, A J; Raicevic, N; Raspiareza, A; Ravdandorj, T; Reimer, P; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rotaru, M; Ruiz Tabasco, J E; Rurikova, Z; Rusakov, S; Salek, D; Sankey, D P C; Sauter, M; Sauvan, E; Schmitt, S; Schoeffel, L; Schoning, A; Schultz-Coulon, H -C; Sefkow, F; Shaw-West, R N; Shtarkov, L N; Shushkevich, S; Sloan, T; Smiljanic, Ivan; Soloviev, Y; Sopicki, P; South, D; Spaskov, V; Specka, Arnd E; Staykova, Z; Steder, M; Stella, B; Stoicea, G; Straumann, U; Sunar, D; Sykora, T; Tchoulakov, V; Thompson, G; Thompson, P D; Toll, T; Tomasz, F; Tran, T H; Traynor, D; Trinh, T N; Truol, P; Tsakov, I; Tseepeldorj, B; Turnau, J; Urban, K; Valkarova, A; Vallee, C; Van Mechelen, P; Vargas Trevino, A; Vazdik, Y; Vinokurova, S; Volchinski, V; von den Driesch, M; Wegener, D; Wissing, Ch; Wunsch, E; Zacek, J; Zalesak, J; Zhang, Z; Zhokin, A; Zimmermann, T; Zohrabyan, H; Zomer, F; Zus, R
2010-01-01
Inclusive charm and beauty cross sections are measured in e-p and e+p neutral current collisions at HERA in the kinematic region of photon virtuality 5vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions.
ATLAS strategy for primary vertex reconstruction during Run-2 of the LHC
Borissov, Guennadi; The ATLAS collaboration; Grimm, Kathryn; Pagan Griso, Simone; Pedersen, Lars Egholm; Prokofiev, Kirill; Rudolph, Matthew Scott; Wharton, Andrew Mark
2015-01-01
The reconstruction of vertices corresponding to proton--proton collisions in ATLAS is an essential element of event reconstruction used in many performance studies and physics analyses. During Run-1 of the LHC, ATLAS has employed an iterative approach to vertex finding. In order to improve the flexibility of the algorithm and ensure continued performance for very high numbers of simultaneous collisions in Run-2 of the LHC and beyond, a new approach to seeding vertex finding has been developed inspired by image reconstruction techniques. This note provides a brief outline of how reconstructed tracks are used to create an image of likely vertex collisions in an event, describes the implementation in the ATLAS software, and presents some preliminary results of the performance of the algorithm in simulation approximating early Run-2 conditions.
Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA
Energy Technology Data Exchange (ETDEWEB)
Aaron, F.D.; Alexa, C.; Preda, T.; Rotaru, M.; Stoicea, G.; Zus, R. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Aldaya Martin, M.; Alimujiang, K.; Antunovic, B.; Bartel, W.; Brandt, G.; Campbell, A.J.; Cholewa, A.; Deak, M.; Boer, Y. de; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Glazov, A.; Gouzevitch, M.; Grell, B.R.; Haidt, D.; Helebrant, C.; Janssen, M.E.; Jung, H.; Katzy, J.; Kleinwort, C.; Knutsson, A.; Kraemer, M.; Krastev, K.; Kutak, K.; Levonian, S.; Lipka, K.; List, J.; Marti, L.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Niebuhr, C.; Nikiforov, A.; Nozicka, M.; Olsson, J.E.; Panagoulias, I.; Papadopoulou, T.; Pitzl, D.; Placakyte, R.; Radescu, V.; Rurikova, Z.; Schmitt, S.; Schoeffel, L.; Sefkow, F.; Staykova, Z.; Steder, M.; Vargas Trevino, A.; Vinokurova, S.; Driesch, M. von den; Wissing, C.; Wuensch, E. [DESY, Hamburg (Germany); Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Loktionova, N.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Asmone, A.; Stella, B. [Dipt. di Fisica Universita di Roma Tre (Italy); INFN Roma 3, Rome (Italy); Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N. [Univ. of Montenegro, Faculty of Science, Podgorica (ME); Baghdasaryan, A.; Ghazaryan, S.; Volchinski, V.; Zohrabyan, H. [Yerevan Physics Inst., Yerevan (Armenia); Barrelet, E. [CNRS/IN2P3, LPNHE, Universites Paris VI et VII, Paris (France); Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B. [Inst. of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Li, G.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F. [CNRS/IN2P3, LAL, Univ. Paris-Sud, Orsay (France); Boudry, V.; Moreau, F.; Specka, A. [CNRS/IN2P3, LLR, Ecole Polytechnique, Palaiseau (France)] [and others
2010-01-15
Inclusive charm and beauty cross sections are measured in e{sup -}p and e{sup +} p neutral current collisions at HERA in the kinematic region of photon virtuality 5{<=}Q {sup 2}{<=}2000 GeV{sup 2} and Bjorken scaling variable 0.0002{<=}x{<=}0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions. (orig.)
Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA
Energy Technology Data Exchange (ETDEWEB)
Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Aldaya Martin, M. [DESY, Hamburg (Germany); Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (RO)] (and others)
2009-06-15
Inclusive charm and beauty cross sections are measured in e{sup -}p and e{sup +}p neutral current collisions at HERA in the kinematic region of photon virtuality 5{<=}Q{sup 2}{<=}2000 GeV{sup 2} and Bjorken scaling variable 0.0002{<=}x{<=}0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb{sup -1}. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions. (orig.)
Exploring complex networks by means of two-variable time series of vertex observables
Oświȩcimka, Paweł; Drożdż, Stanisław
2016-01-01
We investigate the scaling of the cross-correlations calculated for two-variable time series containing vertex properties in the context of complex networks. Time series of such observables are obtained by means of stationary, unbiased random walks. We consider three vertex properties that provide, respectively, short, medium, and long-range information regarding the topological role of a vertex in a given network. We present and discuss results obtained on some well-known network models, as well as on real data representing protein contact networks. Our results suggest that the proposed analysis framework provides useful insights on the structural organization of complex networks. For instance, the analysis of protein contact networks reveals characteristics shared with both scale-free and small-world models.
The neural network Z vertex trigger for the Belle II detector
Energy Technology Data Exchange (ETDEWEB)
Skambraks, Sebastian; Abudinen, Fernando [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6 80805 Muenchen (Germany)
2013-07-01
A novel approach for track triggering is currently studied for the Belle II detector: neural networks are used to predict the event vertex in z direction, using only information from the central drift chamber. The lack in accuracy of classical online vertex reconstruction motivates new studies for the z vertex trigger. Since neural networks are general function approximators, they are well suited for problems where the model is not known a priori. Several methods were investigated, but our studies for single tracks in geometrically restricted areas of the detector have proven the multi layer perceptron to produce the most accurate results, even in the presence of background. This encourages the use of a set of multi layer perceptrons to cover the entire detector. Additionally, the methods presented may lead to online event reconstruction, for Belle II as well as for other running or future detectors.
Modeling & Informatics at Vertex Pharmaceuticals Incorporated: our philosophy for sustained impact
McGaughey, Georgia; Patrick Walters, W.
2017-03-01
Molecular modelers and informaticians have the unique opportunity to integrate cross-functional data using a myriad of tools, methods and visuals to generate information. Using their drug discovery expertise, information is transformed to knowledge that impacts drug discovery. These insights are often times formulated locally and then applied more broadly, which influence the discovery of new medicines. This is particularly true in an organization where the members are exposed to projects throughout an organization, such as in the case of the global Modeling & Informatics group at Vertex Pharmaceuticals. From its inception, Vertex has been a leader in the development and use of computational methods for drug discovery. In this paper, we describe the Modeling & Informatics group at Vertex and the underlying philosophy, which has driven this team to sustain impact on the discovery of first-in-class transformative medicines.
Performance of the ATLAS track and vertex reconstruction in the LHC Run 2
Oide, Hideyuki; The ATLAS collaboration
2016-01-01
Run-2 of the LHC has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity environments and boosted, highly-collimated physics objects. The Insertable B-layer (IBL) is a fourth pixel layer, which was inserted in the innermost region of ATLAS during the long shutdown of the LHC. We will present results showing the performance of the track and vertex reconstruction algorithms using Run-2 data at the LHC and discuss some of the challenges encountered during commissioning. Recent improvements include a factor of three reduction in the reconstruction time, optimisation for the expected conditions, novel techniques to enhance the performance in dense jet cores and time-dependent alignment of sub-detectors. Moreover, data-driven methods to evaluate vertex resolution, fake rates, track reconstruction inefficiencies in dense environments, and track parameter resolution and biases will be shown.
Status of vertex and tracking detector R&D at CLIC
AUTHOR|(SzGeCERN)754272
2015-01-01
The physics aims at the future CLIC high-energy linear e+e- collider set very high precision requirements on the performance of the vertex and tracking detectors. Moreover, these detectors have to be well adapted to the experimental conditions, such as the bunch train structure of the beam and the presence of beam-induced backgrounds. The principal challenges are: a point resolution of a few micron, ultra-low mass (~0.2% X0 per layer for the inner vertex region), very low power dissipation (compatible with air-flow cooling in the inner vertex region) and pulsed power operation, complemented with ~10 ns time stamping capabilities. An overview of the R&D program for pixel and tracking detectors at CLIC will be presented, including recent results on an innovative hybridisation concept based on capacitive coupling between active sensors (HV-CMOS) and readout ASICs (CLICpix).
Constraint Minimum Vertex Cover in K-Partite Graph: Approximation Algorithm and Complexity Analysis
Directory of Open Access Journals (Sweden)
Kamanashis Biswas
2009-08-01
Full Text Available Generally, a graph G, an independent set is a subset S of vertices in G such that no two vertices in S are adjacent (connected by an edge and a vertex cover is a subset S of vertices such that each edge of G has at least one of its endpoints in S. Again, the minimum vertex cover problem is to find a vertex cover with the smallest number of vertices. Consider a k-partite graph G = (V, E with vertex k-partition V = P1 ∪ P2 . . . ∪ Pk and the k integers are kp1, kp2, . . . , kpk. And, we want to find out whether there is a minimum vertex cover in G with at most kp1 vertices in P1 and kp2 vertices in P2 and so on or not. This study shows that the constrained minimum vertex cover problem in k-partite graph (MIN-CVCK is NP-Complete which is an important property of k-partite graph. Many combinatorial problems on general graphs are NP-complete, but when restricted to k-partite graph with at most k vertices then many of these problems can be solved in polynomial time. This paper also illustrates an approximation algorithm for MIN-CVCK and analyzes its complexity. In future work section, we specified a number of dimensions which may be interesting for the researchers such as developing algorithm for maximum matching and polynomial algorithm for constructing k-partite graph from general graph.
Exchange Relations for the q-Vertex Operators of $U_q(\\widehat{sl2})$
Awata, H
1993-01-01
We consider the q-deformed Knizhnik-Zamolodchikov equation for the two point function of q-deformed vertex operators of $U_q(sl_2^)$. We give explicitly the fundamental solutions, the connection matrices and the exchange relations for the q-vertex operators of spin 1/2 and $j \\in {1\\over 2}{\\bf Z}_{\\geq 0}$. Consequently, we confirm that the connection matrices are equivalent to the elliptic Boltzman weights of IRF type obtained by the fusion procedure from ABF models.
Algebraic arctic curves in the domain-wall six-vertex model
Colomo, F
2010-01-01
The arctic curve, i.e. the spatial curve separating ordered (or `frozen') and disordered (or `temperate) regions, of the six-vertex model with domain wall boundary conditions is discussed for the root-of-unity vertex weights. In these cases the curve is described by algebraic equations which can be worked out explicitly from the parametric solution for this curve. Some interesting examples are discussed in detail. The upper bound on the maximal degree of the equation in a generic root-of-unity case is obtained.
Charged free fermions, vertex operators and the classical theory of conjugate nets
Energy Technology Data Exchange (ETDEWEB)
Doliwa, Adam [Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Rome (Italy); Instytut Fizyki Teoretycznej, Uniwersytet Warszawski, Warsaw (Poland); Manas, Manuel [Departamento de Matematica Aplicada y Estadistica, EUIT Aeronautica, Universidad Politecnica de Madrid, Madrid (Spain); Departamento de Fisica Teorica, Universidad Complutense, Madrid (Spain); Martinez Alonso, Luis; Medina, Elena [Departamento de Matematicas, Universidad de Cadiz, Cadiz (Spain); Santini, Paolo Maria [Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Rome (Italy); Dipartimento di Fisica, Universita di Catania, Catania (Italy)
1999-02-19
We show that the quantum field theoretical formulation of the {tau}-function theory has a geometrical interpretation within the classical transformation theory of conjugate nets. In particular, we prove that (i) the partial charge transformations preserving the neutral sector are Laplace transformations, (ii) the basic vertex operators are Levy and adjoint Levy transformations and (iii) the diagonal soliton vertex operators generate fundamental transformations. We also show that the bilinear identity for the multicomponent Kadomtsev-Petviashvili hierarchy becomes, through a generalized Miwa map, a bilinear identity for the multidimensional quadrilateral lattice equations. (author)
Donaldson-Thomas invariants of local elliptic surfaces via the topological vertex
Bryan, Jim
2016-01-01
We compute the Donaldson-Thomas invariants of a local elliptic surface with section. We introduce a new computational technique which is a mixture of motivic and toric methods. This allows us to write the partition function for the invariants in terms of the topological vertex. Utilizing identities for the topological vertex proved in arXiv:1603.05271, we derive product formulas for the partition functions. The connected version of the partition function is written in terms of Jacobi forms. In the special case where the elliptic surface is a K3 surface, we get a new derivation of the Katz-Klemm-Vafa formula.
Building a non-perturbative quark-gluon vertex from a perturbative one
Bermudez, Rocio
2016-10-01
The quark-gluon vertex describes the electromagnetic and the strong interaction among these particles. The description of this interaction at high precision in both regimes, perturbative and non-perturbative, continues being a matter of interest in the context of QCD and Hadron Physics. There exist very helpful models in the literature that explain perturbative aspects of the theory but they fail describing non-perturbative phenomena, as confinement and dynamic chiral symmetry breaking. In this work we study the structure of the quark-gluon vertex in a non-perturbative regime examining QCD, checking results with QED, and working in the Schwinger-Dyson formalism.
Spontaneous Polarization of Kondo problem associated with Higher-spin analog of the 6-vertex model
Fukushima, N
1999-01-01
We study Kondo-type model associated with an integrable Higher-spin analog of the 6-vertex mode, which is constructed by inserting a spin 1/2 to spin 1 lines: $... C^3 \\otimes C^3 \\otimes C^2 \\otimes C^3 \\otimes C^3 ... .$ We formulate the problem in terms of representation theory of quantum affine algebra $U_q(\\hat{sl_2})$. We derive an exact formula of the spontaneous staggered polarization for our model, which corresponds to Baxter's formula for the 6-vertex model.
Imaging the LHC beams with silicon and scintillating fibre vertex detectors
Rihl, M.
2017-02-01
The LHCb Vertex Locator (VELO) is used to reconstruct beam-gas interaction vertices which allows one to obtain precise profiles of the LHC beams. In LHCb, this information is combined with the profile of the reconstructed beam-beam collisions and with the LHC beam currents to perform precise measurements of the luminosity. This beam-gas imaging (BGI) method also allows one to study the transverse beam shapes, beam positions and angles in real time. Therefore, a demonstrator beam-gas vertex detector (BGV) based on scintillating fibre modules has been built and installed in LHC Ring 2 at point 4.
Imaging the LHC beams with silicon and scintillating fibre vertex detectors
Rihl, M
2016-01-01
The LHCb Vertex Locator (VELO) is used to reconstruct beam–gas interaction vertices which allows one to obtain precise profiles of the LHC beams. In LHCb, this information is combined with the profile of the reconstructed beam–beam collisions and with the LHC beam currents to perform precise measurements of the luminosity. This beam–gas imaging (BGI) method also allows one to study the transverse beam shapes, beam positions and angles in real time. Therefore, a demonstrator beam–gas vertex detector (BGV) based on scintillating fibre modules has been built and installed in LHC Ring 2 at point 4.
Vertex and Propagator in $\\Phi^{4}$ Theory from 4PI Effective Action in Two Dimensions
Carrington, M E
2012-01-01
A set of self-consistent nonlinear integral equations for the four-point vertex and the propagator are derived from the 4-loop 4PI effective action for scalar field theories. This set of integral equations are solved in two dimensions through numerical lattice calculations. We compare the calculated results with those of perturbation theories. We find that the 4PI calculations are well consistent with the perturbation ones in perturbative regions. Non-perturbative results are also obtained in the 4PI formalism when the interacting strength becomes large. Furthermore, the full-momentum dependence of the four-point vertex is easily obtained in the 4PI effective action theories.
Nonperturbative calculation of Green and vertex functions in terms of particle contours
Stefanis, N G
1996-01-01
The infrared regime of fermionic Green and vertex functions is studied analytically within a geometric approach which simulates soft interactions by an {\\it effective} theory of contours. Expanding the particle path integral in terms of dominant contours at large distances, all-order results in the coupling constant are obtained for the renormalized fermion propagator and a universal vertex function with physical characteristics close to those associated with the Isgur-Wise function in the weak decays of heavy mesons. The extension to the ultraviolet regime is scetched.
The Color Antisymmetric Ghost Propagator and One-Loop Vertex Renormalization
Furui, Sadataka
2007-01-01
The color matrix elements of the ghost triangle diagram that appears in the triple gluon vertex and the ghost-ghost-gluon triangle diagram that appears in the ghost-gluon-ghost vertex are calculated. The ghost-ghost-gluon triangle contains a loop consisting of two color diagonal ghosts and one gluon and a loop consisting of two color antisymmetric ghosts and one gluon. Consequently, the pQCD argument in the infrared region based on the one particle irreducible diagram should be modified. Impl...
Consequences Of Fully Dressing Quark-Gluon Vertex Function With Two-Point Gluon Lines
Matevosyan, Hrayr H; Tandy, Peter C
2007-01-01
We extend recent studies of the effects of quark-gluon vertex dressing upon the solutions of the Dyson-Schwinger equation for the quark propagator. A momentum delta function is used to represent the dominant infrared strength of the effective gluon propagator so that the resulting integral equations become algebraic. The quark-gluon vertex is constructed from the complete set of diagrams involving only 2-point gluon lines. The additional diagrams, including those with crossed gluon lines, are shown to make an important contribution to the DSE solutions for the quark propagator, because of their large color factors and the rapid growth in their number.
The SuperB Silicon Vertex Tracker and 3D vertical integration
Re, Valerio
2011-01-01
The construction of the SuperB high luminosity collider was approved and funded by the Italian government in 2011. The performance specifications set by the target luminosity of this machine (> 10^36 cm^-2 s^-1) ask for the development of a Silicon Vertex Tracker with high resolution, high tolerance to radiation and excellent capability of handling high data rates. This paper reviews the R&D activity that is being carried out for the SuperB SVT. Special emphasis is given to the option of exploiting 3D vertical integration to build advanced pixel sensors and readout electronics that are able to comply with SuperB vertexing requirements.
Imaging the LHC beams with silicon and scintillating fibre vertex detectors
Rihl, M
2016-01-01
The LHCb Vertex Locator (VELO) is used to reconstruct beam–gas interaction vertices which allows one to obtain precise profiles of the LHC beams. In LHCb, this information is combined with the profile of the reconstructed beam–beam collisions and with the LHC beam currents to perform precise measurements of the luminosity. This beam–gas imaging (BGI) method also allows one to study the transverse beam shapes, beam positions and angles in real time. Therefore, a demonstrator beam–gas vertex detector (BGV) based on scintillating fibre modules has been built and installed in LHC Ring 2 at point 4.
Ishimoto, Yukitaka
2014-01-01
In order to describe two-dimensionally packed cells in epithelial tissues both mathematically and physically, there have been developed several sorts of geometrical models, such as the vertex model, the finite element model, the cell-centered model, the cellular Potts model. So far, in any case, pressures have not neatly been dealt with and curvatures of the cell boundaries have been even omitted through their approximations. We focus on these quantities and formulate them on the vertex model. Thus, a model with the curvatures is constructed and its algorithm is given for simulation. Its possible extensions and applications will also be discussed.
APFEL: A PDF Evolution Library with QED corrections
Bertone, Valerio; Rojo, Juan
2014-01-01
Quantum electrodynamics and electroweak corrections are important ingredients for many theoretical predictions at the LHC. This paper documents APFEL, a new PDF evolution package that allows for the first time to perform DGLAP evolution up to NNLO in QCD and to LO in QED, in the variable-flavor-number scheme and with either pole or MSbar heavy quark masses. APFEL consistently accounts for the QED corrections to the evolution of quark and gluon PDFs and for the contribution from the photon PDF in the proton. The coupled QCD+QED equations are solved in x-space by means of higher order interpolation, followed by Runge-Kutta solution of the resulting discretized evolution equations. APFEL is based on an innovative and flexible methodology for the sequential solution of the QCD and QED evolution equations and their combination. In addition to PDF evolution, APFEL provides a module that computes Deep-Inelastic Scattering structure functions in the FONLL general-mass variable-flavor-number scheme up to O($\\alpha_s^2...
Factorization and N3LLp+NNLO predictions for the Higgs cross section with a jet veto
Becher, Thomas; Neubert, Matthias; Rothen, Lorena
2013-10-01
We have recently derived a factorization formula for the Higgs-boson production cross section in the presence of a jet veto, which allows for a systematic resummation of large Sudakov logarithms of the form , along with the large virtual corrections known to affect also the total cross section. Here we determine the ingredients entering this formula at two-loop accuracy. Specifically, we compute the dependence on the jet-radius parameter R, which is encoded in the two-loop coefficient of the collinear anomaly, by means of a direct, fully analytic calculation in the framework of soft-collinear effective theory. We confirm the result obtained by Banfi et al. from a related calculation in QCD, and demonstrate that factorization-breaking, soft-collinear mixing effects do not arise at leading power in , even for . In addition, we extract the two-loop collinear beam functions numerically. We present detailed numerical predictions for the jet-veto cross section with partial next-to-next-to-next-to-leading logarithmic accuracy, matched to the next-to-next-to-leading order cross section in fixed-order perturbation theory. The only missing ingredients at this level of accuracy are the three-loop anomaly coefficient and the four-loop cusp anomalous dimension, whose numerical effects we estimate to be small.
Factorization and N^3LL_p+NNLO Predictions for the Higgs Cross Section with a Jet Veto
Becher, Thomas; Rothen, Lorena
2013-01-01
We have recently derived a factorization formula for the Higgs-boson production cross section in the presence of a jet veto, which allows for a systematic resummation of large Sudakov logarithms of the form alpha_s^n ln^m(p_T^veto/m_H), along with the large virtual corrections known to affect also the total cross section. Here we determine the ingredients entering this formula at two-loop accuracy. Specifically, we compute the dependence on the jet-radius parameter R, which is encoded in the two-loop coefficient of the collinear anomaly, by means of a direct, fully analytic calculation in the framework of soft-collinear effective theory. We confirm the result obtained by Banfi et al. from a related calculation in QCD, and demonstrate that factorization-breaking, soft-collinear mixing effects do not arise at leading power in p_T^veto/m_H, even for R=O(1). In addition, we extract the two-loop collinear beam functions numerically. We present detailed numerical predictions for the jet-veto cross section with next...
Hatami, H.; Magen, A.; Markakis, V.; Charikar, M.; Jansen, K.; Reingold, O.; Rolim, J.
2006-01-01
We study various SDP formulations for {\\sc Vertex Cover} by adding different constraints to the standard formulation. We show that {\\sc Vertex Cover} cannot be approximated better than $2-o(1)$ even when we add the so called pentagonal inequality constraints to the standard SDP formulation, en route
Anisovich, A V; Sarantsev, A V
2016-01-01
Vertex operators for photo- and electro-production of baryon states with arbitrary spin-parity, $ \\gamma + N\\to B(J^P)$, are constructed. The operators obey gauge invariance and analyticity constraints. Analyticity is realized as a requirement of the generalized Siegert theorem for vertex form factors.
Radiative corrections to the magnetic moments of the proton and the neutron
Kaiser, N
2016-01-01
We estimate the radiative corrections of order $\\alpha/\\pi$ to the magnetic moments of the proton and the neutron. The photon-loop diagram of the vertex-correction type is evaluated with phenomenological nucleon vector form factors. Infrared-finiteness and gauge-invariance require the inclusion of the wave-function renormalization factor from the self-energy diagram. Using recent empirical form factor parametrizations the corrections amount to $\\delta\\kappa_p= -3.42 \\cdot 10^{-3}$ and $\\delta\\kappa_n= 1.34 \\cdot 10^{-3}$. We study also the effects from photon-loops with internal $\\Delta(1232)$-isobars. For two customary versions of the $\\Delta N\\gamma $-vertex and spin-3/2 propagator, these radiative corrections have values of $\\delta\\kappa_p^{(\\Delta)}= (-0.9,\\, 0.0)\\!\\cdot\\! 10^{-3}$ and $\\delta\\kappa_n^{(\\Delta)} = (1.2,\\,-0.8)\\!\\cdot\\! 10^{-3}$, respectively.
On the exact open-closed vertex in plane-wave light-cone string field theory
Lucietti, J; Sinha, A K; Lucietti, James; Schafer-Nameki, Sakura; Sinha, Aninda
2003-01-01
The open-closed vertex in the maximally supersymmetric type IIB plane-wave light-cone string field theory is considered and an explicit solution for the bosonic part of the vertex is derived, valid for all values of the mass parameter, \\mu. This vertex is of relevance to IIB plane-wave orientifolds, as well as IIB plane-wave strings in the presence of D-branes, and their gauge theory duals. Methods of complex analysis are used to develop a systematic procedure for obtaining the solution. This procedure is first applied to the vertex in flat space, and then extended to the plane-wave case. The plane-wave solution for the vertex requires introducing certain ``\\mu-deformed Gamma functions'', which are generalizations of the ordinary Gamma function. The behaviour of the Neumann matrices is graphically illustrated and their large-\\mu asymptotics are analysed.