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A proof of factorization for deep inelastic neutrino scattering

JOURNAL OF PHYSICS COMMUNICATIONS 2020年第2期4卷

作者： Ling, R. Shanghai Dianji Univ Dept Phys Shanghai 201306 Peoples R China

It is proven in this paper that the structure functions for the hadron quantity describing deep inelastic neutrino scattering factor into the product of a short-distance coefficient function, the non-perturbative parton distribution function which encompasses the underlying structure of the target, and the function for soft radiation which does not emerge in the case of electron scattering for which weak radiative corrections are usually practically ignored. This is shown to all orders of perturbative quantum chromodynamics and electroweak theory, and to leading order in the power expansion of the effective field theory used as a tool. It is based on the observation that there is no necessity to go into the partonic level of the physical process, for a generalized version of the operator product expansion affords a framework for the study of inclusive processes, where the momentum carried in by one current operator and out by the other is allowed to go to infinity. It is discovered following this line of argument that the objects entering the factorization theorem need not be SU(2) x U(1) gauge singlets, whether or not we perform the factorization in the symmetric phase. The factorization analysis provides initial conditions for evolution to arbitrary energies that allows for re-summation of large logarithms for loop calculations to the extent of accuracy requested.

关键词： effective field theory operator product expansion parton distribution functions soft radiation

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Cross section predictions of the Z boson in association with jets at 14 TeV center-of-mass energy in proton-proton collisions

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TURKISH JOURNAL OF PHYSICS 2018年第5期42卷 495-500页

作者： Dilsiz, Kamuran Tiras, Emrah Bingol Univ Fac Art & Sci Dept Phys Bingol Turkey Univ Iowa Dept Phys & Astron Fac Sci Iowa City IA 52242 USA Iowa State Univ Fac Sci Dept Phys & Astron Ames IA USA

QCD predictions of the Z (Z -> l(+)l(-)) boson in association with jets (up to 2 jets) in proton-proton collisions are presented in this study. The results are predicted at LO and NLO accuracy using two most recent parton distribution functions, CT14 and MMHT2014. LO and NLO corrections are obtained with LO, NLO, and NNLO PDFs to find out the best PDF, which provides well compatible predictions with the experimental measurements. QCD predictions are performed at 13 and 14 TeV center-of-mass energies. To verify the obtained results, the predictions are compared with the measured results by ATLAS collaboration. NLO QCD predictions obtained by using NLO and NNLO PDFs show good agreement with the experimental data. The comparison of NLO predictions at 13 and 14 TeV center-of-mass energies shows that the Large Hadron Collider will provide approximately 9% more yield at 14 TeV center-of-mass energy than the yield at 13 TeV center-of-mass energy for the Z boson in association with 1 and 2 jets.

关键词： QCD predictions cross section of Z boson Large Hadron Collider parton distribution functions jets

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A study of the role of the PDF uncertainty on the LHC W-boson mass measurement

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JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS 2019年第9期46卷 095002-095002页

作者： Hussein, Moh'd Isaacso, Joshua Huston, Joey Univ Jordan Dept Phys Amman 11942 Jordan Fermilab Natl Accelerator Lab Theoret Phys Dept Batavia IL 60510 USA Michigan State Univ Dept Phys & Astron E Lansing MI 48824 USA

The determination of the W-boson mass through an analysis of the decay charged-lepton transverse momentum distribution has a sizable uncertainty due to the imperfect knowledge of the relevant parton distribution functions (PDFs). In this paper, a quantitative assessment of the W-boson mass uncertainty at the LHC resulting from the PDF uncertainty is examined. We use the CT14 NNLO PDFs with a NNLL + NNLO calculation (ResBos) to simulate the W-boson production and decay kinematics. The uncertainty of the W-boson mass determination is then determined as a function of the boson and lepton kinematics. For W+ production using P-T(W) < 15 GeV and 35 < P-T(l) (GeV) < 45, PDF uncertainties lead (at the 68% CL) to a mass uncertainty for the M(W)(+)of (+16.0-17.5) MeV, (+13.9-14.8) MeV, and (+12.2-19.2) MeV, are determined at 7 TeV, 8 TeV and 13 TeV, respectively. The uncertainties of M-(W) over bar for the same cuts are found to be +15.9-15.6 MeV,(+15.0)(-12.7) MeV and (+14.8-15.3) MeV, at 7 TeV, 8 TeV and 13 TeV, respectively.

关键词： W-boson mass standard model parton distribution functions LHC

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Meson cloud effects on kaon quark distribution functions and the SU(3) flavor symmetry

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Nuclear and Particle Physics Proceedings 2018年 300-302卷 121-125页

作者： Watanabe, Akira Sawada, Takahiro Kao, Chung Wen Institute of High Energy Physics Theoretical Physics Center for Science Facilities Chinese Academy of Sciences Beijing 100049 China University of Chinese Academy of Sciences Beijing 100049 China Department of Physics Osaka City University Osaka 558-8585 Japan Department of Physics Center for High Energy Physics Chung-Yuan Christian University Chung-Li 32023 Taiwan

We present our analysis on the valence quark distribution functions of the K+ meson, νK(u)(x,Q2) and νK(s‾)(x,Q2), taking into account the meson cloud effects in the framework of the chiral constituent quark model.... 详细信息

We present our analysis on the valence quark distribution functions of the K⁺ meson, ν^K(u)(x,Q²) and ν^K(s‾)(x,Q²), taking into account the meson cloud effects in the framework of the chiral constituent quark model. Assuming appropriate bare quark distribution functions at the initial scale, evaluating the Goldstone boson dressing corrections with the model, and performing the QCD evolution, one can obtain the realistic dressed distributions at a certain scale. The phenomenologically satisfactory valence quark distribution of the pion was obtained in the previous study and there are available experimental data of the valence u quark distribution ratio ν^K(u)(x,Q²)/ν^π(u)(x,Q²), which enable us to obtain the kaon quark distribution functions. Besides presenting the resulting dressed distributions, we also show how the meson cloud effects affect the bare distributions in detail. A striking result is that the observed size of the SU(3) flavor symmetry breaking is considerably smaller than those seen in the preceding works based on other approaches. © 2018 Elsevier B.V.

关键词： Chiral constituent quark model Goldstone bosons Meson structure parton distribution functions

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parton distribution functions and nuclear EMC effect in a statistical model

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Chinese Physics C 2010年第9期34卷 1417-1420页

作者：邵立晶张运华马伯强 School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University

A new and simple statistical approach is performed to calculate the parton distribution functions （PDFs） of the nucleon in terms of light-front kinematic *** expressions of x-dependent PDFs are obtained in the whole x *** thereafter,we treat the temperature T as a parameter of the atomic number A to explain the nuclear EMC effect in the region x ∈ [0.2,0.7].We give the predictions of PDF ratios,and they are very different from those by other models,thus experiments aiming at measuring PDF ratios are suggested to provide a discrimination of different models.

关键词： statistical model parton distribution functions EMC effect

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New approach in the quantum statistical parton distribution

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PHYSICS LETTERS B 2017年 775卷 172-177页

作者： Sohaily, Sozha Vaziri (Khamed), Mohammad Shahid Bahonar Univ Kerman Fac Phys Kerman Iran Islamic Azad Univ Kerman Branch Dept Phys Kerman Iran

An attempt to find simple parton distribution functions (PDFs) based on quantum statistical approach is presented. The PDFs described by the statistical model have very interesting physical properties which help to understand the structure of partons. The longitudinal portion of distribution functions are given by applying the maximum entropy principle. An interesting and simple approach to determine the statistical variables exactly without fitting and fixing parameters is surveyed. Analytic expressions of the x-dependent PDFs are obtained in the whole x region [0, 1], and the computed distributions are consistent with the experimental observations. The agreement with experimental data, gives a robust confirm of our simple presented statistical model. (C) 2017 The Authors. Published by Elsevier B.V.

关键词： Quantum statistical model parton distribution functions Nucleon structure Entropy

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Trace of nonperturbative charm content of the nucleon on Z plus c-jet production

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INTERNATIONAL JOURNAL OF MODERN PHYSICS A 2017年第16期32卷

作者： Rostami, S. Khorramian, A. Semnan Univ Fac Phys POB 35195-363 Semnan Iran

We perform a comparison of the impact of different intrinsic charm (IC) models, based on the prediction of the differential cross-sections of Z-boson and c-jet production in pp collision. It is shown that regardless of choosing the model, considering nonperturbative intrinsic charm component increases the magnitude of the cross-section when the Z transverse momentum grows or at large rapidity (y) of the Z. Moreover, to evaluate the effect of different parton distribution functions (PDFs), we also compare the results of two PDF sets in prediction of production Z + c-jet in pp at a center-of-mass energy of 13 TeV with taking into account the intrinsic charm contribution in the proton. It is shown that the various PDF sets give some difference in the description of the Z + c-jet cross-section.

关键词： parton distribution functions heavy quark PDFs intrinsic charm LHC

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APFELgrid: A high performance tool for parton density determinations

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COMPUTER PHYSICS COMMUNICATIONS 2017年 212卷 205-209页

作者： Bertone, Valerio Carrazza, Stefano Hartland, Nathan P. Univ Oxford Rudolf Peierls Ctr Theoret Phys 1 Keble Rd Oxford OX1 3NP England CERN Dept Theoret Phys Geneva Switzerland

We present a new software package designed to reduce the computational burden of hadron collider measurements in parton distribution Function (PDF) fits. The APFELgrid package converts interpolated weight tables provided by APPLgrid files into a more efficient format for PDF fitting by the combination with PDF and as evolution factors provided by APFEL. This combination significantly reduces the number of operations required to perform the calculation of hadronic observables in PDF fits and simplifies the structure of the calculation into a readily optimised scalar product. We demonstrate that our technique can lead to a substantial speed improvement when compared to existing methods without any reduction in numerical accuracy. Program Summary Program Title: APFELgrid Program Files doi: http://***/10.17632/mhwjt5nsg7.1 Licensing provisions: MIT license Programming language: C++ Nature of problem: Fast computation of hadronic observables under the variation of parton distribution functions. Solution method: Combination of interpolated weight grids from APPLgrid files and evolution factors from APFEL into efficient FastKernel tables. External routines/libraries: APPLgrid, APFEL (C) 2016 Elsevier B.V. All rights reserved.

关键词： QCD parton distribution functions Fast predictions

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Unraveling high-energy hadronstructures with lattice QCD

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INTERNATIONAL JOURNAL OF MODERN PHYSICS A 2018年第36期33卷

作者： Zhao, Yong MIT Ctr Theoret Phys 77 Massachusetts Ave Cambridge MA 02139 USA

parton distribution functions are key quantities for us to understand the hadronic structures in high-energy scattering, but they are difficult to calculate from lattice QCD. Recent years have seen fast development of the large-momentum effective theory which allows extraction of the x-dependence of parton distribution functions from a quasi-parton distribution function that can be directly calculated on lattice. The extraction is based on a factorization formula for the quasi-parton distribution function that has been derived rigorously in perturbation theory. A systematic procedure that includes renormalization, perturbative matching, and power corrections has been established to calculate parton distribution functions. Latest progress from lattice QCD has shown promising signs that it will become an effective tool for calculating parton physics.

关键词： parton distribution functions lattice QCD large-momentum effective theory

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Analytical solutions of the QCD⊗QED DGLAP evolution equations based on the Mellin transform technique in NLO approximation

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PHYSICS LETTERS B 2017年 773卷 375-384页

作者： Mottaghizadeh, Marzieh Shahri, Fatemeh Taghavi Eslami, Parvin Ferdowsi Univ Mashhad Dept Phys Mashhad Iran

In this paper we present a new and efficient analytical solutions for evolving the QCD circle times QED DGLAP evolution equations in Mellin space and obtain the parton distribution functions (PDFs) in perturbative QCD including the QED corrections. The validity of our analytical solutions, which have done in the next to leading order QCD and the leading order QED approximations, are checked with the initial parton distributions from newly released CT14QED global analysis code (Schmidt et al., 2016 [9]). The evolved parton distribution functions are in good agreement with CT14QED PDFs set and also with those from APFEL (Bertone et al., 2014 [ 7]) program. Finally, we derived the impact of the NLO QED corrections to the QCD circle times QED DGLAP evolution equations. (C) 2017 The Authors. Published by Elsevier B.V.

关键词： QCD circle times QED DGLAP evolution equations Mellin moment parton distribution functions

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