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ρ meson form factors and parton distribution functions in impact parameter space

CHINESE PHYSICS C 2025年第4期49卷 043104-043104页

作者： Zhang, Jin-Li Nanjing Inst Technol Dept Math & Phys Nanjing 211167 Peoples R China

This study investigates the form factors and impact parameter space parton distribution functions of the rho meson derived from the generalized parton distributions within the Nambu-Jona-Lasinio model framework, employing a proper time regularization scheme. We compare the charge , magnetic , and quadrupole form factors with lattice data. The dressed form factors, and , exhibit good agreement with lattice results;however, is found to be harder than what is observed in lattice calculations. The Rosenbluth cross section for elastic electron scattering on a spin-one particle can be expressed through the structure functions and . Additionally, the tensor polarization can also be formulated in terms of these form factors. We analyze the structure functions , and tensor polarization function;our findings quantitatively align with predicted values across various limits. In impact parameter space, we examine parton distribution functions along with their dependence on longitudinal momentum fraction x and impact parameter . The width distributions in impact parameter space reveal that the range of the charge distribution is the most extensive. In contrast, the transverse magnetic radius falls within a moderate range, while the quadrupole distribution demonstrates the narrowest extent.

关键词： generalized parton distributions form factors parton distribution functions impact parameter space

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The nuclear matter effect on parton distribution functions

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NUCLEAR PHYSICS A 2025年 1060卷

作者： Yang, Weihua Li, Chao Yantai Univ Dept Nucl Phys Yantai 264005 Shandong Peoples R China Nanyang Inst Technol Sch Math & Phys Nanyang 473000 Peoples R China

parton distribution functions (PDFs) are important quantities in describing nucleon structures. They are universal and process-independent. As a matter of fact, nucleon PDFs are inevitably affected by nuclear matter during nuclear scattering process. In order to study the nuclear PDFs (nPDFs), in this paper, we introduce the nucleon pair PDFs (dPDFs) to describe parton distributions in the nucleon pair which is confined to a nucleus. We first of all construct the nuclear state in terms of the nucleonic states and calculate the operator definition of nPDFs. Neglecting the higher order corrections or multi-nucleon correlations, we find that nPDFs can be written as a sum of two terms which respectively correspond to PDFs and dPDFs. Nucleon pair PDFs which stem from nucleon-nucleon correlation are proportional to common nucleon PDFs but suppressed by a factor. Compared with the experimental data, we find that dPDFs can explain the behaviour of the EMC effect. We further calculate the Paschos-Wolfenstein ratio to study the nuclear matter effect on the extraction of weak mixing angle or sin2 theta W by using dPDFs.

关键词： Nuclear matter effect parton distribution functions

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p meson form factors and parton distribution functions in impact parameter space

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Chinese Physics C 2025年第4期49卷 46-56页

作者： Jin-Li Zhang Department of Mathematics and Physics Nanjing Institute of TechnologyNanjing 211167China

This study investigates the form factors and impact parameter space parton distribution functions of the p meson derived from the generalized parton distributions within the Nambu-Jona-Lasinio model framework,employing a proper time regularization *** compare the charge G_(C),magnetic G_(M),and quadrupole G_(Q) form factors with latice *** dressed form factors,G_(C)^(D) and G_(M)^(D),exhibit good agreement with latice results;however,G_(Q)^(D) is found to be harder than what is observed in latice *** Rosenbluth cross section for elastic electron scattering on a spin-one particle can be expressed through the structure functions A(Q^(2))and B(Q^(2)).Additionally,the tensor polarization T_(20)(Q^(2),θ)can also be formulated in terms of these form *** analyze the structure functions A(Q2),B(Q2)and tensor polarization function T2o(Q2,);our findings quantitatively align with predicted values across various *** impact parameter space,we examine parton distribution functions along with their dependence on longitudinal momentum fraction x and impact parameter b+.The width distributions in impact parameter space reveal that the range of the charge distribution q_(C)(x,b_(⊥)^(2))is the most *** contrast,the transverse magnetic radius falls within a moderate range,while the quadrupole distribution q_(Q)(x,b_(⊥)^(2))demonstrates the narrowest extent.

关键词： generalized parton distributions form factors parton distribution functions impact parameter space

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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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Uncertainty of parton distribution functions due to physical observables in a global analysis

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Chinese Physics C 2017年第2期41卷 41-49页

作者： Alireza Aleedaneshvar Muhammad Goharipour Saeedeh Rostami Physics Department 35131-19111 Semnan University Semnan Iran

The recent measurement of the differential γ ＋ c-jet cross section, performed at the Tevatron collider in Run II by the D0 collaboration, is studied in a next-to-leading order（NLO） global QCD analysis to assess its impact on the proton parton distribution functions（PDFs）. We show that these data lead to a significant change in the gluon and charm quark distributions. We demonstrate also that there is an inconsistency between the new high precision HERA I＋II combined data and Tevatron measurement. Moreover, in this study we investigate the impact of older EMC measurements of charm structure function F_c^2 on the PDFs and compare the results with those from the analysis of Tevatron data. We show that both of them have the same impact on the PDFs, and thus can be recognized as the same evidence for the inefficiency of perturbative QCD in dealing with charm production in some kinematic regions.

关键词： parton distribution functions heavy quark PDFs photon production Tevatron

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ManeParse: A Mathematica reader for parton distribution functions

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COMPUTER PHYSICS COMMUNICATIONS 2017年 216卷 126-137页

作者： Clark, D. B. Godat, E. Olness, F. I. Southern Methodist Univ Dept Phys Dallas TX 75275 USA

parton distribution functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken-x and energy scale Q. The LHAPDF project maintains a repository of PDFs from various groups in a new standardized LHAPDF6 format, additionally older formats such as the CTEQ PDS grid format are still in use. ManeParse is a package that provides access to PDFs within Mathematica to facilitate calculation and plotting. The program is self-contained so there are no external links to any FORTRAN, C or C++ programs. The package includes the option to use the built-in Mathematica interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x-values). ManeParse is fast enough to enable simple calculations (involving even one or two integrations) in the Mathematica framework. Program summary Program Title: ManeParse Program Files doi: http://***10.17632/knbsccggg4.1 Licensing provisions: MIT Programming language: Mathematica Nature of problem: PDFs are currently read and interpolated via a FORTRAN or C++ interface. No method exist to read the LHAPDF6 or CTEQ PDFs directly in Mathematica. Solution method: A Mathematica package reads in LHAPDF6 and CTEQ PDF files. The PDFs are parsed into a three-dimensional array in Bjorken-x, scattering energy Q, and parton flavor, and are stored in memory. Provided functions give access to the PDF, the PDF uncertainty, the PDF correlations, and the parton-parton Luminosities. The LHAPDF6 info files are converted from YAML format into Mathematica rules. (C) 2017 Elsevier B.V. All rights reserved.

关键词： QCD Mathematica parton distribution functions PDF PDFs Hadron collider PDF errors Hadronic cross section

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The impact of the LHCb B^± production cross-section on parton distribution functions and determining the mass of heavy quarks

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NUCLEAR PHYSICS A 2018年 979卷 215-236页

作者： Aleedaneshvar, A. Khorramian, A. Semnan Univ Fac Phys POB 35131-19111 Semnan Iran

In this work, the impact of recent measurements of heavy-flavour production in pp collisions on parton distribution functions (PDFs) and their uncertainties is studied. In this regard, the absolute and normalised cross sections of beauty hadron production measured by LHCb at center-of-mass energy of 7 TeV and 13 TeV are separately included in the next-to-leading order (NLO) global QCD analysis together with the measurements of the inclusive and heavy-flavour production cross sections at HERA. It is illustrated that the heavy-flavour data of the LHCb experiment impose additional constraints on the PDFs, especially on the gluon distribution at low partonic fractions x of the proton momentum. One of the most important results of the present analysis is the significant reduction of the gluon uncertainties in the region less than x = 10(-4) that can play a crucial rule in many areas of high energy physics investigations. (C) 2018 Elsevier B.V. All rights reserved.

关键词： parton distribution functions Heavy quark pp collision LHCb

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A MODEL CONSTRUCTION OF SELF-SIMILARITY BASED DOUBLE parton distribution functions FOR PROTON-PROTON COLLISION AT LHC

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INTERNATIONAL JOURNAL OF MODERN PHYSICS A 2013年第17期28卷 13500796-1-13500796-13页

作者： Choudhury, D. K. Jahan, Akbari Gauhati Univ Dept Phys Gauhati 781014 Assam India

We construct a model for double parton distribution functions (dPDFs) based on the notion of self-similarity, pursued earlier for small x physics at HERA. The most general form of dPDFs contains total 13 parameters to be fitted from data of proton-proton collision at LHC. It is shown that the constructed dPDF does not factorize into two single PDFs in conformity with QCD expectation, and it satisfies the condition that at the kinematic boundary x(1) + x(2) = 1 (where x(1) and x(2) are the longitudinal fractional momenta of two partons), the dPDF vanishes.

关键词： Self-similarity parton distribution functions small x

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Statistical effect in the parton distribution functions of the nucleon

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PHYSICS LETTERS B 2009年第1期671卷 30-35页

作者： Zhang, Yunhua Shao, Lijing Ma, Bo-Qiang Peking Univ Sch Phys Beijing 100871 Peoples R China Peking Univ State Key Lab Nucl Phys & Technol Beijing 100871 Peoples R China

A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the x-dependent PDFs are obtained in the whole x region [0, 1], and some features, especially the low-x rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Statistical model parton distribution functions Nucleon structure Light-front formalism

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Quark shapes of most modern parton distribution functions

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TURKISH JOURNAL OF PHYSICS 2017年第6期41卷 545-550页

作者： Ogul, Hasan Sinop Univ Dept Nucl Engn Fac Engn & Architecture Sinop Turkey

parton distribution functions (PDFs) describe the internal structure of the proton and are necessary inputs to almost all theory predictions of hadron colliders. One way to do a precise measurement of a PDF is to measure the lepton charge asymmetry of W boson where u (d) over bar -> W+ and d (u) over bar -> W-. Therefore, u, d, (u) over bar, and (d) over bar quark shapes of the most modern PDF models (NNPDF3.1, NNPDF3.0, CT14, MMHT2014, and HERAPDF2.0) are inspected using the APFEL online cluster in this paper. The ratio of d to u is further investigated since the charge asymmetry is sensitive to the value of d over u momentum distributions in the proton. Q scale dependence of PDFs are further studied in a range from 1 to 100 GeV.

关键词： High energy physics parton distribution functions NNPDF3.1 quarks

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