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Quark counting, Drell-Yan West, and the pion wave function

Physical Review C 2024年第4期110卷 L042201页

作者： Mary Alberg Gerald A. Miller Department of Physics

The relation between the pion's quark distribution function, q(x), its light-front wave function, and the elastic charge form factor, F(Δ2), is explored. The square of the leading-twist pion wave function at a special probe scale, ζH, is determined using models and Poincaré covariance from realistic results for q(x). This wave function is then used to compute form factors with the result that the Drell-Yan-West and quark counting relationships are not satisfied. A new relationship between q(x) and F(Δ2) is proposed.

关键词： parton distribution functions QCD phenomenology Pions Form factors

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Hadronic structure on the light front. VIII. Light scalar and vector mesons

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Physical Review D 2024年第7期109卷 074029-074029页

作者： Wei-Yang Liu Edward Shuryak Ismail Zahed Center for Nuclear Theory Department of Physics and Astronomy Stony Brook University Stony Brook 11794-3800 NY United States

We use the QCD instanton vacuum model to discuss the emergence of the light scalar and vector mesons on the light front. We take into account both the instanton and anti-instanton single and molecular interactions on the light quarks, in the form of nonlocal effective interactions. Although the molecular induced interactions are suppressed by a power of the packing fraction, they are still sufficient to bind the vector mesons, while keeping most of the scalar spectrum relatively unchanged. We explicitly derive the light front distribution amplitudes and partonic functions for the scalar and vector mesons, and compare them after pertinent QCD evolution, to the available empirical and lattice measured counterparts. The Dirac electric form factors for both the pion and ρ meson are derived, and shown to compare well with current data.

关键词： Instantons Large-N expansion in field theory parton distribution functions QCD phenomenology Quantum chromodynamics Strong interaction Light mesons Vector mesons Form factors

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Complete next-to-leading order calculation of single inclusive π0 production in forward proton-nucleus collisions

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Physical Review D 2024年第3期109卷 034018-034018页

作者： Heikki Mäntysaari Yossathorn Tawabutr Department of Physics University of Jyväskylä P.O. Box 35 40014 University of Jyväskylä Finland and Helsinki Institute of Physics P.O. Box 64 00014 University of Helsinki Finland

We present the first fully consistent calculation of inclusive π0 production at forward rapidities at next-to-leading order (NLO) accuracy in proton-lead collisions at s=8.16 TeV within the color glass condensate approach. The center-of-mass energy dependence is determined by the Balitsky-Kovchegov equation with the initial condition constrained at NLO accuracy by the proton structure function measurements. We find that the LHCb data further constrain this nonperturbative input, and that both the NLO corrections to the evolution equation and to the impact factor have significant effects on the nuclear modification factor RpPb. The complete NLO calculation is shown to be in qualitative agreement with the LHCb data, and the predictions are found to be sensitive to the details of the applied deep inelastic scattering (DIS) fit. These results demonstrate the need to perform global analyses of DIS and LHC data in order to probe gluon saturation phenomena at precision level at very small momentum fraction x.

关键词： Fragmentation functions Particle interactions Particle production parton distribution functions Perturbative QCD QCD phenomenology Quantum chromodynamics

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Transverse momentum moments

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Physical Review D 2024年第1期110卷 016003-016003页

作者： Oscar del Rio Alexei Prokudin Ignazio Scimemi Alexey Vladimirov Departamento de Física Teórica & IPARCOS Division of Science Newport News Virginia 23606 USA

We establish robust relations between Transverse Momentum Dependent distributions (TMDs) and collinear distributions. We define weighted integrals of TMDs that we call Transverse Momentum Moments (TMMs) and prove that TMMs are equal to collinear distributions evaluated in some minimal subtraction scheme. The conversion to the modified minimal subtraction (MS¯) scheme can be done by a calculable factor, which we derive up to three loops for some cases. We discuss in detail the zeroth, the first, and the second TMMs and provide phenomenological results for them based on the current extractions of TMDs. The results of this paper open new avenues for theoretical and phenomenological investigation of the three-dimensional and collinear hadron structures.

关键词： parton distribution functions Transverse momentum dependent distribution

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Unraveling subleading twist GTMDs of proton using light-front quark-diquark model

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Physical Review D 2024年第7期110卷 074025页

作者： Shubham Sharma Sameer Jain Harleen Dahiya Department of Physics Dr. B. R. Ambedkar National Institute of Technology Jalandhar 144008 India

This study investigates the subleading twist generalized transverse momentum dependent distributions (GTMDs) of a proton within the light-front quark-diquark model framework. We solve the parametrization equations for the Dirac matrix structure, yielding explicit GTMD expressions for both scalar and vector diquark configurations, leading to expressions for active u and d quarks. This analysis addresses the multidimensional nature of GTMDs by exploring their dependencies on one or two variables while keeping others fixed. Additionally, we extract transverse momentum dependent form factors from GTMDs by integrating over the longitudinal momentum fraction x. The study uses three-dimensional plots to illustrate the variation of transverse momentum dependent form factors with the quark’s transverse momentum p⊥ and the transverse momentum transfer to the proton Δ⊥.

关键词： Generalized parton distributions parton distribution functions Protons

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Analytic Derivation of the Longitudinal Proton Structure Function F_L(x, Q²) and the Reduced Cross Section σ_r(x, Q²) at the Leading Order and the Next-to-leading Order Approximations

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INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS 2021年第10期60卷 3822-3849页

作者： Zarrin, S. Dadfar, S. Univ Sistan & Baluchestan Dept Phys Zahedan Iran

We present a set of formulas to extract the longitudinal proton structure function F-L(x, Q(2)) and the reduced cross section sigma(r)(x, Q(2)) by using Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations and Altarelli-Martinelli equation at the leading order (LO) and the next-to-leading order (NLO) approximations in perturbative quantum chromodynamics (QCD). These formulas are obtained by the Laplace transform method at the virtualities higher than Q(0)(2). We show that, the obtained equations for F-L and sigma(r) depend only on the parton distribution functions (PDF's) at the initial scale Q(0)(2). We obtain the corresponding numerical results in a range of the virtuality Q(0)(2) <= Q(2) <= 800 GeV2 and Bjorken scale 10(-4) <= x <= 1 and compare them with the results achieved by MSTW2008 (Martin et al. Eur. Phys. J 63(2), 189-285, 2009), WT (White and Thorne Phy. Rev. D 75(3), 034005, 2007) and Dipole (b-Sat) model (H. Kowalski, L. Motyka, G. Watt, Phys. Rev. D 74(7), 074016, 2006) predictions and also with data released by the Hadron Electron Ring Accelerator (HERA). Our numerical results show an acceptable agreement with the deep inelastic scattering (DIS) experimental data throughout over a wide range of the Bjorken scale x and the virtuality Q(2), and then can be applied in analyses of the Large Hadron Collider and Future Circular Collider projects.

关键词： Longitudinal Proton Structure function parton distribution functions

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Bottomonium suppression in 5.02 and 8.16 TeV p-Pb collisions

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Physical Review D 2024年第9期109卷 096016-096016页

作者： Michael Strickland Sabin Thapa Ramona Vogt Nuclear and Chemical Sciences Division Lawrence Livermore National Laboratory Livermore California 94551 USA and Physics and Astronomy Department University of California at Davis Davis California 95616 USA

We compute the suppression of ϒ(1S), ϒ(2S), and ϒ(3S) states in p-Pb collisions relative to pp collisions, including nuclear parton distribution function (nPDF) effects, coherent energy loss, momentum broadening, and final-state interactions in the quark-gluon plasma. We employ the EPPS21 nPDFs and calculate the uncertainty resulting from variation over the associated error sets. To compute coherent energy loss and momentum broadening, we follow the approach of Arleo, Peigne, and collaborators. The 3+1D viscous hydrodynamical background evolution of the quark-gluon plasma is generated by anisotropic hydrodynamics. The in-medium suppression of bottomonium in the quark-gluon plasma is computed using a next-to-leading-order open quantum system framework formulated within potential nonrelativistic quantum chromodynamics. We find that inclusion of all these effects provides a reasonable description of experimental data from the ALICE, ATLAS, CMS, and LHCb Collaborations for the suppression of ϒ(1S), ϒ(2S), and ϒ(3S) as a function of both transverse momentum and rapidity.

关键词： Open quantum systems parton distribution functions Quark-gluon plasma Quarkonia Relativistic hydrodynamics

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Using analytic models to describe effective PDFs

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Physical Review D 2024年第3期110卷 036019页

作者： S. A. Ochoa-Oregon D. F. Rentería-Estrada R. J. Hernández-Pinto G. F. R. Sborlini P. Zurita Facultad de Ciencias Físico-Matemáticas Universitat de València—Consejo Superior de Investigaciones Científicas Parc Científic 46980 Paterna Valencia Spain Departamento de Física Fundamental e IUFFyM Institut für Theoretische Physik Departamento de Física Teórica & IPARCOS

parton distribution functions play a pivotal role in hadron collider phenomenology. They are nonperturbative quantities extracted from fits to available data, and their scale dependence is dictated by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. In this article, we discuss machine-assisted strategies to efficiently compute parton distribution functions (PDFs) explicitly incorporating the scale dependence. Analytical approximations to the PDFs as functions of x and Q2, including up to next-to-leading-order effects in quantum chromodynamics, are obtained. The methodology is tested by reproducing the herapdf2.0 set and implementing the analytical expressions in benchmarking codes. It is found that the computational time cost of evaluating the distributions is reduced by ∼50%, while the precision of the simulations stays well under control.

关键词： parton distribution functions Perturbative QCD QCD phenomenology Quantum chromodynamics Machine learning

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Heavy flavor-asymmetric pseudoscalar mesons on the light front

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Physical Review D 2024年第9期110卷 094010页

作者： Chao Shi Pengfei Liu Yi-Lun Du Wenbao Jia Department of Nuclear Science and Technology Jinan 250100 China

We extract the leading Fock-state light front wave functions of heavy flavor-asymmetric pseudoscalar mesons D, B, and Bc from their Bethe-Salpeter wave functions, based on the Dyson-Schwinger equations approach. We then study their leading-twist parton distribution amplitudes, generalized parton distribution functions, and transverse momentum-dependent parton distributions. The spatial distributions of the quark and antiquark on the transverse plane are presented, along with their charge and energy distributions on the light front. We find that in the considered mesons, the heavier quarks carry most of the longitudinal momentum fraction, resulting in narrow x distributions, while the lighter quarks play an active role in shaping the transverse distributions in both spatial and momentum space, exhibiting a duality that embodies characteristics of both light mesons and heavy quarkonium.

关键词： Bethe-Salpeter equation Few-body systems Nonperturbative effects in field theory parton distribution functions Schwinger-Dyson equations

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Impact of recent MINERvA measurement of the antineutrino-proton scattering cross section on the generalized parton distributions

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Physical Review D 2023年第7期108卷 074018-074018页

作者： Fatemeh Irani Muhammad Goharipour Hadi Hashamipour K. Azizi Department of Physics University of Tehran North Karegar Avenue Tehran 14395-547 Iran School of Particles and Accelerators Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395-5531 Tehran Iran Department of Physics Doǧuş University Dudullu-Ümraniye 34775 Istanbul Turkey

We investigate the impact of the new measurement of the antineutrino-proton scattering cross section from the MINERvA Collaboration on generalized parton distributions (GPDs), particularly the polarized GPDs denoted as H˜q. To achieve this, we perform some QCD analyses of the MINERvA data, in addition to all available data of the proton’s axial form factors. We demonstrate that MINERvA data lead to consistent results with other related experimental data, confirming the universality of GPDs. Our results indicate that MINERvA data can impose new constraints on GPDs, particularly on H˜q. Our predictions for the proton’s axial charge radius, WACS cross section, and axial form factor show good consistency with those of other studies and measurements. This leads us to conclude that the result of a more comprehensive analysis, considering all related experimental data, is not only reasonable but also more reliable, even in light of existing tensions among the data. The present study can be considered as a guideline for performing a new and comprehensive QCD global analysis of GPDs including the MINERvA measurements like that presented in Hashamipour et al. [Generalized parton distributions at zero skewness, Phys. Rev. D 107, 096005 (2023).].

关键词： Form factors Generalized parton distributions Particle interactions parton distribution functions Quantum chromodynamics

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