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Full-Text Articles in Physics
The Present And Future Of Qcd, P. Achenbach, D. Adhikari, A. Afanasev, F. Afzal, C. A. Aidala, A. Al-Bataineh, D. K. Almaalol, M. Amaryan, D. Androić, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, E. C. Aschenauer, H. Atac, H. Avakian, T. Averett, C. Ayerbe Gayoso, X. Bai, M. Zurek, Et. Al.
The Present And Future Of Qcd, P. Achenbach, D. Adhikari, A. Afanasev, F. Afzal, C. A. Aidala, A. Al-Bataineh, D. K. Almaalol, M. Amaryan, D. Androić, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, E. C. Aschenauer, H. Atac, H. Avakian, T. Averett, C. Ayerbe Gayoso, X. Bai, M. Zurek, Et. Al.
Physics Faculty Publications
This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming …
Detailed Study Of Quark-Hadron Duality In Spin Structure Functions Of The Proton And Neutron, V. Lagerquist, S. E. Kuhn, N. Sato
Detailed Study Of Quark-Hadron Duality In Spin Structure Functions Of The Proton And Neutron, V. Lagerquist, S. E. Kuhn, N. Sato
Physics Faculty Publications
Background: The response of hadrons, the bound states of the strong force (QCD), to external probes can be described in two different, complementary frameworks: as direct interactions with their fundamental constituents, quarks and gluons, or alternatively as elastic or inelastic coherent scattering that leaves the hadrons in their ground state or in one of their excited (resonance) states. The former picture emerges most clearly in hard processes with high momentum transfer, where the hadron response can be described by the perturbative expansion of QCD, while at lower energy and momentum transfers, the resonant excitations of the hadrons dominate the cross …
Searching For An Enhanced Signal Of The Onset Of Color Transparency In Baryons With D(E,E′P)N Scattering, Shujie Li, Carlos Yero, Jennifer Rittenhouse West, Clare Bennett, Wim Cosyn, Douglas Higinbotham, Misak Sargsian, Holly Szumila-Vance
Searching For An Enhanced Signal Of The Onset Of Color Transparency In Baryons With D(E,E′P)N Scattering, Shujie Li, Carlos Yero, Jennifer Rittenhouse West, Clare Bennett, Wim Cosyn, Douglas Higinbotham, Misak Sargsian, Holly Szumila-Vance
Physics Faculty Publications
Observation of the onset of color transparency in baryons would provide a new means of studying the nuclear strong force and would be the first clear evidence of baryons transforming into a color-neutral point-like size in the nucleus as predicted by quantum chromodynamics. Recent C (e, e′p) results from electron-scattering did not observe the onset of color transparency (CT) in protons up to spacelike four-momentum transfers squared, Q2 = 14.2 GeV 2 . The traditional methods of searching for CT in (e, e′p) scattering use heavy targets favoring kinematics with already initially reduced final state interactions (FSIs) such that …
Neural-Network Analysis Of Parton Distribution Functions From Ioffe-Time Pseudodistributions, Luigi Del Debbio, Tommaso Giani, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos
Neural-Network Analysis Of Parton Distribution Functions From Ioffe-Time Pseudodistributions, Luigi Del Debbio, Tommaso Giani, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos
Physics Faculty Publications
We extract two nonsinglet nucleon Parton Distribution Functions from lattice QCD data for reduced Ioffe-time pseudodistributions. We perform such analysis within the NNPDF framework, considering data coming from different lattice ensembles and discussing in detail the treatment of the different source of systematics involved in the fit. We introduce a recipe for taking care of systematics and use it to perform our extraction of light-cone PDFs.
Complete Matching For Quasidistribution Functions In Large Momentum Effective Theory, Wei Wang, Jian-Hui Zhang, Shuai Zhao, Ruilin Zhu
Complete Matching For Quasidistribution Functions In Large Momentum Effective Theory, Wei Wang, Jian-Hui Zhang, Shuai Zhao, Ruilin Zhu
Physics Faculty Publications
We complete the procedure of extracting parton distribution functions (PDFs) using large momentum effective theory at leading power accuracy in the hadron momentum. We derive a general factorization formula for the quasi-PDFs in the presence of mixing and give the corresponding hard matching kernel at O(αs), both for the unpolarized and for the polarized quark and gluon quasi-PDFs. Our calculation is performed in a regularization-independent momentum subtraction scheme. The results allow us to match the nonperturbatively renormalized quasi-PDFs to normal PDFs in the presence of mixing and therefore can be used to extract flavor-singlet quark PDFs as well …
Challenges With Large Transverse Momentum In Semi-Inclusive Deeply Inelastic Scattering, J. O. Gonzalez-Hernandez, T. C. Rogers, N. Sato, B. Wang
Challenges With Large Transverse Momentum In Semi-Inclusive Deeply Inelastic Scattering, J. O. Gonzalez-Hernandez, T. C. Rogers, N. Sato, B. Wang
Physics Faculty Publications
We survey the current phenomenological status of semi-inclusive deeply inelastic scattering at moderate hard scales and in the limit of very large transverse momentum. As the transverse momentum becomes comparable to or larger than the overall hard scale, the differential cross sections should be calculable with fixed order perturbative QCD (pQCD) methods, while small transverse momentum (transverse-momentum-dependent factorization) approximations should eventually break down. We find large disagreement between HERMES and COMPASS data and fixed order calculations done with modern parton densities, even in regions of kinematics where such calculations should be expected to be very accurate. Possible interpretations are suggested.
One-Loop Evolution Of Parton Pseudo-Distribution Functions On The Lattice, Anatoly Radyushkin
One-Loop Evolution Of Parton Pseudo-Distribution Functions On The Lattice, Anatoly Radyushkin
Physics Faculty Publications
We incorporate recent calculations of one-loop corrections for the reduced Ioffe-time pseudo-distribution m(v, z(3)(2) thorn to extend the leading-logarithm analysis of lattice data obtained by Orginos et al. We observe that the one-loop corrections contain a large term reflecting the fact that effective distances involved in the most important diagrams are much smaller than the nominal distance z(3). The large correction in this case may be absorbed into the evolution term, and the perturbative expansion used for extraction of parton densities at the μ ≈ 2 GeV scale is under control. The extracted parton distribution is rather close to global …
Ψ(2s) Versus J/Ψ Suppression In Proton-Nucleus Collisions From Factorization Violating Soft Color, Yan-Qing Ma, Raju Venugopalan, Kazuhiro Watanabe, Hong-Fei Zhang
Ψ(2s) Versus J/Ψ Suppression In Proton-Nucleus Collisions From Factorization Violating Soft Color, Yan-Qing Ma, Raju Venugopalan, Kazuhiro Watanabe, Hong-Fei Zhang
Physics Faculty Publications
We argue that the large suppression of the ψ(2S) inclusive cross section relative to the J/ψ inclusive cross section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the color glass condensate (CGC) effective field theory and employ an improved color evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The …
Kinematics Of Current Region Fragmentation In Semi-Inclusive Deeply Inelastic Scattering, M. Boglione, J. Collins, L. Gamberg, José O. Gonzalez-Hernandez, Ted C. Rogers, N. Sato
Kinematics Of Current Region Fragmentation In Semi-Inclusive Deeply Inelastic Scattering, M. Boglione, J. Collins, L. Gamberg, José O. Gonzalez-Hernandez, Ted C. Rogers, N. Sato
Physics Faculty Publications
Different kinematical regions of semi-inclusive deeply inelastic scattering (SIDIS) processes correspond to different underlying partonic pictures, and it is important to understand the transition between them. We find criteria in semi-inclusive deeply inelastic scattering (SIDIS) for identifying the current fragmentation region-the kinematical region where a factorization picture with fragmentation functions is appropriate, especially for studies of transverse-momentum-dependent (TMD) functions. This region is distinguished from the central (soft) and target fragmentation regions. The basis of our argument is in the errors in approximations used in deriving factorization. As compared with previous work, we show that it is essential to take account …
Gluon Tmd In Particle Production From Low To Moderate X, I. Balitsky, A. Tarasov
Gluon Tmd In Particle Production From Low To Moderate X, I. Balitsky, A. Tarasov
Physics Faculty Publications
We study the rapidity evolution of gluon transverse momentum dependent distributions appearing in processes of particle production and show how this evolution changes from small to moderate Bjorken x.
E00-110 Experiment At Jefferson Lab Hall A: Deeply Virtual Compton Scattering Off The Proton At 6 Gev, M. Defurne, M. Amaryan, K. A. Aniol, M. Beaumel, H. Benaoum, P. Bertin, C. E. Hyde, P.E. Ulmer, Jefferson Lab Hall A Collaboration
E00-110 Experiment At Jefferson Lab Hall A: Deeply Virtual Compton Scattering Off The Proton At 6 Gev, M. Defurne, M. Amaryan, K. A. Aniol, M. Beaumel, H. Benaoum, P. Bertin, C. E. Hyde, P.E. Ulmer, Jefferson Lab Hall A Collaboration
Physics Faculty Publications
We present final results on the photon electroproduction (→e p → epγ) cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved, which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed, resulting in photon electroproduction cross sections at new kinematic settings for a total of 588 experimental bins. Results of the Q2 and xB dependencies of both …
Rapidity Evolution Of Gluon Tmd From Low To Moderate X, I. Balitsky, A. Tarasov
Rapidity Evolution Of Gluon Tmd From Low To Moderate X, I. Balitsky, A. Tarasov
Physics Faculty Publications
We study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small x << 1 to linear evolution at moderate x ∼ 1.
Beam-Energy-Dependent Two-Pion Interferometry And The Freeze-Out Eccentricity Of Pions Measured In Heavy Ion Collisions At The Star Detector, L. Adamczyk, J.K. Adkins, G. Agakishiev, M.M. Aggarwal, Z. Ahammed, I. Koralt, Star Collaboration
Beam-Energy-Dependent Two-Pion Interferometry And The Freeze-Out Eccentricity Of Pions Measured In Heavy Ion Collisions At The Star Detector, L. Adamczyk, J.K. Adkins, G. Agakishiev, M.M. Aggarwal, Z. Ahammed, I. Koralt, Star Collaboration
Physics Faculty Publications
We present results of analyses of two-pion interferometry in Au + Au collisions at root s(NN) = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown-Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (m(T)) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to …
Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration
Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration
Physics Faculty Publications
We report the first measurements of the moments-mean (M), variance (σ2), skewness (S), and kurtosis (κ)-of the net-charge multiplicity distributions at midrapidity in Au + Au collisions at seven energies, ranging from √ˢᶰᶰ = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ2/M, Sσ, and κσ2, with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ …
Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration
Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration
Physics Faculty Publications
The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry ALL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured ALL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry AL is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and PT. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed …
Virtuality Distributions In Application To Ɣɣ* → Π0 Transition Form Factor At Handbag Level, Anatoly V. Radyushkin
Virtuality Distributions In Application To Ɣɣ* → Π0 Transition Form Factor At Handbag Level, Anatoly V. Radyushkin
Physics Faculty Publications
We outline basics of a new approach to transverse momentum dependence in hard processes. As an illustration, we consider hard exclusive transition process ɣ*ɣ -> π0 at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O(0, z)) describing a hadron with momentum p. Treated as functions of (pz) and z2, they are parametrized through virtuality distribution amplitudes (VDA) Φ(x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z2. For intervals with z+ = 0, we introduce the transverse momentum distribution …
Beam-Energy Dependence Of The Directed Flow Of Protons, Antiprotons, And Pions In Au+Au Collisions, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, I. Koralt, Star Collaboration
Beam-Energy Dependence Of The Directed Flow Of Protons, Antiprotons, And Pions In Au+Au Collisions, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, I. Koralt, Star Collaboration
Physics Faculty Publications
Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y= 0) are reported in √ˢᴺᴺ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeVAu+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter d v1/ d y│y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton d v1/ d y│y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions …
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein
Physics Faculty Publications
We have measured the nuclear transparency of the incoherent diffractive A( e , e ′ ρ0 ) process in 12C and 56Fe targets relative to 2H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ0 ʼs on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (lc), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q2). While the transparency for both 12C and 56Fe …
Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration
Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration
Physics Faculty Publications
Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The data are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance …
High-Energy Amplitudes In N= 4 Sym In The Next-To-Leading Order, Ian Balitsky, Giovanni A. Chirilli
High-Energy Amplitudes In N= 4 Sym In The Next-To-Leading Order, Ian Balitsky, Giovanni A. Chirilli
Physics Faculty Publications
The high-energy behavior of the N = 4 SYM amplitudes in the Regge limit can be calculated order by order in perturbation theory using the high-energy operator expansion in Wilson lines. At large Nc , a typical four-point amplitude is determined by a single BFKL pomeron. The conformal structure of the four-point amplitude is fixed in terms of two functions: pomeron intercept and the coefficient function in front of the pomeron (the product of two residues). The pomeron intercept is universal while the coefficient function depends on the correlator in question. The intercept is known in the first two orders …
Form Factors And Wave Functions Of Vector Mesons In Holographic Qcd, Hovhannes R. Grigoryan, Anatoly V. Radyushkin
Form Factors And Wave Functions Of Vector Mesons In Holographic Qcd, Hovhannes R. Grigoryan, Anatoly V. Radyushkin
Physics Faculty Publications
Within the framework of a holographic dual model of QCD, we develop a formalism for calculating form factors of vector mesons. We show that the holographic bound states can be described not only in terms of eigenfunctions of the equation of motion, but also in terms of conjugate wave functions that are close analogues of quantum-mechanical bound state wave functions. We derive a generalized VMD representation for form factors, and find a very specific VMD pattern, in which form factors are essentially given by contributions due to the first two bound states in the Q2 -channel. We calculate electric …