Nuclear Theory·nucl-th

Tuesday·November 16, 2021

16 papers—10 primary·6 cross-listed

11
Near Threshold Heavy Quarkonium Photoproduction at Large Momentum Transfer
Peng Sun🇨🇳 · Xuan-Bo Tong🇨🇳 · Feng Yuan🇺🇸
Perturbative QCD is applied to investigate the near threshold heavy quarkonium photoproduction at large momentum transfer. We take into account the contributions from the leading three-quark Fock states of the nucleon. The dominant contribution comes from the three-quark Fock state with one unit quark orbital angular momentum (OAM) whereas that from zero quark OAM is suppressed at the threshold. From our analysis, we also show that there is no direct connection between the near threshold heavy quarkonium photoproduction and the gluonic gravitational form factors of the nucleon. Based on the comparison between our result and recent GlueX data of $J / ψ$ photoproduction, we make predictions for $ψ^{'}$ and $Υ$ (1S,2S) states which can be tested in future experiments.
↳ hep-phhep-exnucl-exnucl-thPRD(2022)·44 citations
12
Light-front wavefunctions of mesons by design
Meijian Li🇫🇮 · Yang Li🇨🇳 · Guangyao Chen · Tuomas Lappi🇫🇮 · James P. Vary🇺🇸
We develop a mechanism to build the light-front wavefunctions (LFWFs) of meson bound states on a small-sized basis function representation. Unlike in a standard Hamiltonian formalism, the Hamiltonian in this method is implicit, and the information of the system is carried directly by the functional form and adjustable parameters of the LFWFs. In this work, we model the LFWFs for four charmonium states, $η_{c}$ , $J / ψ$ , $ψ^{'}$ , and $ψ (3770)$ as superpositions of orthonormal basis functions. We choose the basis functions as eigenfunctions of an effective Hamiltonian, which has a longitudinal confining potential in addition to the transverse confining potential from light-front holographic QCD. We determine the basis function parameters and superposition coefficients by employing both guidance from the nonrelativistic description of the meson states and the experimental measurements of the meson decay widths. With the obtained wavefunctions, we study the features of those meson states, including charge radii and parton distribution functions. We use the $J / ψ$ LFWF to calculate the meson production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions, and the $η_{c}$ LFWF to calculate its diphoton transition form factor. Both results show good agreement with experiments. The obtained LFWFs have simple-functional forms and can be readily used to predict additional experimental observables.
↳ hep-phnucl-thEPJC(2022)·25 citations
13
Dragging heavy quark in an anisotropic QCD medium beyond the static limit
Avdhesh Kumar🇮🇳 · Manu Kurian🇮🇳 · Santosh K. Das🇮🇳 · Vinod Chandra🇮🇳
Heavy quark dynamics in an anisotropic QCD medium have been analyzed within the Fokker-Planck approach. Heavy quark drag force and momentum diffusion tensor have been decomposed by employing a general tensor basis for an anisotropic medium. Depending upon the relative orientation of the direction of the momentum anisotropy of the medium and heavy quark motion, two drag and four diffusion coefficients have been estimated in the anisotropic QCD medium. The relative significance of different components of drag and momentum diffusion coefficients has been explored. The dependence of the angle between the anisotropic vector and heavy quark motion to the drag and diffusion coefficients has also been studied. Further, the energy loss of heavy quarks due to the elastic collisional process in an anisotropic medium has been studied. It is seen that the anisotropic contributions to heavy quark transport coefficients and its collisional energy loss have a strong dependence on the direction and strength of momentum anisotropy in the QCD medium.
↳ hep-phnucl-thPRC(2022)·17 citations
14
Systematic study of {\Delta}(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn
J. L. Rodriguez-Sanchez🇪🇸 · J. Benlliure🇪🇸 · I. Vidana🇮🇹 · H. Lenske🇩🇪 · J. Vargas🇪🇸 · C. Scheidenberger🇩🇪 · H. Alvarez-Pol🇪🇸 · J. Atkinson🇩🇪 · T. Aumann🇩🇪 · Y. Ayyad🇪🇸 · S. Beceiro-Novo🇪🇸 · K. Boretzky🇩🇪 and 17 other authors
The fragment separator FRS has been for the first time used to measure the (n,p) and (p,n)-type isobaric charge-exchange cross sections of stable 112,124Sn isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic contribution can be associated to the excitation of isobar {\Delta}(1232) resonances and to the pion emission in s-wave, both in the target and projectile nuclei, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. The data lead to interesting results where we observe a clear quenching of the quasi-elastic component and their comparisons to theoretical calculations demonstrate that the baryonic resonances can be excited in the target and projectile nuclei. To go further in this investigation, we propose to study the excitation of baryonic resonances taking advantage of the combination of high-resolving power magnetic spectrometers with the WASA calorimeter. These new measurements will allow us to determine the momenta of the ejectiles and pions emitted in coincidence after the single isobaric charge-exchange collisions, providing us unique opportunities to study the evolution of the baryonic resonance dynamics with the neutron-proton asymmetry through the use of exotic radioactive ion beams.
↳ nucl-exnucl-thPRC(2022)·10 citations
15
QCD Static Force in Gradient Flow
Nora Brambilla🇩🇪 · Hee Sok Chung🇩🇪 · Antonio Vairo🇩🇪 · Xiang-Peng Wang🇩🇪
We compute the QCD static force and potential using gradient flow at next-to-leading order in the strong coupling. The static force is the spatial derivative of the static potential: it encodes the QCD interaction at both short and long distances. While on the one side the static force has the advantage of being free of the $O (Λ_{QCD})$ renormalon affecting the static potential when computed in perturbation theory, on the other side its direct lattice QCD computation suffers from poor convergence. The convergence can be improved by using gradient flow, where the gauge fields in the operator definition of a given quantity are replaced by flowed fields at flow time $t$ , which effectively smear the gauge fields over a distance of order $t$ , while they reduce to the QCD fields in the limit $t \to 0$ . Based on our next-to-leading order calculation, we explore the properties of the static force for arbitrary values of $t$ , as well as in the $t \to 0$ limit, which may be useful for lattice QCD studies.
↳ hep-phhep-lathep-thnucl-thJHEP(2022)·10 citations
16
NICER view on holographic QCD
Niko Jokela🇫🇮
The holographic models for dense QCD matter work surprisingly well. A general implication seems that the deconfinement phase transition dictates the maximum mass of neutron stars. The nuclear matter phase turns out to be rather stiff which, if continuously merged with nuclear matter models based on effective field theories, leads to the conclusion that neutron stars do not have quark matter cores in the light of all current astrophysical data. We comment that as the perturbative QCD results are in stark contrast with strong coupling results, any future simulations of neutron star mergers incorporating corrections beyond ideal fluid should proceed cautiously. For this purpose, we provide a model which treats nuclear and quark matter phases in a unified framework at strong coupling.
↳ hep-phastro-ph.HEhep-thnucl-thEPJ Web Conf.(2022)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Near Threshold Heavy Quarkonium Photoproduction at Large Momentum Transfer

Light-front wavefunctions of mesons by design

Dragging heavy quark in an anisotropic QCD medium beyond the static limit

Systematic study of {\Delta}(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn

QCD Static Force in Gradient Flow

NICER view on holographic QCD

Affiliations