Nuclear Theory·nucl-th

Thursday·June 13, 2024

10 papers—4 primary·6 cross-listed

05
[Submitted on 11 Jun 2024] (cross-list from hep-ph)
Jet quenching in the glasma phase: medium-induced radiation
João Barata🇺🇸 · Sigtryggur Hauksson🇫🇷 · Xoán Mayo López🇪🇸 · Andrey V. Sadofyev🇵🇹
Inspired by the recent considerations of parton momentum broadening in the glasma phase, we study the medium-induced soft gluon radiation of jet partons at early times in heavy-ion collisions. The glasma state is assumed to be comprised of independent color domains with homogenous longitudinal fields that vary event by event, and we further complete this model with an event-averaging procedure accounting for the finite correlation length. Using this description, we evaluate the rate of medium-induced radiation from an energetic parton at midrapidity in the glasma phase. We mainly focus on SU(2) color fields for simplicity, also referring to the U(1) case and comparing with the BDMPS-Z rate to gain further insight. Our results show that there is an intricate interplay of the synchrotron-like radiation in a single color domain with the destructive interference between different color domains, after the medium averaging is performed. Thus, we find that the emission rate is sensitive to the matter structure, decreasing for a glasma state populated by smaller color domains, i.e. for a glasma with a larger characteristic saturation scale. Our approach can be applied to more realistic backgrounds, and sets the stage for the modelling of jet evolution in the early stages of heavy-ion collisions.
Comments:
30 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2406.07615 [pdf]
PRD(2024)·36 citations
06
[Submitted on 11 Jun 2024] (cross-list from astro-ph.HE)
Semi-Analytical Fokker Planck Models for Nuclear Star Clusters
Karamveer Kaur · Barak Rom · Re'em Sari
We study the dynamics of nuclear star clusters, the dense stellar environments surrounding massive black holes in the centers of galaxies. We consider angular momentum diffusion due to two-body scatterings among stellar objects and energy advection due to gravitational wave emission upon interaction with the central massive black hole. Such dynamics is described by a two-dimensional Fokker-Planck equation in energy-angular momentum space. Focusing on the transition between the diffusion-dominated region and the advection-dominated one, we utilize self-similarity to obtain a full solution for the Fokker-Planck equation. This solution provides the density and flux of the stellar objects in nuclear star clusters. This improves the rate estimates for extreme mass-ratio inspirals, and has interesting implications for a new class of galactic center transients called quasi-periodic eruptions.
Comments:
Submitted to ApJ; comments are welcome
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2406.07627 [pdf]
ApJ(2025)·13 citations
07
[Submitted on 11 Jun 2024] (cross-list from hep-ph)
Lighting up the Photon Wigner Distribution via Dilepton Productions
Yu Shi🇨🇳 · Lin Chen🇨🇳 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳
We present a systematic investigation of lepton pair production through photon-photon fusion processes in heavy-ion collisions. It is demonstrated that the dilepton production at a given impact parameter ( $b_{⊥}$ ) with a fixed transverse momentum imbalance ( $q_{⊥}$ ) can be factorized into a unified formula in terms of the Wigner photon distribution of heavy nuclei. We show that this framework provides a comprehensive description of all the relevant data from RHIC to the LHC, with a strong evidence that the quasi-real photon can be radiated not only from the nucleus as a whole, standing for the coherent contribution, but also from the sub-structures inside the nucleus, representing the incoherent contribution. Further predictions are made for the anisotropies in the correlations between $q_{⊥}$ , $b_{⊥}$ , and the dilepton transverse momentum ( $P_{⊥}$ ). This will help us to constrain the photon Wigner distribution which plays a crucial role to study the gluonic matter of nucleus at small- $x$ through the diffractive photoproduction processes in heavy ion collision.
Comments:
9 pages (main text) plus 18 pages (supplemental material), 25 figures; Version to be published in PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2406.07634 [pdf]
PLB(2025)·13 citations
08
[Submitted on 11 Jun 2024] (cross-list from hep-ph)
Off-shell pion properties: electromagnetic form factors and light-front wave functions
Jurandi Leão (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo Paulo, São Paulo, SP, Brazil, and Instituto Federal de São Paulo, Caraguatatuba, SP, Brazil)🇧🇷 · J. Pacheco B. C. de Melo (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo Paulo, São Paulo, SP, Brazil)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, Brazil)🇧🇷 · Ho-Meoyng Choi (Department of Physics, Teachers College, Kyungpook National University, Daegu, Korea)🇰🇷 · Chueng-Ryong Ji (Department of Physics, North Carolina State University, Raleigh, NC, USA)🇺🇸
The off-shell pion electromagnetic form factors are explored with corresponding off-shell light-front wave functions modeled by constituent quark and anti-quark. We apply the Mandelstam approach for the microscopic computation of the form factors relating the model parameters with the pion decay constant and charge radius. Analyzing the existing data on the cross-sections for the Sullivan process, H(e,e',pi)n, we extract the off-shell pion form factor using the relation derived from the generalized Ward-Takahashi identity for the pion electromagnetic current. They are compared with our previous results from exactly solvable manifestly covariant model of a (3+1)-dimensional fermion field theory. We find that the adopted constituent quark model reproduces the extracted off-shell form factor $F_{1} (Q^{2}, t)$ from the experimental data within a few percent difference and matches well with our previous theoretical simulation which exhibits a variation of about 10\% for the extracted off-shell pion form factor $g (Q^{2}, t)$ . We also identify the pion valence parton distribution function (PDF) and transverse momentum distribution (TMD) in terms of the light-front wave function and discuss their off-shell properties.
Comments:
Use revtex latex, 23 figures, 17 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2406.07743 [pdf]
PRD(2024)·9 citations
09
[Submitted on 12 Jun 2024] (cross-list from hep-ph)
Weak interaction axial form factors of the octet baryons in nuclear medium
G. Ramalho🇰🇷 · K. Tsushima🇧🇷 · Myung-Ki Cheoun🇰🇷
We study the axial-vector and the induced pseudoscalar form factors associated with the weak transitions between the octet baryon members in nuclear medium, using a covariant constituent quark model. We extend previous calculations of the axial transition form factors from the vacuum (free space) to the nuclear medium (symmetric nuclear matter). The extension of the model to the nuclear medium takes into account the modifications of the properties of hadrons in the medium (masses and coupling constants), as determined by the quark-meson coupling model. The axial-vector ( $G_{A}$ ) and the induced pseudoscalar ( $G_{P}$ ) form factors are evaluated for different values of the nuclear density $ρ$ in terms of the square transfer momentum $q^{2} = - Q^{2}$ . We conclude that, in general, the $G_{A}$ and $G_{P}$ form factors are reduced in the nuclear medium. The reduction is stronger for light baryons and high densities. The medium modifications are milder for the heavier octet baryons, particularly at large $Q^{2}$ . The calculations presented here can be used to estimate the cross sections of neutrino and antineutrino scattering with nucleus, and neutrino and antineutrino scattering with hyperons bound to a nucleus, as well as those in the cores of compact stars.
Comments:
42 pages, 24 figures and 6 tables. Published at PRD. Main article reduced. Part of the figures included in Appendices
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2406.07958 [pdf]
PRD(2025)·9 citations
10
[Submitted on 12 Jun 2024] (cross-list from hep-ph)
Constraining the axial-vector X17 interpretation with $^{12}$ C data
Cornelis J.G. Mommers🇩🇪 · Marc Vanderhaeghen🇩🇪
Recent findings of an unexpected, narrow resonance in the $e^{+} e^{-}$ decay spectra of excited states of $^{8}$ Be, $^{4}$ He and $^{12}$ C by the ATOMKI collaboration have received considerable experimental and theoretical attention, whereby a new, 17-MeV vector-like or axial-vector-like boson termed X17 was conjectured as an explanation of the anomaly. Further analysis of all existing constraints disfavors a vector X17 scenario. For a similar analysis of the axial-vector scenario, a calculation of the reduced matrix element of a spin-dipole operator between the excited nuclear state $^{12}$ C(17.23) and the carbon ground state is required. In the present work, we compute the aforementioned reduced matrix element under the assumption that the state $^{12}$ C(17.23) is well represented by the $2 s_{1/2} 1 p_{3/2}^{- 1}$ particle-hole shell-model excitation of the ground state, as supported by experimental data. Within such a framework, our results indicate that, like the vector scenario, the axial-vector interpretation of X17 shows strong tensions with the other existing constraints on the nucleon coupling of a conjectured X17.
Comments:
1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2406.08143 [pdf]
PLB(2024)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

Jet quenching in the glasma phase: medium-induced radiation

Semi-Analytical Fokker Planck Models for Nuclear Star Clusters

Lighting up the Photon Wigner Distribution via Dilepton Productions

Off-shell pion properties: electromagnetic form factors and light-front wave functions

Weak interaction axial form factors of the octet baryons in nuclear medium

Constraining the axial-vector X17 interpretation with 12C data

Affiliations

Constraining the axial-vector X17 interpretation with $^{12}$ C data