Nuclear Theory·nucl-th

Tuesday·April 9, 2024

14 papers—5 primary·9 cross-listed

01
[Submitted on 6 Apr 2024]
$K_{1}^{\pm}$ mesons moving in nuclear matter
Seokwoo Yeo🇰🇷 · HyungJoo Kim🇯🇵 · Su Houng Lee🇰🇷
Observing the mass shifts of mesons immersed in nuclear matter is interesting, as the changes are expected to shed light on the effects of chiral symmetry breaking on the origin of hadron masses. At the same time, it is important to understand the momentum dependence of the masses for spin-1 mesons, as the changes manifest differently across the two polarization modes. Here, the mass shifts of $K_{1}^{\pm}$ mesons with finite three-momentum in nuclear medium are studied in the QCD sum rule approach. We find that the mass of $K_{1}^{+}$ ( $K_{1}^{-}$ ) meson is increased(decreased) by the non-trivial momentum effect in both the transverse and longitudinal modes. Specifically, compared to its rest mass in the nuclear medium, in the transverse mode, the mass of $K_{1}^{+} (K_{1}^{-})$ is observed to shift by +2(-55) MeV, while in the longitudinal mode, the mass shift is +13(-11) MeV, all at a momentum of 0.5 GeV. Exploring the medium modifications of $K_{1}$ meson through kaon beams at J-PARC will provide insights on the partial restoration of chiral symmetry in nuclear matter.
Comments:
9 pages, 6 figures, acknowledgments added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.04532 [pdf]
PRD(2024)·3 citations
02
[Submitted on 6 Apr 2024]
Branch-cut in the shear-stress response function of massless $λ φ^{4}$ with Boltzmann statistics
Gabriel S. Rocha · Isabella Danhoni · Kevin Ingles · Gabriel S. Denicol · Jorge Noronha
Using an analytical result for the eigensystem of the linearized collision term for a classical system of massless scalar particles with quartic self-interactions, we show that the shear-stress linear response function possesses a branch-cut singularity that covers the whole positive imaginary semi-axis. This is demonstrated in two ways: (1) by truncating the exact, infinite linear system of linear equations for the rank-two tensor modes, which reveals the cut touching the origin; and (2) by employing the Trotterization techniques to invert the linear response problem. The former shows that the first pole tends towards the origin and the average separation between consecutive poles tends towards zero as power laws in the dimension of the basis. The latter allows one to obtain the response function in closed form in terms of Tricomi hypergeometrical functions, which possess a branch-cut on the above-mentioned semi-axis. This suggests that the presence of a cut along the imaginary frequency axis of the shear stress correlator, inferred from previous numerical analyses of weakly coupled scalar $λ φ^{4}$ theories, does not arise due to quantum statistics but instead emerges from the fundamental properties of this system's interactions.
Comments:
18 pages, 3 figures, v2: published version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.04679 [pdf]
PRD(2024)·18 citations
03
[Submitted on 7 Apr 2024]
Reconciling the HESS J1731-347 constraints with Parity doublet model
Bikai Gao🇯🇵 · Yan Yan🇨🇳 · Masayasu Harada🇯🇵
The recent discovery of a central compact object (CCO) within the supernova remnant HESS J1731-347, characterized by a mass of approximately $0.7 7_{- 0.17}^{+ 0.20} M_{⊙}$ and a radius of about $10. 4_{- 0.78}^{+ 0.86}$ km, has opened up a new window for the study of compact objects. This CCO is particularly intriguing because it is the lightest and smallest compact object ever observed, raising questions and challenging the existing theories. To account for this light compact star, a mean-field model within the framework of parity doublet structure is applied to describe the hadron matter. Inside the model, part of the nucleon mass is associated with the chiral symmetry breaking while the other part is from the chiral invariant mass $m_{0}$ which is insensitive to the temperature/density. The value of $m_{0}$ affects the nuclear equation of state for uniform nuclear matter at low density and exhibits strong correlations with the radii of neutron stars. We point out that HESS J1731-347 can be explained as the lightest neutron star for $m_{0} ≃ 850$ \,MeV.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.04786 [pdf]
PRC(2024)·37 citations
04
[Submitted on 8 Apr 2024]
Microscopic description of induced fission in a configuration interaction approach
K. Uzawa · K. Hagino · G. F. Bertsch
Even though more than 80 years have passed since the discovery of fission, its microscopic understanding has still been unclear. To clarify the underlying mechanics of induced fission, we analyze the distribution of a fission width using a miscropic framework based on a configuration-interaction approach. The distribution is known to follow a chi-squared distribution, which is characterized by the effective number of decay channels, $ν$ . We introduce an effective Hamitonian for the space of compound nucleus states and estimate $ν$ from the rank of the imaginary part of the effective Hamiltonian. Applying the model to $^{235}$ U(n,f), we succesfully reproduce the empirical value of $ν = 2.3 \pm 1.1$ . We also find that $ν$ is insensitve to the number of fission channels, which is consistent with an experimental finding.
Comments:
6 pages, 3 figures, Proceedings of FUSION23
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.05500 [pdf]
EPJ Web Conf.(2024)·1 citation
05
[Submitted on 8 Apr 2024]
First-order phase transitions in the cores of neutron stars
Oleg Komoltsev🇳🇴
I explore various scenarios for the phase transition within neutron-star matter. I do so by generating large model-agnostic ensemble using Gaussian processes, both with and without explicit inclusion of first-order phase transitions (FOPTs). The ensemble is conditioned with state-of-the-art astrophysical and theoretical inputs in a fully Bayesian approach. I study how the current data affect the posterior probability of the location and the strength of FOPT. I find that the previously observed peak structure of the sound speed remains stable against inclusion of FOPTs. While the current data cannot differentiate between a smooth crossover and a first-order phase transition, 91% of the total evidence consists of equations of state with some form of phase changes, such as FOPT occurring within or terminating the stable branch of neutron stars, or an indication of a crossover to quark matter.
Comments:
Version 5: Used the corrected version of the Marginalized QCD likelihood function. Plots and Bayes factors changed slightly, but the conclusions remain unchanged. 7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2404.05637 [pdf]
PRD(2024)·26 citations
06
[Submitted on 5 Apr 2024] (cross-list from hep-lat)
QCD Predictions for Meson Electromagnetic Form Factors at High Momenta: Testing Factorization in Exclusive Processes
Heng-Tong Ding🇨🇳 · Xiang Gao🇺🇸 · Andrew D. Hanlon🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Qi Shi🇨🇳 · Sergey Syritsyn🇺🇸 · Rui Zhang🇺🇸 · Yong Zhao🇺🇸
We report the first lattice QCD computation of pion and kaon electromagnetic form factors, $F_{M} (Q^{2})$ , at large momentum transfer up to 10 and 28 $GeV^{2}$ , respectively. Utilizing physical masses and two fine lattices, we achieve good agreement with JLab experimental results at $Q^{2} ≲ 4 GeV^{2}$ . For $Q^{2} ≳ 4 GeV^{2}$ , our results provide $ab-initio$ QCD benchmarks for the forthcoming experiments at JLab 12 GeV and future electron-ion colliders. We also test the QCD collinear factorization framework utilizing our high- $Q^{2}$ form factors at next-to-next-to-leading order in perturbation theory, which relates the form factors to the leading Fock-state meson distribution amplitudes. Comparisons with independent lattice QCD calculations using the same framework demonstrate, within estimated uncertainties, the universality of these nonperturbative quantities.
Comments:
Phys. Rev. Lett. 133, 181902; 15 pages, 9 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.04412 [pdf]
PRL(2024)·34 citations
07
[Submitted on 5 Apr 2024] (cross-list from hep-ph)
Quantum mechanical aspects of coherent photoproduction: the limits of coherence, and multiple vector mesons
Spencer R. Klein🇺🇸
Quantum mechanics is central to coherent photoproduction in ultra-peripheral collisions (UPCs). This writeup will discuss some surprising aspects of UPCs that stem from these quantum mechanical roots. The Good-Walker (GW) paradigm, which connects coherent photoproduction with the target nucleus remaining in its ground state. This contrasts with a semi-classical picture, where coherence depends on the positions of the individual nucleons and the momentum transfer. Unlike the GW approach, the semiclassical picture is consistent with the observed data on coherent photoproduction with nuclear breakup, and with coherent photoproduction in peripheral collisions. The semiclassical approach allows for a wider variety of coherent UPC reactions, such as coherent photoproduction of charged mesons, including some non $q q$ exotica. Quantum mechanics is also key to the coherent photoproduction of multiple vector mesons by the interactions of a single ion pair. The vector mesons share a common impact parameter, and so can exhibit richer interference patterns than single mesons. At forward rapidities, the cross sections to produce multiple identical vector mesons are enhanced due to superradiance. With enough statistics, multi-meson events may provide an opportunity to observe stimulated decays.}
Comments:
Presented at the 1st International Workshop on the physics of Ultra Peripheral Collisions (UPC 2023). 9 pages with 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2404.04450 [pdf]
Phys.Proc.UPC(2024)·3 citations
08
[Submitted on 7 Apr 2024] (cross-list from hep-ph)
Influence of the chiral magnetic effect on particle-pair elliptic anisotropy
Han-Sheng Li🇺🇸 · Yicheng Feng🇺🇸 · Fuqiang Wang🇺🇸
Chiral Magnetic Effect (CME) is a phenomenon in which electric charge is separated by a strong magnetic field from local domains of chirality imbalance in quantum chromodynamics. The CME-sensitive, azimuthal correlator difference $Δ γ$ between opposite-sign (OS) and same-sign (SS) charged hadron pairs is contaminated by a major physics background proportional to the particle elliptic anisotropy ( $v_{2}$ ). The CME signal, on the other hand, contributes to the difference in the pair elliptic anisotropies between OS and SS pairs ( $Δ v_{2, pair}$ ). We investigate $Δ v_{2, pair}$ and found its sensitivity to CME to be similar to that of the $Δ γ$ observable.
Comments:
6 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.05032 [pdf]
PRC(2025)·6 citations
09
[Submitted on 8 Apr 2024] (cross-list from hep-ph)
Quasiparton distributions in massive QED2: Toward quantum computation
Sebastian Grieninger🇺🇸 · Kazuki Ikeda🇺🇸 · Ismail Zahed🇺🇸
We analyze the quasi-parton distributions of the lightest $η^{'}$ meson in massive two-dimensional Quantum electrodynamics (QED2) by performing a digital quantum simulation on a classical computer (exact diagonalization). The Hamiltonian and boost operators are mapped onto spin qubits in a spatial lattice with open boundary conditions. The lowest excited state in the exact diagonalization is shown to interpolate continuously between an anomalous $η^{'}$ state at strong coupling,and a non-anomalous heavy meson at weak coupling, with a cusp at the critical point. The boosted $η^{'}$ state follows relativistic kinematics but with large deviations in the luminal limit. The spatial quasi-parton distribution function and amplitude for the $η^{'}$ state are computed numerically for increasing rapidity both at strong and weak coupling, and compared to the exact light front results. The numerical results from the boosted form of the spatial parton distributions, compare fairly with the inverse Fourier transformation of the luminal parton distributions, derived in the lowest Fock space approximation. Our analysis points out some of the limitations facing the current lattice program for the parton distributions.
Comments:
12 pages, 7 figures; v2: matches version published in PRD; title change to conform with APS conventions
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2404.05112 [pdf]
PRD(2024)·27 citations
10
[Submitted on 8 Apr 2024] (cross-list from hep-ph)
Analysis of $B_{s}^{0} \to X (3872) [ψ (2 S)] π^{+} π^{-} (K^{+} K^{-})$ decays
Hao-Nan Wang🇨🇳 · Li-Sheng Geng🇨🇳 · Gang Li🇨🇳 · Ju-Jun Xie🇨🇳
We have phenomenologically investigated the decays $B_{s}^{0} \to X (3872) π^{+} π^{-} (K^{+} K^{-})$ and $B_{s}^{0} \to ψ (2 S) π^{+} π^{-} (K^{+} K^{-})$ . In our analysis, the scalar meson $f_{0} (980)$ is formed through the final state interactions of coupled channels $π π$ and $K K ˉ$ . Our findings indicate that the $π^{+} π^{-}$ invariant mass distribution of the $B_{s}^{0} \to ψ (2 S) π^{+} π^{-}$ decay can be accurately reproduced. Furthermore, we have explored the $π^{+} π^{-} (K^{+} K^{-})$ invariant mass distribution of the $B_{s}^{0} \to X (3872) π^{+} π^{-} (K^{+} K^{-})$ decay, accounting for the different production mechanisms between $X (3872)$ and $ψ (2 S)$ , up to a global factor. It is found that the production rates for $X (3872)$ and $ψ (2 S)$ are much different, which indicates that the structure of $X (3872)$ is more complicated than the $ψ (2 S)$ , which is a conventional $c c ˉ$ state. Additionally, we have considered the contributions from $f_{0} (1500)$ to $π^{+} π^{-}$ and the $ϕ$ meson to $K^{+} K^{-}$ in our analysis. Utilizing the model parameters, we have calculated the branching fraction of $B_{s}^{0} \to X (3872) K^{+} K^{-}$ , and anticipate that the findings of our study can be experimentally tested in the future.
Comments:
7 pages, 6 figures. Typos are corrected, and couplings are renormalized to be dimentionless
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.05114 [pdf]
PRD(2024)·3 citations
11
[Submitted on 8 Apr 2024] (cross-list from hep-ph)
T-odd Parton Distribution Functions and Azimuthal Anisotropy at High Transverse Momentum in $p$ - $p$ and $p$ - $A$ Collisions
Ismail Soudi🇺🇸 · Abhijit Majumder🇺🇸
Various azimuthal anisotropies ( $v_{1}, v_{2}, v_{3}, v_{4}$ ), at high transverse momentum (high- $p_{T}$ ), are shown to arise from the asymmetric scattering of transverse polarized quarks and gluons, arising from unpolarized nucleons (the Boer-Mulders' effect) and resulting in unpolarized hadrons (the Collins effect). Combined with the asymmetric scattering of partons from polarization independent but transverse momentum dependent (TMD) distributions, we obtain a possible mechanism to understand the azimuthal anisotropy of hadrons at large transverse momentum observed in $p$ - $p$ collisions. Constraining the ratio of polarization dependent TMD distributions to polarization independent distributions by comparing with the data from $p$ - $p$ collisions, we find that scaling the acquired transverse momentum of the initial state partons from the proton, due to prescattering before the hard interaction, with the length of the nucleus ( $k_{⊥}^{2} \propto A^{1/3}$ ), straightforwardly yields the azimuthal anisotropy at high $p_{T}$ in $p$ - $A$ collisions.
Comments:
17 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2404.05287 [pdf]
PRC(2025)·8 citations
12
[Submitted on 8 Apr 2024] (cross-list from hep-ph)
Reduction of (pseudo-)Critical Temperatures of Chiral Restoration and Deconfinement Phase Transitions in a Magnetized PNJL Model
Shijun Mao🇨🇳
We investigate the chiral restoration and deconfinement phase transitions under external magnetic field in frame of a Pauli-Villars regularized PNJL model. A running Polyakov loop scale parameter $T_{0} (e B)$ is introduced to mimic the reaction of the gluon sector to the presence of magnetic fields. It is found that a decreasing $T_{0} (e B)$ with magnetic fields can realize the inverse magnetic catalysis phenomena of chiral condensates of $u$ and $d$ quarks, increase of Polyakov loop and the reduction of (pseudo-)critical temperatures of chiral restoration and deconfinement phase transitions.
Comments:
7 pages, 4 figs, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2404.05294 [pdf]
PRD(2024)·9 citations
13
[Submitted on 8 Apr 2024] (cross-list from hep-ph)
$c c ˉ$ and $b b ˉ$ suppression in Glasma
Pooja🇮🇳 · Mohammad Yousuf Jamal🇮🇳 · Partha Pratim Bhaduri🇮🇳 · Marco Ruggieri🇮🇹 · Santosh K. Das🇮🇳
This study investigates the evolution and dissociation dynamics of $c c ˉ$ and $b b ˉ$ pairs within the pre-equilibrium, gluon-dominated stage of high energy nuclear collisions. An attractive potential made of a perturbative Coulomb-like term and of a confining term is used to simulate the attractive strong force in the pairs. Besides, we implement the interaction of the pairs with the evolving Glasma fields by virtue of the Wong equations. The interaction with the classical color fields dominates the dynamics, causing an increase in pair separation and subsequent dissociation. The observed finite probability of dissociation for these states reveals the intricate interplay between QCD dynamics and the suppression of $c c ˉ$ and $b b ˉ$ states during the pre-equilibrium stage. The research highlights differences between $c c ˉ$ and $b b ˉ$ pairs, revealing the role of quark flavor in the dissociation process. Dissociation spectra analysis indicates a peak shift towards higher momentum, reflecting a slight energy gain by the pairs. This investigation provides valuable insights into the complex dynamics of $c c ˉ$ and $b b ˉ$ pairs in the Glasma, which may help in better interpretation of experimental results on further integration with subsequent phases of the created matter.
Comments:
10 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2404.05315 [pdf]
PRD(2024)·24 citations
14
[Submitted on 8 Apr 2024] (cross-list from astro-ph.HE)
Constraints on the dense matter equation of state from young and cold isolated neutron stars
Alessio Marino (1,2) · Clara Dehman (1,2) · Konstantinos Kovlakas (1,2) · Nanda Rea (1,2) · Jose A. Pons (3) · D. Viganò (1,2) ((1) Institute of Space Sciences ICE, CSIC, (2) Institut d'Estudis Espacials de Catalunya IEEC, (3) Universitat d'Alacant)
Neutron stars are the dense and highly magnetic relics of supernova explosions of massive stars. The quest to constrain the Equation of State (EoS) of ultra-dense matter and thereby probe the behavior of matter inside neutron stars, is one of the core goals of modern physics and astrophysics. A promising method involves investigating the long-term cooling of neutron stars, and comparing theoretical predictions with various sources at different ages. However, limited observational data, and uncertainties in source ages and distances, have hindered this approach. In this work, re-analyzing XMM-Newton and Chandra data from dozens of thermally emitting isolated neutron stars, we have identified three sources with unexpectedly cold surface temperatures for their young ages. To investigate these anomalies, we conducted magneto-thermal simulations across diverse mass and magnetic fields, considering three different EoS. We found that the "minimal" cooling model, failed to explain the observations, regardless the mass and the magnetic field, as validated by a machine learning classification method. The existence of these young cold neutron stars suggests that any dense matter EoS must be compatible with a fast cooling process at least in certain mass ranges, eliminating a significant portion of current EoS options according to recent meta-modelling analysis.
Comments:
60 pages, 10 figures, 7 tables; Accepted for publication; first four authors are corresponding authors
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2404.05371 [pdf]
Nature Astron.(2024)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE