Nuclear Theory·nucl-th

Friday·September 27, 2024

9 papers—1 primary·8 cross-listed

01
Medium Effects in MIT Bag Model for quark matter: Self consistent thermodynamical treatment
Suman Pal🇮🇳 · Gargi Chaudhuri🇮🇳
The study of strange quark matter within the framework of the density-dependent MIT Bag model using the Grand Canonical ensemble is thermodynamically inconsistent. In this work, it is shown that if the medium effects are incorporated through a density-dependent Bag pressure in the Grand Canonical ensemble, then the Euler relation is violated. If Euler relation is used then the minimum of energy per baryon does not occur at zero pressure. In order to overcome this inconsistency, we propose the medium effect of the strange quark matter in the form of chemical potential dependent Bag pressure in the grand Canonical ensemble. The density dependent Bag pressure which has been used in Grand Canonical ensemble so far can however be used in Canonical ensemble without violating the laws of thermodynamics. These prescriptions will obey the Euler relation as well as the minimum energy per baryon will coincide with the zero of pressure and hence can be considered to be self consistent. These equations of state in the Grand Canonical ensemble can be further used to construct the Mass-Radius and other structural properties of the strange quark stars as well as hybrid stars. In our present work we have calculated the mass radius diagram of strange stars only using this formalism.
nucl-thPRD(2023)·19 citations
02
Neutron Star with Dark Matter Admixture: A Candidate for Bridging the Mass Gap
M. Vikiaris🇬🇷 · V. Petousis🇨🇿 · M. Veselsky🇨🇿 · Ch.C. Moustakidis🇬🇷
Neutron stars, white dwarfs and black holes are the after death remnants of massive stars. However, according to the most recent observations, the neutron stars maximum mass is between $2.0 - 2.5 M_{⊙}$ while black holes of less than 5 $M_{⊙}$ has not yet been observed. The region between the most massive neutron star and the least massive black hole is called the mass-gap. If indeed its existence is confirmed by future observations, that indicates a gap in our understanding which seeks for explanation. In addition, the existence of compact objects within the mass-gap should also be supported with the help of possible new theoretical scenarios. In this study, we propose a possible explanation for the existence of compact objects within the mass-gap region. Specifically, we propose that the mass-gap region could be bridged by the existence of a hybrid compact object, composed of hadronic and self interacting and non-annihilating fermionic dark matter, considering that the interaction between these two fluids it is only gravitational. Fundamental questions about how these objects form and how they can be detected are also addressed.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thInt.J.Mod.Phys.D(2025)·8 citations
03
Small- $x$ gluon GPD constrained from deeply virtual $J / ψ$ production and gluon PDF through universal-moment parameterization
Yuxun Guo🇺🇸 · Xiangdong Ji🇺🇸 · M. Gabriel Santiago🇺🇸 · Jinghong Yang🇺🇸 · Hao-Cheng Zhang🇨🇳
We phenomenologically constrain the small- $x$ and small- $ξ$ gluon generalized parton distributions (GPDs) with the deeply virtual $J / ψ$ production (DV $J / ψ$ P) in the framework of GPDs through universal moment parameterization (GUMP). We use a hybrid cross-section formula combining collinear factorization to the next-to-leading order (NLO) accuracy of the strong coupling $α_{s}$ , with corrections from non-relativistic QCD to account for the power corrections due to the heavy $J / ψ$ mass. We reach reasonable fit to the measured differential cross-sections of DV $J / ψ$ P by H1 at Hadron-Electron Ring Accelerator (HERA) as well as forward gluon PDFs from JAM22 global analysis. We find that both NLO and non-relativistic corrections are significant for heavy vector meson productions. Of course, the gluon GPD we obtain still contain considerable freedom in need of inputs from other constraints, particularly in the distribution-amplitude-like region.
↳ hep-phnucl-thPRD(2025)·13 citations
04
Polarized and unpolarized gluon PDFs: generative machine learning applications for lattice QCD matrix elements at short distance and large momentum
Talal Ahmed Chowdhury🇧🇩 · Taku Izubuchi🇺🇸 · Methun Kamruzzaman🇺🇸 · Nikhil Karthik🇺🇸 · Tanjib Khan🇧🇩 · Tianbo Liu🇨🇳 · Arpon Paul🇺🇸 · Jakob Schoenleber🇺🇸 · Raza Sabbir Sufian🇺🇸
Lattice quantum chromodynamics (QCD) calculations share a defining challenge by requiring a small finite range of spatial separation $z$ between quark/gluon bilinears for controllable power corrections in the perturbative QCD factorization, and a large hadron boost $p_{z}$ for a successful determination of collinear parton distribution functions (PDFs). However, these two requirements make the determination of PDFs from lattice data very challenging. We present the application of generative machine learning algorithms to estimate the polarized and unpolarized gluon correlation functions utilizing short-distance data and extending the correlation up to $z p_{z} ≲ 14$ , surpassing the current capabilities of lattice QCD calculations. We train physics-informed machine learning algorithms to learn from the short-distance correlation at $z ≲ 0.36$ fm and take the limit, $p_{z} \to \infty$ , thereby minimizing possible contamination from the higher-twist effects for a successful reconstruction of the polarized gluon PDF. We also expose the bias and problems with underestimating uncertainties associated with the use of model-dependent and overly constrained functional forms, such as $x^{α} (1 - x)^{β}$ and its variants to extract PDFs from the lattice data. We propose the use of generative machine learning algorithms to mitigate these issues and present our determination of the polarized and unpolarized gluon PDFs in the nucleon.
↳ hep-lathep-phnucl-thPRD(2025)·17 citations
05
Deformations of the AdS-Schwarzschild black brane and the shear viscosity of the quark-gluon plasma
Roldao da Rocha🇧🇷
Deformations of the AdS $_{5}$ -Schwarzschild black brane, implemented in the AdS/CFT membrane paradigm, are scrutinized in the dual viscous hydrodynamic infrared limit. The latest experimental data analyses, regarding the shear viscosity-to-entropy density ratio of the quark-gluon plasma produced by heavy-ion collisions at the LHC and RHIC, are shown to constrain these deformations severely. Although corroborating with the robustness of the standard AdS $_{5}$ -Schwarzschild black brane against deformations, there is still a margin for mild deformations which may carry 2-loop quantum corrections to gravity, whose implications to the strongly-coupled dual field theory are addressed and discussed.
↳ hep-thnucl-thEur.Phys.J.Plus(2024)·7 citations
06
Determining the Meson Cloud Contribution of Nucleon Electromagnetic Form Factor Using Dispersion Relation
Ek-ong Atthaphan🇹🇭 · Attaphon Kaewsnod🇹🇭 · Kai Xu🇹🇭 · Moh Moh Aung🇹🇭 · Warintorn Sreethawong🇹🇭 · Ayut Limphirat🇹🇭 · Yupeng Yan🇹🇭
We explore the meson cloud contribution to nucleon electromagnetic form factors in dispersion relation approach. In our calculations, experimental data on transition amplitudes for pion-nucleon scatterings are taken directly as inputs, with the assumption that the photon-pion interaction dominates over other meson-photon couplings. Combining with the quark core contribution evaluated in quark model, the proton electromagnetic form factors are well reproduced in the work. The resulting mean-square charge radius of the proton agrees well with experimental data, and the quark core radius is reasonable.
↳ hep-phnucl-th0 citations
07
A Variational Approach to Quantum Field Theory
M. Rovira🇪🇸 · A. Parreño🇪🇸 · R.J. Perry🇪🇸
In strongly coupled field theories, perturbation theory cannot be employed to study the low-energy spectrum. Thus, non-perturbative techniques are required. We employ the variational method, a rigorous, non-perturbative approach which provides variational upper bounds on the energy eigenstates of the theory. An essential step in the variational method is the choice of trial wave function. In this work, we study the viability of employing a neural network as our variational ansatz. As a first step towards phenomenologically interesting strongly coupled theories like quantum chromodynamics, we study scalar field theories with quartic couplings.
↳ hep-lathep-thnucl-thPoS(2025)·2 citations
08
Relativistic diffusion model for hadron production in p-Pb collisions at the LHC
Philipp Schulz🇩🇪 · Georg Wolschin🇩🇪
We investigate charged-hadron production in relativistic heavy-ion collisions of asymmetric systems within a nonequilibrium-statistical framework. Calculated centrality-dependent pseudorapidity distributions for p-Pb collisions at sqrt(s_NN)=5.02 and 8.16 TeV are compared with data from the Large Hadron Collider (LHC). Our approach combines a relativistic diffusion model with formulations based on quantum chromodynamics while utilizing numerical solutions of a Fokker-Planck equation to account for the shift and broadening of the fragmentation sources for particle-production with respect to the stopping (net-baryon) rapidity distributions. To represent the centrality dependence of charged-hadron production in asymmetric systems over a broad region of pseudorapidities, the consideration and precise modelling of the fragmentation sources - along with the central gluon-gluon source - is found to be essential. Specifically, this results in an inversion of the particle-production amplitude from backward- to forward-dominance when transitioning from central to peripheral collisions, in agreement with recent ATLAS and ALICE p-Pb data at sqrt(s_NN)=5.02 TeV.
↳ hep-phnucl-thPRC(2024)·3 citations
09
Unique forbidden beta decays at zero momentum transfer
Chien-Yeah Seng🇺🇸 · Ayala Glick-Magid🇺🇸 · Vincenzo Cirigliano🇺🇸
We report an exploratory study of the $O (α)$ structure-dependent electromagnetic radiative corrections to unique first-forbidden nuclear beta decays. We show that the insertion of angular momentum into the nuclear matrix element by the virtual/real photon exchange opens up the decay at vanishing nuclear recoil momentum which was forbidden at tree level, leading to a dramatic change in the decay spectrum not anticipated in existing studies. We discuss its implications for precision tests on the Standard Model and searches for new physics.
↳ hep-phhep-exnucl-exnucl-thPRL(2025)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE