Nuclear Theory·nucl-th

Tuesday·January 28, 2025

19 papers—13 primary·6 cross-listed

14
Comparing strange and non-strange quark stars within resummed QCD at NLO
Tulio E. Restrepo🇺🇸 · Jean-Loïc Kneur🇫🇷 · Constança Providência🇵🇹 · Marcus Benghi Pinto🇧🇷
We employ the renormalization group optimized perturbation theory (RGOPT) resummation method to evaluate the equation of state (EoS) for strange ( $N_{f} = 2 + 1$ ) and non-strange ( $N_{f} = 2$ ) cold quark matter at NLO. This allows us to obtain the mass-radius relation for pure quark stars and compare the results with the predictions from perturbative QCD (pQCD) at NNLO. Choosing the renormalization scale to generate maximum star masses of order $M = 2 - 2.6 M_{⊙}$ , we show that the RGOPT can produce mass-radius curves compatible with the masses and radii of some recently observed pulsars, regardless of their strangeness content. The scale values required to produce the desired maximum masses are higher in the strange scenario since the EoS is softer in this case. The possible reasons for such behavior are discussed. Our results also show that, as expected, the RGOPT predictions for the relevant observables are less sensitive to scale variations than those furnished by pQCD.
↳ hep-phastro-ph.HEnucl-thPRD(2025)·7 citations
15
Roles of $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ resonances in $γ p \to π^{0} π^{0} p$ reaction within an effective Lagrangian approach
Meng-Yuan Dai🇨🇳 · Si-Wei Liu🇨🇳 · Cheng Chen🇨🇳 · De-Min Li🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳
Roles of the $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ resonances in the $γ p \to π^{0} π^{0} p$ reaction near threshold is investigated within an effective Lagrangian approach. We have calculated the differential cross sections of the $γ p \to π^{0} π^{0} p$ reaction by including the contributions from the $Δ (1232)$ , $N^{*} (1520)$ , and $N^{*} (1650)$ intermediate states decaying into $π^{0} p$ via the $s$ -channel nucleon pole and $t$ -channel $ρ$ exchange, and found that the current experimental measurements can be well reproduced. The production of $Δ (1232)$ is mainly from the mechanism of the $s$ -channel nucleon pole, while the $N^{*} (1520)$ and $N^{*} (1650)$ are produced from the mechanism of the $t$ -channel $ρ$ exchange. It is expected that more experimental data on the $γ p \to π^{0} π^{0} p$ reaction can be used to explore the properties of the low-lying excited baryon states and also the scalar $f_{0} (500)$ and $f_{0} (980)$ mesons.
↳ hep-phnucl-thCPC(2025)·6 citations
16
Explainable autoencoder for neutron star dense matter parameter estimation
Francesco Di Clemente · Matteo Scialpi · Michał Bejger
We present a physics-informed autoencoder designed to encode the equation of state of neutron stars into an interpretable latent space. In particular the input will be encoded in the mass, radius, and tidal deformability values of a neutron star. Unlike traditional black-box models, our approach incorporates additional loss functions to enforce explainability in the encoded representations. This method enhances the transparency of machine learning models in physics, providing a robust proof-of-concept tool to study compact stars data. Our results demonstrate that the proposed autoencoder not only accurately estimates the EoS parameters and central density/pressure but also offers insights into the physical connection between equation of state and observable physical quantities. This framework conceptualizes the physical differential equations themselves as the ``encoders", allowing interpretability of the latent space.
↳ physics.comp-phastro-ph.HEastro-ph.IMnucl-thMach.Learn.Sci.Tech.(2025)·7 citations
17
Microscopic composite systems bound by strong gravity in extra dimensions as candidates for dark matter
V. V. Flambaum🇦🇺
In the Arkani-Hamed-Dimopoulos-Dvali (ADD) model with n extra compactified dimensions, the gravitational potential scales as 1/r^{n+1} and becomes significantly stronger at short distances. We investigate the possibility of forming small-sized composite systems of Standard Model particles bound by this potential. Such bound states, composed of quarks, neutrinos, axions, or other particles, exhibit a small cross-section-to-mass ratio, making them viable candidates for dark matter.
↳ hep-phastro-ph.COnucl-thphysics.atom-phPRD(2025)·2 citations
18
Three flavor QCD phase transition with Möbius domain wall fermions
Yu Zhang🇩🇪 · Yasumichi Aoki🇯🇵 · Shoji Hashimoto🇯🇵 · Issaku Kanamori🇯🇵 · Takashi Kaneko🇯🇵 · Yoshifumi Nakamura🇯🇵
We present an updated study of the $N_{f} = 3$ QCD phase transition using Möbius domain wall fermions. Simulations were performed on $N_{t} = 12$ lattices with aspect ratios ranging from 2 to 4 for various quark masses, at a lattice spacing of $a = 0.1361 (20)$ fm, corresponding to a temperature of 121(2) MeV. To clarify the nature of the phase transition, a large-volume lattice, $4 8^{3} \times 12 \times 16$ , was added to analyze the volume dependence of disconnected chiral susceptibility. By examining the chiral condensate, disconnected chiral susceptibility, and Binder cumulant, and incorporating results from $2 4^{3} \times 12 \times 16$ and $3 6^{3} \times 12 \times 16$ lattices reported in earlier studies, we observe that the transition is consistent with a crossover at a quark mass of approximately $m_{f}^{MS} (2 GeV) \sim 4$ MeV at this temperature. Furthermore, we discuss the effects of residual chiral symmetry breaking on the chiral condensate and disconnected chiral susceptibility for different sizes in the 5th direction.
↳ hep-lathep-thnucl-thPoS(2025)·10 citations
19
Aspects of the dilute Glasma
Markus Leuthner🇦🇹
The Glasma is a semiclassical nonequilibrium state describing the earliest stage in relativistic heavy-ion collisions predicted by the Color Glass Condensate effective theory. It is characterized by strong color fields, which are sourced by color currents pertaining to hard partons in the colliding nuclei. We introduce the (3+1)D dilute Glasma framework, which incorporates the longitudinal and transverse structure of colliding particles and describes the rapidity-dependence of observables like the energy-momentum tensor. This is in stark contrast to the canonical picture of boost-invariance, where nuclei are infinitesimally thin in longitudinal direction, and the rapidity-dependence of observables is lost. We discuss the derivation of the (3+1)D dilute Glasma field-strength tensor, which relies on linearizing the Yang-Mills equations in the dilute approximation, i.e., assuming weak sources. The dilute Glasma energy-momentum tensor can efficiently be evaluated numerically on a lattice. Employing a generalized 3D McLerran-Venugopalan model, we discuss numerical results for the collisions of heavy ions at energies corresponding to experiments at RHIC and the LHC. We discover longitudinal flow that differs significantly from Bjorken flow and argue that this is a consequence of taking into account the longitudinal extension of nuclei. Furthermore, we find limiting fragmentation as a universal feature of the dilute Glasma analytically and numerically. Finally, we study the applicability of the dilute Glasma to proton-proton collisions and show the necessary modifications to reproduce experimental multiplicity distributions.
↳ hep-phnucl-th4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Comparing strange and non-strange quark stars within resummed QCD at NLO

Roles of Δ(1232), N∗(1520), and N∗(1650) resonances in γp→π0π0p reaction within an effective Lagrangian approach

Explainable autoencoder for neutron star dense matter parameter estimation

Microscopic composite systems bound by strong gravity in extra dimensions as candidates for dark matter

Three flavor QCD phase transition with Möbius domain wall fermions

Aspects of the dilute Glasma

Affiliations

Roles of $Δ (1232)$ , $N^{} (1520)$ , and $N^{} (1650)$ resonances in $γ p \to π^{0} π^{0} p$ reaction within an effective Lagrangian approach