Mon·Sep 1, 2025Monday·September 1, 2025

1. 01*

   Probing the onset of collectivity via scaled particle spectra in ultrarelativistic nuclear collisions

   Thiago S. Domingues🇧🇷 · Fernando G. Gardim🇧🇷 · David D. Chinellato🇦🇹 · Gabriel S. Denicol🇧🇷 · Andre V. Giannini🇵🇹 · Matthew Luzum🇧🇷 · Cicero D. Muncinelli🇧🇷 · Jorge Noronha🇺🇸 · Tiago Nunes da Silva🇧🇷 · Jun Takahashi🇧🇷 · Giorgio Torrieri🇧🇷

   We identify a novel scaling in the transverse momentum spectra of produced particles, obtained by removing the global scales of multiplicity and mean transverse momentum. Hydrodynamic simulations and experimental data reveal an almost universal scaled spectrum across centralities, systems, and even small systems, pointing to its origin in the collective, fluid-like dynamics of the QGP. Comparing this observable with Bayesian a priori distributions shows its independent constraining power on QCD transport properties, while also exposing limitations of current models. A detailed posterior analysis will be pursued in future work, opening a new avenue to refine our understanding of collectivity in heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2026)·3 citations
2. 02*

   SMASH: Results from hadronic transport for heavy-ion collisions at high densities

   Hannah Elfner🇩🇪 · Renan Góes-Hirayama🇩🇪

   This mini-review summarizes the general setup and some highlight results from the hadronic transport approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). We start by laying out the software development structures as well as the particle properties and how they are determined by elementary collisions. The different ways to produce light clusters in SMASH, either by coalescence or dynamic multi-particle reactions, are explained. The constraints on nuclear mean fields and the corresponding equation of state from collective flow observables are discussed. In addition, we show how fluctuations associated with a potential critical endpoint survive through the hadronic rescattering stage. Besides hadronic observables, electromagnetic probes offer nice possibilities to study the properties of matter. We present results on collisional broadening of resonances and elliptic flow of dileptons. Last but not least, we review how SMASH can be employed as part of a hybrid approach including a Bayesian analysis for transport coefficients as a function of temperature and chemical potential. We end with an outlook how the hybrid approach has been recently extended to lower collision energies by dynamical fluidization initial conditions.

   ↳ nucl-thnucl-ex7 citations
3. 03*

   A Benchmark Study of the Relativistic Plane Wave Impulse Approximation for Polarized ($\vec{p},2\vec{p}$) Reactions on the 3s${}_{1/2}$ state in ${}^{208}$Pb at 392 MeV

   T. Mello🇧🇼 · G. C. Hillhouse🇧🇼 · J. P. W. Diener🇧🇼

   The Relativistic Plane Wave Impulse Approximation (RPWIA) is benchmarked against the established Relativistic Distorted Wave Impulse Approximation (RDWIA) for exclusive proton-induced proton knockout reactions ($\vec{p},2\vec{p}$) from the 3s${}_{1/2}$ state in ${}^{208}$Pb at 392 MeV. While the RDWIA provides the proper description of the reaction, the RPWIA-which neglects nuclear distortion and absorption effects-fails dramatically for absolute cross-sections, requiring a scaling factor of $\frac{1}{26}$ to match the data. However, within $\pm 10$ MeV of the recoilless condition, the RPWIA quantitatively describes the analyzing power ($A_y$) data and yields similar results as the RDWIA predictions for all polarization transfer observables (D${}_{i^{\prime }j}$). These polarization transfer observables are insensitive to the choice of the Relativistic Mean Field model used. The study establishes clear boundaries for the RPWIA's utility: computationally simple predictions for polarization observables near zero recoil, but essential reliance on the RDWIA for spectroscopic factor extraction.

   ↳ nucl-thnucl-exPRC(2026)·0 citations
4. 04*

   Small $x$ behavior in QCD from maximal entanglement and conformal invariance

   Sebastian Grieninger🇺🇸 · Kun Hao🇨🇳 · Dmitri E. Kharzeev🇺🇸 · Vladimir Korepin🇺🇸

   Recent evidence suggests that, at small Bjorken $x$, QCD evolution drives the proton into a state of maximal entanglement. If the evolution kernel is assumed to be conformally invariant -- as is the case for the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation -- we can describe it by a conformal field theory. Moreover, the central charge $c$ of the corresponding conformal field theory emerges as the key parameter governing the $x$-dependence of both the entanglement entropy and the structure function. Here we apply the exact Bethe Ansatz methods to the quantum spin chain dual to Lipatov's high energy effective action to extract the central charge of the theory, and find that $c=1$. This implies the $\sim x^{-1/3}$ small $x$ behavior for the structure function -- the prediction that can be tested at the forthcoming Electron-Ion Collider.

   ↳ hep-phhep-thnucl-exnucl-th+1PRD(2026)·5 citations
5. 05*

   Neutron Dark Decay in Neutron Stars: The Role of the Symmetry Energy

   M. Divaris🇬🇷 · Ch.C. Moustakidis🇬🇷

   We conduct a systematic investigation of the influence of the nuclear symmetry energy on the proposed neutron decay into dark matter particles within the cores of neutron stars. Unlike the majority of previous studies that considered only pure neutron matter, the present analysis is extended to encompass $\beta$-stable nuclear matter. Furthermore, in relation to previous studies, the interactions between dark matter and baryons are incorporated and systematically studied regarding their effect on the structure of neutron stars. Our findings indicate that the nuclear symmetry energy plays a critical role in shaping the total equation of state (EoS) for dense neutron star matter containing dark sector components. The strength of interactions among dark matter particles, as well as between dark matter and baryons, is shown to be pivotal in determining both the composition and the macroscopic properties of neutron stars. The concurrent tuning of interaction strengths alongside the symmetry energy parameters may facilitate a more accurate reproduction of recent observational data relevant to neutron star properties. In any case, the extent to which the proposed dark decay of the neutron is affected by the extreme conditions prevailing in the interior of neutron stars remains an open problem.

   ↳ nucl-thastro-ph.SRhep-phnucl-exNucl.Theor.(2025)·2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.