Thu·Jun 19, 2025Thursday·June 19, 2025

1. 01*

   Charged-particle production in pp collisions at 13.6 TeV and Pb-Pb collisions at 5.36 TeV with ALICE

   Tulika Tripathy (for the ALICE collaboration)🇫🇷

   The first measurements of the charged-particle pseudorapidity density, $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta$, in proton-proton (pp) collisions at $\sqrt{s}=$ 13.6 TeV and in lead-lead (Pb-Pb) collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.36 TeV are presented. The analysis is based on Run 3 data recorded in 2022 and 2023, using the upgraded ALICE detector at the LHC. The average charged-particle pseudorapidity density $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta ⟩$ in pp collisions was measured at midrapidity ($|\eta |<$0.5) with the upgraded central barrel detectors, such as the Inner Tracking System and the Time Projection Chamber and, at forward pseudorapidity ($-$3.6 $<|\eta |<-$ 2.4), using the newly installed Muon Forward Tracker (MFT). For Pb-Pb collisions, the measurement was performed in different centrality classes, ranging from the most central 0-5$\%$) to the peripheral (70-80$\%$) collisions.

   nucl-exhep-ex0 citations
2. 02*

   Ambiguities in the Partial-Wave Analysis of the Photoproduction of Pairs of Pseudoscalar Mesons

   J. Guo🇺🇸 · E. Barriga🇺🇸 · K. Scheuer🇺🇸 · A. Austregesilo🇺🇸 · P. Eugenio🇺🇸 · D. I. Glazier🇬🇧 · B. Grube🇺🇸 · W. Imoehl🇺🇸 · C. A. Meyer🇺🇸 · A. Ostrovidov🇺🇸 · J. R. Stevens🇺🇸

   Applying the technique of partial-wave analysis, there are cases where more than one set of underlying complex-valued amplitudes can describe the measured observables. These ambiguities can sometimes be resolved using additional information, but assumptions are often required. It is known that the partial-wave analysis of two-pseudoscalar meson systems produced in photoproduction with a linearly polarized photon beam is free from discrete ambiguities stemming from the Barrelet zeros when the nucleon spin is ignored. In this article, we show that continuous ambiguities are possible for certain wave sets, even though the discrete ambiguities do not appear. We also explore ways to resolve these ambiguities and determine the maximal amount of information that can be obtained from analyses that suffer from these continuous ambiguities.

   ↳ hep-phnucl-exnucl-thPRD(2025)·1 citation
3. 03*

   Low-metallicity nova explosions: a site for weak rp-process nucleosynthesis

   Athanasios Psaltis🇨🇦 · Jordi José · Richard Longland🇺🇸 · Christian Iliadis🇺🇸

   Classical novae are common cataclysmic events involving a binary system of a white dwarf and a main sequence or red giant companion star. In metal-poor environments, these explosions produce ejecta different from their solar counterparts due to the accretion of sub-solar metallicity material onto the white dwarf. In particular, it has been suggested that the nucleosynthesis flow in such low-metallicity nova explosions extends up to the Cu-Zn region, much beyond the expected endpoint, around Ca, predicted for solar-metallicity classical novae. This behavior resembles a weak rp-process, and such nuclear activity has never been observed in accreting white dwarf binaries with typical accretion flows. In this work, we study the characteristics of the weak rp-process for four nova models with metallicities $Z=2\times 10^{-9}$, $10^{-7}$, $2\times 10^{-6}$, and $2\times 10^{-5}$, and explore the impact of the nuclear physics uncertainties via a Monte Carlo sensitivity study. We identify nuclear reactions whose uncertainties affect the production of intermediate-mass nuclei under these conditions. These reactions and relevant nuclear quantities are targets for measurements at stable or radioactive beam facilities to reduce their rate uncertainties.

   ↳ astro-ph.HEastro-ph.SRnucl-exApJ(2025)·6 citations
4. 04*

   Manifestation of quark effects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering

   Sergei P. Maydanyuk (1 and 2)🇨🇳 · K. Tsushima (3)🇧🇷 · G. Ramalho (4)🇰🇷 · Peng-Ming Zhang (5) ((1) Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences, Huizhou, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, 03680, Ukraine, (3) Laboratório de Física Teórica e Computacional - LFTC, Programa de Pósgraduação em Astrofísica e Física Computacional, Universidade Cidade de São Paulo, 01506-000 São Paulo, São Paulo, Brazil, (4) Department of Physics and OMEG Institute, Soongsil University, Seoul, Republic of Korea, (5) School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai, China)🇨🇳

   \textbf{Background} (1) The incoherent emission of photons is dominant comparing to coherent one in proton-nucleus scattering. The incoherent bremsstrahlung is very sensitive to the magnetic moments of nucleons in nuclei. (2) According to the quark-meson coupling (QMC) model, the nucleon magnetic moments in nuclei are enhanced relative to those in vacuum, originating from the quark structure of nucleons. \textbf{Purpose} Investigate possibilities of observing quark effects in nuclei by the analysis of bremsstrahlung in nuclear reactions. \textbf{Methods} Analyse the bremsstrahlung cross sections with established model in proton-nucleus scattering, by extending with inclusion of in-medium modified nucleon magnetic moments in nuclei by the QMC model. \textbf{Results} (1) After calibrating the model without the quark effects for experimental data (TAPS Collaboration data for $p+\text{isotope}[197]Au$), we calculate the cross sections and observe the slight difference between the spectra for models with and without quark effects. Such result is found for the first time, confirming possibilities of observing the quark effects in the spectra of bremsstrahlung. (2) As found, quark effects are not enough to be observed in middle and heavy nuclei, as they have dominant incoherent contributions. (3) \isotope[18]{C} has minimal incoherent contribution concerning other carbon isotopes, where the quark effects should be minimal. In ratios between the spectra for \isotope[18]{C} and \isotope[12]{C} with and without the quark effects the difference is clearly observed. \textbf{Conclusions} We establish the new physical observable for the quark effects in nuclei in the bremsstrahlung accompanied in the nuclear reactions, which can be measured. The present suggestion is for the first time in both theoretically and experimentally to study the quark effects in nuclei via the bremsstrahlung.

   ↳ nucl-thhep-phnucl-exPLB(2026)·2 citations
5. 05*

   Towards a microscopic description of nucleus-nucleus collisions

   Matteo Vorabbi🇺🇸 · Michael Gennari🇩🇪 · Paolo Finelli🇮🇹 · Carlotta Giusti🇮🇹 · Petr Navrátil🇨🇦

   We present the first results of a comprehensive microscopic approach to describe nucleus-nucleus elastic collisions by means of an optical potential derived at first order in multiple-scattering theory and computed by folding the projectile and target nuclear densities with the nucleon-nucleon $t$ matrix, which describes the interaction between each nucleon of the projectile and each nucleon of the target. Chiral interactions are consistently used in the calculation of the $t$ matrix and of the nonlocal nuclear densities, which are computed within the ab initio no-core shell model. Cross sections calculated for $\alpha$ collisions on ${}^{12}$C and ${}^{16}$O at projectile energies in the range 100-300 MeV are presented and compared with available data. For momentum transfer $q$ up to about $1.0$ fm${}^{-1}$ our results are in good agreement with the experimental data, whereas for higher momenta a reduction of the imaginary contributions is needed.

   ↳ nucl-thnucl-exPRL(2025)·4 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.