Tue·Nov 12, 2024Tuesday·November 12, 2024

1. 01*

   Mass measurements of neutron-rich nuclides using the Canadian Penning Trap to inform predictions in the $r$-process rare-earth peak region

   D. Ray🇨🇦 · N. Vassh🇨🇦 · B. Liu🇺🇸 · A.A. Valverde🇺🇸 · M. Brodeur🇺🇸 · J.A. Clark · G.C. McLaughlin🇺🇸 · M.R. Mumpower🇺🇸 · R. Orford🇺🇸 · W.S. Porter🇺🇸 · G. Savard🇺🇸 · K. S. Sharma🇨🇦 and 16 other authors

   Studies aiming to determine the astrophysical origins of nuclei produced by the rapid neutron capture process ($r$ process) rely on nuclear properties as inputs for simulations. The solar abundances can be used as a benchmark for such calculations, with the $r$-process rare-earth peak (REP) around mass number ($A$) 164 being of special interest due to its presently unknown origin. With the advancement of rare isotope beam production over the last decade and improvement in experimental sensitivities, many of these REP nuclides have become accessible for measurement. Masses are one of the most critical inputs as they impact multiple nuclear properties, namely the neutron-separation energies, neutron capture rates, $\beta$-decay rates, and $\beta$-delayed neutron emission probabilities. In this work, we report masses of 20 neutron-rich nuclides (along the Ba, La, Ce, Pr, Nd, Pm, Gd, Dy and Ho isotopic chains) produced at the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The masses were measured with the Canadian Penning trap (CPT) mass spectrometer using the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique. We then use these new masses along with previously published CPT masses to inform predictions for a Markov Chain Monte Carlo (MCMC) procedure aiming to identify the astrophysical conditions consistent with both solar data and mass measurements. We show that the MCMC responds to this updated mass information, producing refined results for both mass predictions and REP abundances.

   nucl-exnucl-th5 citations
2. 02*

   Study of baryon-strangeness and charge-strangeness correlations in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV with ALICE

   Swati Saha (for the ALICE Collaboration)🇮🇳

   In the quest to unravel the mysteries of the strong force and the underlying properties of the quark-gluon plasma, the ALICE collaboration at CERN has carried out a comprehensive study focusing on the correlations between net-conserved quantities such as net-baryon, net-charge and net-strangeness. These correlations play a crucial role in the study of QCD phase structure as they are closely related to the ratios of thermodynamic susceptibilities in lattice QCD calculations. This work mainly focuses on the correlations between net-kaon and net-proton, and net-kaon and net-charge in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV using data recorded during LHC Run 2. The net-proton and net-kaon serve as proxies for net-baryon and net-strangeness, respectively, with measurements analyzed as a function of collision centrality. Theoretical predictions from the Thermal-FIST model are compared with experimental results, providing insights into the effects of resonance decays and charge conservation laws on the correlations.

   nucl-exhep-exEPJ Web Conf.(2025)·2 citations
3. 03*

   Proton emission in ultraperipheral Pb-Pb collisions at $\sqrt{{\text{s}}_{\text{NN}}}=5.02$ TeV

   ALICE Collaboration

   The first measurements of proton emission accompanied by neutron emission in the electromagnetic dissociation (EMD) of ${}^{208}$Pb nuclei in the ALICE experiment at the LHC are presented. The EMD protons and neutrons emitted at very forward rapidities are detected by the proton and neutron Zero Degree Calorimeters of the ALICE experiment. The emission cross sections of zero, one, two, and three protons accompanied by at least one neutron were measured in ultraperipheral ${}^{208}$Pb--${}^{208}$Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The 0p and 3p cross sections are described by the RELDIS model within their measurement uncertainties, while the 1p and 2p cross sections are underestimated by the model by 17-25%. According to this model, these 0p, 1p, 2p, and 3p cross sections are associated, respectively, with the production of various isotopes of Pb, Tl, Hg, and Au in the EMD of ${}^{208}$Pb. The cross sections of the emission of a single proton accompanied by the emission of one, two, or three neutrons in EMD were also measured. The data are significantly overestimated by the RELDIS model, which predicts that the (1p,1n), (1p,2n), and (1p,3n) cross sections are very similar to the cross sections for the production of the thallium isotopes ${}^{206,205,204}$Tl.

   nucl-exhep-exPRC(2025)·11 citations
4. 04*

   Measurements of differential two-particle number and transverse momentum correlation functions in pp collisions at $\sqrt{\text{s}}$ = 13 TeV

   ALICE Collaboration

   Differential two-particle normalized cumulants ($R_2$) and transverse momentum correlations ($P_2$) are measured as a function of the relative pseudorapidity and azimuthal angle difference $(\Delta \eta ,\Delta \phi )$ of charged particle pairs in minimum bias pp collisions at $\sqrt{\text{s}}$ = 13 TeV. The measurements use charged hadrons in the pseudorapidity region of $|\eta |<0.8$ and the transverse momentum range \mbox{0.2 $<{\text{p}}_{\mathrm{T}}<$ 2.0 $\mathrm{GeV}/\text{c}$} in order to focus on soft multiparticle interactions and to complement prior measurements of these correlation functions in p-Pb and Pb-Pb collisions. The correlation functions are reported for both unlike-sign and like-sign pairs and their charge-independent and charge-dependent combinations. Both the $R_2$ and $P_2$ measured in pp collisions exhibit features qualitatively similar to those observed in p--Pb and Pb--Pb collisions. The $\Delta \eta$ and $\Delta \phi$ root mean square widths of the near-side peak of the correlation functions are evaluated and compared with those observed in p-Pb and Pb-Pb collisions and show smooth evolution with the multiplicity of charged particles produced in the collision. The comparison of the measured correlation functions with predictions from PYTHIA8 shows that this model qualitatively captures their basic structure and characteristics but feature important differences. In addition, the $R_2^{\mathrm{CD}}$ is used to determine the charge balance function of hadrons produced within the detector acceptance of the measurements. The integral of the balance function is found to be compatible with those reported by a previous measurement in Pb--Pb collisions.

   nucl-exhep-exEPJC(2025)·6 citations
5. 05*

   Suppression of Spin Transfer to $\Lambda$ Hyperon in Deep-Inelastic Scattering

   Xiaoyan Zhao🇨🇳 · Zuo-tang Liang🇨🇳 · Tianbo Liu🇨🇳 · Ya-jin Zhou🇨🇳

   We investigate $\Lambda$ production in semi-inclusive deep-inelastic scattering using a polarized lepton beam and find that the spin transfer is significantly suppressed by target fragmentation. As further demonstrated by a model estimation, experimental data can be well described once the target fragmentation is taken into account, which alleviates the tension with calculations solely based on current fragmentation. Our findings suggest that, at the energies of existing fixed-target experiments, the separation of current and target fragmentation regions is not distinct. Spin transfer as well as other spin effects offers a sensitive probe into the origin of the produced hadron.

   ↳ hep-phhep-exnucl-exPRL(2025)·8 citations
6. 06*

   Heavy Flavor Production at the Large Hadron Collider: A Machine Learning Approach

   Raghunath Sahoo🇮🇳

   Charmonia suppression has been considered as a smoking gun signature of quark-gluon plasma. However, the Large Hadron Collider has observed a lower degree of suppression as compared to the Relativistic Heavy Ion Collider energies, due to regeneration effects in heavy-ion collisions. Though proton collisions are considered to be the baseline measurements to characterize a hot and dense medium formation in heavy-ion collisions, LHC proton collisions with its new physics of heavy-ion-like QGP signatures have created new challenges. To understand this, the inclusive charmonia production at the forward rapidities in the dimuon channel is compared with the corresponding measurements in the dielectron channel at the midrapidity as a function of final state charged particle multiplicity. None of the theoretical models quantitatively reproduce the experimental findings leaving out a lot of room for theory. To circumvent this and find a reasonable understanding, we use machine learning tools to separate prompt and nonprompt charmonia and open charm mesons using the decay daughter track properties and the decay topologies of the mother particles. Using PYTHIA8 data, we train the machine learning models and successfully separate prompt and nonprompt charm hadrons from the inclusive sample to study various directions of their production dynamics. This study enables a domain of using machine learning techniques, which can be used in the experimental analysis to better understand charm hadron production and build possible theoretical understanding.

   ↳ hep-phhep-exnucl-exnucl-th0 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.