Fri·Aug 16, 2024Friday·August 16, 2024

1. 01*

   Collective behaviour in proton number fluctuations seen in $\sqrt{s_{NN}}=$ 2.4 GeV Au+Au collisions

   Ali Bazgir🇵🇱 · Maciej Rybczynski🇵🇱 · Uzair A. Shah🇵🇱 · Zbigniew Wlodarczyk🇵🇱

   At energies of a few GeV per nucleon, nuclear collisions exhibit phenomena more complex than the individualistic nucleon interactions observed at much higher energies. From recent results on proton number fluctuations in Au + Au collisions at $\sqrt{s_{NN}}=2.4$~GeV obtained by the HADES experiment at GSI, we suggest that measuring the multiplicity distributions heavy-ion collisions can be used to probe density fluctuations associated with correlation phenomena. By using the combinant analysis, one can obtain new information contained in them and otherwise unavailable, which may broaden our knowledge of the particle interactions mechanism.

   ↳ nucl-thhep-phnucl-exPLB(2024)·0 citations
2. 02*

   Ab initio computations from ${}^{78}$Ni towards ${}^{70}$Ca along neutron number $N=50$

   B. S. Hu🇨🇦 · Z. H. Sun · G. Hagen🇺🇸 · G. R. Jansen🇺🇸 · T. Papenbrock🇺🇸

   We present coupled-cluster computations of nuclei with neutron number $N=50$ "south" of ${}^{78}$Ni using nucleon-nucleon and three-nucleon forces from chiral effective field theory. We find an erosion of the magic number $N=50$ toward ${}^{70}$Ca manifesting itself by an onset of deformation and increased complexity in the ground states. For ${}^{78}$Ni, we predict a low-lying rotational band consistent with recent data, which up until now has been a challenge for ab initio nuclear models. Ground states are deformed in ${}^{76}$Fe, ${}^{74}$Cr, and ${}^{72}$Ti, although the spherical states are too close in energy to unambiguously identify the shape of the ground state within the uncertainty estimates. In ${}^{70}$Ca, the potential energy landscape from quadrupole-constrained Hartree-Fock computations flattens, and the deformation becomes less rigid. We also compute the low-lying spectra and $B(E2)$ values for these neutron-rich $N=50$ nuclei.

   ↳ nucl-thnucl-exPLB(2024)·18 citations
3. 03*

   Bayesian Inference analysis of jet quenching using inclusive jet and hadron suppression measurements

   R. Ehlers🇺🇸 · Y. Chen🇺🇸 · J. Mulligan🇺🇸 · Y. Ji🇺🇸 · A. Kumar🇨🇦 · S. Mak🇺🇸 · P. M. Jacobs🇺🇸 · A. Majumder🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · R. Datta🇺🇸 and 41 other authors

   The JETSCAPE Collaboration reports a new determination of the jet transport parameter $\hat{q}$ in the Quark-Gluon Plasma (QGP) using Bayesian Inference, incorporating all available inclusive hadron and jet yield suppression data measured in heavy-ion collisions at RHIC and the LHC. This multi-observable analysis extends the previously published JETSCAPE Bayesian Inference determination of $\hat{q}$, which was based solely on a selection of inclusive hadron suppression data. JETSCAPE is a modular framework incorporating detailed dynamical models of QGP formation and evolution, and jet propagation and interaction in the QGP. Virtuality-dependent partonic energy loss in the QGP is modeled as a thermalized weakly-coupled plasma, with parameters determined from Bayesian calibration using soft-sector observables. This Bayesian calibration of $\hat{q}$ utilizes Active Learning, a machine--learning approach, for efficient exploitation of computing resources. The experimental data included in this analysis span a broad range in collision energy and centrality, and in transverse momentum. In order to explore the systematic dependence of the extracted parameter posterior distributions, several different calibrations are reported, based on combined jet and hadron data; on jet or hadron data separately; and on restricted kinematic or centrality ranges of the jet and hadron data. Tension is observed in comparison of these variations, providing new insights into the physics of jet transport in the QGP and its theoretical formulation.

   ↳ hep-phnucl-exnucl-thPRC(2025)·56 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.