Fri·Oct 6, 2023Friday·October 6, 2023

1. 01*

   Hypertriton lifetime

   D. Gazda🇨🇿 · A. Pérez-Obiol🇪🇸 · A. Gal🇮🇱 · E. Friedman🇮🇱

   Over the last decade, conflicting values of the hypertriton ${}_{\Lambda }^3\mathrm{H}$ lifetime $\tau ({}_{\Lambda }^3\mathrm{H})$ were extracted from relativistic heavy-ion (RHI) collision experiments, ranging from values compatible with the free-$\Lambda$ lifetime ${\tau }_{\Lambda }$-as expected naively for a very weakly bound $\Lambda$ in ${}_{\Lambda }^3\mathrm{H}$-to lifetimes as short as $\tau ({}_{\Lambda }^3\mathrm{H})\approx (0.4-0.7){\tau }_{\Lambda }$. In a recent work [Phys. Lett. B 811, 135916 (2020)] we studied this ${}_{\Lambda }^3\mathrm{H}$ lifetime puzzle theoretically using realistic three-body ${}_{\Lambda }^3\mathrm{H}$ and ${}^3\mathrm{He}$ wave functions computed within the ab initio no-core shell model approach with interactions derived from chiral effective field theory. In particular, $\tau ({}_{\Lambda }^3\mathrm{H})$ was found to be strongly correlated with the $\Lambda$ separation energy $B_{\Lambda }$ in ${}_{\Lambda }^3\mathrm{H}$, the value of which is rather poorly known experimentally and, in addition, is known to suffer from sizable theoretical uncertainties inherent in the employed nuclear and hypernuclear interaction models. In the present work we find that these uncertainties propagate into $\tau ({}_{\Lambda }^3\mathrm{H})$, and thus limit considerably the theoretical precision of its computed value. Although none of the conflicting RHI measured $\tau ({}_{\Lambda }^3\mathrm{H})$ values can be excluded, but rather can be attributed to a poor knowledge of $B_{\Lambda }$, we note the good agreement between the lifetime value $\tau ({}_{\Lambda }^3\mathrm{H})=238(27)$ ps computed at the lowest value $B_{\Lambda }=66$ keV reached by us and the very recent ALICE measured lifetime value ${\tau }^{\mathrm{ALICE}}({}_{\Lambda }^3\mathrm{H})=253(11)(6)$ ps associated with the ALICE measured $B_{\Lambda }$ value $B_{\Lambda }^{\mathrm{ALICE}}=102(63)(67)$ keV [Phys. Rev. Lett. 131, 102302 (2023)].

   ↳ nucl-thhep-phnucl-exPRC(2024)·5 citations
2. 02*

   Study of azimuthal anisotropy of ${\rm Y}$(1S) mesons in pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

   CMS Collaboration

   The azimuthal anisotropy of ${\rm Y}$(1S) mesons in high-multiplicity proton-lead collisions is studied using data collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 8.16 TeV. The ${\rm Y}$(1S) mesons are reconstructed using their dimuon decay channel. The anisotropy is characterized by the second Fourier harmonic coefficients, found using a two-particle correlation technique, in which the ${\rm Y}$(1S) mesons are correlated with charged hadrons. A large pseudorapidity gap is used to suppress short-range correlations. Nonflow contamination from the dijet background is removed using a low-multiplicity subtraction method, and the results are presented as a function of ${\rm Y}$(1S) transverse momentum. The azimuthal anisotropies are smaller than those found for charmonia in proton-lead collisions at the same collision energy, but are consistent with values found for ${\rm Y}$(1S) mesons in lead-lead interactions at a nucleon-nucleon center-of-mass energy of 5.02 TeV.

   ↳ hep-exnucl-exPLB(2024)·10 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.