Fri·Jan 26, 2024Friday·January 26, 2024

1. 01*

   Long-sought isomer turns out to be the ground state of ${}^{76}$Cu

   L. Canete🇫🇮 · S. Giraud🇫🇷 · A. Kankainen🇫🇮 · B. Bastin🇫🇷 · F. Nowacki🇫🇷 · P. Ascher🇫🇷 · T. Eronen🇫🇮 · V. Girard Alcindor🇫🇷 · A. Jokinen🇫🇮 · A. Khanam🇫🇮 · I.D. Moore🇫🇮 · D. Nesterenko🇫🇮 and 8 other authors

   Isomers close to the doubly magic nucleus ${}^{78}$Ni ($Z=28$, $N=50$) provide essential information on the shell evolution and shape coexistence far from stability. The existence of a long-lived isomeric state in ${}^{76}$Cu has been debated for a long time. We have performed high-precision mass measurements of ${}^{76}$Cu with the JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line facility and confirm the existence of such a isomeric state with an excitation energy $E_x=64.8(25)$ keV. Based on the ratio of detected ground- and isomeric-state ions as a function of time, we show that the isomer is the shorter-living state previously considered as the ground state of ${}^{76}$Cu. The result can potentially change the conclusions made in previous works related to the spin-parity and charge radius of the ${}^{76}$Cu ground state. Additionally, the new ${}^{76}$Cu$(n,\gamma )$ reaction $Q$-value has an impact on the astrophysical rapid neutron-capture process.

   nucl-exPLB(2024)·3 citations
2. 02*

   Estimates of Lee-Yang zeros and a possible critical point on the pion condensate boundary in the QCD isospin phase diagram using an unbiased exponential resummation on the lattice

   Sabarnya Mitra🇮🇳

   Without invoking any cumulant determination at the input level, we present here the first calculations of direct estimates of the Lee-Yang zeros of QCD partition function in (2+1)-flavor QCD. These zeros are obtained in complex isospin chemical potential ${\mu }_I$ plane using the unbiased exponential resummation formalism on $N_{\tau }=8$ lattices and with physical quark masses. For different temperatures, we illustrate the stability of the zeros closest to the origin from which, we subsequently procure the radius of convergence estimates. From the temperature-dependence study of the real and imaginary parts of these zeros, we try estimating one of the possible critical points forming the second order pion condensate critical line in the isospin phase diagram. Further, we compare these resummed estimates with the corresponding Mercer-Roberts estimates of the subsequent Taylor series expansions of the first three partition function cumulants. We also outline comparisons between resummed and Taylor series results of these cumulants for real and imaginary values of ${\mu }_I$ and highlight the behavior of different expansion orders within and beyond the obtained resummed estimates of radius of convergence. We also re-establish that this resummed radius of convergence can efficiently capture the onset of overlap problem for finite real ${\mu }_I$ simulations.

   ↳ hep-lathep-phnucl-exnucl-thPRD(2025)·5 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.