Fri·Nov 29, 2019Friday·November 29, 2019

1. 01*

   First direct measurement of the intrinsic dipole moment in pear-shaped thorium isotopes

   M. M. R. Chishti · D. O'Donnell🇬🇧 · G. Battaglia · M. Bowry🇨🇦 · D. A. Jaroszynski🇬🇧 · B. S. Nara Singh🇬🇧 · M. Scheck🇬🇧 · P. Spagnoletti🇬🇧 · J. F. Smith🇬🇧

   It is now well established that atomic nuclei composed of certain combinations of protons and neutrons can adopt reflection-asymmetric, or octupole-deformed, shapes at low excitation energy. These nuclei show promise in the search for a permanent atomic electric dipole moment, the existence of which has implications for physics beyond the Standard Model. Theoretical studies have suggested that certain isotopes of thorium may have the largest octupole deformation. However, due to experimental challenges, the extent of the octupole collectivity in the low-energy states in these thorium nuclei has not yet been demonstrated. This paper reports measurements of the lifetimes of low-energy states in 228Th (Z = 90) undertaken using the mirror symmetric centroid difference method, which is a direct electronic fast-timing technique. Lifetime measurements of the low-lying Jp = 1- and 3- states, which are the first for a thorium isotope, have allowed the B(E1) rates and the intrinsic dipole moment to be determined. The results are in agreement with those of previous theoretical calculations allowing the extent of the octupole deformation of 228Th to be estimated. This study indicates that the nuclei 229Th and 229Pa (Z = 91) may be good candidates for the search for a permanent atomic electric dipole moment.

   nucl-exNat.Phys.(2020)·55 citations
2. 02*

   J/$\psi$p Scattering Length from GlueX Threshold Measurements

   Igor Strakovsky (GWU)🇺🇸 · Denis Epifanov (Budker Ins)🇷🇺 · Lubomir Pentchev (JLab)🇺🇸

   The quality of the recent GlueX $J/\psi$ photoproduction data from Hall~D at Jefferson Laboratory, and the proximity of the data to the energy threshold, gives access to a variety of interesting physics aspects. As an example, an estimation of the $J/\psi$-nucleon scattering length ${\alpha }_{J/\psi p}$ is provided within the vector meson dominance model. It results in $|{\alpha }_{J/\psi p}|=(3.08\pm 0.55(stat.)\pm 0.45(syst.))$~mfm.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2020)·48 citations
3. 03*

   Studying the effect of the hadronic phase in nuclear collisions with PYTHIA and UrQMD

   André Vieira da Silva🇧🇷 · Christian Bierlich🇩🇰 · David Dobrigkeit Chinellato🇧🇷 · Jun Takahashi🇧🇷

   In this work, we couple Pb-Pb events simulated with the PYTHIA Angantyr event generator at $\sqrt{s_{\mathrm{NN}}}=2.76$ and $5.02$~TeV with the hadronic cascade simulator UrQMD to study the effect of the hadronic phase on observables such as charged-particle multiplicity densities, transverse momentum spectra and identified particle ratios, giving special emphasis to short-lived resonances.

   ↳ nucl-thnucl-exSpringer Proc.Phys.(2020)·6 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.