Tue·Feb 4, 2020Tuesday·February 4, 2020

1. 01*

   Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory

   S. Al Kharusi🇨🇦 · G. Anton🇩🇪 · I. Badhrees🇨🇦 · P.S. Barbeau🇺🇸 · D. Beck🇺🇸 · V. Belov🇷🇺 · T. Bhatta🇺🇸 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · G.F. Cao🇨🇳 · W.R. Cen🇨🇳 · C. Chambers🇨🇦 and 96 other authors

   We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden non-unique $\beta$-decay transition ${}^{137}\text{Xe}(7/2^{-})\to {}^{137}\text{Cs}(7/2^{+})$. The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultra-low background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal-to-background ratio of more than 99-to-1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden non-unique $\beta$-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

   nucl-exnucl-thPRL(2020)·11 citations
2. 02*

   Higher harmonic non-linear flow modes of charged hadrons in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   Anisotropic flow coefficients, $v_n$, non-linear flow mode coefficients, ${\chi }_{n,mk}$, and correlations among different symmetry planes, ${\rho }_{n,mk}$ are measured in Pb-Pb collisions at \sqrt{s_\rm{NN}}=5.02 TeV. Results obtained with multi-particle correlations are reported for the transverse momentum interval 0.2<p_\rm{T}<5.0 GeV/$c$ within the pseudorapidity interval $0.4<|\eta |<0.8$ as a function of collision centrality. The $v_n$ coefficients and ${\chi }_{n,mk}$ and ${\rho }_{n,mk}$ are presented up to the ninth and seventh harmonic order, respectively. Calculations suggest that the correlations measured in different symmetry planes and the non-linear flow mode coefficients are dependent on the shear and bulk viscosity to entropy ratios of the medium created in heavy-ion collisions. The comparison between these measurements and those at lower energies and calculations from hydrodynamic models places strong constraints on the initial conditions and transport properties of the system.

   nucl-exhep-exJHEP(2020)·64 citations
3. 03*

   Coupling of shape and pairing vibrations in a collective Hamiltonian based on nuclear energy density functionals

   J. Xiang · Z. P. Li · T. Niksic🇭🇷 · D. Vretenar🇭🇷 · W. H. Long🇨🇳

   The quadrupole collective Hamiltonian, based on relativistic energy density functionals, is extended to include a pairing collective coordinate. In addition to quadrupole shape vibrations and rotations, the model describes pairing vibrations and the coupling between shape and pairing degrees of freedom. The parameters of the collective Hamiltonian are determined by constrained self-consistent relativistic mean-field plus Bardeen-Cooper-Schrieffer (RMF+BCS) calculations in the space of intrinsic shape and pairing deformations. The effect of coupling between shape and pairing degrees of freedom is analyzed in a study of low-energy spectra and transition rates of four axially symmetric $N=92$ rare-earth isotones. When compared to results obtained with the standard quadrupole collective Hamiltonian, the inclusion of dynamical pairing increases the moment of inertia, lowers the energies of excited $0^{+}$ states and reduces the E0-transition strengths, in better agreement with data.

   ↳ nucl-thnucl-exPRC(2020)·21 citations
4. 04*

   NA61/SHINE shining more light on the onset of deconfinement

   Maciej P. Lewicki🇵🇱 · Ludwik Turko🇵🇱

   NA61/SHINE has recently completed data acquisition for its original programme on strong interactions. The Collaboration has gathered rich data on collisions of ions in a two-dimensional scan: varying the beam energy and the sizes of colliding nuclei. The most recent analysis of hadron production in ${}^{40}$Ar+${}^{45}$Sc and ${}^7$Be+${}^9$Be interactions deliver some puzzling results which none of the theoretical models can reproduce.

   ↳ hep-exnucl-exCERN EP Newsletter, December 2019, p. 67-…·7 citations
5. 05*

   Thermal modifications of quarkonia and heavy quark diffusion from a comparison of continuum-extrapolated lattice results to perturbative QCD

   Anna-Lena Lorenz🇩🇪 · Heng-Tong Ding🇨🇳 · Olaf Kaczmarek🇩🇪 · Hiroshi Ohno🇯🇵 · Hauke Sandmeyer🇩🇪 · Hai-Tao Shu🇩🇪

   We investigate the in-medium modifications of heavy quarkonia in the vector channel and the heavy quark diffusion coefficient by comparing Euclidean correlators from the lattice to a perturbative spectral function. On the lattice side, we work with continuum extrapolated data from four different large and fine lattices with Clover-improved Wilson fermions in the quenched approximation at five temperatures (0.75, 1.1, 1.3, 1.5 and 2.25$T_c$). On the perturbative side, we use a combination of pNRQCD and vacuum asymptotics to describe the spectral function. After accounting for systematic errors, we obtain a spectral function that is suited to describe the bound state region. This spectral function describes charmonium well without a resonance peak at any of our analyzed temperatures above $T_c$, while we observe a thermally broadened resonance peak for bottomonium that is only melted at our largest temperature, $2.25T_c$. For the transport contribution we assume a Breit-Wigner shaped peak and find that the drag coefficient of charm quarks is larger than that of bottom quarks.

   ↳ hep-lathep-phnucl-exnucl-thPoS(2020)·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.