Thu·May 20, 2021Thursday·May 20, 2021

1. 01*

   Measurements of $\Xi {\left(1530\right)}^0$ and $\overline{\Xi }{\left(1530\right)}^0$ production in proton-proton interactions at $\sqrt{s_{NN}}$ = 17.3 GeV in the NA61/SHINE experiment

   A. Acharya · H. Adhikary · K.K. Allison · N. Amin · E.V. Andronov · T. Antićić · V. Babkin · Y. Balkova M. Baszczyk · S. Bhosale · A. Blondel · M. Bogomilov · A. Brandin and 131 other authors

   Double-differential yields of $\Xi {\left(1530\right)}^0$ and $\overline{\Xi }{\left(1530\right)}^0$ resonances produced in \pp interactions were measured at a laboratory beam momentum of 158~\GeVc. This measurement is the first of its kind in \pp interactions below LHC energies. It was performed at the CERN SPS by the \NASixtyOne collaboration. Double-differential distributions in rapidity and transverse momentum were obtained from a sample of 26$\cdot$10${}^6$ inelastic events. The spectra are extrapolated to full phase space resulting in mean multiplicity of $\Xi {\left(1530\right)}^0$ (6.73 $\pm$ 0.25 $\pm$ 0.67)$\times 10^{-4}$ and $\overline{\Xi }{\left(1530\right)}^0$ (2.71 $\pm$ 0.18 $\pm$ 0.18)$\times 10^{-4}$. The rapidity and transverse momentum spectra and mean multiplicities were compared to predictions of string-hadronic and statistical model calculations.

   nucl-exhep-exEPJC(2021)·11 citations
2. 02*

   Symmetry energy at high densities from neutron/proton flow excitation functions

   P. Russotto🇮🇹 · A. Le Fèvre🇩🇪 · J. Łukasik🇵🇱 · K. Boretzky🇩🇪 · M.D. Cozma🇷🇴 · E. De Filippo🇮🇹 · I. Gašparić🇭🇷 · Y. Leifels🇩🇪 · I. Lihtar🇭🇷 · S. Pirrone🇮🇹 · G. Politi🇮🇹 · W. Trautmann🇩🇪

   Determination of the high density behavior of the symmetry energy through the simultaneous measurement of elliptic flow excitation functions of neutrons, protons and light clusters is proposed. The elliptic flow developed in relativistic heavy ion collisions has been proven theoretically and experimentally to have a unique sensitivity and robustness in probing the symmetry energy up to around $2{\rho }_o$. The knowledge of the density dependence of the symmetry energy in a broad range of densities will provide a missing link for astrophysical predictions of the neutron star mass--radius relation. In particular, the data colud provide tighter constraints on the slope parameter L and entirely new limits on $K_{sym}$, the currently poorly constrained symmetry energy curvature parameter.

   nucl-ex12 citations
3. 03*

   Heavy baryon spectrum with chiral multiplets of scalar and vector diquarks

   Yonghee Kim🇯🇵 · Yan-Rui Liu🇨🇳 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵

   Chiral effective theory of scalar and vector diquarks is formulated according to the linear sigma model. The main application is to describe the ground and excited states of singly heavy baryons with a charm or bottom quark. Applying the potential quark model between the diquark and the heavy quark ($Q=c,b$), we construct a heavy-quark--diquark model. The spectra of the positive- and negative-parity states of ${\Lambda }_Q$, ${\Sigma }_Q$, ${\Xi }_Q^{{(}^{\prime })}$ and ${\Omega }_Q$ are obtained. The masses and interaction parameters of the effective theory are fixed partly from the lattice QCD data and also from fitting low-lying heavy baryon masses. We find that the negative parity excited states of ${\Xi }_Q$ (flavor $\bar{3}$) are different from those of ${\Lambda }_Q$, because of the inverse hierarchy of the pseudoscalar diquark. On the other hand, ${\Sigma }_Q,{\Xi }_Q^{\prime }$ and ${\Omega }_Q$ (flavor $6$) baryons have similar spectra. We compare our results of the heavy-quark--diquark model with experimental data as well as the quark model.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·27 citations
4. 04*

   High sensitivity characterization of an ultra-high purity NaI(Tl) crystal scintillator with the SABRE proof-of-principle detector

   F. Calaprice🇺🇸 · S. Copello🇮🇹 · I. Dafinei🇮🇹 · D. D'Angelo🇮🇹 · G. D'Imperio🇮🇹 · G. Di Carlo🇮🇹 · M. Diemoz🇮🇹 · A. Di Giacinto🇮🇹 · A. Di Ludovico🇺🇸 · A. Ianni🇮🇹 · M. Iannone🇮🇹 · F. Marchegiani🇮🇹 and 14 other authors

   We present new results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator operated in the SABRE proof-of-principle detector setup. The amount of potassium contamination, determined by the direct counting of radioactive ${}^{40}$K, is found to be $2.2\pm 1.5$ ppb, lowest ever achieved for NaI(Tl) crystals. With the active veto, the average background rate in the crystal in the 1-6 keV energy region-of-interest (ROI) is $1.20\pm 0.05$ counts/day/kg/keV, which is a breakthrough since the DAMA/LIBRA experiment. Our background model indicates that the rate is dominated by ${}^{210}$Pb and that about half of this contamination is located in the PTFE reflector. We discuss ongoing developments of the crystal manufacture aimed at the further reduction of the background, including data from purification by zone refining. A projected background rate lower than $\sim$0.2 counts/day/kg/keV in the ROI is within reach. These results represent a benchmark for the development of next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles.

   ↳ physics.ins-dethep-exnucl-exPRD(2021)·21 citations
5. 05*

   Impact of a positron beam at JLab on an unbiased determination of DVCS Compton Form Factors

   H. Dutrieux🇫🇷 · V. Bertone🇫🇷 · H. Moutarde🇫🇷 · P. Sznajder🇵🇱

   The impact of potential future measurements of beam charge asymmetries on the current knowledge of Compton form factors is evaluated. Elaborating on the results of a global neural network fit to deeply virtual Compton scattering data, a Bayesian reweighting analysis quantifies the improved determination of the real part of the Compton form factor $\mathcal{H}$. Such an improvement is particularly relevant for the experimental determination of the proton mechanical properties or for universality studies of generalized parton distributions through analyses of virtual Compton scattering in both spacelike and timelike regions.

   ↳ hep-phhep-exnucl-exEPJA(2021)·11 citations
6. 06*

   Fission fragment distributions of neutron-rich nuclei based on Langevin calculations: toward r-process simulations

   Mizuki Okubayashi🇯🇵 · Shoya Tanaka🇯🇵 · Yoshihiro Aritomo🇯🇵 · Shoma Ishizaki🇯🇵 · Shota Amano🇯🇵 · Nobuya Nishimura🇯🇵

   The nuclear fission of very neuron-rich nuclei related to the r-process is essential for the termination of nucleosynthesis flows on the nuclear chart and the final abundances. Nevertheless, most of the available fission data for the r-process calculations are based on theory predictions, including phenomenological treatments. In this study, we calculated a series of nuclear fission distribution for neutron-rich nuclei away from the beta-stability line. As most of these nuclei are experimentally unknown, we are based on theoretical calculations based on the dynamical fission model with the Langevin method. We performed fission distribution calculations for neutron-rich actinoid nuclei, applicable to the r-process nucleosynthesis simulations. In the present paper, we compared the obtained mass and charge distributions with experimental data. We also show the results of the systematic behaviour of mass distribution for neutron-rich U and Fm isotopes.

   ↳ nucl-thastro-ph.HEastro-ph.SRnucl-ex0 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.