Mon·Feb 24, 2020Monday·February 24, 2020

1. 01*

   Nuclear modification factors, directed and elliptic flow of electrons from open heavy flavor decays in Au+Au collisions from STAR

   Matthew Kelsey🇺🇸

   We present the analyses of single electrons from semileptonic bottom and charm hadron decays at mid-rapidity in $\sqrt{s_{NN}}$ = 200 and 54.4 GeV Au+Au collisions (talk in Heavy-Flavor session III). The data at $\sqrt{s_{NN}}$ = 200 GeV incorporate information from the Heavy Flavor Tracker which enables the topological separation of electrons originating from bottom and charm hadron decays. We report the first STAR measurements at $\sqrt{s_{NN}}$ = 200 GeV of $v_2$ for bottom decay electrons as a function of $p_T$ and $v_1$ for charm decay electrons as a function of electron rapidity. Additionally, we present the improved measurements of heavy-flavor decay electron $R_{AA}$ and a new measurement of the ratio of $R_{CP}$ between bottom and charm decay electrons. Finally, we also report the measurement of non-photonic electron $v_2$ in $\sqrt{s_{NN}}$ = 54.4 GeV data collected during the 2017 RHIC run.

   nucl-exhep-exNPA(2021)·6 citations
2. 02*

   Strangeness in Nuclei and Neutron Stars

   Laura Tolos🇩🇪 · Laura Fabbietti🇩🇪

   We review the present status of the experimental and theoretical developments in the field of strangeness in nuclei and neutron stars. We start by discussing the $\bar{K}N$ interaction, that is governed by the presence of the $\Lambda (1405)$. We continue by showing the two-pole nature of the $\Lambda (1405)$, and the production mechanisms in photon-, pion-, kaon-induced reactions as well as proton-proton collisions, while discussing the formation of $\bar{K}NN$ bound states. We then move to the theoretical and experimental analysis of the properties of kaons and antikaons in dense nuclear matter, paying a special attention to kaonic atoms and the analysis of strangeness creation and propagation in nuclear collisions. Next, we examine the $\varphi$ meson and the advances in photoproduction, proton-induced and pion-induced reactions, so as to understand its properties in dense matter. Finally, we address the dynamics of hyperons with nucleons and nuclear matter, and the connection to the phases of dense matter with strangeness in the interior of neutron stars.

   nucl-exhep-exhep-phnucl-thPPNP(2020)·312 citations
3. 03*

   Quasi-$\gamma$ band in ${}^{\text{114}}$Te

   Prithwijita Ray · H. Pai · Sajad Ali · Anjali Mukherjee · A. Goswami · S. Rajbanshi · S. Chakraborty · G. Gangopadhyay · Md. S. R. Laskar · R. Palit · G. H. Bhat · S. Jehangir and 7 other authors

   The low-lying non-yrast states in ${}^{114}$Te have been investigated using the Indian National Gamma Array through the fusion-evaporation reaction ${}^{112}$Sn(${}^4$He, 2n) at a beam energy of 37 MeV. Eight new $\gamma$-transitions have been placed in the level scheme to establish the quasi-$\gamma$ band in this nucleus. Spin and parity of several excited states have been assigned from the present spectroscopy measurements. The comparison of experimental results on the observed bands with the Interacting Boson Model (IBM) and Triaxial Projected Shell Model (TPSM) confirming the existence of the quasi-$\gamma$ band structure in the ${}^{114}$Te nucleus.

   nucl-exnucl-thPRC(2020)·13 citations
4. 04*

   Search for CME in U+U and Au+Au collisions in STAR with different approaches of handling backgrounds

   Jie Zhao (for the STAR collaboration)🇺🇸

   The chiral magnetic effect (CME) refers to charge separation along a strong magnetic field between left- and right-handed quarks, caused by interactions with topological gluon fields from QCD vacuum fluctuations. We present two approaches to handle the dominant elliptic flow ($v_2$) background in the three-particle correlator ($\Delta {\gamma }_{112}$), sensitive to CME. In the first approach, we present the $\Delta {\gamma }_{112}$ and $\Delta {\gamma }_{123}$ measurements in U+U and Au+Au collisions. While hydrodynamic simulations including resonance decays and local charge conservation predict that $\Delta {\gamma }_{112}$ scaled by $N_{\mathrm{part}}/v_2$ will be similar in U+U and Au+Au collisions, the projected B-field exhibits a distinct difference between the two systems and with varying $N_{\mathrm{part}}$. Therefore, U+U and Au+Au collisions provide configurations with different expectations for both CME signal and background. Moreover, the three-particle observable $\Delta {\gamma }_{123}$ scaled by $N_{\mathrm{part}}/v_3$ provide baseline measurement for only the background. In the second approach, we handle the $v_2$ background by measuring $\Delta {\gamma }_{112}$ with respect to the planes of spectators measured by Zero Degree Calorimeters and participants measured by Time Projection Chamber. These measurements contain different amounts of contributions from CME signal (along B-field, due to spectators) and $v_2$ background (determined by the participant geometry). With the two $\Delta {\gamma }_{112}$ measurements, the possible CME signal and the background contribution can be determined. We report such a measurement in Au+Au collisions at $\sqrt{s_{NN}}=$ 27 GeV with the newly installed event plane detector, and report the new findings in U+U system where the spectator-participant plane correlations are expected to differ from those in Au+Au collisions.

   nucl-exnucl-thNPA(2021)·11 citations
5. 05*

   Improved search for two body muon decay ${\mu }^{+}\to e^{+}{X}_H$

   A. Aguilar-Arevalo🇲🇽 · M. Aoki🇯🇵 · M. Blecher🇺🇸 · D.I. Britton🇬🇧 · D. vom Bruch🇨🇦 · D.A. Bryman🇨🇦 · S. Chen🇨🇳 · J. Comfort🇺🇸 · S. Cuen-Rochin🇨🇦 · L. Doria🇩🇪 · P. Gumplinger🇨🇦 · A. Hussein🇨🇦 and 12 other authors

   Charged lepton flavor violating muon decay ${\mu }^{+}\to e^{+}{X}_H$, where $X_H$ is a massive neutral boson, was sought by searching for extra peaks in the muon decay ${\mu }^{+}\to e^{+}\nu \bar{\nu }$ energy spectrum in the $m_{X_H}$ mass region $47.8-95.1$ MeV/$c^2$. No signal was found and 90% confidence level upper limits were set on the branching ratio $\Gamma ({\mu }^{+}\to e^{+}{X}_H)/\Gamma ({\mu }^{+}\to e^{+}\nu \bar{\nu })$ at the level of $10^{-5}$ for this region.

   ↳ hep-exnucl-exPRD(2020)·35 citations
6. 06*

   Measurements of ZnWO${}_4$ anisotropic response to nuclear recoils for the ADAMO project

   P. Belli🇮🇹 · R. Bernabei🇮🇹 · F. Cappella🇮🇹 · V. Caracciolo🇮🇹 · R. Cerulli🇮🇹 · N. Cherubini🇮🇹 · F.A. Danevich🇺🇦 · A. Incicchitti🇮🇹 · D.V. Kasperovych🇺🇦 · V. Merlo🇮🇹 · E. Piccinelli🇮🇹 · O.G. Polischuk🇺🇦 · V.I. Tretyak🇺🇦

   Anisotropic scintillators can offer a unique possibility to exploit the so-called directionality approach in order to investigate the presence of those Dark Matter (DM) candidates inducing nuclear recoils. In fact, their use can overcome the difficulty of detecting extremely short nuclear recoil traces. In this paper we present recent measurements performed on the anisotropic response of a ZnWO${}_4$ crystal scintillator to nuclear recoils, in the framework of the ADAMO project. The anisotropic features of the ZnWO${}_4$ crystal scintillators were initially measured with $\alpha$ particles; those results have been also confirmed by the additional measurements presented here. The experimental nuclear recoil data were obtained by using a neutron generator at ENEA-CASACCIA and neutron detectors to tag the scattered neutrons; in particular, the quenching factor values for nuclear recoils along different crystallographic axes have been determined for three different neutron scattering angles (i.e. nuclear recoils energies). From these measurements, the anisotropy of the light response for nuclear recoils in the ZnWO${}_4$ crystal scintillator has been determined at 5.4 standard deviations.

   ↳ physics.ins-dethep-exnucl-exEPJA(2020)·30 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.