Tue·Jul 26, 2022Tuesday·July 26, 2022

1. 01*

   Measurement of the Parity-Odd Angular Distribution of Gamma Rays From Polarized Neutron Capture on ${}^{35}$Cl

   N. Fomin🇺🇸 · R. Alarcon🇺🇸 · L. Alonzi🇺🇸 · E. Askanazi · S. Baeßler🇺🇸 · S. Balascuta🇷🇴 · L. Barrón-Palos🇲🇽 · A. Barzilov · D. Blyth · J.D. Bowman · N. Birge🇺🇸 · J.R. Calarco🇺🇸 and 52 other authors

   We report a measurement of two energy-weighted gamma cascade angular distributions from polarized slow neutron capture on the ${}^{35}$Cl nucleus, one parity-odd correlation proportional to $\overrightarrow{s_n}\cdot \overrightarrow{k_{\gamma }}$ and one parity-even correlation proportional to $\overrightarrow{s_n}\cdot \overrightarrow{k_n}\times \overrightarrow{k_{\gamma }}$. A parity violating asymmetry can appear in this reaction due to the weak nucleon-nucleon (NN) interaction which mixes opposite parity S and P-wave levels in the excited compound ${}^{36}$Cl nucleus formed upon slow neutron capture. If parity-violating (PV) and parity-conserving (PC) terms both exist, the measured differential cross section can be related to them via $\frac{d\sigma }{d\Omega }\propto 1+A_{\gamma ,PV}\cos \theta +A_{\gamma ,PC}\sin \theta$. The PV and PC asymmetries for energy-weighted gamma cascade angular distributions for polarized slow neutron capture on ${}^{35}$Cl averaged over the neutron energies from 2.27~meV to 9.53~meV were measured to be $A_{\gamma ,PV}=(-23.9\pm 0.7)\times 10^{-6}$ and $A_{\gamma ,PC}=(0.1\pm 0.7)\times 10^{-6}$. These results are consistent with previous experimental results. Systematic errors were quantified and shown to be small compared to the statistical error. These asymmetries in the angular distributions of the gamma rays emitted from the capture of polarized neutrons in ${}^{35}$Cl were used to verify the operation and data analysis procedures for the NPDGamma experiment which measured the parity-odd asymmetry in the angular distribution of gammas from polarized slow neutron capture on protons.

   nucl-exnucl-thPRC(2022)·2 citations
2. 02*

   Dynamical development of proton cumulants and correlation functions in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV from a multiphase transport model

   Qian Chen🇨🇳 · Guo-Liang Ma🇨🇳

   Higher-order cumulants of the distributions of conserved charges, such as net-baryon number, are sensitive to the quantum chromodynamics(QCD) phase transition and the QCD critical point. We calculate the cumulants and correlation functions of proton, antiproton, and net-proton multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV using a multiphase transport model(AMPT). The AMPT model can basically describe the trends of cumulants, cumulant ratios, (normalized) correlation functions of the proton and net-proton measured by the STAR experiment. The multiproton (baryon) correlations in the AMPT model are consistent with the expectation from baryon number conservation. We demonstrate that multiproton (baryon) correlations suffer the dynamical evolution of heavy-ion collisions. Our results provide a baseline for searching for the possible critical behaviors at the critical end point in relativistic heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exPRC(2022)·11 citations
3. 03*

   Probing initial geometrical anisotropy and final azimuthal anisotropy in heavy-ion collisions at Large Hadron Collider energies through event-shape engineering

   Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇹 · Raghunath Sahoo🇮🇳

   Anisotropic flow is accredited to have effects from the initial state geometry and fluctuations in the nuclear overlap region. The elliptic flow ($v_2$) and triangular flow ($v_3$) coefficients of the final state particles are expected to have influenced by eccentricity (${\epsilon }_2$) and triangularity (${\epsilon }_3$) of the participants, respectively. In this work, we study $v_2$, $v_3$, ${\epsilon }_2$, ${\epsilon }_3$ and the correlations among them with respect to event topology in the framework of a multi-phase transport model (AMPT). We use transverse spherocity and reduced flow vector as event shape classifiers in this study. Transverse spherocity has the unique ability to separate events based on geometrical shapes, i.e., jetty and isotropic, which pertain to pQCD and non-pQCD domains of particle production in high-energy physics, respectively. We use the two-particle correlation method to study different anisotropic flow coefficients. We confront transverse spherocity with a more widely used event shape classifier -- reduced flow vector ($q_n$) and they are found to have significant (anti-)correlations among them. We observe significant spherocity dependence on $v_2$, $v_3$ and ${\epsilon }_2$. This work also addresses transverse momentum dependent crossing points between $v_2$ and $v_3$, which varies for different centrality and spherocity percentiles.

   ↳ hep-phhep-exhep-thnucl-ex+1PRD(2023)·26 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.