Fri·Jul 10, 2020Friday·July 10, 2020

1. 01*

   Beam-Energy Dependence of the Directed Flow of Deuterons in Au+Au Collisions

   STAR Collaboration: J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · A. Aparin · E. C. Aschenauer · M. U. Ashraf and 351 other authors

   We present a measurement of the first-order azimuthal anisotropy, $v_1(y)$, of deuterons from Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, and 39 GeV recorded with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The energy dependence of the $v_1(y)$ slope, $d{v}_1/dy{|}_{y=0}$, for deuterons, where $y$ is the rapidity, is extracted for semi-central collisions (10-40\% centrality) and compared to that of protons. While the $v_1(y)$ slopes of protons are generally negative for $\sqrt{s_{NN}}>$ 10 GeV, those for deuterons are consistent with zero, a strong enhancement of the $v_1(y)$ slope of deuterons is seen at the lowest collision energy (the largest baryon density) at $\sqrt{s_{NN}}=$ 7.7 GeV. In addition, we report the transverse momentum dependence of $v_1$ for protons and deuterons. The experimental results are compared with transport and coalescence models.

   nucl-exPRC(2020)·25 citations
2. 02*

   Exploring the QCD phase diagram via the collision energy dependence of multi-particle femtoscopy with PHENIX

   Mate Csanad (for the PHENIX Collaboration)🇭🇺

   Exploration of the rich structure of the QCD phase diagram is an important topic in the RHIC heavy ion program. One of the ultimate goals of this program is to search for the critical endpoint. Investigation of the space-time structure of hadron emissions at various phase transition points using Bose-Einstein correlations of identical bosons may provide insight on the location of the critical endpoint. PHENIX has performed comprehensive measurements of the Bose-Einstein correlation in Au+Au collisions at sqrt(sNN) = 15, 19, 27, 39, 62.4, and 200 GeV, where we incorporated Levy-type source functions to describe the measured correlation functions. We put particular focus on one of the parameters of the Levy-type source functions, the index of stability alpha, which is related to one of the critical exponents (the so-called correlation exponent eta). We have measured its collision energy and centrality dependence. We have also extended our analysis from two-particle to three-particle correlations to characterize the nature of the hadron emission source. The three particle correlations confirmed the findings of the two-particle correlations, and also provide insight on the pion production mechanism beyond the core-halo model.

   nucl-exJ.Phys.Conf.Ser.(2020)·4 citations
3. 03*

   Scaling of Charged particle multiplicity in 28Si-nucleus interactions

   N. Ahmad🇮🇳

   Multiplicity distributions and their scaling behaviour for various types of secondary charged particles produced in 28Si-nucleus collisions at 4.5A and 14.5A GeV are investigated. The validity of KNO scaling and its generalized form has been tested by studying the parameters, Sn (z ) and Sn ( Z') The data obey KNO-G scaling for lower multiplicity events and departs from the predictions at the tails of the distributions.

   ↳ hep-exnucl-ex0 citations
4. 04*

   Measurement of inclusive J/$\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV by the STAR experiment

   STAR Collaboration: J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · A. Aparin · E. C. Aschenauer · M. U. Ashraf and 352 other authors

   We report on new measurements of inclusive J/$\psi$ polarization at mid-rapidity in p+p collisions at $\sqrt{s}$ = 200 GeV by the STAR experiment at RHIC. The polarization parameters, ${\lambda }_{\theta }$, ${\lambda }_{\varphi }$, and ${\lambda }_{\theta \varphi }$, are measured as a function of transverse momentum ($p_T$) in both the Helicity and Collins-Soper (CS) reference frames within $p_T<10$ GeV/$C$. Except for ${\lambda }_{\theta }$ in the CS frame at the highest measured $p_T$, all three polarization parameters are consistent with 0 in both reference frames without any strong $p_T$ dependence. Several model calculations are compared with data, and the one using the Color Glass Condensate effective field theory coupled with non-relativistic QCD gives the best overall description of the experimental results, even though other models cannot be ruled out due to experimental uncertainties.

   ↳ hep-exnucl-exPRD(2020)·28 citations
5. 05*

   Exploring the centrality dependence of elliptic and triangular flows

   V.L. Korotkikh🇷🇺 · A.M. Snigirev🇷🇺

   A detailed study of elliptical and triangular eccentricities in the initial state of relativistic heavy ion collisions is presented. A model of randomly distributed sources of energy density in the transverse plane based on the effective theory of Color Glass Condensate is used. This model describes well the ALICE and ATLAS data for Pb+Pb collisions at center-of-mass energy 5.02 TeV per nucleon pair in a wide range of centralities, if the second $v_2$ and third $v_3$ harmonics of the anisotropic flow are simply implied to be proportional to the eccentricities ${\epsilon }_2$ and ${\epsilon }_3$ as a reasonable approximation. The eccentricity ${\epsilon }_2$ is closely related with the collision geometry and its centrality dependence is mainly determined by the edge diffuseness of the region of the uniform distribution of the saturation pulse of the oncoming nucleus. The eccentricity ${\epsilon }_3$ is completely determined by the chaotic fluctuations of the source position in the region of overlapping nuclei and is substantially dependent on the overlap area only.

   ↳ hep-phnucl-exnucl-th0 citations
6. 06*

   Gamow-Teller strength in ${}^{48}$Ca and ${}^{78}$Ni with the charge-exchange subtracted second random-phase approximation

   D. Gambacurta🇮🇹 · M. Grasso🇫🇷 · J. Engel🇺🇸

   We develop a fully self-consistent subtracted second random-phase approximation for charge-exchange processes with Skyrme energy-density functionals. As a first application, we study Gamow-Teller excitations in the doubly-magic nucleus ${}^{48}$Ca, the lightest double-$\beta$ emitter that could be used in an experiment, and in ${}^{78}$Ni, the single-beta-decay rate of which is known. The amount of Gamow-Teller strength below 20 or 30 MeV is considerably smaller than in other energy-density-functional calculations and agrees better with experiment in ${}^{48}$Ca, as does the beta-decay rate in ${}^{78}$Ni. These important results, obtained without \textit{ad hoc} quenching factors, are due to the presence of two-particle -- two-hole configurations. Their density progressively increases with excitation energy, leading to a long high-energy tail in the spectrum, a fact that may have implications for the computation of nuclear matrix elements for neutrinoless double-$\beta$ decay in the same framework.

   ↳ nucl-thnucl-exPRL(2020)·49 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.