Thu·Feb 27, 2020Thursday·February 27, 2020

1. 01*

   In-Medium Jet Modification Measured by PHENIX Via two-particle Correlations and High $p_T$ Hadrons in $A+A$ Collisions

   Anthony Hodges · PHENIX Collaboration

   The first evidence of jet quenching was observed at RHIC via suppression of single high $p_T$ hadron $R_{AA}$ and the disappearance of the away-side jet peak in two-particle correlations. Since then, hadron $R_{AA}$ and two-particle correlations continue to be useful probes of the QGP in heavy ion collisions, since the particles involved are fragments of the jets produced in the initial hard scattering. PHENIX recently improved the width measurements extracted from ${\pi }^0$-hadron correlations after removing the higher order flow terms in the underlying event subtraction. Measurements of the away-side jet correlated with high $p_T$ neutral pions show an increase in low momentum particle production at wide angles consistent with theoretical expectations for energy loss. The system size dependence of energy loss is further investigated at PHENIX by measuring the absolute yield and $R_{AA}$ for various hadron species at high $p_T$ in several collision systems including $U+U$ and $Cu+Au$. These proceedings will present the newest PHENIX $R_{AA}$ and two-particle correlation measurements and their role in our understanding of jet quenching and medium response in heavy ion collisions

   nucl-exNPA(2021)·0 citations
2. 02*

   Wood-Saxon alpha potential for p-nuclei ${}^{106}$Cd and ${}^{113}$In

   Dipali Basak · Chinmay Basu

   Alpha elastic scattering of p-nuclei were studied for calculating optical potentials. Choice of the $\alpha$-optical potentials are important to measure the reaction rates of p-process. ${}^{106}$Cd$(\alpha ,\alpha {)}^{106}$Cd and ${}^{113}$In$(\alpha ,\alpha {)}^{113}$In elastic scattering cross-section data were used to determine the potential parameter sets at E${}_{lab}$= 16.1-27 MeV for ${}^{106}$Cd and E${}_{lab}$=16.14, 19.4 MeV for ${}^{113}$In system. A Wood-Saxon potential form factor is used for both real and imaginary part. The potential parameters extracted in the present study exhibit a satisfactory result with respect to existing global potential parameters.

   nucl-exnucl-thIJMPE(2020)·1 citation
3. 03*

   Measurement of the charge separation along the magnetic field with Signed Balance Function in 200 GeV Au + Au collisions at STAR

   Yufu Lin (for the STAR Collaboration)🇨🇳

   Experimental searches for Chiral Magnetic Effect (CME) in heavy-ion collisions have been going on for a decade, and so far there is no conclusive evidence for its existence. Recently, the Signed Balance Function (SBF), based on the idea of examining the momentum ordering of charged pairs along the in- and out-of-plane directions, has been proposed as a probe of CME. In this approach, a pair of observables is invoked: one is $r_{\mathrm{rest}}$, the out-of-plane to in-plane ratio of $\Delta B$ measured in pair's rest frame, where $\Delta B$ is the difference between signed balance functions; The other is a double ratio, $R_{\mathrm{B}}=r_{\mathrm{rest}}/r_{\mathrm{lab}}$, where $r_{\mathrm{lab}}$ is a measurement similar to $r_{\mathrm{rest}}$ but measured in the laboratory frame. These two observables give opposite responses to the CME-driven charge separation compared to the background correlations arising from resonance flow and global spin alignment. Both $r_{\mathrm{rest}}$ and $R_{\mathrm{B}}$ being larger than unity can be regarded as a case in favor of the existence of CME. It is found experimentally that $r_{\mathrm{rest}}$, $r_{\mathrm{lab}}$ and $R_{\mathrm{B}}$ are larger than unity in Au+Au collisions at 200 GeV, and larger than realistic model calculations with no CME implemented. These findings are difficult to be explained by a background-only scenario.

   nucl-exhep-exhep-phnucl-thNPA(2021)·8 citations
4. 04*

   Heavy Quark Energy Loss in the Quark-Gluon Plasma in the Moller theory

   B. Blok (Technion)🇮🇱

   We study the energy loss of a heavy quark propagating in the Quark-Gluon Plasma (QGP) in the framework of the Moller theory, including possible large Coulomb logarithms as a perturbation to BDMPSZ bremsstrahlung, described in the Harmonic Oscillator (HO) approximation. We derive the analytical expression that describes the energy loss in the entire emitted gluon frequency region. In the small frequencies region, for angles larger than the dead cone angle, the energy loss is controlled by the BDMPSZ mechanism, while for larger frequencies it is described by N=1 term in the GLV opacity expansion. We estimate corresponding quenching rates for different values of the heavy quark path and different $m/E$ ratios.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2020)·5 citations
5. 05*

   Reconstructing particle number distributions with convoluting volume fluctuations

   ShinIchi Esumi🇯🇵 · Kana Nakagawa🇯🇵 · Toshihiro Nonaka🇨🇳

   We propose methods to reconstruct particle distributions with and without considering initial volume fluctuations. This approach enables us to correct for detector efficiencies and initial volume fluctuations simultaneously. Our study suggests such a tool could investigate the possible bimodal structure of net-proton distribution in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$7.7 GeV a signature of first-order phase transition and critical point [arXiv:1804.04463,arXiv:1811.04456].

   ↳ physics.data-anhep-phnucl-exNucl.Instrum.Meth.A(2021)·14 citations
6. 06*

   Higher-order cumulants of net-charge distributions from local charge conservation

   Igor Altsybeev🇷🇺

   In studies of heavy-ion collisions, fluctuations of conserved quantities are considered as an important signal of the transition between the hadronic and partonic phases of nuclear matter. In this paper, it is investigated how the local charge conservation affects higher-order cumulants of net-charge distributions at LHC energies. Simple expressions for the cumulants are derived under the assumption that particle-antiparticle pairs are produced in local processes from sources that are nearly uncorrelated in rapidity. For calculations with these expressions, one needs to know only the second cumulant of net-charge distribution and low-order cumulants of particle number distribution, which are directly measurable experimentally. It is argued that if one wishes to relate susceptibilities with cumulants of net-proton distributions, the developed model provides a better baseline than the conventional Skellam limit or models based on monte-carlo simulations.

   ↳ nucl-thhep-exnucl-exPoS(2022)·4 citations
7. 07*

   Estimations of Cross-Sections for Photonuclear Reaction on Calcium Isotopes by Artificial Neural Networks

   S. Akkoyun · H. Kaya

   The nuclear reaction induced by photon is one of the important tools in the investigation of atomic nuclei. In the reaction, a target material is bombarded by photons with high-energies in the range of gamma-ray energy range. In the bombarding process, the photons can statistically be absorbed by a nucleus in the target material. Then the excited nucleus can decay by emitting proton, neutron, alpha and light particles or photons. By performing photonuclear reaction on the target, it can be easily investigated low-lying excited states of the nuclei. In the present work, ({\gamma}, n) photonuclear reaction cross-sections on different calcium isotopes have been estimated by using artificial neural network method. The method is a mathematical model that mimics the brain functionality of the creatures. The correlation coefficient values of the method for both training and test phases being 0.99 indicate that the method is very suitable for this purpose.

   ↳ nucl-thnucl-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.