Fri·Jul 8, 2016Friday·July 8, 2016

1. 01*

   Hydrodynamic flow amplitude correlations in event-by-event fluctuating heavy-ion collisions

   Jing Qian🇨🇳 · Ulrich Heinz🇺🇸

   The effects of event-by-event fluctuations in the initial geometry of the colliding nuclei are important in the analysis of final flow observables in relativistic heavy-ion collisions. We use hydrodynamic simulations to study the amplitude correlations between different orders of event-by-event fluctuating anisotropic flow harmonics. While the general trends seen in the experimental data are qualitatively reproduced by the model, deviations in detail, in particular for peripheral collisions, point to the need for more elaborate future calculations with a hybrid approach that describes the late hadronic stage of the evolution microscopically. It is demonstrated explicitly that the observed anti-correlation between $v_2$ and $v_3$ is the consequence of approximately linear hydrodynamic response to a similar anti-correlation of the corresponding initial eccentricities ${ϵ}_2$ and ${ϵ}_3$. For $n>3$, the hydrodynamic correlations between $v_{2,3}$ and $v_n$ deviate from the rescaled correlations among the corresponding initial eccentricities, demonstrating nonlinear mode coupling effect in higher order flows.

   ↳ nucl-thhep-phnucl-exPRC(2016)·39 citations
2. 02*

   Resonance decay effect on conserved number fluctuations in a hadron resonance gas model

   D. K. Mishra🇮🇳 · P. Garg🇺🇸 · P. K. Netrakanti🇮🇳 · A. K. Mohanty🇮🇳

   We study the effect of charged secondaries coming from resonance decay on the net-baryon, net-charge and net-strangeness fluctuations in high energy heavy-ion collisions within the hadron resonance gas (HRG) model. We emphasize the importance of including weak decays along with other resonance decays in the HRG, while comparing with the experimental observables. The effect of kinematic cuts on resonances and primordial particles on the conserved number fluctuations are also studied. The HRG model calculations with the inclusion of resonance decays and kinematical cuts are compared with the recent experimental data from STAR and PHENIX experiments. We find a good agreement between our model calculations and the experimental measurements for both net-proton and net-charge distributions.

   ↳ hep-phnucl-exnucl-thPRC(2016)·31 citations
3. 03*

   Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions

   Lin Chen🇨🇳 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳 · Han-Zhong Zhang🇨🇳

   Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in $pp$ and peripheral $AA$ collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening $⟨p_{\perp }^2⟩$ and the so-called jet quenching parameter $\hat{q}$ can be extracted from the angular de-correlations observed in $AA$ collisions. A global ${\chi }^2$ analysis of dihadron and hadron-jet angular correlation data renders the best fit $⟨p_{\perp }^2⟩\sim 13{\text{GeV}}^2$ for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.

   ↳ hep-phnucl-exnucl-thPLB(2017)·91 citations
4. 04*

   On the structure observed in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction at J-PARC

   Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. amd Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U. and ICC, Barcelona U.)🇪🇸

   A theoretical investigation is done to clarify the origin of the peak structure observed near the $K^{-}pp$ threshold in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction of the J-PARC E15 experiment, which could be a signal of the lightest kaonic nuclei, that is, the $\bar{K}NN(I=1/2)$ state. For the investigation, we evaluate the $\Lambda p$ invariant mass spectrum assuming two possible scenarios to interpret the experimental peak. One assumes that the $\Lambda (1405)$ resonance is generated after the emission of an energetic neutron from the absorption of the initial $K^{-}$, not forming a bound state with the remaining proton. This uncorrelated $\Lambda (1405)p$ system subsequently decays into the final $\Lambda p$. The other scenario implies that, after the emission of the energetic neutron, a $\bar{K}NN$ bound state is formed, decaying eventually into a $\Lambda p$ pair. Our results show that the experimental signal observed in the in-flight ${}^3\text{He}(K^{-},\Lambda p)n$ reaction at J-PARC is qualitatively well reproduced by the assumption that a $\bar{K}NN$ bound state is generated in the reaction, definitely discarding the interpretation in terms of an uncorrelated $\Lambda (1405)p$ state.

   ↳ hep-phnucl-exnucl-thPTEP(2016)·58 citations
5. 05*

   Testing the running coupling $k_T$-factorization formula for the inclusive gluon production

   F.O. Durães🇧🇷 · A.V. Giannini🇧🇷 · V.P. Goncalves🇧🇷 · F.S. Navarra🇧🇷

   The inclusive gluon production at midrapidities is described in the Color Glass Condensate formalism using the $k_T$ - factorization formula, which was derived at fixed coupling constant considering the scattering of a dilute system of partons with a dense one. Recent analysis demonstrated that this approach provides a satisfactory description of the experimental data for the inclusive hadron production in $pp/pA/AA$ collisions. However, these studies are based on the fixed coupling $k_T$ - factorization formula, which does not take into account the running coupling corrections, which are important to set the scales present in the cross section. In this paper we consider the running coupling corrected $k_T$ - factorization formula conjectured some years ago and investigate the impact of the running coupling corrections on the observables. In particular, the pseudorapidity distributions and charged hadrons multiplicity are calculated considering $pp$, $dAu/pPb$ and $AuAu/PbPb$ collisions at RHIC and LHC energies. We compare the corrected running coupling predictions with those obtained using the original $k_T$ - factorization assuming a fixed coupling or a prescription for the inclusion of the running of the coupling. Considering the Kharzeev - Levin - Nardi unintegrated gluon distribution and a simplified model for the nuclear geometry, we demonstrate that the distinct predictions are similar for the pseudorapidity distributions in $pp/pA/AA$ collisions and for the charged hadrons multiplicity in $pp/pA$ collisions. On the other hand, the running coupling corrected $k_T$ - factorization formula predicts a smoother energy dependence for $dN/d\eta$ in $AA$ collisions.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2016)·17 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.