Nuclear Theory·nucl-th

Wednesday·October 25, 2017

7 papers—2 primary·5 cross-listed

03
[Submitted on 20 Oct 2017] (cross-list from hep-ph)
Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at $s_{N N} = 2.76$ TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model
V.Yu. Naboka🇺🇦 · Yu.M. Sinyukov🇺🇦 · G.M. Zinovjev🇺🇦
The photon transverse momentum spectrum and its anisotropy from Pb+Pb collisions at the CERN Large Hadron Collider energy $s_{N N} = 2.76$ TeV are investigated within the integrated hydrokinetic model (iHKM). Photon production is accumulated from the different processes at the various stages of relativistic heavy ion collisions: from the primary hard photons of very early stage of parton collisions to the thermal photons from equilibrated quark-gluon and hadron gas stages. Along the way a hadronic medium evolution is treated in two distinct, in a sense opposite, approaches: chemically equilibrated and chemically frozen system expansion. Studying the centrality dependence of the results obtained allows us to conclude that a relatively strong transverse momentum anisotropy of thermal radiation is suppressed by prompt photon emission which is an isotropic. We find out that this effect is getting stronger as centrality increases because of the simultaneous increase in the relative contribution of prompt photons in the soft part of the spectra. The substantial results obtained in iHKM with nonzero viscosity ( $η / s = 0.08$ ) for photon spectra and $v_{2}$ coefficients are mostly within the error bars of experimental data, but there is some systematic underestimation of both observables for the near central events. We claim that a situation could be significantly improved if an additional photon radiation that accompanies the presence of a deconfined environment is included. Since a matter of a space-time layer where hadronization takes place is actively involved in anisotropic transverse flow, both positive contributions to the spectra and $v_{2}$ are considerable, albeit such an argument needs further research and elaboration.
Comments:
21 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1710.07689 [pdf]
PRC(2018)·11 citations
04
[Submitted on 24 Oct 2017] (cross-list from hep-ph)
Different production sources of light nuclei in relativistic heavy-ion collisions
Rui-qin Wang🇨🇳 · Jun Song🇨🇳 · Gang Li🇨🇳 · Feng-lan Shao🇨🇳
We propose a new method, i.e., an exclusive quark combination model + an inclusive hadron recombination model, to study different production sources of light nuclei in relativistic heavy-ion collisions. We take deuterons and $^{3}$ He produced in Pb-Pb collisions at $s_{N N} = 2.76$ TeV as examples to present contributions of different production sources by studying their rapidity densities $d N / d y$ , yield ratios and transverse momentum ( $p_{T}$ ) spectra just after the hadronization as well as at the final kinetic freeze-out. We find that: only very small fractions of $d$ and $^{3}$ He are created just after the hadronization; nucleons from $Δ$ resonance decays make a much larger contribution to the regeneration of light nuclei at the hadronic phase stage, and this contribution takes about 79\% and 92\% for $d$ and $^{3}$ He, respectively, observed at the final kinetic freeze-out. We also find that yield ratios $d / p$ , $^{3}$ He $/ p$ and $^{3}$ He $/ d$ are good observables to probe contributions for light nuclei from different production sources, and provide a natural explanation for constant values of $d / p$ and $^{3}$ He $/ p$ as a function of the averaged charged multiplicity measured by the ALICE Collaboration.
Comments:
12 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1710.08572 [pdf]
CPC(2019)·10 citations
05
[Submitted on 24 Oct 2017] (cross-list from hep-lat)
Thermal modifications of charmonia and bottomonia from spatial correlation functions
Heng-Tong Ding🇨🇳 · Olaf Kaczmarek🇩🇪 · Anna-lena Kruse🇩🇪 · Swagato Mukherjee🇺🇸 · Hiroshi Ohno🇺🇸 · Hauke Sandmeyer🇩🇪 · Hai-Tao Shu🇨🇳
We present our study on the thermal modifications of charmonia and bottomonia from spatial correlation functions at zero and nonzero momenta in quenched QCD. To accommodate the heavy quarks on the lattice we performed simulations on very fine lattices at a fixed beta value corresponding to a lattice spacing $a^{- 1} = 22.8$ GeV on $19 2^{3} \times 32$ , $19 2^{3} \times 48$ , $19 2^{3} \times 56$ , $19 2^{3} \times 64$ and $19 2^{3} \times 96$ lattices using clover-improved Wilson fermions. These lattices correspond to temperatures of $2.25 T_{c}$ , $1.50 T_{c}$ , $1.25 T_{c}$ , $1.10 T_{c}$ and $0.75 T_{c}$ . To increase the signal to noise ratio in the axial-vector and scalar channels we used multi-sources for the measurement of spatial correlation functions. By investigating on the differences between spatial and temporal correlators as well as the temperature dependence of screening masses we will discuss the thermal effects in different channels of quarkonium states. Besides this the dispersion relation of the screening mass at different momenta is also discussed.
Comments:
8pages, 5 figures, Proceedings of the 35rd International Symposium on Lattice Field Theory, Granada, Spain
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1710.08587 [pdf]
EPJ Web Conf.(2018)·1 citation
06
[Submitted on 24 Oct 2017] (cross-list from hep-th)
Wilson loop calculation in QGP using non-supersymmetric AdS/CFT
Somdeb Chakraborty🇮🇳 · Kuntal Nayek🇮🇳 · Shibaji Roy🇮🇳
Previously, two of the present authors obtained the decoupling limit and the corresponding throat geometry of non-supersymmetric D3 brane solution of type IIB string theory. In analogy with the supersymmetric case, it describes the gravity dual of a non-supersymmetric gauge theory with QCD-like properties such as running coupling and confinement (or mass gap) in certain range of its parameters. In this paper, we consider a `black' version of the non-supersymmetric D3 brane solution in the decoupling limit and use this gravity background to holographically compute the expectation value of a time-like Wilson loop which, in turn, is related to the potential of a heavy quark-antiquark pair. By boosting the gravity solution along one of the brane directions and placing the pair at an arbitrary orientation with this direction, we numerically obtain the variation of the screening length as well as the potential with velocity, its orientation with respect to the direction of motion and other parameters of the theory. Remarkably enough, our results are in qualitative agreement with those obtained holographically in supersymmetric gauge theories indicating that these features are quite robust and universal as they are insensitive to the presence of any supersymmetry in the theory. The physical interpretations of the variations with respect to the other parameters of the theory, not observed in supersymmetric theory, have also been given.
Comments:
21 pages, 10 figures; v2:some corrections made and a footnote added; v3: more clarifications and some references added, version to appear in Nucl. Phys. B
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1710.08631 [pdf]
NPB(2018)·11 citations
07
[Submitted on 24 Oct 2017] (cross-list from hep-ph)
Correlation of strange particles production with multiplicity in a multi-pomeron exchange model
G. Feofilov🇷🇺 · V. Kovalenko🇷🇺 · A. Puchkov (Saint Petersburg State University)🇷🇺
We propose a further development of a multi-pomeron exchange model of pp and p $p ˉ$ collisions at high energy. The model describes consistently multiplicity, transverse momentum of charged particles and their correlation in wide energy range (from ISR to LHC) by introducing string collectivity effects in pp collisions. The particles species differentiation is implemented according to Schwinger mechanism. Due to the influence of higher resonances on the yields of observed particles, we implement the production of a large set of hadron resonances with cascade decays. We present the results on pion, kaon and proton yields as a function of the collision energy and the correlation of strange and multi-strange hadrons with multiplicity and compare the results with experimental data.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1710.08895 [pdf]
3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at sNN​​=2.76 TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model

Different production sources of light nuclei in relativistic heavy-ion collisions

Thermal modifications of charmonia and bottomonia from spatial correlation functions

Wilson loop calculation in QGP using non-supersymmetric AdS/CFT

Correlation of strange particles production with multiplicity in a multi-pomeron exchange model

Affiliations

Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at $s_{N N} = 2.76$ TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model