Nuclear Theory·nucl-th

Tuesday·December 29, 2015

19 papers—12 primary·7 cross-listed

13
Surprisingly large uncertainties in temperature extraction from thermal fits to hadron yield data at LHC
Volodymyr Vovchenko🇩🇪 · Horst Stoecker🇩🇪
The conventional hadron-resonance gas (HRG) model with the Particle Data Group (PDG) hadron input, full chemical equilibrium, and the hadron type dependent eigenvolume interactions is employed to fit the hadron mid-rapidity yield data of ALICE Collaboration for the most central Pb+Pb collisions. For the case of point-like hadrons the well-known fit result $T = 154 \pm 2$ MeV is reproduced. However, the situation changes if hadrons have different eigenvolumes. In the case when all mesons are point-like while all baryons have an effective hard-core radius of 0.3 fm the $χ^{2}$ temperature dependence of the $χ^{2}$ has a broad minimum in the temperature range of $155 - 210$ MeV, with fit quality comparable to the $T \sim 155$ MeV minimum in the point-particle case. Very similar result is obtained when only baryon-baryon eigenvolume interactions are considered, with eigenvolume parameter taken from previous fit to ground state of nuclear matter. Finally, when we apply the eigenvolume corrections with mass-proportional eigenvolume $v_{i} \sim m_{i}$ , fixed to particular proton hard-core radius $r_{p}$ , we observe a second minimum in the temperature dependence of the $χ^{2}$ , located at the significantly higher temperatures. For instance, at $r_{p} = 0.5$ fm the fit quality is better than in the point-particle HRG case in a very wide temperature range of $170 - 320$ MeV, which gives an uncertainty in the temperature determination from the fit to the data of 150 MeV. These results show that thermal fits to the heavy-ion hadron yield data are very sensitive to the modeling of the short-range repulsion eigenvolume between hadrons, and that chemical freeze-out temperature can be extracted from the LHC hadron yield data only with sizable uncertainty.
↳ hep-phhep-exhep-latnucl-ex+1J.Phys.G(2017)·47 citations
14
Origins of the di-jet asymmetry in heavy ion collisions
José Guilherme Milhano🇨🇭 · Korinna Christine Zapp🇨🇭
The di-jet asymmetry --- the measure of the momentum imbalance in a di-jet system --- is a key jet quenching observable. Using the event generator \jewel we show that the di-jet asymmetry is dominated by fluctuations both in proton-proton and in heavy ion collisions. We discuss how in proton-proton collisions the asymmetry is generated through recoil and out-of-cone radiation. In heavy ion collisions two additional sources contribute to the asymmetry, namely energy loss fluctuations and differences in path length. The latter is shown to be a sub-leading effect. We discuss the implications of our results for the interpretation of this observable.
↳ hep-phnucl-exnucl-thEPJC(2016)·130 citations
15
Spin Physics through QCD Instantons
Yachao Qian🇺🇸 · Ismail Zahed🇺🇸
We review some aspects of spin physics where QCD instantons play an important role. In particular, their large contributions in semi-inclusive deep-inelastic scattering and polarized proton on proton scattering. We also review their possible contribution in the $P$ -odd pion azimuthal charge correlations in peripheral $AA$ scattering at collider energies.
↳ hep-phnucl-thAnnals Phys.(2016)·13 citations
16
Strange matter and strange stars in a thermodynamically self-consistent perturbation model with running coupling and running strange quark mass
J. F. Xu🇨🇳 · G. X. Peng🇨🇳 · F. Liu🇨🇳 · D. F. Hou🇨🇳 · L. W. Chen🇨🇳
A quark model with running coupling and running strange quark mass, which is thermodynamically self-consistent at both high and lower densities, is presented and applied to study properties of strange quark matter and structure of compact stars. An additional term to the thermodynamic potential density is determined by meeting the fundamental differential equation of thermodynamics. It plays an important role in comparatively lower density and ignorable at extremely high density, acting as a chemical-potential dependent bag constant. In this thermodynamically enhanced perturbative QCD model, strange quark matter still has the possibility of being absolutely stable, while the pure quark star has a sharp surface with a maximum mass as large as about 2 times the solar mass and a maximum radius of about 11 kilometers.
↳ hep-phastro-ph.SRnucl-thPRD(2015)·48 citations
17
Entropic destruction of a moving heavy quarkonium
Kazem Bitaghsir Fadafan🇮🇷 · Seyed Kamal Tabatabaei🇮🇷
Recently it has been shown that the peak of the quarkonium entropy at the deconfinement transition is related to the emergent entropic force which destructs the quarkonium. Using the AdS/CFT correspondence, we consider dissociation of a moving heavy quarkonium by entropic force. We find that the entropic force destructs the moving quarkonium easier than the static case which is expected from perturbative weakly coupled plasma. By considering the Maxwell charge, we study the effect of medium on the destruction of heavy quarkonium. It is shown that the quarkonium dissociates easier in the medium.
↳ hep-phhep-lathep-thnucl-thPRD(2016)·38 citations
18
Heavy ion collisions and cosmology
Stefan Floerchinger🇩🇪
There are interesting parallels between the physics of heavy ion collisions and cosmology. Both systems are out-of-equilibrium and relativistic fluid dynamics plays an important role for their theoretical description. From a comparison one can draw interesting conclusions for both sides. For heavy ion physics it could be rewarding to attempt a theoretical description of fluid perturbations similar to cosmological perturbation theory. In the context of late time cosmology, it could be interesting to study dissipative properties such as shear and bulk viscosity and corresponding relaxation times in more detail. Knowledge and experience from heavy ion physics could help to constrain the microscopic properties of dark matter from observational knowledge of the cosmological fluid properties.
↳ hep-phnucl-thNPA(2016)·4 citations
19
The Polyakov loop at next-to-next-to leading order
Matthias Berwein🇩🇪 · Nora Brambilla🇩🇪 · Peter Petreczky🇺🇸 · Antonio Vairo🇩🇪
We calculate the next-to-next-to-leading correction to the expectation value of the Polyakov loop or equivalently to the free energy of a static charge. This correction is of order $g^{5}$ . We show that up to this order the free energy of the static charge is proportional to the quadratic Casimir operator of the corresponding representation. We also compare our perturbative result with the most recent lattice results in SU(3) gauge theory.
↳ hep-phhep-lathep-thnucl-thPRD(2016)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE

Surprisingly large uncertainties in temperature extraction from thermal fits to hadron yield data at LHC

Origins of the di-jet asymmetry in heavy ion collisions

Spin Physics through QCD Instantons

Strange matter and strange stars in a thermodynamically self-consistent perturbation model with running coupling and running strange quark mass

Entropic destruction of a moving heavy quarkonium

Heavy ion collisions and cosmology

The Polyakov loop at next-to-next-to leading order

Affiliations