Nuclear Theory·nucl-th

Friday·June 28, 2019

10 papers—6 primary·4 cross-listed

07
Critical behavior of the bulk viscosity in QCD
Mauricio Martinez🇺🇸 · Thomas Schaefer🇺🇸 · Vladimir Skokov🇺🇸
We study the behavior of the bulk viscosity $ζ$ in QCD near a possible critical endpoint in the phase diagram. We verify the expectation that $(ζ / s) \sim a (ξ / ξ_{0})^{x_{ζ}}$ , where $s$ is the entropy density, $ξ$ is the correlation length, $ξ_{0}$ is the non-critical correlation length, $a$ is a constant and $x_{ζ} ≃ 3$ . Using a recently developed equation of state that includes a critical point in the universality class of the Ising model we estimate the constant of proportionality $a$ . We find that $a$ is typically quite small, $a \sim O (1 0^{- 4})$ . We observe, however, that the result is sensitive to the commonly made assumption that the Ising temperature axis is approximately aligned with the QCD baryon chemical potential axis. If this is not the case, then the critical $ζ / s$ can approach the non-critical value of $η / s$ , where $η$ is the shear viscosity, even if the enhancement of the correlation length is modest, $ξ / ξ_{0} \sim 2$ .
↳ hep-phnucl-thPRD(2019)·48 citations
08
Experimental searches for the chiral magnetic effect in heavy-ion collisions
Jie Zhao🇺🇸 · Fuqiang Wang🇺🇸
The chiral magnetic effect (CME) in quantum chromodynamics (QCD) refers to a charge separation (an electric current) of chirality imbalanced quarks generated along an external strong magnetic field. The chirality imbalance results from interactions of quarks, under the approximate chiral symmetry restoration, with metastable local domains of gluon fields of non-zero topological charges out of QCD vacuum fluctuations. Those local domains violate the $P$ and $C P$ invariance, potentially offering a solution to the strong $C P$ problem in explaining the magnitude of the matter-antimatter asymmetry in today's universe. Relativistic heavy-ion collisions, with the likely creation of the high energy density quark-gluon plasma and restoration of the approximate chiral symmetry, and the possibly long-lived strong magnetic field, provide a unique opportunity to detect the CME. Early measurements of the CME-induced charge separation in heavy-ion collisions are dominated by physics backgrounds. Major efforts have been devoted to eliminate or reduce those backgrounds. We review those efforts, with a somewhat historical perspective, and focus on the recent innovative experimental undertakings in the search for the CME in heavy-ion collisions.
↳ nucl-exhep-exhep-phnucl-thPPNP(2019)·123 citations
09
Theoretical study of $^{173}$ YbOH to search for the nuclear magnetic quadrupole moment
Daniel E. Maison🇷🇺 · Leonid V. Skripnikov🇷🇺 · Victor V. Flambaum🇦🇺
CP-violating interaction of the nuclear magnetic quadrupole moment (MQM) with electrons in the ytterbium mono-hydroxide molecule, $^{173}$ YbOH, is considered. Both the magnetic quadrupole moment (MQM) of the $^{173}$ Yb nucleus and the molecular interaction constant WM are estimated. Electron correlation effects are taken into account within the relativistic Fock-space coupled cluster method. Results are interpreted in terms of the strength constants of CP-violating nuclear forces, neutron EDM, QCD vacuum angle $θ$ , quark EDM and chromo-EDM.
↳ physics.atom-phhep-phnucl-thPRA(2019)·47 citations
10
A look at multiplicity distributions via modified combinants
M.Rybczynski🇵🇱 · Z.Wlodarczyk🇵🇱 · G.Wilk🇵🇱
The experimentally measured multiplicity distributions exhibit, after closer inspection, peculiarly enhanced void probability and oscillatory behavior of the modified combinants. We show that both these features can be used as additional sources of information, not yet fully explored, on the mechanism of multiparticle production. We provide their theoretical understanding within the class of compound distributions.
↳ hep-phnucl-thUkr.J.Phys.(2019)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Critical behavior of the bulk viscosity in QCD

Experimental searches for the chiral magnetic effect in heavy-ion collisions

Theoretical study of 173YbOH to search for the nuclear magnetic quadrupole moment

A look at multiplicity distributions via modified combinants

Affiliations

Theoretical study of $^{173}$ YbOH to search for the nuclear magnetic quadrupole moment