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Nikita Tsegelnik

Publications and source records attributed to Nikita Tsegelnik.

2 recordsLinked to original sources

The Static Heavy Quark-Antiquark Potential within String Theory in Arbitrary Stationary Backgrounds

We consider a static open string in arbitrary stationary spacetime, which can represent a heavy quark-antiquark pair within the holographic framework or effective theory. Generally, the string profile is not symmetric with respect to the turning point, and the symmetry restores for a simple string configuration in backgrounds with certain constraints. We identify a wide family of metrics for which the symmetry is preserved, enabling a direct isolation of the linear-in-distance term in the static potential for simple symmetric string configurations, even in non-diagonal backgrounds. As a first example, we apply our formulas to the black brane dual to the $\mathcal{N}=4$ SYM plasma at finite temperature. We find that the separation distance between quarks, $L$, is given in terms of a hypergeometric function, while the potential, $V$, consists of two distinct contributions: a term linear in the separation and a term that involves its derivative by temperature. Analysis of the leading terms in the series expansion reveals that the temperature corrections of the separation distance leads to the "swallowtail" behavior. Further, applying our formulas to the Rindler-AdS spacetime dual to an accelerated $\mathcal{N}=4$ SYM plasma, we obtain analytic expressions for the distance and potential in terms of the elliptic integrals, which in the large Hawking temperature (large acceleration or small curvature) limit come to the conformal results for pure AdS. Then, we show that the distance between quarks decreases, the static potential between them increases, and the characteristic temperatures increase with an acceleration, $a_c$. However, we observe that an acceleration-scaled potential, $a_c V$, as a function of the acceleration-scaled distance, $a_c L$, does not depend on the certain value of the acceleration.

hep-th↗

$Λ$ and $\overlineΛ$ Freeze-Out Distributions and Global Polarizations in Au+Au Collisions

The gold--gold collisions at $\sqrt{s_{NN}}=7.7$ and $11.5$GeV are simulated within the PHSD transport model. In each collision event, the spectator nucleons are separated and the fluidization procedure for the participants is performed. The local velocities are determined in the Landau frame and the kinematic and thermal vorticity fields are evaluated. We analyze the thermodynamic properties of the cells where $Λ$s and $\overlineΛ$s were born or had their last interaction. Such cells contribute to the formation of the observed global polarization of hyperons induced by the thermal vorticity of the medium. The $\overlineΛ$ polarization signal is found to be mainly determined by hot, dense, and highly vortical cells at the earlier stage of the collision, whereas the $Λ$ polarization signal is accumulated over the longer time and includes cells with lower vorticity. The calculated global polarizations for both $Λ$s and $\overlineΛ$s agree well with the experimental finding by the STAR collaboration at energy $\sqrt{s_{NN}}=11.5$GeV. For collisions at $\sqrt{s_{NN}}=7.7$GeV, we can reproduce the STAR data for $Λ$ hyperons, but significantly underpredict the observed global polarization of $\overlineΛ$. Furthermore, we consider the centrality dependence of the hyperon polarization in collisions at 7.7GeV. It increases with an increase of centrality, reaches a maximum at 65--75%, and then starts decreasing rapidly for peripheral collisions.

nucl-th↗