Holographic bottomonium formation in a cooling strong-interaction medium at finite baryon density

TL;DR

This paper models how bottomonium states form and narrow in a cooling, dense quark-gluon medium using holography, showing that baryon density lowers the formation temperature of these states.

Contribution

It introduces a holographic model adjusted to lattice QCD and experimental data to study bottomonium formation at finite baryon density and temperature.

Findings

Narrow bottomonium states emerge at about 150 MeV at zero baryon density.

Excited states form at slightly lower temperatures, decreasing with higher baryon density.

Baryon density shifts formation temperatures downward by approximately 15 MeV at 200 MeV chemical potential.

Abstract

The shrinking of the bottomonium spectral function towards narrow quasi-particle states in a cooling strong-interaction medium at finite baryon density is followed within a holographic bottom-up model. The 5-dimensional Einstein-dilaton-Maxwell background is adjusted to lattice-QCD results of sound velocity and susceptibilities. The zero-temperature bottomonium spectral function is adjusted to experimental $\Upsilon$ ground-state mass and first radial excitations. At baryo-chemical potential $\mu_B = 0$, these two pillars let emerge the narrow quasi-particle state of the $\Upsilon$ ground state at a temperature of about 150 MeV. Excited states are consecutively formed at lower temperatures by about 10 (20) MeV for the $2S$ ($3S$) vector states. The baryon density, i.e. $\mu_B > 0$, pulls that formation pattern to lower temperatures. At $\mu_B =$ 200 MeV, we find a shift by about 15 MeV.