Equilibration of hadrons in HICs via Hagedorn States

TL;DR

This paper models the hadronization process in heavy-ion collisions using Hagedorn states, demonstrating rapid equilibration and reproducing experimental particle ratios and spectra.

Contribution

It introduces a covariant bootstrap model for Hagedorn states that effectively describes hadronization and rapid equilibration in heavy-ion collisions.

Findings

Hagedorn states reproduce strange particle ratios.

Energy spectra show thermal-like distribution at T_H.

Equilibration time scales are reduced to 2-5 fm/c.

Abstract

Hagedorn states (HS) are a tool to model the hadronization process which occurs in the phase transition region between the quark gluon plasma (QGP) and the hadron resonance gas (HRG). These states are believed to appear near the Hagedorn temperature $T_H$ which in our understanding equals the critical temperature $T_c$. A covariantly formulated bootstrap equation is solved to generate the zoo of these particles characterized baryon number $B$, strangeness $S$ and electric charge $Q$. These hadron-like resonances are characterized by being very massive and by not being limited to quantum numbers of known hadrons. All hadronic properties like masses, spectral functions etc.are taken from the hadronic transport model Ultra Relativistic Quantum Molecular Dynamics (UrQMD). Decay chains of single Hagedorn states provide a well description of experimentally observed multiplicity ratios of strange and multi-strange particles. In addition, the final energy spectra of resulting hadrons show a thermal-like distribution with the characteristic Hagedorn temperature $T_H$. Box calculations including these Hagedorn states are performed. Indeed, the time scales leading to equilibration of the system are drastically reduced down to 2...5 fm/c.