Hagedorn Thermostat: A Novel View of Hadronic Thermodynamics

TL;DR

This paper presents a microcanonical analysis of Hagedorn systems, demonstrating their role as perfect thermostats with a temperature near the Hagedorn temperature, and explores how mass spectrum cut-offs influence hadronization temperatures in particle collisions.

Contribution

It introduces a new microcanonical framework for Hagedorn systems and explains their thermostatic properties, providing insights into the universal hadronization temperature observed in experiments.

Findings

Hagedorn systems act as perfect thermostats at temperature T_H.

Presence of a mass cut-off affects the temperature for large particle numbers.

The model explains the universal hadronization temperature in high-energy collisions.

Abstract

A microcanonical treatment of Hagedorn systems, i.e. finite mass hadronic resonances with an exponential mass spectrum controlled by the Hagedorn temperature $T_H$, is performed. We show that, in the absence of any restrictions, a Hagedorn system is a perfect thermostat, i.e. it imparts its temperature $T_H$ to any other system in thermal contact with it. We study the thermodynamic effects of the lower mass cut-off in the Hagedorn mass spectrum. We show that in the presence of a single Hagedorn resonance the temperature of any number of $N_B$ Boltzmann particles differs only slightly from $T_H$ up to the kinematically allowed limit $N_B^{kin}$. For $N_B > N_B^{kin}$ however, the low mass cut-off leads to a decrease of the temperature as $N_B$ grows. The properties of Hagedorn thermostats naturally explain a single value of hadronization temperature observed in elementary particle collisions at high energies and lead to some experimental predictions.