Why are the dilepton temperatures at the relativistic heavy-ion colliders are constant, T ~ 0.3 GeV?

TL;DR

The paper investigates why the dielectron emission temperature remains constant at approximately 0.3 GeV across a wide range of collision energies in heavy-ion experiments, suggesting a universal underlying mechanism.

Contribution

It provides an analysis of the energy-independent dielectron temperature, proposing explanations for this universal behavior in relativistic heavy-ion collisions.

Findings

Dielectron spectra show a constant temperature T ≈ 0.3 GeV across energies 27-5020 GeV.

The universal temperature suggests a fundamental 'thermostat' mechanism in heavy-ion collisions.

Raises questions about the underlying physics governing this temperature invariance.

Abstract

The STAR collaboration at RHIC and the ALICE collaboration at the LHC have reported dielectron spectra in the intermediate mass region, M = (1-3) GeV, which reveal a strikingly constant, energy-independent emission temperature $T_{IMR} \simeq 0.3~\textrm{GeV}$ over a broad range of collision energies, $\sqrt{s_{NN}} = 27 - 5020~\textrm{GeV}$. This unexpected ''thermostat'' behavior raises fundamental questions: why does the temperature remain constant despite increasing collision energy,and what mechanism governs this apparent universality?