Deuterons at LHC: "snowballs in hell" via hydrodynamics and hadronic afterburner

TL;DR

This paper explains how deuterons can survive at high temperatures in heavy-ion collisions by combining hydrodynamics and hadronic afterburners, accurately reproducing experimental data without free parameters.

Contribution

It provides a microscopic explanation for deuteron survival at freeze-out temperatures using a combined hydrodynamic and hadronic model with known reaction cross-sections.

Findings

Reproduces deuteron $p_T$ spectra and $B_2(p_T)$ without free parameters.

Demonstrates deuteron survival at $T=155$ MeV through microscopic reactions.

Supports thermal production of deuterons in heavy-ion collisions.

Abstract

The deuteron yield in Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV is consistent with thermal production at a freeze-out temperature of $T = 155$ MeV. The existence of deuterons with binding energy of 2.2 MeV at this temperature was described as "snowballs in hell". We provide a microscopic explanation of this phenomenon, utilizing relativistic hydrodynamics and switching to a hadronic afterburner at the above mentioned temperature of $T = 155$ MeV. The measured deuteron $p_T$-spectra and coalescence parameter $B_2(p_T)$ are reproduced without free parameters, only by implementing experimentally known cross-sections of deuteron reactions with hadrons, most importantly $\pi d \leftrightarrow \pi n p$.