Lifetime of the eta' meson at low temperature

TL;DR

This paper investigates how the lifetime of the eta' meson changes at low temperatures, showing a significant increase in width from vacuum to 120 MeV temperature, linked to QCD anomalies.

Contribution

It combines Chiral Perturbation Theory and resonance inclusion to determine eta' meson lifetime variations with temperature in a novel way.

Findings

Eta' meson width increases from 200 keV to 10 MeV at 120 MeV temperature.

Uses combined theoretical frameworks to analyze in-medium meson properties.

Provides insights into QCD anomaly effects at finite temperature.

Abstract

This work constitutes one part of an investigation of the low-temperature changes of the properties of the eta' meson. In turn these properties are strongly tied to the U(1)_A anomaly of Quantum Chromodynamics. The final aim is to explore the interplay of the chiral anomaly and in-medium effects. We determine the lifetime of an eta' meson being at rest in a strongly interacting medium as a function of the temperature. To have a formally well-defined low-energy limit we use in a first step Chiral Perturbation Theory for a large number of colors. We determine the pertinent scattering amplitudes in leading and next-to-leading order. In a second step we include resonances that appear in the same mass range as the eta' meson. The resonances are introduced such that the low-energy limit remains unchanged and that they saturate the corresponding low-energy constants. This requirement fixes all coupling constants. We find that the width of the eta' meson is significantly increased from about 200 keV in vacuum to about 10 MeV at a temperature of 120 MeV.