Sound waves in hadronic matter

TL;DR

This paper investigates log-periodic oscillations in high-energy particle spectra, proposing that these oscillations indicate the presence of sound waves in hadronic matter during collisions, offering new insights into particle production processes.

Contribution

It introduces the idea that log-periodic oscillations in transverse momentum spectra are due to sound waves in the collision system, providing a novel interpretation of experimental data.

Findings

Log-periodic oscillations suggest sound wave formation in hadronic matter.

The oscillations can be modeled as log-periodic variations in the temperature parameter.

This interpretation offers new insights into the dynamics of high-energy collisions.

Abstract

We argue that recent high energy CERN LHC experiments on transverse momenta distributions of produced particles provide us new, so far unnoticed and not fully appreciated, information on the underlying production processes. To this end we concentrate on the small (but persistent) log-periodic oscillations decorating the observed $p_T$ spectra and visible in the measured ratios $R = \sigma_{data}\left( p_T\right)/\sigma_{fit}\left( p_T\right)$. Because such spectra are described by quasi-power-like formulas characterised by two parameters: the power index $n$ and scale parameter $T$ (usually identified with temperature $T$), the observed log-periodic behaviour of the ratios $R$ can originate either from suitable modifications of $n$ or $T$ (or both, but such a possibility is not discussed). In the first case $n$ becomes a complex number and this can be related to scale invariance in the system, in the second the scale parameter $T$ exhibits itself log-periodic oscillations which can be interpreted as the presence of some kind of sound waves forming in the collision system during the collision process, the wave number of which has a so-called self similar solution of the second kind. Because the first case was already widely discussed we concentrate on the second one and on its possible experimental consequences.