Possible scaling behaviour of the multiplicities ratio in leptoproduction of charged pions in nuclear medium

TL;DR

This paper introduces a new scaling variable, tau, based on hadron formation time, which allows the parametrization of multiplicity ratios in leptoproduction of charged pions across different nuclei, revealing potential universal behavior.

Contribution

It proposes the concept of tau scaling, a novel parametrization of multiplicity ratios in SIDIS data using a single variable related to hadron formation time, simplifying the analysis of nuclear effects.

Findings

Tau scaling describes multiplicity ratios as a linear function of tau.

Parameters in the tau scaling are independent of kinematic variables.

The approach suggests a universal behavior in nuclear medium effects.

Abstract

In this paper it is demonstrated that based on two-dimensional distributions in semi-inclusive deep inelastic scattering (SIDIS) data, obtained recently by the HERMES experiment at DESY on different nuclei, which contains data for charged pions produced in $z$ slices as a function of $\nu$, and in a $\nu$ slices as a function of $z$, it it is possible to parametrise a ratio of multiplicities on nucleus and deuterium (per nucleon) $R_M^{h}$ in a form of a function of a single variable $\tau$, which has the physical meaning of the formation time of hadron. We call this effect $\tau$ scaling. $\tau$ is a function of two variables $\nu$ and $z$. It is also shown that $R_M^{h}$ can be presented in a form of a linear polynomial of $\tau$, $a_{11}$ + $\tau a_{12}$, where parameters $a_{11}$ and $a_{12}$ do not depend on $\nu$ and $z$.