Possible scaling behaviour of the multiplicities ratio in leptoproduction of charged pions in nuclear medium
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 $ν$, and in a $ν$ 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 $τ$, which has the physical meaning of the formation time of hadron. We call this effect $τ$ scaling. $τ$ is a function of two variables $ν$ and $z$. It is also shown that $R_M^{h}$ can be presented in a form of a linear polynomial of $τ$, $a_{11}$ + $τa_{12}$, where parameters $a_{11}$ and $a_{12}$ do not depend on $ν$ and $z$.