# Hadronization in semi-inclusive deep-inelastic scattering on nuclei

## TL;DR

This study investigates how hadronization varies across different nuclei using semi-inclusive deep-inelastic scattering data, revealing dependencies on nuclear size, energy transfer, and other kinematic variables, with implications for understanding partonic energy loss.

## Contribution

The paper provides new detailed measurements of hadron multiplicities on various nuclei, highlighting the dependence on nuclear size and kinematic variables, and introduces the variable L_c to describe hadronization behavior.

## Key findings

- Hadron multiplicities decrease with nuclear size A for all hadron types.
- R_A^h increases with virtual-photon energy
u and decreases with energy fraction z.
- Evidence suggests partonic energy-loss mechanisms at large transverse momentum.

## Abstract

A series of semi-inclusive deep-inelastic scattering measurements on deuterium, helium, neon, krypton, and xenon targets has been performed in order to study hadronization. The data were collected with the HERMES detector at the DESY laboratory using a 27.6 GeV positron or electron beam. Hadron multiplicities on nucleus A relative to those on the deuteron, R_A^h, are presented for various hadrons (\pi^+, \pi^-, \pi^0, K^+, K^-, p, and \bar{p}) as a function of the virtual-photon energy \nu, the fraction z of this energy transferred to the hadron, the photon virtuality Q^2, and the hadron transverse momentum squared p_t^2. The data reveal a systematic decrease of R_A^h with the mass number A for each hadron type h. Furthermore, R_A^h increases (decreases) with increasing values of \nu (z), increases slightly with increasing Q^2, and is almost independent of p_t^2, except at large values of p_t^2. For pions two-dimensional distributions also are presented. These indicate that the dependences of R_A^{\pi} on \nu and z can largely be described as a dependence on a single variable L_c, which is a combination of \nu and z. The dependence on L_c suggests in which kinematic conditions partonic and hadronic mechanisms may be dominant. The behaviour of R_A^{\pi} at large p_t^2 constitutes tentative evidence for a partonic energy-loss mechanism. The A-dependence of R_A^h is investigated as a function of \nu, z, and of L_c. It approximately follows an A^{\alpha} form with \alpha \approx 0.5 - 0.6.