Transverse momentum broadening of hadrons produced in semi-inclusive deep-inelastic scattering on nuclei

TL;DR

This study measures how the average squared transverse momentum of mesons produced in deep-inelastic scattering varies with nuclear size, revealing an increase with atomic mass and dependencies on certain kinematic variables.

Contribution

First direct measurement of nuclear mass dependence of transverse momentum broadening for mesons in deep-inelastic scattering experiments.

Findings

<pt^2> increases with atomic mass number

Broadening depends on Q^2 and x variables

Effect diminishes as z approaches unity

Abstract

The first direct measurement of the dependence on target nuclear mass of the average squared transverse momentum <pt**2> of pi+, pi-, and K+ mesons from deep-inelastic lepton scattering is obtained as a function of several kinematic variables. The data were accumulated at the HERMES experiment at DESY, in which the HERA 27.6 GeV lepton beam was scattered off several nuclear gas targets. The average squared transverse momentum was clearly observed to increase with atomic mass number. The effect increases as a function of Q**2 and x and remains constant as a function of both the virtual photon energy nu and the fractional hadron energy z, except that it vanishes as z approaches unity.