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

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.

Figures (2)

• Figure 1: The $p_t$-broadening for $\pi ^+$, $\pi ^-$, and $K^+$ mesons as a function of atomic mass number A. The inner error bars represent the statistical uncertainties; the total bars represent the total uncertainty, obtained by adding statistical and systematic uncertainties in quadrature.
• Figure 2: From left to right, the $\nu$, $Q^2$, $x$, and $z$ dependence of $\langle p_t^2 \rangle$ for D (top row) and $p_t$-broadening (remaining rows) for $\pi^+$ and $\pi^-$ produced on He, Ne, Kr, and Xe targets and for $K^+$ produced on a Xe target (bottom row). The inner error bars represent the statistical uncertainties; the total error bars represent the total uncertainty, evaluated as the sum in quadrature of statistical and systematic uncertainties.