Scaled Momentum Spectra in Deep Inelastic Scattering at Hera

Abstract

Charged particle production has been studied in deep inelastic scattering (DIS) using an integrated luminosity of about 0.44 fb −1 taken with the ZEUS detector at HERA. The fragmentation properties of the struck quark in deep inelastic scattering have been investigated in the current fragmentation region of the Breit frame as a function of the exchanged boson virtuality Q 2 . The measured evolution of scaled momentum distributions are compared to next-to-leading order calculations convoluted with the fragmentation functions obtained from e + e − experiments. Scaling violations are observed. The scaled momentum spectra are also compared to predictions based on a modified leading-logarithmic QCD approximation and Monte Carlo event generators.

Scaled momentum spectra in deep inelastic scattering at HERA

“…The tracks used in the analysis had to be associated with the primary interaction vertex and were required to be in the region of high CTD acceptance, |η| < 1.75, where η = − ln(tan θ/2) is the pseudorapidity of the track in the laboratory frame with θ being the polar angle of the measured track with respect to the proton direction. The tracks had to pass through at least three CTD superlayers and were required to have a transverse momentum, P track T > 150 Me V. The details of the event reconstruction are similar to those in a previous ZEUS publication [3] and are described in detail elsewhere [50].…”