K*0 and phi Meson Production in Proton-Nucleus Interactions at sqrt(s) = 41.6 GeV

TL;DR

This study measures the production cross sections of strange vector mesons K*0, K*0bar, and phi in proton-nucleus collisions at 41.6 GeV, revealing the atomic number dependence and observing the Cronin effect for these mesons.

Contribution

First measurement of the atomic number dependence and the Cronin effect for strange vector mesons in proton-nucleus interactions at this energy.

Findings

Atomic number dependence characterized by alpha values close to 1.

Total cross sections for K*0, K*0bar, and phi mesons determined.

Observation of the Cronin effect for strange vector mesons.

Abstract

The inclusive production cross sections of the strange vector mesons K*0, K*0bar, and phi have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic number dependence is parametrised as sigma(pA) = sigma(pN)*A**alpha, where sigma(pN) is the proton-nucleon cross section. Within the phase space accessible, alpha(K*0) = 0.86+/-0.03, alpha(K*0bar) = 0.87+/-0.03, and alpha(phi) = 0.96+/-0.02. The total proton-nucleon cross sections, determined by extrapolating the differential measurements to full phase space, are sigma(pN->K*0) = 5.06+/-0.54 mb, sigma(pN->K*0bar) = 4.02+/-0.45 mb, and sigma(pN->phi) = 1.17+/-0.11 mb. The Cronin effect is observed for the first time for vector mesons containing strange quarks; compared to the measurements of Cronin et al. for K+- mesons, the measured values of alpha for phi mesons coincide with those of K- mesons for all transverse momenta, while the enhancement for K*0 / K*0bar mesons is smaller.