Momentum dependence of near-threshold photoproduction of - hyperons off nuclei and their properties in the nuclear medium
Abstract
We study the near-threshold inclusive photoproduction of - hyperons off 12C and 184W target nuclei within a first-collision model relying on the nuclear spectral function and including incoherent - production in direct elementary γp K+K+- and γn K+K0- processes. The model takes into account the impact of the nuclear effective scalar K+, K0, - and their Coulomb potentials on these processes as well as the absorption of final - hyperons in nuclear matter, the binding of intranuclear nucleons and their Fermi motion. We calculate the absolute differential cross sections and their ratios for the production of - hyperons off these nuclei at laboratory polar angles 45 by photons with energies of 2.5 and 3.0 GeV, with and without imposing the phase space constraints on the - emission angle in the respective γp center-of-mass system. We also calculate the momentum dependence of the transparency ratio for - hyperons for the 184W/12C combination at these photon energies. We show that the - momentum distributions (absolute and relative) at the adopted initial photon energies possess, contrary to the transparency ratio for - hyperons, a definite sensitivity to the considered changes in the scalar - nuclear mean-field potential at saturation density 0 in the low-momentum range of 0.1--0.8 GeV/c. Therefore, the precise measurements of these distributions in a dedicated experiment at the CEBAF facility will provide valuable information on the - in-medium properties, which will be supplementary to that inferred from studying of the (K-,K+) reactions at initial momenta of 1.6--1.8 GeV/c.