Phenomenological analysis ofK+-meson production in proton-nucleus collisions

Abstract

We investigate the experimental data, total and differential cross sections, on the production of K + -mesons in pA interactions at projectile energies between Tp = 0.8 and 2.9 GeV, covering the transition across the free nucleon-nucleon threshold at 1.58 GeV. No clear evidence for the expected change of the dominant reaction mechanism from two-step to direct kaon production is found. It is suggested that further data, in particular at forward angles, are taken in order to clarify the situation. It also is shown that, independent of the beam energy and emission angle, the invariant K + -production cross sections show an overall exponential scaling behaviour with the squared four-momentum transfer between the beam proton and the produced K + -meson for t<−0.05 GeV 2 . The most recent data from COSY-Jülich, differential cross sections measured for t>0 GeV 2 , show a strongly different t dependence. Further data at forward angles and different beam energies are needed in order to exploit this region of kinematically extreme conditions.

φ-meson photoproduction from nuclei

“…For instance theoretical studies [69,70,71,72,73] on low energy K + , ρ, ω and φ-meson production in proton nucleus collisions indicate dominance of the two-step process with intermediate πmesons. This result is strongly supported by measurements of the A-dependence and two-particle correlations in K + -meson production from pA reactions [71,74,75,76,77]. Further investigations on incoherent φ-meson photoproduction require measurement of differential cross section with absolute normalization.…”

Strangeness in nuclei and neutron stars

“…All deviations for the UrQMD model are scaled by the factor indicated in black. Right panel: Calculated K + spectra measured in p + C reactions at energies above the threshold as compared to the experimental results of the ANKE Collaboration [137]. Full red line: Standard IQMD version.…”

Strangeness production close to the threshold in proton–nucleus and heavy-ion collisions

“…In Fig. iv.3 we compare the simulations in the standard version with experimental p+C → K + data measured at COSY by the ANKE Collaboration [104,105] at very small laboratory angles (0 • ≤ θ ≤ 6 • ), and at energies around threshold (E beam = 1.2, 1.5, 2.0 and 2.3 GeV). There is an uncertainty in the absolute values of about 20% due to the ANKE cross section determination [106].…”