The pp→K+ Σ +n cross-section from missing-mass spectra

Abstract

We utilize existing inclusive data on K + -meson momentum spectra of the reaction pp→K + X at Tp = 2.3 -2.85 GeV to deduce total cross sections for pp→K + Σ + n. The method used to extract those cross sections is explained and discussed in detail. Our result for Tp = 2.85 GeV is consistent with the data point from a direct measurement at the same beam energy. The cross section obtained for Tp = 2.3 GeV is with 13.7 ± 2.3 µb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration at a somewhat lower beam energy, indicating that the pp→K + Σ + n reaction cross section could exhibit a rather unusual energy dependence. PACS. 13.75.Ev Hyperon-nucleon interactions -13.75.Jz Kaon-baryon interactions -14.20.Gk Baryon resonances with S=0 -25.40.Ny Resonance reactions

Cross sections of the pp→K+Σ+n reaction close to threshold

“…The COSY-11 data [8] are shown as squares, the ANKE data point as a full diamond [6]. Cross section values reported by Sibirtsev et al [25] are shown as triangles. The solid curve is the phase space dependence normalized to the present data.…”

“…Sibirtsev et al [25] performed a similar analysis to extract the cross section from higher energy inclusive kaon spectra. These results are also shown.…”

“…For Σ production we used for the present data the matrix elements from the present analysis, for those of Refs. [20,26] we used the result from [25]. For the data of [6], the total cross section for the sum of the reactions pp → Σ 0 p and pp → Σ + n is about 9 µb.…”

Dynamics of Hyperon Production

“…To clarify the situation existing data on K + -meson momentum spectra from the pp→K + X reaction were utilized [15]. The data were analyzed with the missing mass method and the extracted total cross sections are shown in Fig.4 by solid triangles.…”

“…Note that the enhancement of the pp→K + Λp cross section at low energies is due to the FSI. The triangles are results evaluated [15] from the pp→K + X reaction. This is a quite unexpected observation [6].…”