Analysis of the differential cross sections for the reaction pp --> ppK+K- in view of the K+K- interaction

TL;DR

This study investigates the K+K- interaction in pp-->ppK+K- reactions using differential cross section distributions, revealing large uncertainties in scattering length measurements at low excess energies.

Contribution

It introduces a novel analysis of event distributions with generalized Dalitz plots to extract K+K- scattering parameters from experimental data.

Findings

K+K- scattering length at 10 MeV: (11 ± 8) + i(0 ± 6) fm

K+K- scattering length at 28 MeV: (0.2 ± 0.2) + i(0.0 ± 0.5) fm

Results are consistent with very low interaction strength due to large uncertainties.

Abstract

Measurements of the pp-->ppK+K- reaction, performed with the experiment COSY-11 at the Cooler Synchrotron COSY, show a significant difference between the obtained excitation function and theoretical expectations including pp-FSI >. The discrepancy may be assigned to the influence of K+K- or K-p interaction. This interaction should manifest itself in the distributions of the differential cross section. This thesis presents an analysis of event distributions as a function of the invariant masses of two particle subsystems. In particular in the analysis two generalizations of the Dalitz plot proposed by Goldhaber and Nyborg are used. The present Investigations are based on the experimental data determined by the COSY-11 collaboration from two measurements at excess energies of Q = 10 MeV and 28 MeV. The experimental distributions are compared to results of Monte Carlo simulations generated with various parameters of the K+K- and K-p interaction. The values of the K+K- scattering length, extracted from two data sets for Q = 10 MeV and 28 MeV amount to: a_K+K- = (11 +- 8) + i(0 +- 6) fm for Q = 10 MeV, and a_K+K- = (0.2 +-0.2) + i(0.0 +- 0.5) fm for Q = 28 MeV, Due to the low statistics, the extracted values have large uncertainties and are consistent with very low values of the real and imaginary part of the scattering length.