Generalized Dalitz Plot analysis of the near threshold pp-->ppK+K- reaction in view of the K+K- final state interaction

TL;DR

This study performs a detailed Dalitz plot analysis of the near-threshold pp→ppK+K- reaction, confirming the enhancement due to final state interactions and estimating the K+K- scattering length from low-energy invariant mass distributions.

Contribution

It introduces a generalized Dalitz plot approach to analyze the pp→ppK+K- reaction near threshold, incorporating final state interactions and providing the first estimate of the K+K- scattering length.

Findings

Confirmation of near-threshold enhancement due to final state interactions.

Estimated K+K- scattering length: |Re(a)| ≈ 0.5-4.0 fm, Im(a) ≈ 3.0 fm.

Validation of the interaction model using invariant mass distributions.

Abstract

The excitation function for the $pp\to ppK^+K^-$ reaction revealed a significant enhancement close to threshold which may plausibly be assigned to the influence of the $pK^-$ and $K^+K^-$ final state interactions. In an improved reanalysis of COSY-11 data for the $pp\to ppK^+K^-$ reaction at excess energies of Q = 10 MeV and 28 MeV including the proton-K- interaction the enhancement is confirmed. Invariant mass distributions for the two- and three-particle subsystems allow to test at low excess energies the ansatz and parameters for the description of the interaction in the ppK+K- system as derived from the COSY-ANKE data. Finally, based for the first time on the low energy K+K- invariant mass distributions and the generalized Dalitz plot analysis, we estimate the scattering length for the K+K- interaction to be |Re(a_K^+K^-)| = 0.5 + 4.0 -0.5 fm and Im(a_K^+K^-) = 3.0 +- 3.0 fm.