Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

TL;DR

This study analyzes KS KL coupled decays and KL-Be interactions using data from the CMD-2 detector, measuring regeneration cross sections and searching for CP violation in phi meson decays.

Contribution

It provides the first detailed analysis of KS KL coupled decays and KL-Be interactions at VEPP-2M, including measurements of regeneration cross sections and decay distributions.

Findings

Regeneration cross section of 53 ± 17 mb for KL mesons at 110 MeV/c

No CP violation observed in KL decays to pi+ pi-

Measured angular distribution of KS mesons after regeneration

Abstract

The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.