Abstract
KLOE-2 extends the physics program of the forerunner KLOE experiment, especially in the field of discrete symmetries tests with neutral kaons. KLOE and KLOE-2 have collected together the largest sample of electron-positron collisions at an energy equal to the φ-meson mass, corresponding to about 2.4×1010 produced φ mesons. The latest results on neutral kaon physics at KLOE will be reviewed, together with the status and prospects of the analyses of KLOE-2 data. A new measurement of the charge asymmetry in KS semileptonic decays with 1.7 fb−1 of KLOE data, which improves the sensitivity of previous measurements of about a factor two, will be presented. Furthermore, the status of the analysis devoted to directly test T and CPT symmetries in neutral kaons transitions, as well as the search of the pure CP-violating KS → 3π0 decay using part of the recently acquired KLOE-2 dataset, will be presented.
Highlights
Flavoured neutral mesons are a powerful tool for testing fundamental discrete symmetries and their combinations such as CP and CPT
KLOE and KLOE-2 have been operated at the DAΦ√NE φ-factory [3,4,5], which provided electron-positron collisions at the φ meson mass peak, s ≈ 1020 MeV. φ-meson decays into neutral kaons pairs – occurring with a branching fration of about 34% – were recorded by the KLOE apparatus, consisting of a huge cylindrical drift chamber (DC) [6], whose ∼50 m3
The charge asymmetry for KL was precisely determined from the KTeV experiment at Fermilab: AL = (3.322±0.058stat ±0.047syst)×10−3 [11], while the most precise measurement of AS was performed by the KLOE collaboration using 410 pb−1 of integrated luminosity collected in 2001-2002: AS = (1.5 ± 9.6stat ± 2.9syst) × 10−3 [12]
Summary
Flavoured neutral mesons are a powerful tool for testing fundamental discrete symmetries and their combinations such as CP and CPT. Neutral kaons are extensively used to search for manifestations of symmetry violations as they are translated to constraints on the properties of the mesons [1]. The KLOE experiment has contributed to determine most of the properties of neutral kaons as well as a number of tests of CP and CPT symmetries [2]. The KLOE dataset is still being analysed with the aim of obtaining more precise results on the charge asymmetry in semileptonic KS decays and preforming a first direct CPT test in transitions of neutral kaons. The KLOE-2 experiment has ended its data taking on March 2018, collecting about 5 fb−1 of data, which will allow to enhance the upper limit set on the branching fraction of the pure CP-violating decay KS → 3π0 by KLOE
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