Search for the CP violating KS → 3π° decay with the KLOE detector

3rd Symposium on Prospects in the Physics of Discrete Symmetries

Silarski, M.^1

Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland^1

关键词: Branching ratio;    Direct measurement;    Electromagnetic calorimeter;    Prompt photons;    Spurious cluster;    Upper limits;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/447/1/012028/pdf
DOI  :  10.1088/1742-6596/447/1/012028

来源: IOP

【 摘 要 】

We present a new search for the KS → 3π0decay performed with the KLOE detector operating at the DAΦNE φ-factory. The KS mesons were tagged via registration of KL mesons which crossed the drift chamber without decaying and interacted with the KLOE electromagnetic calorimeter. The KS → 3π0decay was then searched requiring six prompt photons. To suppress background, originating from fake KS tags and KS → 2π0decays with additional two spurious clusters, we have performed a discriminant analysis based on kinematical fit, testing of the signal and background hypotheses and exploiting of the differences in kinematics of the KS decays into 2π0and 3π0. In a sample of about 1.7·109φ → KSKL events we have found no candidates in data and simulated background samples. Normalizing to the number of KS → 2π0events in the same sample, we have set the upper limit on the KS → 3π0branching ratio BR(KS → 3π0) -8at 90% C.L., five times lower than the previous limit. This upper limit can be translated into a limit on the modulus of the η000 parameter amounting to |η000|