Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 89: Experimentelle Methoden 3

T 89.3: Talk

Wednesday, March 29, 2017, 17:15–17:30, JUR 253

Photon rejection for the K⁺→π⁺νν measurement and search for the π⁰→invisible decay at the NA62 experiment — •Letizia Peruzzo — Johannes Gutenberg University Mainz

In June 2015 the NA62 experiment at CERN began its physics data taking with the aim to collect in three years around 100 K⁺→π⁺νν events and measure the branching ratio with a precision about 10%. Well predicted inside the Standard Model, Br(K⁺→π⁺νν)=(9.11±0.72)·10⁻¹¹, this decay is closely related to the CKM matrix elements |V_td| and |V_ts| and any deviation from the theoretical Br could open many scenarios of physics beyond the Standard Model. The suppression of the main K⁺ decays, which have Br several order of magnitude higher than the K⁺→π⁺νν signal, is the primary task of NA62. In particular two types of decays are very crucial to suppress: K⁺→µ⁺ν and K⁺→π⁺π⁰. For this reason good particle identification and photon veto systems are needed for the experiment. A directly spin-off of the K⁺→π⁺νν measurement is the search for the π⁰→invisible decay where the π⁰ comes from K⁺→π⁺π⁰ events. The same signature of π⁰→invible with respect the K⁺→π⁺νν signal allows to perform the two measurements using the same dataset and analysis pillars. This talk describes the NA62 photon rejection performance reached in the 2016 run and the perspective for the measurement of π⁰→invisible.