Speaker
Stephanie Su
(University of Michigan)
Description
The KOTO experiment is a particle physics experiment located in J-PARC, Japan, aiming to explore physics beyond the Standard Model by measuring the branching ratio of the KL →π^0 νν ̅ decay. This decay has not yet been observed. The branching ratio predicted by the Standard Model of (3.0±0.3)×10-11 and the current experimental upper limit established by KEK E391a is 2.6×10-8.
The signal of KL →π^0 νν ̅ decay has the signature of two photons on the calorimeter with no signal on the veto detectors. It also has a large transverse momentum due to missing neutrinos. Kaons that decay outside the beam line with final product of two photons, such as KL →γγ and KL →π^+ π^- π^0, can appear to have large transverse momentum due to kaon scattering and beam interaction with the detectors. These off-axis kaon decay events can impact the upper limit of KL →π^0 νν ̅ branching ratio. Aluminum targets located at the upstream of the KOTO detector and inside the decay-volume were used to study kaon beam profile, which provided off-axis kaon decay vertex information. The beam profile provided insights on background contributions to the signal. Studies on the kaon beam profile and background identification from kaon scattering will be presented in this talk.
Primary author
Stephanie Su
(University of Michigan)