Quest for KL→π0ννˉ

Abstract
The KL→π0ννˉ decay is one of the most sensitive probes of physics beyond the Standard Model. Since this decay is highly suppressed and theoretically clean within the Standard Model, any deviation of the measured branching ratio from the predicted value of 3 x 10-11 would constitute clear evidence for new physics.
Experimentally, however, this decay mode is extremely challenging. The parent neutral KL cannot be directly observed, and the only visible particles in the final state are the two photons from the π0 decay. Moreover, numerous background processes can mimic the signal. Over the years, many experiments have been proposed, employing a variety of experimental strategies. Currently, the J-PARC KOTO experiment sets the most stringent upper limit on the branching ratio.
In this seminar, the speaker will review the different experimental approaches that have been developed to search for this decay, discuss how various background sources were identified and mitigated, and present a new experiment proposed for the future.
This talk aims to provide theorists with a behind-the-scenes view of the experimental effort underlying a single-number result, and to share with experimentalists the challenges and excitement of designing and executing a high-sensitivity rare-decay experiment.