Exploring beyond standard model of particle physics with search for rare muon decay

Searching for charged lepton flavour violating (cLFV) processes is a powerful tool to explore new physics beyond the standard model of particle physics. The motivation of this type of experiment is getting higher since new physics at much higher energy scale can be probed compared to the experiments at the energy frontier machine LHC where any sign of new physics has not been observed yet. The MEG experiment searches for the LFV decay of muon, μ⁺ → e⁺γ with an unprecedented sensitivity, which is high enough to test the predictions by many of the well-motivated models of new physics. No sign of the μ⁺ → e⁺γ decay was observed in the full dataset of the MEG experiment taken between 2009 and 2013, setting a thirty times more stringent constraint on the existence of this decay mode compared to the previous experiment. An upgraded experiment, MEG II, where ten times higher sensitivity is achievable using more intense muon beam and upgraded detectors with much better performance, is soon to begin. (author)