Decay kinematics in the aether: Pion decay, kaon decay, and superluminal Cherenkov radiation

Abstract

Pion and kaon decay, π → μ + νμ, K → μ + νμ, into muons and GeV neutrinos is investigated with regard to a possible superluminal neutrino speed. Photonic Cherenkov emission by superluminal high-energy charges is shown to be forbidden by causality violation. A proper causality interpretation of decay processes outside the lightcone involving superluminal particles requires an absolute spacetime conception based on a distinguished frame of reference (aether frame). The universal reference frame is physically manifested as the rest frame of the cosmic microwave background (CMB) radiation. The propagation of particles and radiation modes in the CMB rest frame is determined by dispersive wave equations coupled to isotropic permeability tensors. The decay of ∼50 GeV pions and ∼85 GeV kaons generating the CERN neutrino beam to Gran Sasso (CNGS) is analyzed in this context. Causality constraints on the group velocity of the ∼17 GeV muon neutrinos produced in the decay are derived and compared to recent experimental bounds on the neutrino speed.