Regular Article - Theoretical Physics
Kaon decays shedding light on massless dark photons
Department of Physics, National Taiwan University, 106, Taipei, Taiwan
2 Physics Division, National Center for Theoretical Sciences, 300, Hsinchu, Taiwan
Accepted: 9 August 2020
Published online: 5 September 2020
We explore kaon decays with missing energy carried away by a massless dark photon, , assumed to have flavor-changing dipole-type couplings to the d and s quarks. We consider in particular the neutral-kaon modes and and their counterparts, as well as the charged-kaon channel , each of which also has an ordinary photon, , in the final state. In addition, we look at and . Interestingly, the same interactions give rise to the flavor-changing two-body decays of hyperons with missing energy and are subject to model-independent constraints that can be inferred from the existing hyperon data. Taking this into account, we obtain branching fractions and which can be as high as and , respectively, one or both of which may be within the sensitivity reach of the KOTO experiment. Furthermore, we find that and are allowed to be maximally of order as well, which may be probed by NA62. Complementarily, the hyperon modes can have rates which are potentially accessible by BESIII. Thus, these ongoing experiments could soon be able to offer significant tests on the existence of the massless dark photon.
© The Author(s) 2020
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