https://doi.org/10.1140/epjc/s10052-020-8338-3
Regular Article - Theoretical Physics
Kaon decays shedding light on massless dark photons
1
Department of Physics, National Taiwan University, 106, Taipei, Taiwan
2
Physics Division, National Center for Theoretical Sciences, 300, Hsinchu, Taiwan
Received:
15
June
2020
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
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Funded by SCOAP3
