Is there a new weakly interacting boson of mass 214 MeV?

Abstract

We consider the existence of the stated X0 (214 MeV) in Σ+ → pμ+μ− decay found by the HyperCP collaboration. We assume that a fundamental spin zero boson X0 coupled to quarks leads to flavor changing s → dX0 process. We estimate the scalar and pseudoscalar coupling constants by considering Σ+ → pX0 and K+ → π+X0 processes, and find that pseudoscalar coupling dominates. We then evaluate the branching ratios for KL → π0π0X0, π+π−X0 and Ω− → Ⅺ−X0 decays. These rates are found to be in the measurable ranges.