On the possibility of a new boson [formula omitted] in [formula omitted

Abstract

We consider the existence of the state 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−→Ξ−X0 decays. All these rates are found to be in the measurable ranges. We also comment on X0 coupling to muons and constraints from muon g−2.