U-boson and the HyperCP exotic events

TL;DR

This paper proposes that a very light U-boson from an extended supersymmetric model can explain HyperCP's observed rare decay events, highlighting its unique flavor-changing neutral current mechanisms.

Contribution

It introduces the U-boson as a novel candidate for the HyperCP events and details its flavor-changing interactions at both tree and loop levels, differing from previous explanations.

Findings

U-boson can account for HyperCP decay anomalies

Loop-induced s→d U transition is significant

Distinct from pseudoscalar Higgs or sgoldstino explanations

Abstract

We show that the very light spin-1 gauge U-boson of the extra $U(1)'$ gauge model in the framework of the supersymmetric standard model extension can be a good candidate of the new light particle suggested by the HyperCP experiment. We demonstrate that the flavor changing neutral currents (FCNCs) for the HyperCP events in the decay of $\Sigma^{+}\to p \mu^{+} \mu^{-}$ can be generated at both tree and loop levels. In particular, we find that the loop induced $s\to d U$ transition due to the tensor-type interaction with the dimension-5 electric dipole operator plays a very important role on the FCNCs. Our explanation of the HyperCP data with the spin-1 U-boson is different from that based on a light pseudoscalar Higgs boson or sgoldstino in the literature. In particular, the U-boson involves a rich phenomenology in particle physics as well as cosmology.