Rare decay $\pi^{0}\to e^+ e^-$ constraints on the light CP-odd Higgs in NMSSM

TL;DR

This paper uses the rare decay of the neutral pion to constrain the properties of a hypothetical light CP-odd Higgs in the NMSSM, showing that certain anomalies and discrepancies cannot be explained within this model.

Contribution

It provides new constraints on the light CP-odd Higgs in NMSSM from rare pion decay measurements, ruling out specific mass scenarios and potential explanations for observed anomalies.

Findings

The decay constraints exclude the 214.3 MeV Higgs scenario.

The decay data cannot resolve the 3σ discrepancy in theoretical and experimental ${ m f B}( ext{π}^0 o e^+ e^-)$.

Combined constraints rule out the Higgs explanation for the HyperCP anomaly.

Abstract

We constrain the light CP-odd Higgs $A_{1}^{0}$ in NMSSM via the rare decay $\pi^{0}\to e^{+}e^{-}$. It is shown that the possible $3\sigma$ discrepancy between theoretical predictions and the recent KTeV measurement of ${\cal B}({\pi}^{0}\to e^+ e^-)$ cannot be resolved when the constraints from $\Upsilon\to\gamma A_1^0$, $a_{\mu}$ and $\pi^{0}\to \gamma \gamma$ are combined. Furthermore, the combined constraints also exclude the scenario involving $m_{A_1^0}=214.3$ MeV, which is invoked to explain the anomaly in the $\Sigma^{+}\to p \mu^{+}\mu^{-}$ decay found by the HyperCP Collaboration.