Tests of the Atomki anomaly in lepton pair decays of heavy mesons

TL;DR

This paper investigates the potential effects of a hypothetical light vector boson, X17, on heavy meson decays, suggesting that certain decay channels could be significantly enhanced, providing a pathway for experimental verification or stronger bounds.

Contribution

It introduces a theoretical framework to analyze X17's impact on heavy meson decays, proposing specific decay channels for experimental testing of this new particle.

Findings

Decays of D*+ and D_s*+ mesons could be significantly enhanced by X17.

Current bounds allow for observable effects in heavy meson decays.

Experimental searches can confirm or constrain the existence of X17.

Abstract

The anomalies recently reported in lepton pair transitions of $^8$Be$^*$ and $^4$He nuclei may be attributed to the existence of a feebly interacting light vector boson $X17$. We study the effects of this hypothetical particle in the semileptonic $H^* \to H e^+e^-$ decays ($H$ a $Q\bar{q}$ meson) in the framework of the HQET+VMD model. Using current bounds and the universality assumption of the $X17$ boson to quarks, we find that decays of $D^{*+}$ and $D_s^{*+}$ mesons can be importantly enhanced relative to the dominant photon-mediated contributions. Dedicated experimental searches at current heavy meson factories may confirm the existence of this light boson or set stronger bounds of their couplings to ordinary matter.