# 17 MeV Atomki anomaly from short-distance structure of spacetime

## TL;DR

This paper proposes that the 17 MeV anomaly observed in $^8$Be nuclear transitions is due to a new gauge boson originating from the short-distance structure of spacetime, offering a novel theoretical perspective.

## Contribution

It introduces a model where the 17 MeV gauge boson arises from spacetime structure rather than an extra U(1) symmetry, explaining its small coupling constant.

## Key findings

- The new gauge boson has axial couplings dominating the transition matrix element.
- The coupling constant is estimated to be around 10^{-4} to 10^{-5}.
- The model provides insight into the smallness of the coupling constant.

## Abstract

An anomaly observed recently in the $^8$Be nuclear transition by the Atomki collaboration hints at a weakly-coupled, light new gauge boson with a mass of about $17$ MeV. In this paper, we propose that this new gauge boson comes from a short-distance structure of the spacetime, rather than from an extension of the Standard Model through adding an extra $\mathrm{U}(1)$ gauge symmetry. The dominant contribution to the relevant matrix element of the $^8$Be nuclear transition is given by the axial couplings. In order to account for the $^8$Be anomaly and satisfy the current experimental constraints, the coupling constant of the new gauge boson should be about $\mathcal{O}(10^{-4}-10^{-5})$. Our theoretical model allows understanding the origin of the smallness of the coupling constant, which is still missing or being incompletely understood in the models at which the new gauge boson has the axial couplings.