Where to find $X(17)$?

Abstract

The Atomki anomaly puts forward the hypothesis of an $X(17)$ particle to explain its observation. Utilizing experimental results from the Atomki experiments, measurements of the electron's anomalous magnetic moment, beam dump experiments, the KLOE-2 experiment, the PADME experiment, and the parity-violating Møller scattering experiment, we derive constraints on the $Xee$ coupling of the $X(17)$ boson to electrons. It is found that the scalar and pseudoscalar models can be excluded by Atomki experiments due to the parity conservation, and the pure axial-vector model is excluded at 98\% C.L. Meanwhile, the analyses in both pure vector and the vector $\pm$ axial-vector models consistently show that the $Xee$ coupling is of the vector type and has an almost fixed value, $\left(6.78\pm 0.042\right)\times 10^{-4}\lesssim |{\epsilon }_e^v|\lesssim \left(6.93\pm 1.66\right)\times 10^{-4}$ in unit of electric charge $e$.

24 pages, 5 figures, 1 table; writing polished