Implications of last NA64 results and the electron $g_{e}-2$ anomaly for the X(16.7) boson survival

TL;DR

This paper analyzes recent experimental bounds and electron magnetic moment data to evaluate the viability of the X(16.7) boson, finding that certain coupling models remain consistent with observations and can explain g-2 anomalies.

Contribution

It demonstrates that models with nonzero V ± A couplings of the X(16.7) boson can survive experimental constraints and account for electron and muon g-2 anomalies.

Findings

Pure vector or axial vector couplings are excluded at 90% C.L.

Models with V ± A couplings remain viable.

Such models can explain both electron and muon g-2 anomalies.

Abstract

We point out that last NA64 bound on coupling constant of hypothetical $X(16.7 MeV)$ vector boson with electrons plus the recent value of the anomalous electron magnetic moment exclude at 90 \% C.L. purely vector or axial vector couplings of $X(16.7)$ boson with electrons. Models with nonzero $V \pm A$ coupling constant with electron survive and they can explain both the electron and muon $g - 2$ anomalies.