X(16.7) production in electron\u2013positron collision

Abstract

The anomaly found in the excited ^8text {Be} nuclear transition to its ground state is attributed to a spin-1 gauge boson X(16.7). To hunt for this boson, we propose two traps: e^+e^-rightarrow Xgamma and J/psi rightarrow Xgamma , both following with Xrightarrow e^+e^- decay. We adopt the “vector minus axial-vector” interaction hypothesis. Analysis on the X(16.7) decay length, production rates, differential distribution with respect to the e^+e^- invariant-mass spectrum, and the signal-to-noise ratios (SNR) after the smearing at BESIII detector are discussed in detail. Given the coupling strength of X to vector/axial-vector currents g_f^{v/a}sim 10^{-3} at BESIII: (1) there would be about 6000 X measurable events per year in electron–positron collision, yet with a large background after smearing; (2) while in J/psi decays, we find that the axial-vector current may come into play; though merely 52 events may appear, the SNR are inspiring even after smearing.