X(16.7) production in electron–positron collision

Abstract

The anomaly found in the excited 8Be 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-→ Xγ and J/ ψ→ Xγ, both following with X→ 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 gfv/a∼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/ ψ 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.