X(16.7) production in electron–positron collision

Abstract

Abstract The anomaly found in the excited $$^8\text {Be}$$ 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: $$e^+e^-\rightarrow X\gamma $$ e+e-→Xγ and $$J/\psi \rightarrow X\gamma $$ J/ψ→Xγ , both following with $$X\rightarrow e^+e^-$$ 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 $$e^+e^-$$ 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 $$g_f^{v/a}\sim 10^{-3}$$ 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 $$J/\psi $$ 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.