A study of relativistic corrections to $J\mathrm{/}\psi \to p\bar{p}$ decay

We study relativistic corrections in exclusive $S$-wave charmonium decays into proton-antiproton final state. We calculate the NRQCD corrections to the dominant decay amplitude, which depend on the nucleon twist-3 light-cone distribution amplitudes only. It is shown that in this case the collinear factorisation is also valid beyond the leading-order approximation. Our numerical estimates show that relativistic correction of relative order $v^2$ provides large numerical impact.