Angular distributions in $J/ψ(ρ,ω)$ states near threshold

Abstract

A resonance X(3872), first observed in the decays $B \to K X$, has been seen to decay to $J/ψπ^+ π^-$. The $π^+ π^-$ mass spectrum peaks near its kinematic upper limit, prompting speculation that the dipion system may be in a $ρ^0$. The decay $X(3872) \to J/ψω$ also has been observed. The reaction $γγ\to J/ψπ^+ π^-$ has been studied. Consequently, angular distributions in decays of $J/ψ(ρ^0,ω)$ states near threshold are of interest, and results are presented.