Angular Distributions for Heavy Quarkonium Decays into Baryon--Antibaryon Pairs

Based on the naive quark model, we calculate angular distributions for heavy quarkonium decays into pN*(1440), decuplet baryon pairs, and octet--decuplet baryon pairs. The general formulae of angular distributions are given explicitly. Quark mass effects on the violation of the helicity conservation and the prospect to look for them in J/ψ hadronic decays are discussed.