Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
Article; Proceedings Paper
We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/ψ &RARR; γ pp decays. In the case of S-wave fit, the peak mass is below 2m(p) at M = 1859(-10)(+3)(stat)(-25)(+5) (syst)MeV and the total width is &UGamma; < 30MeV at the 90% confidence level. And we also find near-threshold enhancement in the invariant mass spectrum of p&ULambda;+c.c. in J/ψ pK(-)&ULambda;+c.c. decays. The mass is m = 2075 &PLUSMN; 12(stat) &PLUSMN; 5(syst)MeV and width is &UGamma; = 90 &PLUSMN; 35(stat) &PLUSMN; 9(syst)MeV. A K-&ULambda; near-threshold enhancement is also studied and it has m = 1.50 &SIM; 1.65GeV, &UGamma; = 70 &SIM; 110MeV with BR(J/ψ &RARR; pN*(X)) x BR(N*(X) &RARR; K&ULambda;) &SIM; 2 x 10(-4).