Published in:
Physical Review D 70,7 (2004) 072001;
Link to original published article:
http://dx.doi.org/10.1103/PhysRevD.70.072001
Abstract
Using data collected by the CLEO III detector at CESR, we report on measurements of Y(1S) decays to charmonium final states. The data sample used for this analysis consists of 21.2x10(6) Y(1S) decays, representing about 35 times more data than previous CLEO Y(1S) data samples. We present substantially improved measurements of the branching fraction B(Y(1S)-->J/psi+X) using J/psi-->mu(+)mu(-) and J/psi-->e(+)e(-) decays. The branching fractions for these two modes are averaged, thereby obtaining: B(Y(1S)-->J/psi+X)=(6.4+/-0.4(stat)+/-0.6(syst))x10(-4). A greatly improved measurement of the J/psi momentum distribution is presented and indicates a spectrum which is much softer than predicted by the color-octet model and somewhat softer than the color-singlet model. First measurements of the J/psi polarization and production angle are also presented. In addition, we report on the first observation of Y(1S)-->psi(2S)+X and evidence for Y(1S)-->chi(cJ)+X. Their branching fractions are measured relative to B(Y(1S)-->J/psi+X) and are found to be {[B(Y(1S)-->psi(2S)+X)]/[B(Y(1S)-->J/psi+ X)]}=0.41+/-0.11(stat)+/-0.08(syst), {[B(Y(1S)-->chi(c1)+X)]/[B(Y(1S)-->J/psi+X)]}=0.35+/- 0.08(stat)+/-0.06(syst), {[B(Y(1S)-->chi(c2)+X)]/[B(Y(1S)-->J/psi+X)]}=0.52+/-0.12(stat)+/-0.09(syst), and {[B(Y(1S)-->chi(c0)+X)]/[B(Y(1S)-->J/psi+X)]}<7.4 at 90% confidence level. The resulting feed-down contributions to J/psi are [24+/-6(stat)+/-5(syst)]% for psi(2S), [11+/-3(stat)+/-2(syst)]% for chi(c1), [10+/-2(stat)+/-2(syst)]% for chi(c2), and <8.2% at 90% confidence level for chi(c0). These measurements (apart from chi(c0)) are about a factor of 2 larger than expected based on the color-octet model.
Keywords
b-quark production;; = 1.8 tev;; j/psi production;; (p)over-bar-p collisions;; p(p)over-bar collisions;; e&e annihilation;; root-s=1.8 tev;; gamma-decay;; cleo;; e(+)e(-)
Date of this Version
January 2004