Charmonium Spectroscopy from Radiative Decays of the J/psi and Psi'.
Abstract
The Crystal Ball NaI(Tl) detector was used to study the photon spectra from the following inclusive charmonium decays:. e('+)e(') (>) J/PSI(3095) (>) GAMMA + Hadrons. e('+)e(') (>) PSIPRIME(3684) (>) GAMMA + Hadrons. Data were collected at the Stanford Linear Accelerator Center's electronpositron colliding beam machine, SPEAR, intermittently over a two and half year period, beginning at the end of 1978. The Cystal Ball detector consists of a highly segmented array of 732 NaI(Tl) crystals (16 radiation lengths) covering about 98% of 4 pi steradians, and is used to measure the photon energies, directions, and lateral shower distributions. Centrally located spark and proportional chambers are used for charged particle recognition. As a result, this detector is excellently suited for studying the radiative transitions among the charmonium family of states: (i) from PSIPRIME(3684) to the triplet P states, CHI(3415), CHI(3510), and CHI(3550); (ii) from PSIPRIME(3684) and J/PSI(3095) to the singlet S state ETAc(2984); and (iii) from PSIPRIME(3684) to the radially excited singlet S state ETAc'(3592). The analysis of 1,800,000 PSIPRIME(3684) and 2,200,000 J/PSI(3095) decays yields the following spectrum of states: CHI0(3418), CHI1(3512), CHI2(3558), ETAc(2984), and ETAc'(3592), each with a (+OR)4 MeV error on its mass. The branching ratios are measured to be: B(PSIPRIME(3684)(>)GAMMA+CHIJ) = (9.9(+OR)0.5(+OR)0.8)%, (9.0(+OR)0.5(+OR)0.7)%, and (8.0(+OR)0.5(+OR)0.7)%, for J = 0, 1, 2, respectively; B(PSIPRIME(3684)(>)GAMMA+ETAc) = (0.28(+OR)0.06)% and B(J/PSI(3095)(>)GAMMA+ETAc) = (1.27(+OR)0.36)%; and B(PSIPRIME(3684)(>)GAMMA+ETAc') = (0.51.2)% at the 90% confidence level. Values for the natural line widths are obtained: Width(CHIJ) = (13.520.4) MeV, < 3.8 MeV, (0.854.9) MeV, for J = 0, 1, 2, respectively (90% C.L.); Width(ETAc) = (11.5+4.5/4.0) MeV; and Width(ETAc') < 7 MeV (90% C.L.). The cascade product branching ratios B(PSIPRIME(3684)( >)GAMMA(+OR)CHIJ) times B(CHIJ(>)GAMMA+J/PSI(3095)) were measured for J = 1 and 2 to be: (2.56(+OR)0.12(+OR )0.20)% and (0.99(+OR)0.10(+OR)0.08)%, respectively. No signal was seen for the J = 0 transition, with an upper limit above its previously measured product branching ratio. The results of this analysis are compared with the predictions of the charmonium models.
 Publication:

Ph.D. Thesis
 Pub Date:
 1983
 Bibcode:
 1983PhDT........48G
 Keywords:

 Physics: Elementary Particles and High Energy