The MARK III Collaboration

The decays J/+ + 77rr+7rrand J/$J + 7K+K-, MK+K< 2.0 GeV/c2, have been studied. Measurements are presented for BR(11, + 7 f (1270)) . BR( f (1270) + T+T-), BR(+ + ~~(1720)) . BR(B(1720) + m+F), BR($ + 7 f’(1525)) BR(f’(1525) + W-K-), and BR(T,! J + 70)) -BR(B(1720) + K+K-). A higher mass structure is observed in the z + z channel. The spin of the 0(1720) is established with high confidence. The polarization structure of the f (1270), f’(1525), and 8(1720) have been determined. Submitted to Physical Review D t Work supported in part by the Department of Energy, under contracts DE-ACOS76SF00515, DE-AC02-76ER01195, DE-AC03-81ER40050, DE-AM03-76SF0034, and by the National Science Foundation. 1. Radiative Decays of the J/v) into 77r+7rand yK+KThis paper deals with J/t) radiative decays to m+zsystems of all kinematitally accessible invariant masses and to K+Ksystems below 2.0 GeV/c2. [‘l KK masses above 2.0 GeV/c2 have been treated separately.12] Quantum Chromodynamics (QCD) admits the possibility of colorless bound states of two or more gluons which have been named glueballs. Radiative decays of the J/T) h ave been suggested131 as promising modes for glueball searches. The ratio of J/t,b decays via 7gg to those via ggg, according to perturbative QCD, is r(J/+ --) w) 36 2 a 2.2cY, 2 F(J/11, + 999) = Ye,l++ *** a8 [ 7r 1 For CX~ = 0.2, this leads to a branching fraction BR(J/+ + 72g) 5 10% . Thus, a substantial fraction of all J/t) decays are expected to proceed through the radiative decay diagram. Hadronic final states produced from the two gluon system have C = + and I = 0. It was calculated141 that Jpc = O++,O-+, 2++ dominate the J/$ + 7X final state and that Jpc = l-and l-+ are suppressed. The final states most accessible are those containing two or three pseudoscalars. Two pseudoscalars can combine to produce states with Jpc = 0++,2++, while three pseudoscalars can form Jpc = O-+ states. In the 2++ channel, the f (1270) appears very prominently in the zz mode. The production characteristics (i.e. the population of the different polarization states) of this final state have been measured by the MARK II and Crystal Ball experiments.15p61 The f’(1525) h as b een seen by the MARK II experiment[8] in the K+Kfinal state. The 8(1720) h as been observed in the qq and K+Kdecay modes by the Crystal Ball and Mark II experiments, respectively; they have only set limits on its decay to zz. [s~‘l. The 8(1720) has been suggested as a glueball candidate.lgl The S* (975), an I = 0, O++ state, is notably absent from radiative J/T) decays. 2. The Mark III Detector The Mark III detector[lol is’a general purpose magnetic spectrometer, optimized for the SPEAR energy region. The design goal was a detector capable of complete reconstruction of exclusive final states. At SPEAR, the mean charged and neutral multiplicities are each about four. The momentum spectra for charged and neutral particles peaks at 500 MeV/c and 250 MeV/c, respectively. The salient features of the detector are: 1. A beryllium beam pipe with a low mass trigger chamber to minimize multiple scattering. 2. A charged-track solid-angle coverage of 85% of 47r, and a neutral track coverage of 95% of 4~. 3. Good particle identification for the charged tracks using a time of flight system (TOF) with a resolution of 190 ps. 4. A finely segmented shower counter with good detection efficiency for low energy photons, good electron-hadron separation, and an energy resolution of AE/E = 17%/a. 5. Two layers of steel and muon counters outside the solenoidal coil for muon-hadron separation covering 65% of 47r. The detector design is shown in axial and transverse views in Figs. 2.1 and 2.2, respectively. 3. The 77r+7rFinal State Event Selection for J/~/J + yrr+rrThe radiative photon must be observed in the shower counter. Events are required to have fewer than 5 isolated photons, where ‘isolated’ means cos B,, < 0.95. More than one photon is allowed since the products of charged hadrons interacting in the shower counter are sometimes counted as photons.