The state of the sites on the surface 7= T does... ." Equation ( 7) should read Io, (&)

Using 2674 nb−1 of data taken at √s from 5.00 to 7.25 GeV with a trigger sensitive to decays of lower-mass particles produced in two-photon collisions, we have observed 56±12 events consistent with the reaction e+e−→e+e−η, η→γγ. Background has been subtracted using separated-beam data. We obtain Γγγ(η)=0.56±0.16 keV and the pseudoscalar-nonet mixing angle θP=−17.6°±3.6°.Received 13 September 1983DOI:https://doi.org/10.1103/PhysRevD.28.2896©1983 American Physical Society

From a partial-wave analysis of the $K\overline{K}\ensuremath{\pi}$ system in the decay $\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}\ensuremath{\gamma}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$, it is determined that the quantum numbers of the $K\overline{K}\ensuremath{\pi}$ resonance at 1440 MeV, previously identified as the $E(1420)$, are ${J}^{\mathrm{PC}}={0}^{\ensuremath{-}+}$. This new particle has been named the $\ensuremath{\iota}$.

Evidence for a new resonance theta..-->..etaeta in the process J/psi..--> gamma..etaeta is presented. The resonance parameters of the theta are M = 1640 +- 50 MeV and GAMMA = 220/sup +100//sub -/70 MeV. J/sup P/C = 2/sup + +/ is preferred over 0/sup + +/.

We investigate the four-photon final state produced in γγ colissions. In the π 0 π 0 channel we observe f(1270) production with predominantly helicity 2 and measure a partial width Γ γγ 2.9 +0.6 −0.4 ± keV (independent of assumptions on the helicity). We observe A 2 (1310) production in the π 0 η channel and find a partial width Γ γγ = 0.77 ± 0.18 ± 0.27 KeV (assuming helicity 2). We give an upper limit for f ≈ ηη .

A search has been made with the Crystal Ball Detector for axionlike particles in radiative $\frac{J}{\ensuremath{\Psi}}$ decays. An upper limit on the branching ratio $B(\frac{J}{\ensuremath{\Psi}}\ensuremath{\rightarrow}\ensuremath{\gamma}+a)<1.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ (90% C.L.) is obtained. This result holds for long-lived, noninteracting pseudoscalar or vector particles of mass less than 1 GeV. Thus, this experiment also places stringent limits on the existence of other possible light bosons such as those arising in supersymmetric theories.

The Crystal Ball detector at SPEAR has been used to investigate the decays '#'+YYJ/9,J/J~(ete-or b+v') resulting from production of 8x105 .#f .From this selection of the data we measure the branching ratios for the processes q'-'(7) or T~)J/$ and.$'+yx,x-+yJ/+.An analysis of the angular correlations in the latter process furnishes measurements of the x(3.55) and x(3.51) spins and of the multipole structure of the radiative transitions.1.'

An ${{\ensuremath{\eta}}_{c}}^{\ensuremath{'}}$ candidate state is observed at a mass $M=3592\ifmmode\pm\else\textpm\fi{}5$ MeV and with a natural linewidth $\ensuremath{\Gamma}<8$ MeV (95% confidence level), by using the "crystal ball" NaI(Tl) detector at the Stanford Linear Accelerator Center (SPEAR). The evidence is found in the inclusive photon spectrum in decays of the ${\ensuremath{\psi}}^{\ensuremath{'}}(3684)$, where a signal is observed corresponding to a radiative transition to this state with branching ratio between 0.2% and 1.3% (95% confidence interval, including an uncertainty due to correlation with width).

Evidence for a new resonance $\ensuremath{\theta}\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\eta}$ in the process $\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\eta}\ensuremath{\eta}$ is presented. The resonance parameters of the $\ensuremath{\theta}$ are $M=1640\ifmmode\pm\else\textpm\fi{}50$ MeV and $\ensuremath{\Gamma}={220}_{\ensuremath{-}70}^{+100}$ MeV. ${J}^{\mathrm{PC}}={2}^{++}$ is preferred over ${0}^{++}$.

The decay Jψ→γf(1270), f(1270)→π0π0 has been studied. The γf decay branching ratio is measured to be (1.48±0.25±0.30)×10−3. A fit to the f production and decay angular distributions yields the values A1A0=0.88±0.13 and A2A0=0.04±0.19, where Aλ are the f helicity amplitudes. These results disagree with the values predicted from a QCD two-gluon-exchange model.Received 14 December 1981DOI:https://doi.org/10.1103/PhysRevD.25.3065©1982 American Physical Society