TWO PHOTON EXCITATION OF THE TENSOR MESON f0 (1270)

We have measured charged particle pair production in two-photon scattering at the e+e- storage ring PETRA. While the main source of such events is the production of lepton pairs, the presence of an additional process is clearly indicated by the measured invariant mass distribution of the two particles and their angular distributions. We determine that the excess is mainly due to the decay f0(1270)→π+π-. We derive a width Γ(f0→γγ)=3.2±0.2±0.6 keV (statistical and systematic). © 1981 Springer-Verlag

Rho rho production by two photon scattering

SIGLEDEGerman

Evidence for a spin 1 gluon in three jet events

SIGLEDEGerman

The hadronic final state in e+e−e^{+}e^{-} annihilation at c.m. energies of 13, 17 and 27.4 GeV

Results on the hadronic final state in e/sup +/e/sup -/ annihilation at 13, 17 and 27.4 GeV are presented. There is no compelling evidence for the existence of the t quark in these data, which are in general agreement with a simple quark parton model. Some tentative indications of QCD effects are observed in the p/sub T//sup 2/ distributions

PROPERTIES OF HADRON FINAL STATES IN e+ e- ANNIHILATION AT 13-GeV AND 17-GeV CENTER-OF-MASS ENERGIES

We have observed e+e− hadrons at C.M. energies of 13 GeV and 17 GeV at PETRA using the TASSO detector. We find R(13 GeV) = 5.6 ± 0.7 and R(17 GeV) = 4.0 ± 0.7. The additional systematic uncertainty is 20%. Comparing inclusive charged hadron spectra we observe scaling between 5 GeV and 17 GeV for x = p/pbeam > 0.2; however the 13 GeV cross section is above the 17 GeV cross section for smaller x. This may be due to copious b production. The events become increasingly jet like at high energies as evidenced by a shrinking sphericity distribution with increasing energy

PRODUCTION AND PROPERTIES OF THE tau LEPTON IN e+ e- ANNIHILATION AT c.m. ENERGIES FROM 12-GeV TO 31.6-GeV

We have observed τ production in e+e− annihilation at centre-of-mass energies between 12 and 31.6 GeV with cross sections in agreement with the QED τ-pair cross section. Branching ratios for τ decay have been measured and are consistent with the world averages. We have determined the cutoff parameters of QED Λ+ (Λ−) to be > 73 GeV (82 GeV) and have obtained an upper limit on the τ lifetime of 1.4 × 10−12 s(95% CL)

CHARGED PION, KAON, PROTON AND ANTI-PROTON PRODUCTION IN HIGH-ENERGY e+ e- ANNIHILATION

Production of pions, kaons, protons and antiprotons has been studied in e+e− annihilations at 12 and 30 GeV centre of mass energy using time of flight techniques. The fractional yield of charged kaons and baryons appears to rise with outgoing particle momentum. At our highest energy at least 40% of e+e− annihilations into hadrons are estimated to contain baryon