Search For Exotic Tau-decays

The Crystal Ball detector at the Doris II storage ring at DESY was used to search for the exotic decay processes tau -> e gamma, tau -> e pi0, tau -> e eta. No signal was observed. We obtained the following 90% CL upper limits on the branching fractions:B(tau -> e gamma)< 2.0x10^(-4),B(tau -> e pi0) < 1.4x10^(-4),B(tau -> e eta) < 2.4x10^(-4)

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies

*Measurement of the Branching Ratios for the Decays Tau->Hadron Pi-0-Nu and Tau->Hadron Pi-0-Pi-0-Nu

Contains fulltext : 29793.pdf (publisher's version ) (Open Access

Experimental upper limits for the hadronic transitions Υ(2S)→ηΥ\Upsilon (2S)\to \eta \Upsilon(1S) and Υ(2S)→π0Υ\Upsilon (2S)\to \pi^0\Upsilon(1S)

Using the Crystal Ball detector at thee+e− storage ring DORIS-II, we have searched for the hadronic transitions Υ(2S)→ηΥ(1S) and Υ(2S)→π0Υ(1S) in exclusive decays where the Υ(1S) decays into ane+e− or aµ+µ- pair and the η and π0 are detected by their decay modes η→γγ, η→γγ and π0→γγ. From the number of observed events we derive, after consideration of possible background sources, upper limits on the branching ratiosB(Υ(2S)→ηΥ(1S))<0.7% andB(Υ(2S)→π0Υ(1S))<0.8% at the 90% confidence level

The electron spectrum fromB meson decays

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonicB meson decays at thee+e− storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic.B decays to charmed states BR(B→evX$_c$)=(11.7±0.4±1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is |Vcb|=0.052±0.006. The model dependence of both results is included in the error. We have not observed semileptonicB decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where nob→c decays contribute, we find BR(B→evX$_u$)/BR(B→evX$_c$)<6.5% at the 90% confidence level. This corresponds to an upper limit |V$_{ub}$/V$_{cb}$|<0.21

The Electron Spectrum From B-meson Decays

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonic B meson decays at the e+ e– storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic B decays to charmed states BR(B -> e nu Xc )=(11.7+-0.4+-1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is |Vcb |=0.052+-0.006. The model dependence of both results is included in the error. We have not observed semileptonic B decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where no b->c decays contribute, we find BR(B -> e nu Xu )/BR(B -> e nu Xc )<6.5% at the 90% confidence level.this corresponds to an upper limit |V ub /V cb |