Measurement of bb¯ production correlations, B0B¯0 mixing, and a limit on εB in pp¯ collisions at s=1.8 TeV
Physical Review D American Physical Society (APS) 55:5 (1997) 2546-2558
Measurement of bb̄ production correlations, B0B̄0 mixing, and a limit on ∈B in pp̄ collisions at √s=1.8 TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 55:5 (1997) 2547-2558
Abstract:
We present measurements of correlated bb̄ cross sections, μ-μ, correlations, the average B0B̄0 mixing parameter χ̄, and a limit on the CP-violating parameter ∈B. For these measurements, we use muon pairs from bb double semileptonic decays. The data used in this analysis were taken with the Collider_Detector at Fermilab and represent an integrated luminosity of 17.4±0.6 pb-1. The results concerning bb̄ production correlations are compared to predictions of next-to-leading order QCD computations.Search for lepton flavor violation in ep collisions at 300 GeV center of mass energy
Zeitschrift fur Physik C-Particles and Fields 73:4 (1997) 613-628
Abstract:
Using the ZEUS detector at the HERA electron-proton collider, we have searched for lepton flavor violation in ep collisions at a center-of-mass energy (√s) of 300 GeV. Events of the type e + p → ℓ + X with a final-state lepton of high transverse momentum, ℓ = μ or τ, were sought. No evidence was found for lepton flavor violation in the combined 1993 and 1994 data samples, for which the integrated luminosities were 0.84 pb-1 for e-p collisions and 2.94 pb-1 for e+p collisions. Limits on coupling vs. mass are provided for leptoquarks and R-parity violating squarks. For flavor violating couplings of electromagnetic strength, we set 95% confidence level lower limits on leptoquark masses between 207 GeV and 272 GeV, depending on the leptoquark species and final-state lepton. For leptoquark masses larger than 300 GeV, limits on flavor-changing couplings are determined, many of which supersede prior limits from rare decay processes. © Springer-Verlag 1997.Measurement of elastic ω photoproduction at HERA ZEUS Collaboration
Zeitschrift für Physik C Particles and Fields Springer Nature 73:1 (1997) 73-84
Abstract:
The reaction γp →ωp(ω → π+π−π0 and π0 → γ γ) has been studied in ep interactions using the ZEUS detector at photon-proton centre-of-mass energies between 70 and 90GeV and ∣t∣ < 0.6GeV2, where t is the squared four momentum transferred at the proton vertex. The elastic ω photoproduction cross section has been measured to be σγp → ωp = 1.21 ±0.12 ±0.23 μb. The differential cross section dσγp→ωp/d¦t¦ has an exponential shape e−b∣t∣ with a slope b =10.0 ± 1.2 ± 1.3 GeV−2. The angular distributions of the decay pions are consistent with s-channel helicity conservation. When compared to low energy data, the features of ω photoproduction as measured at HERA energies are in agreement with those of a soft diffractive process. Previous measurements of the ρ0 and ϕ photoproduction cross sections at HERA show a similar behaviour.Comparison of ZEUS Data with Standard Model Predictions for e^+ p -> e^+ X Scattering at High x and Q^2
ArXiv hep-ex/9702015 (1997)