Bose-Einstein correlations in one and two dimensions in deep inelastic scattering
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 583:3-4 (2004) 231-246
Abstract:
Bose-Einstein correlations in one and two dimensions have been studied in deep inelastic ep scattering events measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb-1. The correlations are independent of the virtuality of the exchanged photon, Q2, in the range 0.1 < Q2 < 8000 GeV2. There is no significant difference between the correlations in the current and target regions of the Breit frame for Q2 > 100 GeV2. The two-dimensional shape of the particle-production source was investigated, and a significant difference between the transverse and the longitudinal dimensions of the source is observed. This difference also shows no Q2 dependence. The results demonstrate that Bose-Einstein interference, and hence the size of the particle-production source, is insensitive to the hard subprocess. © 2004 Published by Elsevier B.V.Isolated tau leptons in events with large missing transverse momentum at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 583:1-2 (2004) 41-58
Abstract:
A search for events containing isolated tau leptons and large missing transverse momentum, not originating from the tau decay, has been performed with the ZEUS detector at the electron-proton collider HERA, using 130 pb -1 of integrated luminosity. A search was made for isolated tracks coming from hadronic tau decays. Observables based on the internal jet structure were exploited to discriminate between tau decays and quark- or gluon-induced jets. Three tau candidates were found, while 0.40 -0.13+0.12 were expected from Standard Model processes, such as charged current deep inelastic scattering and single W ±-boson production. To search for heavy-particle decays, a more restrictive selection was applied to isolate tau leptons produced together with a hadronic final state with high transverse momentum. Two candidate events survive, while 0.20±0.05 events are expected from Standard Model processes. © 2004 Published by Elsevier B.V.41.8-nm Xe8+ laser driven in a plasma waveguide
Physical Review A - Atomic, Molecular, and Optical Physics 70:2 (2004)
Abstract:
The results of the first experimental demonstration of a short-wavelength laser driven within a gas-filled capillary-discharge waveguide were described. The xenon gas was mixed with the hydrogen and strong lasing on the 4d 95d-4d95p transition in Xe8+ at 41.8 nm was observed. Analysis shows that lasing was strongly correlated with good guiding of the pump pulse and numerical simulations indicate that gain is likely to have been achieved over a significant fraction of the 30 mm length of the capillary. The success of this proof-of-principle experiment suggests that this and other short-wavelength lasers could be driven within waveguides of this type, leading to increased energy output and reduced beam divergence.High-Q2 neutral current cross sections in e+ p deep inelastic scattering at √s = 318 GeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 70:5 (2004)
Abstract:
Cross sections for e+ p neutral current deep inelastic scattering have been measured at a center-of-mass energy of √s = 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 63.2 pb -1. The double-differential cross section, d2σ/ dxdQ2, is presented for 200 GeV2 < Q2 < 30 000 GeV2 and for 0.005 < x < 0.65. The single-differential cross sections dσ/dQ2, dσ/dx and dσ/dy are presented for Q2 > 200 GeV2. The effect of Z-boson-exchange is seen in dσ/dx measured for Q2 > 10 000 GeV2. The data presented here were combined with ZEUS e+ p neutral current data taken at √s = 300 GeV and the structure function F2em was extracted. All results agree well with the predictions of the Standard Model.Observation of KS 0KS 0 resonances in deep inelastic scattering at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 578:1-2 (2004) 33-44