Search for contact interactions in deep inelastic e+p → e+X scattering at HERA
European Physical Journal C 14:2 (2000) 239-254
Abstract:
In a search for signatures of physics processes beyond the Standard Model, various eeqq vector contact-interaction hypotheses have been tested using the high-Q2 deep inelastic neutral-current e+p scattering data collected with the ZEUS detector at HERA. The data correspond to an integrated luminosity of 47.7pb-1 of e+p interactions at 300 GeV center-of-mass energy. No significant evidence of a contact-interaction signal has been found. Limits at the 95% confidence level are set on the contact-interaction amplitudes. The effective mass scales Λ corresponding to these limits range from 1.7 TeV to 5 TeV for the contact-interaction scenarios considered.Search for resonances decaying to e+-jet in e+p interactions at HERA
European Physical Journal C 16:2 (2000) 253-267
Abstract:
The e+-jet invariant mass spectrum produced in the reaction e+p → e+ X has been studied at a center-of-mass energy of 300 GeV. The data were collected using the ZEUS detector operating at the HERA collider, and correspond to an integrated luminosity of 47.7 pb-1. The observed mass spectrum is in good agreement with Standard Model expectations up to an e+-jet mass of 210 GeV. Above this mass, some excess is seen. The angular distribution of these events is typical of high-Q2 neutral current events and does not give convincing evidence for the presence of a narrow scalar or vector state. Limits are presented on the product of cross section and branching ratio for such a state and are interpreted as limits on leptoquark or R-parity-violating squark production. Specific leptoquark types are ruled out at 95% confidence level for coupling strength λ = 0.3 for masses between 150 and 280 GeV.Simulations of the propagation of high-intensity laser pulses in discharge-ablated capillary waveguides
Journal of the Optical Society of America B: Optical Physics 17:9 (2000) 1565-1570
Abstract:
We present the results of simulations of the propagation of high-intensity laser pulses in discharge-ablated capillary waveguides. The limitations of this type of waveguide for pulse intensities of the order of 1016 W cm-2 are discussed. However, for higher intensities we describe a new regime of quasi-matched guiding, that results in significant improvements in guiding performance. The effect on quasi-matched guiding of changing the atomic numbers of the atoms that compose the plasma waveguide is discussed. Calculations are presented for boron capillaries that show quasi-matched guiding over lengths of 32 mm for an input intensity of 5 × 10 17 Wcm-2. © 2000 Optical Society of America.Simulations of the propagation of high-intensity laser pulses in discharge-ablated capillary waveguides
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest (2000) 293-294
Abstract:
An overview is given on the results of numerical simulations of the propagation of high-intensity pules through discharge-ablated capillary waveguides. The numerical code solves the paraxial wave equation for a plasma undergoing optical field ionization, and so accounts for refractive defocusing due to further ionization by the propagating pulse.W production and the search for events with an isolated high-energy lepton and missing transverse momentum at HERA
PHYSICS LETTERS B 471:4 (2000) 411-428