An analysis of the CDF monojet data

An analysis is presented of events with a single jet and significant missing transverse energy selected from 4.7 pb[sup [minus]1] of p[bar p] data at [radical]s = 1800 GeV. The goal is to identify events of the type p[bar p] [yields] Z[sup 0] + jet; Z[sup 0] [yields] [nu][bar [nu]]. Event selection backgrounds are discussed. The number of observed monojet events is compared to the number of observed Z[sup 0] [yields] e[sup +]e[sup [minus]] events in which the Z[sup 0] is accompanied by a jet. We measure the number of light neutrino species to be N[sub v] = 2.2 [plus minus] 1.5 and we place an upper limit on the cross section for new physics of 8.3 pb (95% C.L.

Effects of genuine dimension-six Higgs operators

We systematically discuss the consequences of genuine dimension-six Higgs operators. These operators are not subject to stringent constraints from electroweak precision data. However, they can modify the couplings of the Higgs boson to electroweak gauge bosons and, in particular, the Higgs self-interactions. We study the sensitivity to which those couplings can be probed at future e"+e"- linear colliders in the sub-TeV and in the multi-TeV range. We find that for #sq root#(s) = 500 GeV with a luminosity of 1 ab"-"1 the anomalous WWH and ZZH couplings may be probed to about the 0.01 level, and the anomalous HHH coupling to about the 0.1 level. (orig.)Available from TIB Hannover: RA 2999(02-222) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Signals for virtual leptoquark exchange at colliders

We study the effects of virtual leptoquark exchange on charged current and neutral current process at HERA, on di-lepton production at the Tevatron, and on quark pair production at LEP II. We present the areas of parameter space that can be excluded at these colliders by searching for deviations from Standard Model expectations

Dispersion relations for vacuum-polarization functions in electroweak physics

SIGLEAvailable from TIB Hannover: RA 2999(91-103) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

High polarization photocathode R D at SLAC

This paper describes recent progress on the development of high polarization photocathodes for polarized electron sources. A strained InGaAs cathode has achieved a maximum electron-spin polarization of 71% and has demonstrated the strain enhancement of polarization for the first time. Strained GaAs cathodes have yielded polarizations as high as 90% with much higher quantum efficiency

TeV resonances in top physics at the LHC

We consider the possibility of studying novel particles at the TeV scale with enhanced couplings to the top quark via top quark pair production at the LHC and VLHC. In particular we discuss the case of neutral scalar and vector resonances associated with a strongly interacting electroweak symmetry breaking sector. We constrain the couplings of these resonances by imposing appropriate partial wave unitarity conditions and known low energy constraints. We evaluate the new physics signals via WW#->#tt for various models without making approximation for the initial state W bosons, and optimize the acceptance cuts for the signal observation. We conclude that QCD backgrounds overwhelm the signals in both the LHC and a 200 TeV VLHC, making it impossible to study this type of physics in the tt channel at those machines. (orig.)Available from TIB Hannover: RA 2999(03-002) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Quartic gauge boson couplings at linear colliders Interplay of WWZ/ZZZ production and WW-fusion

We study new physics effects to the quartic gauge boson couplings formulated by the electroweak chiral Lagrangian. Five next-to-leading order operators characterize the anomalous quartic gauge interactions which involve pure Goldstone boson dynamics for the electroweak symmetry breaking. We estimate the typical size of these couplings in different strongly-interacting models and examine the sensitivity to directly probing them via the WWZ/ZZZ triple gauge boson production at the high energy linear colliders. The important roles of polarized e"- and e"+ beams are stressed. We then compare the results with those from the W-pair production of the WW-fusion processes, and analyze the interplay of these two production mechanisms for an improved probe of the quartic gauge boson interactions. (orig.)Available from TIB Hannover: RA 2999(97-140) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Observation of electron polarization above 80% in photoemission from strained III-V compounds

Spin-polarized electron photoemission has been investigated for strained III--V compounds; (1) strained In{sub x}Ga{sub 1-x}As epitaxially grown on a GaAs substrate, and (2) strained GaAs grown on a GaAs{sub 1-x}P{sub x} buffer layer. The lattice mismatched heterostructure results in a highly strained epitaxial layer, and electron spin polarization as high as 90% has been observed

First maps of the soft X-ray diffuse background from the ROSAT XRT/PSPC all-sky survey

This paper presents an initial version of the diffuse background results from the ROSAT soft X-ray all-sky survey. These maps cover #approx# 98% of the sky in the 1/4 keV, 3/4 keV, and 1.5 keV bands, with #approx# 2 angular resolution and high sensitivity for low surface brightness extended features. The effects of non-X-ray contamination and X-rays of solar system origin have been eliminated to the greatest possible extent, but discrete X-ray sources have not been removed. The much improved angular resolution, statistical precision, and completeness of coverage of these maps reveals considerable structure over the entire 0.1 - 2.0 keV energy range that was not observed previously. The data agree well with previous all-sky surveys in terms of absolute normalization and zero point. (orig.)Available from TIB Hannover: RN 9303(335) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Intense diagnostic neutral beam development for ITER

For the next-generation, burning tokamak plasmas such as ITER, diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasma parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 25-kA, 100-kV, 1-{mu}s accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance