2442394
Precision Beam Parameter Monitoring in a Measurement of the Weak Mixing Angle in Moeller Scattering
A precision measurement of the parity nonconserving left-right asymmetry, A{sub LR}, in Moeller scattering (e{sup -}e{sup -} {yields} e{sup -}e{sup -}) is currently in progress at the Stanford Linear Accelerator Center (SLAC). This experiment, labeled SLAC-E158, scatters longitudinally polarized electrons off atomic electrons in an unpolarized hydrogen target at a Q{sup 2} of 0.03 (GeV/c){sup 2}. The asymmetry, which is the fractional difference in the scattering cross-sections, measures the effective pseudo-scalar weak neutral current coupling, g{sub ee}, governing Moeller scattering. This quantity is in turn proportional to (1/4 - sin{sup 2} {theta}{sub w}), where {theta}{sub w} is the electroweak mixing angle. The goal is to measure the asymmetry to a precision of 1 x 10{sup -8} which corresponds to {delta}(sin{sup 2} {theta}{sub w}) {approx} 0.0007. Since A{sub LR} is a function of the cross-sections, and the cross-sections depend on the beam parameters, the desired precision of A{sub LR} places stringent requirements on the beam parameters. This paper investigates the requirements on the beam parameters and discusses the means by which they are monitored and accounted for.
118149084
Search for Diphoton Events with Large Missing Transverse Energy in 6.3 fb--1 of pp¯ Collisions using the D0 Detector at the Fermilab Tevatron Collider
A search for diphoton events with large missing transverse energy produced in p{bar p} collisions at {radical}s = 1.96 TeV is presented. The data were collected with the D0 detector at the Fermilab Tevatron Collider between 2002 and 2010, and correspond to 6.3 fb{sup -1} of integrated luminosity. The observed missing transverse energy distribution is well described by the Standard Model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the Standard Model. In a gauge mediated supersymmetry breaking scenario, the breaking scale {Lambda} is excluded for {Lambda} < 124 TeV. In a universal extra dimension model including gravitational decays, the compactification radius R{sub c} is excluded for R{sub c}{sup -1} < 477 GeV.
125338982
Operation and efficiency of the DO Central Track Trigger