J. L. Willis

Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production

A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/{ital c} proton beam incident on Be, Fe, and W targets is reported. The behavior of the Drell-Yan ratios at small target-parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross-section ratios as a function of the incident-parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus. {copyright} {ital 1999} {ital The American Physical Society}

The PyCBC search for gravitational waves from compact binary coalescence

We describe the PyCBC search for gravitational waves from compactobject binary coalescences in advanced gravitational-wave detector data. The search was used in the first Advanced LIGO observing run and unambiguously identified two black hole binary mergers, GW150914 and GW151226. At its core, the PyCBC search performs a matched-filter search for binary merger signals using a bank of gravitational-wave template waveforms. We provide a complete description of the search pipeline including the steps used to mitigate the effects of noise transients in the data, identify candidate events and measure their statistical significance. The analysis is able to measure false-alarm rates as low as one per million years, required for confident detection of signals. Using data from initial LIGO’s sixth science run, we show that the new analysis reduces the background noise in the search, giving a 30% increase in sensitive volume for binary neutron star systems over previous searches.

Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800 GeV/c

We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. The muon angular distributions in the dilepton rest frame have been measured over the kinematic range 4.5<m{mu mu}<15 GeV/c{2}, 0<p{T}<4 GeV/c, and 0<x{F}<0.8. No significant cos2phi dependence is found in these proton-induced Drell-Yan data, in contrast with the situation for pion-induced Drell-Yan data. The data are compared with expectations from models which attribute the cos2phi distribution to a QCD vacuum effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function h{1}{perpendicular}. Constraints on the magnitude of the sea-quark h{1}{perpendicular} structure functions are obtained.

Implementing a search for aligned-spin neutron star-black hole systems with advanced ground based gravitational wave detectors

detectors, and an estimate of the rate of background events. We restrict attention to neutron star{black hole (NS-BH) binary systems, and we compare a search using non-spinning templates to one using templates that include spins aligned with the orbital angular momentum. To run the searches we implement the binary inspiral matched-lter computation in PyCBC, a new software toolkit for gravitational-wave data analysis. We nd that the inclusion of aligned-spin eects signicantly increases the astrophysical reach of the search. Considering astrophysical NS-BH systems with non-precessing black hole spins, for dimensionless spin components along the orbital angular momentum uniformly distributed in ( 1; 1), the sensitive volume of the search with aligned-spin templates is increased by 50% compared to the non-spinning search; for signals with aligned spins uniformly distributed in the range (0:7; 1), the increase in sensitive volume is a factor of 10.

Improved measurement of the anti-d / anti-u asymmetry in the nucleon sea

Measurements of the ratio of Drell-Yan yields from an 800 \rm{GeV/c} proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of anti-down (

Measurement of Upsilon production for p + p and p + d interactions at 800 GeV/c.

\bar{d}

J/psi polarization in 800-GeV p-Cu interactions.

) to anti-up (

Acceleration of generalized hypergeometric functions through precise remainder asymptotics

\bar{u}

New coordinates for the amplitude parameter space of continuous gravitational waves

) quark distributions in the proton sea is determined over a wide range in Bjorken-

d̄/ū asymmetry and the origin of the nucleon sea

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