arXiv subjects

B. Abbott

Publications and source records attributed to B. Abbott.

At least 55 records · Page 3Linked to original sources

arXiv2003

Analysis of LIGO data for gravitational waves from binary neutron stars

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$ per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range 1--3 $M_\odot$.

gr-qc↗

arXiv2003

Setting upper limits on the strength of periodic gravitational waves using the first science data from the GEO600 and LIGO detectors

Data collected by the GEO600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar J1939+2134 at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: a frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar's gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar's equatorial ellipticity.

gr-qc↗

arXiv2001

Search for Electroweak Production of Single Top Quarks in ppbar Collisions

We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb.

hep-ex↗

arXiv2001

Inclusive Jet Production in pbar p Collisions

We report a new measurement of the pseudorapidity (eta) and transverse-energy (Et) dependence of the inclusive jet production cross section in pbar b collisions at sqrt(s) = 1.8 TeV using 95 pb**-1 of data collected with the DZero detector at the Fermilab Tevatron. The differential cross section d^2sigma/dEt deta is presented up to |eta| = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.

hep-ex↗

arXiv2001

High-p_T Jets in pbarp Collisions at sqrt{s} = 630 and 1800 GeV

Results are presented from analyses of jet data produced in pbarp collisions at sqrt{s} = 630 and 1800 GeV collected with the DO detector during the 1994-95 Fermilab Tevatron Collider run. We discuss details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at sqrt{s} = 630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at sqrt{s} = 630 and 1800 GeV are compared to next-to-leading-order QCD predictions. The order alpha_s^3 calculations are in good agreement with the data. We also use the data at sqrt{s} = 1800 GeV to rule out models of quark compositeness with a contact interaction scale less than 2.2 TeV at the 95% confidence level.

hep-ex↗

arXiv2000

Ratios of Multijet Cross Sections in p-pbar Collisions at sqrt(s)=1.8 TeV

We report on a study of the ratio of inclusive three-jet to inclusive two-jet production cross sections as a function of total transverse energy in p-pbar collisions at a center-of-mass energy sqrt{s} = 1.8 TeV, using data collected with the D0 detector during the 1992-1993 run of the Fermilab Tevatron Collider. The measurements are used to deduce preferred renormalization scales in perturbative O(alpha_s^3) QCD calculations in modeling soft-jet emission.

hep-ex↗

arXiv2000

Measurement of the Angular Distribution of Electrons from W->e nu Decays Observed in ppbar Collisions at sqrt(s)=1.8 TeV

We present the first measurement of the electron angular distribution parameter alpha_2 in W to e nu events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the D0 detector during the 1994--1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1 +/- alpha_1 cos theta* + alpha_2 cos^2 theta*), where theta* is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters alpha_1 and alpha_2 become functions of p_T^W, the W boson transverse momentum. This measurement provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W boson mass measurement.

hep-ex↗

arXiv2000

Cross Section for b Jet Production in pbar-p Collisions at sqrt(s) = 1.8 TeV

Bottom quark production in pbar-p collisions at sqrt(s)=1.8 TeV is studied with 5 inverse picobarns of data collected in 1995 by the DO detector at the Fermilab Tevatron Collider. The differential production cross section for b jets in the central rapidity region (|y(b)| < 1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, DO results are found to be higher than, but compatible with, next-to-leading-order QCD predictions.

hep-ex↗

arXiv2000

Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV

Inclusive dijet production at large pseudorapidity intervals (delta_eta) between the two jets has been suggested as a regime for observing BFKL dynamics. We have measured the dijet cross section for large delta_eta in ppbar collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic cross section increases strongly with the size of delta_eta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of a_{BFKL}(20GeV)=1.65+/-0.07.

hep-ex↗

arXiv2000

The b-bbar Production Cross Section and Angular Correlations in p-pbar Collisions at sqrt(s) = 1.8 TeV

We present measurements of the b-bbar production cross section and angular correlations using the D0 detector at the Fermilab Tevatron p-pbar Collider operating at sqrt(s) = 1.8 TeV. The b quark production cross section for |y(b)|<1.0 and p_T(b)>6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and bbar quarks, measured from the azimuthal opening angle between their decay muons, also agree in shape with the next-to-leading order QCD prediction.

hep-ex↗

arXiv2000

Limits on Anomalous WWgamma and WWZ Couplings from WW/WZ->enujj Production

Limits on anomalous WWgamma and WWZ couplings are presented from a study of WW/WZ->enujj events in ppbar collisions at sqrt{s}=1.8 TeV. Results from the analysis of data collected using the D0 detector during the 1993-1995 Tevatron collider run at Fermilab are combined with those of an earlier study from the 1992-1993 run. A fit to the transverse momentum spectrum of the W boson yields direct limits on anomalous WWgamma and WWZ couplings. With the assumption that the WWgamma and WWZ couplings are equal, we obtain -0.34< lambda < 0.36 (with Delta kappa=0) and -0.43< Delta kappa < 0.59 (with lambda=0) at the 95 confidence level for a form-factor scale Lambda=2.0 TeV.

hep-ex↗

arXiv2000

Limits on Quark Compositeness from High Energy Jets in PbarP Collisions at 1.8 TeV

Events in PbarP collisions at sqrt(s)=1.8 TeV with total transverse energy exceeding 500 GeV are used to set limits on quark substructure. The data are consistent with next-to-leading order QCD calculations. We set a lower limit of 2.0 TeV at 95% confidence on the energy scale Lambda_LL for compositeness in quarks, assuming a model with a left-left isoscalar contact interaction term. The limits on Lambda_LL are found to be insensitive to the sign of the interference term in the Lagrangian.

hep-ex↗

arXiv2000

A measurement of the W boson mass using large rapidity electrons

We present a measurement of the W boson mass using data collected by the D0 experiment at the Fermilab Tevatron during 1994--1995. We identify W bosons by their decays to e-nu final states where the electron is detected in a forward calorimeter. We extract the W boson mass, Mw, by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11,089 W -> e nu decay candidates. We use a sample of 1,687 dielectron events, mostly due to Z -> ee decays, to constrain our model of the detector response. Using the forward calorimeter data, we measure Mw = 80.691 +- 0.227 GeV. Combining the forward calorimeter measurements with our previously published central calorimeter results, we obtain Mw = 80.482 +- 0.091 GeV.

hep-ex↗

arXiv2000

Spin Correlation in tt-bar Production from pp-bar Collisions at sqrt(s)=1.8 TeV

The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.

hep-ex↗

arXiv2000

A Measurement of the W to tau+nu Production Cross Section in p-pbar Collisions at sqrt(s) = 1.8 TeV

We report on a measurement of sigma(p-pbar to W+X) times B(W to tau+nu) in p-pbar collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity of 18 pb^-1 of data collected with the D0 detector during 1994-1995. We find that sigma(p-pbar to W+X) times B(W to tau+nu) = 2.22 +- 0.09 (stat) +- 0.10 (syst) +- 0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, g_tau^W / g_e^W, be unity. We find g_tau^W / g_e^W = 0.980 +- 0.031, in agreement with lepton universality.

hep-ex↗

arXiv2000

Small Angle Muon and Bottom Quark Production in pbarp Collisions at sqrt(s) = 1.8 TeV

This Letter describes a measurement of the muon cross section originating from b quark decay in the forward rapidity range 2.4 < y(mu) < 3.2 in pbarp collisions at sqrt(s) = 1.8 TeV. The data used in this analysis were collected by the D0 experiment at the Fermilab Tevatron. We find that NLO QCD calculations underestimate b quark production by a factor of four in the forward rapidity region. A cross section measurement using muon+jet data has been included in this version of the paper.

hep-ex↗

arXiv2000

A Search for Dilepton Signatures from Minimal Low-Energy Supergravity in $p\bar{p}$ Collisions at $\sqrt{s}=1.8$ TeV

We report on a search for supersymmetry using the DØdetector. The 1994-1996 data sample of $\sqrt{s}=1.8$ TeV $p\bar{p}$ collisions was analyzed for events containing two leptons ($e$ or $μ$), two or more jets, and missing transverse energy. Assuming the minimal supergravity model, with $A_0=0$ and $μ<0$, various thresholds were employed to optimize the search. No events were found beyond expectation from background. We set a lower limit at the 95% C.L. of 255 GeV/$c^2$ for equal mass squarks and gluinos for $\tanβ=2$, and present exclusion contours in the $(m_0,m_{1/2})$ plane for $\tanβ=2$--6.

hep-ex↗

arXiv2000

A Measurement of the W Boson Mass Using Electrons at Large Rapidities

We report a measurement of the W boson mass based on an integrated luminosity of 82/pb from p-pbar collisions at sqrt(s) = 1.8 TeV recorded in 1994-1995 by the D0 detector at the Fermilab Tevatron. We identify W bosons by their decays to e-nu, where the electron is detected in the forward calorimeters. We extract the mass by fitting the transverse mass and the electron and neutrino transverse momentum spectra of 11,089 W boson candidates. We measure Mw = 80.691 +- 0.227 GeV. By combining this measurement with our previously published central calorimeter results from data taken in 1992-1993 and 1994-1995, we obtain Mw = 80.482 +- 0.091 GeV.

hep-ex↗