arXiv subjects

D0 collaboration

Publications and source records attributed to D0 collaboration.

At least 19 recordsLinked to original sources

arXiv2017

Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of $\sqrt s =1.96$ TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is $A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025$. The combined inclusive and differential asymmetries are consistent with recent standard model predictions.

hep-ex↗

arXiv2011

Measurement of the relative branching ratio of B^0_s to J/psi f_{0}(980) to B_{s}{0} to J/psi phi

We present a measurement of the relative branching fraction, R_{f_{0}/phi}, of B_{s}^{0} to J/ψf_{0}(980), with f_{0}(980) to pi^+ pi^-, to the process B_{s}^{0} to J/psi phi, with phi to K^+K^-. The J/psi f_{0}(980) final state corresponds to a CP-odd eigenstate of B_{s}^{0} that could be of interest in future studies of CP violation. Using approximately 8fb^-1 of data recorded with the D0 detector at the Fermilab Tevatron Collider, we find R_{f_{0}/phi} = 0.275 +- 0.041(stat) +- 0.061(syst).

hep-ex↗

arXiv2009

Searches for new physics in top events at the Tevatron

During the past years the CDF and D0 detectors have collected large amounts of data obtaining a relatively pure sample of pair-produced top quarks and a well understood sample containing singly-produced top quarks. These samples have been used for the precise measurement of the top quark properties, and have set stringent limits on new physics in the top sample. This reports presents the latest results from the CDF and D0 collaborations on the search for new physics within the top sample using an integrated data sample of up to 3.6 fb-1.

hep-ex↗

arXiv2008

Simultaneous measurement of the ratio B(t->Wb)/B(t->Wq) and the top quark pair production cross section with the D0 detector at sqrt(s)=1.96 TeV

We present the first simultaneous measurement of the ratio of branching fractions, R=B(t->Wb)/B(t->Wq), with q being a d, s, or b quark, and the top quark pair production cross section sigma_ttbar in the lepton plus jets channel using 0.9 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV collected with the D0 detector. We extract R and sigma_ttbar by analyzing samples of events with 0, 1 and >= 2 identified b jets. We measure R = 0.97 +0.09-0.08 (stat+syst) and sigma_ttbar = 8.18 +0.90-0.84 (stat+syst)} +/-0.50 (lumi) pb, in agreement with the standard model prediction.

hep-ex↗

arXiv2005

B-identification for Level 2: The Silicon Track Trigger at D0

This article describes the Silicon Track Trigger (STT) which has been fully commissioned in 2004 at the DO experiment. The STT allows to enrich already at the second trigger level the data sample with events containing B-mesons. The STT achieves this by providing within about 50 microseconds tracks with an impact parameter resolution of around 50 micrometer. The article shows preliminary results of the trigger performance and presents a fast b-identification algorithm for the second trigger level.

physics.ins-det↗

arXiv2003

Observation of Diffractively Produced W and Z Bosons in pbar-p Collisions at root-s = 1800 GeV

Using the D0 detector, we have observed events produced in pbar-p collisions that contain W or Z bosons in conjunction with very little energy deposition (``rapidity gaps'') in large forward regions of the detector. The fraction of W boson events with a rapidity gap (a signature for diffraction) is 0.89\pm^{0.19}_{0.17}%, and the probability that the non-diffractive background fluctuated to yield the observed diffractive signal is 3 x 10^{-14}, corresponding to a significance of 7.5 sigma. The Z boson sample has a gap fraction of 1.44 \pm^{0.61}_{0.52}%, with a significance of 4.4 sigma. The diffractive events have very similar properties to the more common non-diffractive component.

hep-ex↗

arXiv2003

Multiple Jet Production at Low Transverse Energies in p-pbar Collisions at Root(s) = 1.8 TeV

We present data on multiple production of jets with transverse energies near 20 GeV in p-pbar collisions at Root(s) = 1.8 TeV. QCD calculations in the parton-shower approximation of PYTHIA and HERWIG and the next-to-leading order approximation of JETRAD are compared to the data for one, two, three, and four jet inclusive production. Transverse energy spectra and multiple jet angular and summed transverse-energy distributions are adequately described by the shower approximation while next-to-leading order calculations describe the data poorly.

hep-ex↗

arXiv2002

Search for the Production of Single Sleptons through R-parity Violation in p bar{p} Collisions at sqrt{s}=1.8 TeV

We report the first search for supersymmetric particles via s-channel production and decay of smuons or muon sneutrinos at hadronic colliders. The data for the two-muon and two-jets final states were collected by the DO experiment, and correspond to an integrated luminosity of 94 +/- 5 pb^{-1}. Assuming that R-parity is violated via the single coupling lambda^{prime}_{211}, the number of candidate events is in agreement with expectation from the standard model. Exclusion contours are given in the (m_0,m_{1/2}) and (m_{tilde{chi}},m_{tilde{nu}}) planes for lambda^{prime}_{211}=0.09, 0.08 and 0.07.

hep-ex↗

arXiv2001

Search for R-parity Violating Supersymmetry in Dimuon and Four-Jets Channel

We present results of a search for R-parity-violating decay of the neutralino chi_1^0, taken to be the Lightest Supersymmetric Particle. It is assumed that this decay proceeds through one of the lepton-number violating couplings lambda-prime_2jk (j=1,2; k=1,2,3). This search is based on 77.5 pb-1 of data, collected by the D0 experiment at the Fermilab Tevatron in ppbar collisions at a center of mass energy of 1.8 TeV in 1992-1995.

hep-ex↗

arXiv2001

Subjet Multiplicity of Gluon and Quark Jets Reconstructed with the $k_{\perp}$ Algorithm in $p\bar{p}$ Collisions

The D0 Collaboration has studied for the first time the properties of hadron-collider jets reconstructed with a successive-combination algorithm based on relative transverse momenta ($k_{\perp}$) of energy clusters. Using the standard value D = 1.0 of the jet-separation parameter in the $k_{\perp}$ algorithm, we find that the $p_T$ of such jets is higher than the $E_T$ of matched jets reconstructed with cones of radius R = 0.7, by about 5 (8) GeV at $p_T \approx 90$ (240) GeV. To examine internal jet structure, the $k_{\perp}$ algorithm is applied within D = 0.5 jets to resolve any subjets. The multiplicity of subjets in jet samples at $\sqrt{s} = 1800$ GeV and 630 GeV is extracted separately for gluons ($M_g$) and quarks ($M_q$), and the ratio of average subjet multiplicities in gluon and quark jets is measured as $(M_{g} - 1) / (M_{q} - 1) = 1.84 \pm 0.15 (stat.) \pm ^{0.22}_{0.18} (sys.)$. This ratio is in agreement with the expectations from the HERWIG Monte Carlo event generator and a resummation calculation, and with observations in $e^+e^-$ annihilations, and is close to the naive prediction for the ratio of color charges of $C_A/C_F = 9/4 = 2.25$.

hep-ex↗

arXiv2001

Differential cross section for W boson production as a function of transverse momentum in proton-antiproton collisions at 1.8 TeV

We report a measurement of the differential cross section for W boson production as a function of its transverse momentum in proton-antiproton collisions at sqrt{s} = 1.8 TeV. The data were collected by the D0 experiment at the Fermilab Tevatron Collider during 1994-1995 and correspond to an integrated luminosity of 85 pb^{-1}. The results are in good agreement with quantum chromodynamics over the entire range of transverse momentum.

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

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

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

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↗