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The D0 experiment's integrated luminosity for Tevatron Run IIa

Description: An essential ingredient in all cross section measurements is the luminosity used to normalize the data sample. In this note, we present the final assessment of the integrated luminosity recorded by the D0 experiment during Tevatron Run IIa. The luminosity measurement is derived from hit rates from the products of inelastic proton-antiproton collisions registered in two arrays of scintillation counters called the luminosity monitor (LM) detectors. Measured LM rates are converted to absolute luminosity using a normalization procedure that is based on previously measured inelastic cross sections and the geometric acceptance and efficiency of the LM detectors for registering inelastic events. During Run IIa, the LM detector performance was improved by a sequence of upgrades to the electronic readout system and other factors summarized in this note. The effects of these changes on the reported luminosity were tracked carefully during the run. Due to the changes, we partition the run into periods for which different conversions from measured LM rates to absolute luminosity apply. The primary upgrade to the readout system late in Run IIa facilitated a reevaluation of the overall normalization of the luminosity measurement for the full data sample. In this note, we first review the luminosity measurement technique employed by D0. We then summarize the changes to the LM system during Run IIa and the corresponding normalization adjustments. The effect of the adjustments is to increase D0's assessment of its recorded integrated luminosity compared to what was initially reported during Run IIa. The overall increase is 13.4% for data collected between April 20, 2002 (the beginning of Run IIa data used for physics analysis) and February 22, 2006 (the end of Run IIa).
Date: April 1, 2007
Creator: Andeen, T.; Casey, B.C.K.; DeVaughan, K.; Enari, Y.; Gallas, E.; Krop, D. et al.
Partner: UNT Libraries Government Documents Department

Determination of the effective inelastic p anti-p cross-section for the D0 Run II luminosity measurement

Description: The authors determine the effective inelastic p{bar p} cross-section into the D0 Luminosity Monitor for all run periods prior to September 2004. This number is used to relate the measured inelastic collision rate to the delivered luminosity. The key ingredients are the inelastic p{bar p} cross-section, the Luminosity Monitor efficiency, and the modeling of kinematic distributions for various inelastic processes used to determine the detector acceptance. The resulting value is {sigma}{sub p{bar p},eff} = 46 {+-} 3 mb.
Date: November 1, 2004
Creator: Edwards, T.; U., /Manchester; Yacoob, S.; Andeen, T.; U., /Northwestern; Begel, M. et al.
Partner: UNT Libraries Government Documents Department

Search for the Higgs boson in H ---> WW(*) decays in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: We present a search for the standard model Higgs boson in H {yields} WW{sup (*)} decays with e{sup +}e{sup -}, e{sup {+-}}{mu}{sup {-+}} and {mu}{sup +}{mu}{sup -} final states in p{bar p} collisions at a center-of-mass energy of {radical}s = 1.96 TeV. The data, collected from April 2002 to June 2004 with the D0 detector, correspond to an integrated luminosity of 300-325 pb{sup -1}, depending on the final state. The number of events observed is consistent with the expectation from backgrounds. Limits from the combination of all three channels on the Higgs production cross section times branching ratio {sigma} x BR(H {yields} WW{sup (*)}) are presented.
Date: August 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the t anti-t production cross section in p anti-p collistions at s**(1/2) = 1.96-TeV in dilepton final states

Description: The authors present a measurement of the top quark pair (t{bar t}) production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using events with two charged leptons in the final state. This analysis utilizes an integrated luminosity of 224-243 pb{sup -1} collected with the D0 detector at the Fermilab Tevatron Collider. They observe 13 events in the e{sup +}e{sup -}, e{mu} and {mu}{sup +} {mu}{sup -} channels with an expected background of 3.2 {+-} 0.7 events. For a top quark mass of 175 GeV, we measure a t{bar t} production cross section of {sigma}{sub t{bar t}} = 8.6{sub -2.7}{sup +3.2}(stat) {+-} 1.1(syst) {+-} 0.6(lumi) pb, consistent with the standard model prediction.
Date: May 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Production of WZ events in p anti-p collisions at s**(1/2) = 1.96-TeV and limits on anomalous WWZ couplings

Description: The authors present results from a search for WZ production with subsequent decay to {ell}{nu}{ell}'{bar {ell}}' ({ell} and {ell}' = e or {mu}) using 0.30 fb{sup -1} of data collected by the D0 experiment between 2002 and 2004 at the Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71 {+-} 0.08 events, we measure the WZ production cross section to be 4.5{sub -2.6}{sup +3.8} pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0 < {Delta}{kappa}{sub Z} < 2.4 for form factor scale {Lambda} = 1 TeV, and -0.48 < {lambda}{sub Z} < 0.48 and -0.49 < {Delta}g{sub 1}{sup Z} < 0.66 for {Lambda} = 1.5 TeV.
Date: April 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Search for neutral supersymmetric Higgs bosons in multijet events at s**(1/2) = 1.96-TeV

Description: We have performed a search for neutral Higgs bosons produced in association with bottom quarks in p{bar p} collisions, using 260 pb{sup -1} of data collected with the D0 detector in Run II of the Fermilab Tevatron Collider. The cross sections for these processes are enhanced in many extensions of the standard model (SM), such as in its minimal supersymmetric extension at large tan {beta}. The results of our analysis agree with expectations from the SM, and we use our measurements to set upper limits on the production of neutral Higgs bosons in the mass range of 90 to 150 GeV.
Date: April 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Search for single top quark production in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: We present a search for electroweak production of single top quarks in the s-channel and t-channel using neural networks for signal-background separation. We have analyzed 230 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy of 1.96 TeV and find no evidence for a single top quark signal. The resulting 95% confidence level upper limits on the single top quark production cross sections are 6.4 pb in the s-channel and 5.0 pb in the t-channel.
Date: May 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Search for first-generation scalar leptoquarks in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors report on a search for pair production of first-generation scalar leptoquarks (LQ) in p{bar p} collisions at {radical}s = 1.96 TeV using an integrated luminosity of 252 pb{sup -1} collected at the Fermilab Tevatron collider by the D0 detector. They observe no evidence for LQ production in the topologies arising from LQ{ovr LQ} {yields} eqeq and LQ{ovr LQ} {yields} eqvq, and derive 95% C.L. lower limits on the LQ mass as a function of {beta}, where {beta} is the branching fraction for LQ {yields} eq. The limits are 241 and 218 GeV/c{sup 2} for {beta} = 1 and 0.5, respectively. These results are combined with those obtained by D0 at {radical}s = 1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c{sup 2}.
Date: December 1, 2004
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Search for large extra spatial dimensions in dimuon production at D0

Description: We present the results of a search for the e.ects of large extra spatial dimensions in p{bar p} collisions at {radical}s = 1.96 TeV in events containing a pair of energetic muons. The data correspond to 246 pb{sup -1} of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C.L. lower limits on the fundamental Planck scale between 0.85 TeV and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date.
Date: June 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

The Upgraded D0 detector

Description: The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.
Date: July 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, D. L.; Adams, M. et al.
Partner: UNT Libraries Government Documents Department

Study of Z gamma events and limits on anomalous Z Z gamma and Z gamma gamma couplings in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors present a measurement of the Z{gamma} production cross section and limits on anomalous ZZ{gamma} and Z{gamma}{gamma} couplings for form-factor scales of {Lambda} = 750 and 1000 GeV. The measurement is based on 138 (152) candidate events in the ee{gamma} ({mu}{mu}{gamma}) final state using 320 (290) pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are |h{sub 10,30}{sup Z}| < 0.23, |h{sub 20,40}{sup Z}| < 0.020, |h{sub 10,30}{gamma}| < 0.23, and |h{sub 20,40}{gamma}| < 0.019 for {Lambda} = 1000 GeV.
Date: February 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the t anti-t production cross section in p anti-p collisions at s**(1/2) = 1.96-TeV using lepton + jets events with lifetime b-tagging

Description: We present a measurement of the top quark pair (t{bar t}) production cross section ({sigma}{sub t{bar t}}) in p{bar p} collisions at {radical}s = 1.96 TeV using 230 pb{sup -1} of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the t{bar t} purity of the selected sample. For a top quark mass of 175 GeV, we measure {sigma}{sub t{bar t}} = 8.6{sub -1.5}{sup +1.6}(stat. + syst.) {+-} 0.6 (lumi.) pb, in agreement with the standard model expectation.
Date: April 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the p - anti-p ---> W gamma + X cross section at s**(1/2) = 1.96-TeV and WW gamma anomalous coupling limits

Description: The WW{gamma} triple gauge boson coupling parameters are studied using p{bar p} {yields} {ell}{nu}{gamma} + X({ell} = e, {mu}) events at {radical}s = 1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162 pb{sup -1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p{bar p} {yields} W({gamma}) + X {yields} {ell}{nu}{gamma} + X with E{sub T}{sup {gamma}} > 8 GeV and {Delta}R{sub {ell}{gamma}} > 0.7 is 14.8 {+-} 1.6(stat) {+-} 1.0(syst) {+-} 1.0(lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < {Delta}{kappa}{sub {gamma}} < 0.96 and -0.20 < {lambda}{sub {gamma}} < 0.20.
Date: March 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the t anti-t production cross section in p anti-p collisions at s**(1/2) = 1.96 = TeV using kinematic characteristics of lepton + jets events

Description: We present a measurement of the top quark pair (t{bar t}) production cross section ({sigma}{sub t{bar t}}) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV using 230 pb{sub -1} of data collected by the D0 detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the t{bar t} content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure {sigma}{sub t{bar t}} = 6.7{sub -1.3}{sup +1.4}(stat){sub -1.1}{sup +1.6}(syst) {+-} 0.4(lumi)pb, in good agreement with the standard model prediction.
Date: April 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

First measurement of sigma (p anti-p ---> Z) . Br (Z ---> tau tau) at s**(1/2) = 1.96- TeV

Description: The authors present a measurement of the cross section for Z production times the branching fraction to {tau} leptons, {sigma} {center_dot} Br(Z {yields} {tau}{sup +}{tau}{sup -}), in p{bar p} collisions at {radical}s = 1.96 TeV in the channel in which one {tau} decays into {mu}{nu}{sub {mu}}{nu}{sub {tau}}, and the other into hadrons + {nu}{sub {tau}} or e{nu}{sub e}{nu}{sub {tau}}. The data sample corresponds to an integrated luminosity of 226 pb{sup -1} collected with the D0 detector at the Fermilab Tevatron collider. The final sample contains 2008 candidate events with an estimated background of 55%. From this they obtain {sigma} {center_dot} Br(Z {yields} {tau}{sup +}{tau}{sup -}) = 237 {+-} 15(stat) {+-} 18(sys) {+-} 15(lum) pb, in agreement with the standard model prediction.
Date: December 1, 2004
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Measurement of inclusive differential cross sections for Upsilon(1S) production in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors present measurements of the inclusive production cross sections of the {Upsilon}(1S) bottomonium state in p{bar p} collisions at {radical}s = 1.96 TeV. Using the {Upsilon}(1S) {yields} {mu}{sup +}{mu}{sup -} decay mode for a data sample of 159 {+-} 10 pb{sup -1} collected by the D0 detector at the Fermilab Tevatron collider, they determine the differential cross sections as a function of the {Upsilon}(1S) transverse momentum for three ranges of the {Upsilon}(1S) rapidity: 0 < |y{sup {Upsilon}}| {le} 0.6, 0.6 < |y{sup {Upsilon}}| {le} 1.2, and 1.2 < |y{sup {Upsilon}}| {le} 1.8.
Date: February 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department