Showing papers by "Alberto Santoro published in 2000"
TL;DR: In this article, the bb-bar Image production cross section and angular correlations using the DO detector at the Fermilab Tevatron pp-bar Collider operating at?s = 1.8 TeV were extracted from single muon and dimuon data samples.
107 citations
TL;DR: In this article, bottom quark production in pbar-p collisions at 1.8 TeV was studied with 5 inverse picobarns of data collected in 1995 by the DO detector at the Fermilab Tevatron Collider.
Abstract: 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.
64 citations
TL;DR: In this article, the W boson mass was extracted by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11 089 decay candidates.
Abstract: \We present a measurement of the W boson mass using data collected by the DO experiment at the Fermilab Tevatron during 1994-1995. We identify W bosons by their decays to ev final states where the electron is detected in a forward calorimeter. We extract the W boson mass M-W 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 1687 dielectron events, mostly due to Z-->ee decays, to constrain our model of the detector response. Using the forward calorimeter data, we measure M-w=80.691+/-0.227 GeV. Combining the forward calorimeter measurements with our previously published central calorimeter results, we obtain M-W= 80.482 +/-0.091 GeV.
59 citations
TL;DR: In this article, a new measurement of the cross section for the production of isolated photons, with transverse energies above 10 GeV and pseudorapidities |eta| 36 GeV, was reported.
Abstract: We report a new measurement of the cross section for the production of isolated photons, with transverse energies (ET) above 10 GeV and pseudorapidities |eta| 36 GeV.
54 citations
TL;DR: In this paper, the authors apply a quasi-model independent strategy to search for new high p-T physics in approximately 100 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV collected by the DZero experiment during 1992-1996 at the Fermilab Tevatron.
Abstract: We apply a quasi-model-independent strategy ("Sleuth") to search for new high p_T physics in approximately 100 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV collected by the DZero experiment during 1992-1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states and demonstrate sensitivity to a variety of models predicting new phenomena at the electroweak scale. No evidence of new high p_T physics is observed.
45 citations
TL;DR: In this article, 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 was presented.
Abstract: 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.
43 citations
TL;DR: A measurement of the transverse momentum distribution of Z bosons produced in p&pmacr; collisions at sqrt[s] = 1.8 TeV from data collected by the DO experiment at the Fermilab Tevatron Collider is presented.
Abstract: We present a measurement of the transverse momentum distribution of Z bosons produced in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and a current resummation calculation. We also use our data to extract values of the non-perturbative parameters for a particular version of the resummation formalism, obtaining significantly more precise values than previous determinations.
40 citations
University of California, Santa Cruz1, University of Mississippi2, Fermilab3, CINVESTAV4, Tel Aviv University5, Illinois Institute of Technology6, University of South Carolina7, University of Cincinnati8, Kansas State University9, Tufts University10, Benemérita Universidad Autónoma de Puebla11, University of Wisconsin-Madison12, Yale University13, Princeton University14, Stanford University15
TL;DR: In this paper, Jezabek et al. present the results of a five-dimensional amplitude analysis of the Λ c + → pK − π + system based on 946±38 reconstructed decays.
36 citations
TL;DR: The dijet cross section for large Deltaeta in pp collisions at sqrt[s]=1800 and 630 GeV is measured using the D0 detector and the partonic cross section increases strongly with the size of Deltaeta.
Abstract: Inclusive dijet production at large pseudorapidity intervals (Delta eta) between the two jets has been suggested as a regime for observing Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. We have measured the dijet cross section for large Delta eta in p (p) over bar collisions at root s = 1800 and 630 GeV using the D0 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 alpha(BFKL)(20 GeV) = 1.65 +/- 0.07.
36 citations
TL;DR: In this paper, the authors present a search for electroweak production of single top quarks in the electron+jets and muon-jets decay channels using data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DO detector between 1992 and 1995.
Abstract: We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ≈90pb -1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DO 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 pp→tb+X of 39 pb. The upper limit for the t-channel process pp→tqb+X is 58 pb.
29 citations
TL;DR: In this paper, second-generation leptoquark (LQ) pairs were searched for in the mm+jets channel using 94+/-5 pb(-1) of pp collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996.
Abstract: We have searched for second-generation leptoquark (LQ) pairs in the mm+jets channel using 94+/-5 pb(-1) of pp collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the mnu+jets and nunu+jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and beta, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of 200(180) GeV/c(2) for beta = 1(1 / 2) are set at the 95% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of beta.
University of Mississippi1, Fermilab2, Tel Aviv University3, University of Massachusetts Amherst4, Stanford University5, Illinois Institute of Technology6, University of South Carolina7, Yale University8, University of Cincinnati9, Benemérita Universidad Autónoma de Puebla10, University of California, Santa Cruz11, CINVESTAV12, Kansas State University13, Tufts University14, University of Wisconsin-Madison15, Princeton University16
TL;DR: In this article, the authors measured asymmetries in the production of Λ c + and Λc − baryons in the E791 experiment at Fermilab.
University of Mississippi1, Fermilab2, Tel Aviv University3, University of Massachusetts Amherst4, Stanford University5, Illinois Institute of Technology6, University of South Carolina7, Yale University8, University of Cincinnati9, Benemérita Universidad Autónoma de Puebla10, University of California, Santa Cruz11, CINVESTAV12, Tufts University13, Kansas State University14, University of Wisconsin-Madison15, Princeton University16
TL;DR: In this article, the authors measured asymmetries in the production of Λc+ and − baryons in the E791 experiment at Fermilab, with an asymmetry of (12.7±3.3)% independent of Feynman x (xF) and transverse momentum squared (pT2).
TL;DR: In this paper, it was shown that the ratio of the tau and electron electroweak charged current couplings to the W boson, g(T)(W)/g(e)(W) = 0.980 +/- 0.031.
Abstract: of data collected with the DO detector during 1993-1995. We find that a(p (p) over bar --> W + X)B(W --> 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(T)(W)/g(e)(W), be unity. We find g(T)(W)/g(e)(W) = 0.980 +/- 0.031, in agreement with lepton universality.
TL;DR: In this paper, a fit to the transverse momentum spectrum of the W boson yields direct limits on anomalous W-B boson couplings with the assumption that the couplings are equal.
Abstract: Limits on anomalous $\mathrm{WW}\ensuremath{\gamma}$ and $\mathrm{WWZ}$ couplings are presented from a study of $WW/W\stackrel{\ensuremath{\rightarrow}}{Z}e\ensuremath{
u}\mathrm{jj}$ events produced in $p\overline{p}$ collisions at $\sqrt{s}=1.8 \mathrm{TeV}.$ Results from the analysis of data collected using the D\O{} 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 $\mathrm{WW}\ensuremath{\gamma}$ and $\mathrm{WWZ}$ couplings. With the assumption that the $\mathrm{WW}\ensuremath{\gamma}$ and $\mathrm{WWZ}$ couplings are equal, we obtain $\ensuremath{-}0.34l\ensuremath{\lambda}l0.36$ (with $\ensuremath{\Delta}\ensuremath{\kappa}=0)$ and $\ensuremath{-}0.43l\ensuremath{\Delta}\ensuremath{\kappa}l0.59$ (with $\ensuremath{\lambda}=0)$ at the 95% confidence level for a form-factor scale $\ensuremath{\Lambda}=2.0 \mathrm{TeV}.$
TL;DR: In this article, a lower limit of 2.0 TeV at 95% confidence on the energy scale Lambda(LL) for compositeness in quarks was established assuming a model with a left-left isoscalar contact interaction interaction term.
Abstract: Events in (p) over bar p collisions at root 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.
University of Mississippi1, University of Cincinnati2, CINVESTAV3, Illinois Institute of Technology4, Kansas State University5, Yale University6, Tufts University7, Fermilab8, University of Wisconsin-Madison9, Benemérita Universidad Autónoma de Puebla10, University of South Carolina11, University of California, Santa Cruz12, University of Massachusetts Amherst13, Stanford University14, Tel Aviv University15
TL;DR: In this article, the authors studied the correlation between the transverse and longitudinal momenta of the two D mesons and the relative production rates for different types of D meson pairs.
Abstract: We present a study of correlations between D and $${\overline D}$$
mesons produced in 500 GeV/cπ−-nucleon interactions, based on data from experiment E791 at Fermilab. We have fully reconstructed 791 ± 44 charm meson pairs to study correlations between the transverse and longitudinal momenta of the two D mesons and the relative production rates for different types of D meson pairs. We see slight correlations between the longitudinal momenta of the D and the $${\bar D}$$
, and significant correlations between the azimuthal angle of the D and the $${\bar D}$$
. The experimental distributions are compared to a next-to-leading-order QCD calculation and to predictions of the PYTHIA/JETSET Monte Carlo event generator. We observe less correlation between transverse momenta and different correlations between longitudinal momenta than these models predict for the default values of the model parameters. Better agreement between data and theory might be achieved by tuning the model parameters or by adding higher order perturbative terms, thus contributing to a better understanding of charm production. The relative production rates for the four sets of charm pairs, $$D^0{{\overline D}^0}, D^0 D^{-}, D^+{{\overline D}^0}, D^+ D^{-}$$
as calculated in the PYTHIA/JETSET event generator with the default parameters, agree with data as far as the relative ordering, but predict too many $$D^+ {{\overline D}^0}$$
pairs and too few $$D^+ D^{-}$$
pairs.