Showing papers by "Alberto Santoro published in 2002"
TL;DR: In this article, the authors study the Dalitz plot of the decay of the scalar sector in hadron spectroscopy and obtain a good fit when the presence of an additional scalar resonance is allowed.
Abstract: We study the Dalitz plot of the decay ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ with a sample of 15090 events from Fermilab experiment E791. Modeling the decay amplitude as the coherent sum of known $K\ensuremath{\pi}$ resonances and a uniform nonresonant term, we do not obtain an acceptable fit. If we allow the mass and width of the ${K}_{0}^{*}(1430)$ to float, we obtain values consistent with those from PDG but the ${\ensuremath{\chi}}^{2}$ per degree of freedom of the fit is still unsatisfactory. A good fit is found when we allow for the presence of an additional scalar resonance, with mass $797\ifmmode\pm\else\textpm\fi{}19\ifmmode\pm\else\textpm\fi{}43\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{\mathrm{c}}^{\mathrm{2}}$ and width $410\ifmmode\pm\else\textpm\fi{}43\ifmmode\pm\else\textpm\fi{}87\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{\mathrm{c}}^{2}$. The mass and width of the ${K}_{0}^{*}(1430)$ become $1459\ifmmode\pm\else\textpm\fi{}7\ifmmode\pm\else\textpm\fi{}5\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{\mathrm{c}}^{\mathrm{2}}$ and $175\ifmmode\pm\else\textpm\fi{}12\ifmmode\pm\else\textpm\fi{}12\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{\mathrm{c}}^{\mathrm{2}}$, respectively. Our results provide new information on the scalar sector in hadron spectroscopy.
187 citations
TL;DR: A search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrt[s] = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider finds no evidence for signal.
Abstract: We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrt[s] = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the ( M(H+/-),tan(beta)) parameter space where the decay t--> H(+)b has a branching fraction >0.36 and B(H+/--->tau(nu)(tau)) is large.
54 citations
TL;DR: The central inclusive jet cross section has been measured using a successive-combination algorithm for reconstruction of jets using 87.3 pb−1 of data collected with the DO detector at the Fermilab Tevatron Collider during 1994-1995.
30 citations
TL;DR: In this article, the W boson mass was measured using the DO detector and a data sample of 82 pb(-1) from the Fermilab Tevatron collider.
Abstract: We have measured the W boson mass using the DO detector and a data sample of 82 pb(-1) from the Fermilab Tevatron collider. This measurement uses W-->enu decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such "edge" electrons have not been used in any previous DO analysis, and represent a 14% increase in the W boson sample size. For these electrons, new response and resolution parameters are determined, and revised backgrounds and underlying event energy flow measurements are made. When the current measurement is combined with previous DO W boson mass measurements, we obtain M-W=80.483+/-0.084 GeV. The 8% improvement from the previous DO measurement is primarily due to the improved determination of the response parameters for non-edge electrons using the sample of Z bosons with non-edge and edge electrons.
28 citations
TL;DR: In this paper, the D empty set Collaboration studied the properties of hadron-collider jets reconstructed with a successive-combination algorithm based on relative transverse momenta (k(perpendicular to)) of energy clusters.
Abstract: The D empty set 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(perpendicular to)) of energy clusters. Using the standard value D = 1.0 of the jet-separation parameter in the k(perpendicular to) 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) approximate to90 (240) GeV. To examine internal jet structure, the k(perpendicular to) algorithm is applied within D = 0.5 jets to resolve any subjets. The multiplicity of subjets in jet samples at roots = 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+/-0.15 (stat)(-0.18)(+0.22) (syst). 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.
24 citations
TL;DR: In this paper, the D empty set detector was used to study events produced in (p) over barp collisions that contain large forward regions with very little energy deposition ("rapidity gaps") and concurrent jet production at center of mass energies of roots = 630 and 1800 GeV.
18 citations
TL;DR: In this paper, the transverse mass spectrum of the W boson Gamma(W) was determined from the W-->e+nu(e) decay channel and the decay width was found to be 2.23(-0.14)(+0.15)(stat)+/-0.10(syst) GeV, consistent with the expectation from the standard model.
Abstract: Based on 85 pb-1 data of p (p) over bar collisions at roots=1.8 TeV collected using the D empty set detector at Fermilab during the 1994-1995 run of the Tevatron, we present a direct measurement of the total decay width of the W boson Gamma(W). The width is determined from the transverse mass spectrum in the W-->e+nu(e) decay channel and found to be Gamma(W)=2.23(-0.14)(+0.15)(stat)+/-0.10(syst) GeV, consistent with the expectation from the standard model.
14 citations
TL;DR: In this article, the authors performed a search for scalar top quark pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of p (p) over bar events corresponding to 108.3 pb (-1) of data collected with the D0 detector at Fermilab.
Abstract: We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of p (p) over bar events corresponding to 108.3 pb (-1) of data collected with the D0 detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, (t) over tilde-->b (χ) over tilde (+)(1) and (t) over tilde-->bl (ν) over tilde , no evidence for signal is found. We derive cross-section limits as a function of stop ((t) over tilde), chargino ((χ) over tilde (+)(1)), and sneutrino ((ν) over tilde ) masses.
14 citations
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, Princeton University13, Kansas State University14, Tufts University15, University of Wisconsin-Madison16
TL;DR: In this article, differential cross sections for the production of D ∗± (2010) produced in 500 ǫ c π − nucleon interactions from experiment E791 at Fermilab, as functions of Feynman- x ( x F ) and transverse momentum squared ( p T 2 ), were reported.
12 citations
TL;DR: The results of a search for leptoquark (LQ) pairs in (85.2+/-3.7) pb(-1) of pp* collider data collected by the D0 experiment at the Fermilab Tevatron were presented in this paper.
Abstract: We present the results of a search for leptoquark (LQ) pairs in (85.2+/-3.7) pb(-1) of pp* collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on sigma(pp*-->LQLQ-->nunu+jets) as a function of the mass of the leptoquark (m(LQ)). Assuming the decay LQ-->nuq, we exclude scalar leptoquarks for m(LQ) < 98 GeV/c(2), and vector leptoquarks for m(LQ) < 200 GeV/c(2) and coupling which produces the minimum cross section, at a 95% confidence level.
12 citations
TL;DR: In this article, a search for R-parity-violating decay of the neutralino chi_1^0, taken to be the Lightest Supersymmetric Particle, is presented.
Abstract: 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.
TL;DR: The first search for supersymmetric particles via s-channel production and decay of smuons or muon sneutrinos at hadronic colliders was reported in this article.
Abstract: 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 D0 experiment and correspond to an integrated luminosity of 94+/-5 pb(-1). Assuming that R parity is violated via the single coupling lambda(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((χ) over bar),m((ν) over bar)) planes for lambda(211)(')=0.09, 0.08, and 0.07.
01 Jan 2002
TL;DR: In this article, a search for evidence of minimal supergravity (MSUGRA) in 92.7 pb(-1) of data collected with the D empty set detector at the Fermilab Tevatron p (p) over bar collider at roots=1.8 TeV was described.
Abstract: We describe a search for evidence of minimal supergravity (MSUGRA) in 92.7 pb(-1) of data collected with the D empty set detector at the Fermilab Tevatron p (p) over bar collider at roots=1.8 TeV. Events with a single electron, four or more jets, and large missing transverse energy were used in this search. The major backgrounds are from W+jets, misidentified multijet, t (t) over bar, and WW production. We observe no excess above the expected number of background events in our data. A new limit in terms of MSUGRA model parameters is obtained.