We combine the D0 measurement of the width difference between the light and heavy B_s^0 mass eigenstates and of the CP-violating mixing phase determined from the time-dependent angular distributions ...in the B_s -> J/psi phi decays along with the charge asymmetry in semileptonic decays also measured with the D0 detector. With the additional constraint from the world average of the flavor-specific B_s^0 lifetime, we obtain Delta Gamma_s = (\Gamma_L - \Gamma_H) = 0.13 +- 0.09 ps\(^{-1}\) and phi_s = -0.70 ^{+0.47}_{-0.39}. The data sample corresponds to an integrated luminosity of 1.1 fb^{-1} accumulated with the D0 detector at the Fermilab Tevatron Collider.
A search for the pair production of scalar top quarks, or stops, has been performed in 360 pb-1 of data from p pbar collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at ...the Fermilab Tevatron collider. The stop decay mode considered is stop into c chi, where chi is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data and standard model expectation are in agreement, and a 95% C.L. exclusion domain in the stop and chi mass plane has been determined, extending the domain excluded by previous experiments.
We report a measurement of the \(B^0_{s}\) lifetime in the semileptonic decay channel \(B^0_{s}\to D^-_s \mu^{+}\nu X\) (and its charge conjugate), using approximately 0.4 fb\(^{-1}\) of data ...collected with the D0 detector during 2002 -- 2004. We have reconstructed 5176 \(D^-_s \mu^{+}\) signal events, where the \(D_s^-\) is identified via the decay \(D_s^-\to \phi\pi^-\), followed by \(\phi\to K^+ K^-\). Using these events, we have measured the \(B^0_s\) lifetime to be \(\tau(B^0_{s}) = 1.398 \pm 0.044\) \(({stat}) ^{+0.028}_{-0.025}\) \(({syst}) {ps}\). This is the most precise measurement of the \(B_s^0\) lifetime to date.
A search for direct production of scalar bottom quarks (sb) is performed with 310 pb-1 of data collected by the DO experiment in ppbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron ...Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos chi0_1, with chi0_1 assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m_sb,m_chi0_1) mass plane, improving significantly upon the results from Run I of the Tevatron.
Phys.Rev.Lett.89:261801,2002 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.
We present a measurement of the fraction f_+ of right-handed W bosons produced in top quark decays, based on a candidate sample of ttbar events in the l+jets and dilepton decay channels corresponding ...to an integrated luminosity of 370 pb^-1 collected by the DO detector at the Fermilab Tevatron ppbar Collider at sqrt{s}=1.96 TeV. We reconstruct the decay angle theta^* for each lepton. By comparing the \cos\theta^* distribution from the data with those for the expected background and signal for various values of f_+, we find $f_+=0.056 +- 0.080 (stat) +- 0.057 (syst)}. (f_+ < 0.23 at 95% C.L.), consistent with the standard model prediction of f_+=3.6 x10^-4.
We report on a measurement of the \(B^0_d\) mixing frequency and the calibration of an opposite-side flavor tagger in the DØexperiment. Various properties associated with the \(b\) quark on the ...opposite side of the reconstructed \(B\) meson were combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance was tested with data, using a large sample of reconstructed semileptonic \(B \to \mu \dzero X\) and \(B \to \mu \dst X\) decays, corresponding to an integrated luminosity of approximately 1 fb\(^{-1}\). The events were divided into groups depending on the value of the combined tagging variable, and an independent analysis was performed in each group. Combining the results of these analyses, the overall effective tagging power was found to be eD^2 = (2.48 \pm 0.21 (stat.) ^{+0.08}_{-0.06} (syst.))%. The measured \(B^0_d\) mixing frequency dmd = 0.506 \pm 0.020 {\rm (stat) \pm 0.016 (syst) ps}^{-1} is in good agreement with the world average value.
A search for leptoquarks has been performed in 310 pb-1 of data from ppbar collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider. The ...topology analyzed consists of acoplanar jets with missing transverse energy. The data show good agreement with standard model expectations, and a lower mass limit of 136 GeV has been set at the 95% C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.
Phys.Rev.D67:052001,2003 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.
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