Showing papers by "Zhengguo Zhao published in 2006"
15 Sep 2006-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996 as discussed by the authors, and the detector has been upgraded to take advantage of improvements to the Tevoton and to enhance its physics capabilities.
Abstract: 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.
425 citations
TL;DR: The first direct two-sided bound on the oscillation frequency was reported in this article, where a large sample of semileptonic decays corresponding to approximately 1 fb$^{-1}$ of integrated luminosity collected by the \dzer\ experiment in 2002--2006 during Run II of the Fermilab Tevatron Collider was used.
Abstract: We report the first direct two-sided bound on the $B^0_s$ oscillation frequency using a large sample of $B^0_s$ semileptonic decays corresponding to approximately 1 fb$^{-1}$ of integrated luminosity collected by the \dzer\ experiment in 2002--2006 during Run II of the Fermilab Tevatron Collider. The flavor (i.e., $B^0_s$ or $\bar{B}^0_s$) of the \bs meson at the time of production was found using an opposite-side tagging technique, and the flavor at the time of decay was determined from the charge of the muon in the partially reconstructed decay $\bs\to \mu^{+}D_{s}^{-}X$, $D_{s}^{-}\to \phi \pi^{-}$, $\phi\to K^{+}K^{-}$. A likelihood scan over the oscillation frequency, $\Delta m_s$, gives a most probable value of 19 ps$^{-1}$ and a range of $17 < \Delta m_s < 21$ ps$^{-1}$ at the 90% C.L. At $\Delta m_s=19$ ps$^{-1}$, the amplitude method yields a result that deviates from the hypothesis of an oscillation amplitude of zero by 2.5 standard deviations, corresponding to a two-sided C.L. of 1%.
167 citations
TL;DR: In this article, the authors measured the cross section for the inclusion of isolated photons in p anti-p collisions at 1.96 TeV with the D0 detector at the Fermilab Tevatron Collider.
70 citations
TL;DR: The results of a search for squarks and gluinos using data from p p ¯ collisions recorded at a center-of-mass energy of 1.96 TeV by the DO detector at the Fermilab Tevatron Collider are reported in this article.
44 citations
TL;DR: In this paper, a search for the production of neutral Higgs bosons decaying into {tau}{sup +}{tau} final states in p{bar p} collisions at a center-of-mass energy of 1.96 TeV is presented.
Abstract: A search for the production of neutral Higgs bosons {Phi} decaying into {tau}{sup +}{tau}{sup -} final states in p{bar p} collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325 pb{sup -1}, were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for {Phi}b({bar b}) {yields} b{bar b}b({bar b}) and are interpreted in the minimal supersymmetric standard model.
28 citations
TL;DR: In this paper, a search for the pair production of second generation scalar leptoquarks (LQ_2) in ppbar collisions at the center-of-mass energy sqrt(s) = 1.96 TeV, using data corresponding to an integrated luminosity of 294 +- 19 pb^-1 recorded with the D0 detector was conducted.
19 citations
TL;DR: In this article, the authors present the results of a search for the production of an excited state of the muon, mu*, in proton antiproton collisions at root s = 1.96 TeV.
Abstract: We present the results of a search for the production of an excited state of the muon, mu(*), in proton antiproton collisions at root s =1.96 TeV. The data have been collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 380 pb(-1). We search for mu(*) in the process p (p) over bar ->mu(*)mu, with the mu(*) subsequently decaying to a muon plus photon. No excess above the standard model expectation is observed in data. Interpreting our data in the context of a model that describes mu(*) production by four-fermion contact interactions and mu(*) decay via electroweak processes, we set a 95% confidence level production cross section upper limit ranging from 0.057 to 0.112 pb, depending on the mass of the excited muon. Choosing the scale for contact interactions to be Lambda=1 TeV, excited muon masses below 618 GeV are excluded.
15 citations
TL;DR: In this article, the authors search for a heavy resonance decaying into a Z+jet final state in p (p) over bar collisions at a center of mass energy of 1.96 TeV at the Fermilab Tevatron collider using the D0 detector.
Abstract: We have searched for a heavy resonance decaying into a Z+jet final state in p (p) over bar collisions at a center of mass energy of 1.96 TeV at the Fermilab Tevatron collider using the D0 detector. No indication for such a resonance was found in a data sample corresponding to an integrated luminosity of 370 pb(-1). We set upper limits on the cross section times branching fraction for heavy resonance production at the 95% C.L. as a function of the resonance mass and width. The limits are interpreted within the framework of a specific model of excited quark production.
13 citations
TL;DR: In the framework of minimal supergravity, limits on the coupling parameter lambda(211)('), are set, extending significantly previous results obtained in Run I of the Tevatron and at the CERN LEP collider.
Abstract: We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon sneutrinos in the channels mu ->chi(0)(1)mu, mu ->chi(0)(2,3,4)mu, and nu(mu)->chi(+/-)(1,2)mu. We analyzed 0.38 fb(-1) of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function of slepton and gaugino masses. In the framework of minimal supergravity, we set limits on the coupling parameter lambda(')(211), extending significantly previous results obtained in Run I of the Tevatron and at the CERN LEP collider.
13 citations
TL;DR: In this article, the authors measured R = 1.03(-0.17) (stat + syst), in good agreement with the standard model, and set lower limits of R > 0.61 and vertical bar V-tb vertical bar < 0.78 at 95% confidence level.
12 citations
TL;DR: In this article, a search for the standard model Higgs boson in H --> WW(*) decays with e+e-, e+/-mu-/+, and mu+mu- final states in pp collisions at a center-of-mass energy of square root of s = 1.96 TeV.
Abstract: We present a search for the standard model Higgs boson in H --> WW(*) decays with e+e-, e+/-mu-/+, and mu+mu- final states in pp collisions at a center-of-mass energy of square root of 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(-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 boson production cross section times branching ratio sigma x BR(H --> WW(*) are presented.
TL;DR: In this article, an upper bound on the branching ratio of the neutral current decay B-s(0)->phi mu(+)mu(+) = 4.1x10(-6) at the 95% C.L.
Abstract: We present a search for the flavor-changing neutral current decay B-s(0)->phi mu(+)mu(-) using about 0.45 fb(-1) of data collected in p (p) over bar collisions at root s=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to B-s(0)-> J/psi phi of B(B-s(0)->phi mu(+)mu(-))/B(B-s(0)-> J/psi phi) J/psi phi, the limit corresponds to B(B-s(0)->phi mu(+)mu(-))< 4.1x10(-6) at the 95% C.L., the most stringent upper bound to date.
TL;DR: In this article, the authors present the results of a search for a new particle X produced in p p ¯ collisions at s = 196 TeV and subsequently decaying to Zγ using data collected with the DO detector at the Fermilab Tevatron Collider.
18 Jul 2006
TL;DR: The Global Linear Collider (GLD) as discussed by the authors is a detector for the International Linear Collider that consists of a large calorimeter and a gaseous central tracker placed in a moderate magnetic field, both electro-magnetic and hadron calorimeters being placed inside the magnetic coil.
Abstract: The GLD is a detector for the experiment at the International Linear Collider (ILC). It consists of a large calorimeter and a gaseous central tracker placed in a moderate magnetic field, both electro-magnetic and hadron calorimeters being placed inside the magnetic coil to have enough hermeticity and good jet energy resolution. The outline of the GLD is presented.