Search for Leptoquarks with the D0 detector

We report on D0 searches for leptoquarks (LQ) predicted in extended gauge theories and composite models to explain the symmetry between quarks and leptons. Data samples obtained with the D0 detector from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV corresponding to intergrated luminosities of 1--4 inverse-fb were analyzed. No evidence for the production of such particles were observed and lower limits on leptoquark masses are set.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

Search for Squarks and Gluinos with the D0 detector

We report on D0 searches for scalar quarks (tilde-q) and gluinos (tilde-g), the superpartners of quark and gluons, in topologies involving jets and missing transverse energies. Data samples obtained with D0 detector from proton anti-proton collisions at a center-of-mass energy of 1.96 TeV corresponding to an intergrated luminosities of 1-4 inverse-fb were analyzed. No evidence for the production of such particles were observed and lower limits on squarks and gluino masses were set.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

A search for charge 1/3 third generation leptoquarks in muon channels

Leptoquarks are exotic particles that have color, electric charge, and lepton number and appear in extended gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations corresponding to the three quark and lepton generations. We are searching for charge 1/3 third generation leptoquarks produced in p{bar p} collisions at {radical}s = 1.96 TeV using data collected by the D0 detector. Such leptoquarks would decay into either a tau-neutrino plus a b-quark or, if heavy enough, to a tau-lepton plus a t-quark. We present preliminary results on an analysis where both leptoquarks decay into neutrinos giving a final state with missing energy and two b-quarks using 367 pb{sup -1} of Run II D0 data taken between August 2002 and September 2004. We place upper limits on {sigma}(p{bar p} {yields} LQ{ovr LQ})B{sup 2} as a function of the leptoquark mass M{sub LQ}. Assuming B = 1, we exclude at the 95% confidence level third generation leptoquarks with M{sub LQ} < 197 GeV/c{sup 2}

A search for charge one third third generation leptoquarks in muon channels

Includes bibliographical references (pages [93]-100).Leptoquarks are exotic particles that have color, electric charge, and lepton number and appear in extended gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations corresponding to the three quark and lepton generations. We are searching for charge 1/3 third generation leptoquarks produced in pp̅ collisions at [squareroot s]=1.96 TeV using data collected by the D0 detector. Such leptoquarks would decay into either a tauneutrino plus a b-quark or, if heavy enough, to a tau-lepton plus a t-quark. We present preliminary results on an analysis where both leptoquarks decay into neutrinos, giving a final state with missing energy and two b-quarks using 367 pb⁻¹ of Run II D0 data taken between August 2002 and September 2004. We place upper limits on σ(pp̅ LQL̅Q̅)B² as a function of the leptoquark mass M[sub LQ]. Assuming B = 1, we exclude at the 95% confidence level third generation leptoquarks with M[sub LQ] < 197 GeV/c².Ph.D. (Doctor of Philosophy

Tests of CMS Hadron Forward Calorimeter Upgrade Readout Box Prototype

A readout box prototype for CMS Hadron Forward calorimeter upgrade is built and tested in CERN H2 beamline. The prototype is designed to enable simultaneous tests of different readout options for the four anode upgrade PMTs, new front-end electronics design and new cabling. The response of the PMTs with different readout options is uniform and the background response is minimal. Multi-channel readout options further enhance the background elimination. Passing all the electronics, mechanical and physics tests, the readout box proves to be capable of providing the forward hadron calorimeter operations requirements in the upgrade era

Measurement of spin correlation between top and antitop quarks produced in ppˉp\bar{p} collisions at s=1.96\sqrt{s} = 1.96 TeV

We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.We present a measurement of the correlation between the spins of t and t¯ quarks produced in proton–antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb−1 . The measured value of the correlation coefficient in the off-diagonal basis, Ooff=0.89±0.22(stat+syst) , is in agreement with the standard model prediction, and represents evidence for a top–antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations