Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session K13: Searches II |
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Sponsoring Units: DPF Chair: Ulrich Heintz, Boston University Room: Hyatt Regency Jacksonville Riverfront City Terrace 9 |
Sunday, April 15, 2007 1:15PM - 1:27PM |
K13.00001: Inclusive Search for Squark/Gluino Production at CDF Gianluca de Lorenzo, Monica D'Onofrio, Mario Martinez-Perez We present the preliminary results of a search for squarks and gluinos in proton-antiproton collisions at $\sqrt{s} = 1.96$~TeV at the Tevatron, based on 1~$\rm fb^{-1}$ of data collected by the CDF experiment in Run II. The search is performed on events with multiple jets and large missing transverse energy in the final state, within the framework of the Minimal Supersymmetric Standard Model and assuming that R-parity is conserved. The measurement is compared to the Standard Model predictions and limits on the gluino and squark masses are extracted. [Preview Abstract] |
Sunday, April 15, 2007 1:27PM - 1:39PM |
K13.00002: Effects of Gluino and Neutralino Phases on Squark Pair Production at Hadron Colliders Ahmet Turan Alan, Kerem Canko\c{c}ak, Durmus A. Demir We analyze impact of finite CP-odd phases of gluinos and neutralinos on the squark pair production at hadron colliders. We focus exclusively on the first (and also the second) family squarks which exhibit, to an excellent approximation, no chirality and flavor mixings. Therefore, production cross sections of such squarks provide an excellent probe of possible CP-odd phases in gaugino masses. We analyze individual final states $\widetilde{q}_L\widetilde{q}_L^{\star}$, $\widetilde{q} _R\widetilde{q}_R^{\star}$ and $\widetilde{q}_L\widetilde{q}_R^ {\star}$ as well as $\widetilde{q}_L\widetilde{q}_L$, $\widetilde{q}_R\widetilde{q}_R$ and $\widetilde{q}_L\widetilde {q}_R$ for determining their sensitivities to the CP-odd phases. In addition, we compute the total cross section and compare it with predictions of the CP-conserving theory. In general, production rates of same-charge squarks measure 4-5 times higher than those of the opposite-charge squarks, and CP- odd phases significantly modify the cross sections expected in CP-conserving limit. [Preview Abstract] |
Sunday, April 15, 2007 1:39PM - 1:51PM |
K13.00003: Searching for Long-lived Particle Signatures at Hadron Colliders Todd Adams Several extensions of the Standard Model include new, long-lived particles that can decay after travelling centimeters to meters. Two of these are R-parity violating supersymmetry and ``hidden valley'' models. In hadron collider experiments, the decays of such particle create unique signals such detached vertices or kinks in charged particle tracks. This talk discusses some of the experimental challenges of observing decays of long-lived particles in collider detectors such as at the Tevatron or LHC. [Preview Abstract] |
Sunday, April 15, 2007 1:51PM - 2:03PM |
K13.00004: ABSTRACT WITHDRAWN |
Sunday, April 15, 2007 2:03PM - 2:15PM |
K13.00005: Single and Pair Production of Heavy Leptons in $E_6$ Model A. Tolga Tasci, Ahmet Turan Alan, Nurettin Karagoz We investigate the single and pair production of new heavy leptons via string inspired $E_{6}$ model at future linear colliders. Signal and corresponding backgrounds for these leptons are studied. We have found that single production of heavy leptons is more relevant than that of pair production, as expected. For a maximal mixing value of 0.1, the upper mass limits of 2750 GeV in the single case and 1250 GeV in the pair production case are obtained at $\sqrt{s}=3$ TeV collider option. [Preview Abstract] |
Sunday, April 15, 2007 2:15PM - 2:27PM |
K13.00006: Search for scalar top admixture in the $t\bar{t}\rightarrow\ell+$jets channel Su-Jung Park We report on a search for scalar top quark pair production in the lepton+jets channel. Just like Standard Model top quarks, scalar top quarks are produced in pairs in proton-antiproton collisions. One of the preferred scenarios is for the scalar top to decay to a b-quark and a chargino, with the chargino subsequently decaying into a real or virtual W boson and a neutralino. The neutralino escapes without being detected. Thus, the final state signature can be a lepton, two b-jets and two light quark jets, which is identical to the signature of Standard Model $t\bar{t}$ production. We use the kinematic differences between the exotic and the Standard Model scenarios to separate the two. [Preview Abstract] |
Sunday, April 15, 2007 2:27PM - 2:39PM |
K13.00007: Search for pair production of third generation leptoquarks in the $\tau\tau b \bar{b}$ final state with the D0 detector Yuan Hu We report the the search for the third generation leptoquarks in $p\bar{p}$ collisions at a center-of-mass energy of $\sqrt{s} = 1.96$ TeV using data with an integrated luminosity of 982 pb$^{-1}$ collected by the D0 dectector at Run II of the Fermilab Tevatron. Leptoquarks are assumed to be pair produced and each decays into a $\tau$ lepton and a b quark with a branching ratio $\beta=100\% $. The signature is a di-$\tau$ plus di-b-jet final state where one $\tau$ is required to decay into a $\mu$ and the other $\tau$ decays hadronically. No evidence for third generation leptoquarks production is observed, and limits are set on $\sigma(p\bar{p}\rightarrow{\mathrm LQ3} \overline{\mathrm LQ3}\rightarrow\tau^+ b\tau^- \bar{b}$. [Preview Abstract] |
Sunday, April 15, 2007 2:39PM - 2:51PM |
K13.00008: Direct search for Z' in the di-electron channel in $p\bar{p}$ collisions at 1.96 TeV using the D0 detector at Fermilab Ioannis Katsanos The existence of a heavy partner of the Z boson, a so-called Z' boson, is proposed in many extensions of the Standard Model, including grand unified theories, extended technicolor models, and models with extra dimensions. We report on a direct search in the di-electron invariant mass spectrum for evidence of Z' production, using data taken with the D0 detector at the Fermilab Tevatron $p\bar{p}$ collider at a center-of-mass energy of $\sqrt{s}=1.96$ TeV. We will present preliminary results using data collected during RunIIa with integrated luminosity of 1 fb$^{-1}$. [Preview Abstract] |
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