Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session H9: LHC SUSY Searches |
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Sponsoring Units: DPF Chair: Mike Tuts, Columbia University Room: Grand G |
Sunday, May 1, 2011 10:45AM - 10:57AM |
H9.00001: Search for supersymmetry in same-sign dilepton channel at $\sqrt{s}$ = 7 TeV with 35$pb^{-1}$ Brokk Toggerson We present a search for R-parity conserving supersymmetry in final states with exactly two same charge leptons ($e$,$\mu$) and with $E_{\mathrm{T}}^{\mathrm{miss}} > 100\mathrm{\ Ge\kern -0.1em V}$ using 35\mbox{pb$^{-1}$} of pp collisions at $\sqrt{s} = 7\mathrm{\ Te\kern -0.1em V}$. We present the status of our analysis in the context of a simplified Lagrangian designed to reduce the number of search parameters by adding only gluino, squark, slepton, $\widetilde{W}^{\pm, 0}$, and LSP to the Standard Model. The masses and branching ratios of these additional particles are free parameters. We present our results as limits on the topologies in this simplified Lagrangian produced from strong interactions yielding same-sign dilepton events. Such a framework includes more phenomenologically distinct mass hierarchies than other presentations such as mSUGRA, and can be extended to other SUSY-like searches such as UED. [Preview Abstract] |
Sunday, May 1, 2011 10:57AM - 11:09AM |
H9.00002: Search for new physics with same-sign di-leptons, jets, and missing transverse energy in pp-collisions at 7 TeV Ronald Remington \def\etmiss{\not\!\!{E_{T}}} We present the results of a search for new physics involving events with 2 same-sign leptons, jets, and missing transverse energy. The search is performed using data collected in the 2010 LHC run at $\sqrt{s} = $7 TeV, corresponding to a total integrated luminosity 34.7~pb$^{-1}$. The leptons used in the analysis are muons ($p_T>5$~GeV, $|\eta|<2.4$) and electrons ($p_T>10$~GeV, $|\eta|<2.4$). The hadronic activity is characterized by the total transverse energy, $H_T$, of all jets with $E_T>30$~GeV and $|\eta|<2.5$. The $H_T$ is required to be greater than 300~GeV and must be built from a minimum of two jets in an event. The missing transverse energy, $\etmiss$, is built by using the energy flow objects and is required to be greater than 30~GeV. We observe 1 event, which is statistically consistent with the total expected Standard Model background rate of $0.8 \pm 0.31$ events. Given this lack of an excess, we set limits on the parameter space of SUSY models with universal and non-universal gaugino masses scales. The general limit on cross section $\sigma$ times the event acceptance, $A$, described above is $\sigma \times A^{\rm{theory}} \times A^{\rm{exp}} < 0.13$~pb at 95\% C.L.. A parameterization of the experimental acceptance, $A^{\rm{exp}}$, is also presented, which can be applied to any given model. [Preview Abstract] |
Sunday, May 1, 2011 11:09AM - 11:21AM |
H9.00003: A search for new physics in three or more lepton modes in pp collisions at $\sqrt{s}= 7$ TeV Christopher Edelmaier We present searches for physics beyond the Standard Model involving three or more leptons, including muons, electrons, and taus. We apply selection cuts requiring hadronic jet energy, missing transverse energy, and combinations of both. Using three or more leptons in this search affords us smaller backgrounds from electroweak and QCD processes, yielding a clean analysis of events. We compare our results with several SUSY scenarios. [Preview Abstract] |
Sunday, May 1, 2011 11:21AM - 11:33AM |
H9.00004: Search for New Physics using the $\alpha_{\mathrm{T}}$ variable in multijet events using b-tagging Paul Geffert We present a search for new physics in $34.6~\mathrm{pb}^{-1}$ of $pp$ collisions at $\sqrt{s}=7$~TeV in the all hadronic mode with the signature of large transverse momentum imbalance and one or more b-quark jets. This momentum imbalance is described by the kinematic variable $\alpha_{\mathrm{T}}$, which substantially reduces the QCD background. Using data driven background estimation methods, we predict $2.34\pm 0.54$ and observe 1 event. We set $95\%$ confidence level upper limits on benchmark Supersymmetry signal models. [Preview Abstract] |
Sunday, May 1, 2011 11:33AM - 11:45AM |
H9.00005: Search for New Physics in multijet events with significant missing transverse energy using b-tagging Harold Nguyen We present a search for physics beyond the Standard Model based on events with significant missing transverse energy, at least three jets, and at least one identified b-jet. The b-jets plus MET sample presents a unique topological signature for a model-independent analysis, which complements those of leptons+jets+MET and jets+MET without b-tagging. The study is based on a sample of 36 pb$^{-1}$ collected with the CMS detector in $pp$ collisions at $\sqrt{s} = 7$~TeV. We show the implications of our background determination estimates using data-driven methods, and set model-independent limits for anomalous signatures. [Preview Abstract] |
Sunday, May 1, 2011 11:45AM - 11:57AM |
H9.00006: Search for Matter Symmetry Violation with Inclusive Multileptons Dmitry Hits We present a multi-channel search for new physics with a signature of three or more leptons in the final state based on data collected by CMS in the LHC 2010 run. We categorize the events into exclusive search channels and, using both Monte Carlo and data driven methods, we estimate the backgrounds for each channel. We then organize the channels in a hierarchical order that is inversely proportional to the amount of background. Using a data sample of 35~$pb^{-1}$ at a total collision energy of 7 TeV, we probe new physics such as matter symmetry violation in the leptonic sector in theories with partner particles, leptonic $R$-parity violation in Supersymmetry being one example. [Preview Abstract] |
Sunday, May 1, 2011 11:57AM - 12:09PM |
H9.00007: Search for Long-Lived Particles out-of-time with LHC Collisions in ATLAS Joshua Cogan R-hadrons are massive, long-lived particles predicted in several Supersymmetry~scenarios. Studies exploring the discovery potential of R-hadrons~at the ATLAS detector have mainly focused on gluino R-hadrons. ~This talk describes a search for gluinos which have come to rest within the detector~volume, particularly the calorimeter, and decay at some later time.~ We search for jets produced from the 2- or 3- body decays of the gluinos that have stopped within the calorimeter. ~The search is conducted in empty bunch crossings to greatly reduce backgrounds from pp collisions.~ Simple selection criteria enable the discrimination of signal events from the main background, which comes from cosmic rays. [Preview Abstract] |
Sunday, May 1, 2011 12:09PM - 12:21PM |
H9.00008: Search for New Physics in the Trilepton Channel at the ATLAS Detector Steve Farrell Several potential models for new physics predict final states with three or more leptons produced at the LHC. This trilepton signature has low background from Standard Model processes and thus offers great potential for discovery. In Supersymmetry this signature comes from the decay chains of new heavy particles mediated by the electroweak gauge bosons. We present a search for SUSY-like processes with the ATLAS detector using 35pb$^{-1}$ at $\sqrt{s}=7$ TeV. We look for events with three or more isolated leptons of any flavor, high energy hadronic jets, and large missing transverse momentum. Our analysis is formulated in terms of a simplified model expressed as an effective Lagrangian that can test a large family of SUSY models. [Preview Abstract] |
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