### Session L9: LHC Searches

Chair: Nancy Marinelli, University of Notre Dame
Room: Grand G

 Sunday, May 1, 2011 3:30PM - 3:42PM L9.00001: Measurement of the $b$-tagging efficiency using events with jets containing muons Samvel Khalatyan We present a measurement of the b-tagging efficiency using $32\;\rm pb^{-1}$ of data collected in 2010 with the CMS detector operating at the proton-proton LHC with $\sqrt{s} =$ 7 TeV. The measurement is based on data samples that have at least two reconstructed jets and a non-isolated muon close to one of the jets. The measurements are made as a function of the jet $p_T$ and $\eta$. Results are presented for different $b$-tagging algorithms that identify $b$-jets based on the track's impact parameters or by fully reconstructing the secondary decay vertex. Sunday, May 1, 2011 3:42PM - 3:54PM L9.00002: Discovery prospects for Higgs $\to ZZ \to 2l2j$ and implications for other resonances Andrew Whitbeck Searches for Higgs-like resonances are of particular interest at the LHC. In this talk, an analysis for a Higgs decay channel, $H \to ZZ \to$2 leptons and 2 jets, at the CMS experiment is discussed. Projected sensitivities for exclusion obtained from Monte Carlo studies are presented. Implications for exclusion of other exotic resonances, such as Kaluza-Klein Gravitons, are discussed. Sunday, May 1, 2011 3:54PM - 4:06PM L9.00003: Search for a Heavy Resonance Decaying into an e mu Pair at ATLAS Scott Aefsky We present a search for a heavy resonance decaying into an e-mu final state using 35 pb-1 of data collected by the ATLAS detector at the LHC in pp collisions at 7 TeV. The number of observed e-mu events in data is compared to the Standard Model predictions. We interpret the results in terms of the production of both R-parity violating (RPV) sneutrinos and Lepton Flavor Violating Z'. We present direct bounds on the RPV and LFV couplings as a function of the sneutrino and Z' masses. Sunday, May 1, 2011 4:06PM - 4:18PM L9.00004: Search for a heavy gauge boson $W^{\prime}$ in the final state with an electron and large missing transverse energy in $pp$ collisions at $\sqrt{s} = 7$~TeV Darren Puigh A search for a heavy gauge boson $W^{\prime}$ has been conducted by the CMS experiment at the LHC in the decay channel with an electron and large transverse energy imbalance, using proton-proton collision data corresponding to an integrated luminosity of 36 pb$^{-1}$. No excess above standard model expectations is seen in the transverse mass distribution of the electron-(missing $E_T$) system. Assuming standard-model-like couplings and decay branching fractions, a $W^{\prime}$ boson with a mass less than 1.36 TeV/$c^2$ is excluded at 95\% confidence level. Sunday, May 1, 2011 4:18PM - 4:30PM L9.00005: ABSTRACT WITHDRAWN Sunday, May 1, 2011 4:30PM - 4:42PM L9.00006: Search for Resonances in the Dimuon Mass Distribution in pp Collisions at $\sqrt{s} = 7$ TeV Jordan Tucker The CMS Collaboration has performed a search for a narrow resonance in the $\mu^+\mu^-$ channel. The data correspond to an integrated luminosity of 40 pb$^{-1}$ from pp collisions at $\sqrt{s} = 7$~TeV provided by the CERN LHC. Such resonances can arise from new heavy gauge bosons, $Z^\prime$, or Randall-Sundrum Kaluza-Klein gravitons, $G_{KK}$. We present upper limits on the ratio of cross sections times branching fractions $\sigma\left({\rm pp} \rightarrow Z^\prime/G_{\rm KK} + X \rightarrow \mu^+\mu^- + X\right)/\sigma\left({\rm pp} \rightarrow Z^0 + X \rightarrow \mu^+\mu^- + X\right)$. Sunday, May 1, 2011 4:42PM - 4:54PM L9.00007: Search for high mass resonances in the dielectron channel in pp collisions at $\sqrt{s} = 7$ TeV Vladlen Timciuc A search for a narrow resonance in the dielectron channel has been performed at the CMS Experiment. The data were collected using the CMS detector at the Large Hadron Collider. A total integrated luminosity of 35 pb$^{-1}$ of data from $pp$ collisions at center-of-mass energy of 7 TeV was used for this analysis. The dielectron mass spectrum is found to be in agreement with expectations from Standard Model processes and an upper limit on the cross section ratio of massive resonance production to $Z$ peak production is computed. At 95\% confidence level, the production of SSM $Z'$ and $Z'_{\Psi}$ bosons are excluded for masses below 0.96 and 0.73 TeV/$c^2$ respectively. The corresponding limits for Randall-Sundrum graviton production for couplings of 0.1 and 0.05 are 0.93 and 0.73 TeV/$c^2$. Sunday, May 1, 2011 4:54PM - 5:06PM L9.00008: General analysis of signals with two leptons and missing energy at the Large Hadron Collider Chien-Yi Chen , Ayres Freitas A signal of two leptons and missing energy is challenging to analyze at the Large Hadron Collider (LHC) since it offers only few kinematical handles. This signature generally arises from pair production of heavy charged particles which each decay into a lepton and a weakly interacting stable particle. Here this class of processes is analyzed with minimal model assumptions by considering all possible combinations of spin 0, $\frac{1}{2}$ or 1, and of weak iso-singlets, -doublets or -triplets for the new particles. Adding to existing work on mass and spin measurements, two new variables for spin determination and an asymmetry for the determination of the couplings of the new particles are introduced. It is shown that these observables allow one to independently determine the spin and the couplings of the new particles, except for a few cases that turn out to be indistinguishable at the LHC. These findings are corroborated by results of an alternative analysis strategy based on an automated likelihood test. Sunday, May 1, 2011 5:06PM - 5:18PM L9.00009: $\mathbf{ H^\pm \rightarrow \chi^\pm \chi^0 \to 3\ell + E_{\mathrm{T}}^{\mathrm{miss}}}$ Searches Caleb Lampen \def\met{\not\!\!{E_{T}}} In some supersymmetric (SUSY) models, a charged Higgs boson ($\rm H^\pm$) can decay into a chargino-neutralino ($\rm\chi^\pm_i \chi^0_j$) pair producing a final state containing three leptons (electron/muon) and missing transverse energy ($3\ell+\met$). Such a decay could provide extra sensitivity to the $\rm H^\pm$ in the region of SUSY parameter space near tan$\beta$ = 7, where the $\rm H^\pm$ Standard Model decays have reduced significance. We present a signature search on early ATLAS data, setting an exclusion limit on an excess of $3\ell+\met$ events over the Standard Model background. Such an excess could be evidence of generic SUSY, the $\rm H^\pm \to \chi^\pm_i \chi^0_j$ decay, or both.