Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session G8: BSM via Resonances |
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Sponsoring Units: DPF Chair: Sasha Pranko, Lawrence Berkeley National Laboratory Room: Grand F |
Sunday, May 1, 2011 8:30AM - 8:42AM |
G8.00001: Search for pair production of doubly charged Higgs bosons in the $H^{++}H^{--}\rightarrow\tau^{+}\tau^{+}\tau^{-}\tau^{-}$ final state at D0 Louise Suter The first search at a hadron collider for pair production of doubly charged Higgs bosons decaying into a $\tau^{+}\tau^{+}\tau^{-}\tau^{-}$ final state is presented. The search was performed in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV with an integrated luminosity of 6.2 fb$^{-1}$ as collected by the D0 experiment at the Fermilab Tevatron Collider during Run IIb. The results are used to set 95\% C.L. upper limits on the doubly charged Higgs production cross section. [Preview Abstract] |
Sunday, May 1, 2011 8:42AM - 8:54AM |
G8.00002: Search for a New Hadronic Resonance using Jet Ensembles at CDF Claudia Seitz, Eva Halkiadakis, Amitabh Lath We present a model independent search for three-jet hadronic resonances within multi-jets events in $\sqrt{s}$ = $1.96$ TeV $p \bar{p}$ collisions at the Fermilab Tevatron using the CDF II detector. Pair production of $SU(3)\_C$ adjoint Majorana fermions such as supersymmetric gluinos that decay through hadronic R-parity violation to three quarks is used to quantify our sensitivity to new physics. Selection criteria based on the kinematics of an ensemble of jet combinations within each event help to extract signal from copious QCD background. Our background estimates include all-hadronic ttbar decays that have a signature similar to signal. We observe no significant excess outside the top mass window in 3.2 $fb^{-1}$ of data in an invariant mass range 77 GeV/c$^2$ to 240 GeV/c$^2$ and place 95\% C.L. limits on the pair production cross section of gluinos each decaying to three jets as a function of gluino mass. [Preview Abstract] |
Sunday, May 1, 2011 8:54AM - 9:06AM |
G8.00003: Search for High-Mass Resonances in the Dilepton Final State with the ATLAS Detector Jeremy Love The ATLAS detector has recorded 45 pb$^{-1}$ of integrated luminosity in $\sqrt{s}$ = 7 TeV proton-proton collisions at the CERN Large Hadron Collider. This data offers an opportunity to directly test the Standard Model at new energy scales. Many beyond the Standard Model theories predict new narrow high-mass resonances that can decay to dilepton final states. We present the results of our search for such resonances as a function of invariant mass in the e$^+$e$^-$ and $\mu^+\mu^-$ decay channels. [Preview Abstract] |
Sunday, May 1, 2011 9:06AM - 9:18AM |
G8.00004: Search for collimated muon pairs (lepton jets) in the CMS experiment at LHC Aysen Tatarinov We present an inclusive, signature-based search for groups of collimated muon pairs also known as lepton jets, arising from spectroscopic cascades in a hidden sector accessible only through high-energy collisions, using the CMS detector. In several signatures defined by number of muon pairs per collimated group and number of groups per event, we search for the lightest on-shell state in the hidden spectrum with a mass-peak fit and interpret the results using two representative benchmark models: SUSY dark matter with a $U(1)_{\rm dark}$ and NMSSM Higgs escaping LEP limits via Higgs-to-Higgs decays. [Preview Abstract] |
Sunday, May 1, 2011 9:18AM - 9:30AM |
G8.00005: Search for Dijet Resonances in the Dijet Mass Distribution at CMS in pp Collisions Chiyoung Jeong We present a measurement of the dijet invariant mass spectrum and search for new particles decaying to dijets at CMS in pp collisions. The dijet mass distribution of the two leading jets is measured and compared to QCD predictions from PYTHIA propagated through the CMS detector simulation. We fit the observed dijet mass spectrum with a parameterization, search for dijet resonances, and set upper limits at 95\% confidence level on the resonance cross section. These generic cross section limits are compared with theoretical predictions for the cross section for several models of new particles: string resonances, axigluons, colorons, excited quarks, E6 diquarks, Randall-Sundrum gravitons, $W'$ and $Z'$. [Preview Abstract] |
Sunday, May 1, 2011 9:30AM - 9:42AM |
G8.00006: Searching for New Physics at the LHC in t tbar production in the all-hadronic decay mode using top quark tagging Yiu Cheung Many new physics models predict resonances with masses in the TeV range which decay into a pair of top quarks. With its large cross section, $t\bar{t}$ production at the Large Hadron Collider (LHC) offers an excellent opportunity to search for such particles. We present a detailed study of the discovery potential of the CERN Large Hadron Collider, operating at its design energy of $\sqrt{s}=14$ TeV, for Kaluza-Klein (KK) excitations of the gluon in bulk Randall-Sundrum (RS) models in $t\bar{t}$ production where both top quarks decay hadronically and are identified via top-tagging. Our calculations take into account the finite resolution of detectors, the anticipated top-tagging efficiency and light jet misidentification probability, and include the dominant di-jet background. We derive semi-realistic $5\sigma$ discovery limits for nine different KK gluon scenarios. We also analyze the capabilities of the LHC experiments to differentiate between individual KK gluon models. We find that, for the projected top-tagging efficiencies and light jet misidentification probabilities, and for the parameters and models chosen, KK gluons with masses up to about 4 TeV can be discovered at the LHC or a luminosity upgraded LHC. The ability of the LHC to discriminate between different bulk RS models, and to measure the couplings of the KK gluons is found to be highly model dependent. [Preview Abstract] |
Sunday, May 1, 2011 9:42AM - 9:54AM |
G8.00007: ABSTRACT WITHDRAWN |
Sunday, May 1, 2011 9:54AM - 10:06AM |
G8.00008: Interpreting the CMS ``ridge'' in 7 TeV p-p collisions from the LHC Lanny Ray The CMS Collaboration recently reported two-particle angular correlations for charged particle production from 0.9, 2.36 and 7 TeV p-p collisions [1]. For the higher multiplicity 7 TeV events long-range correlations on relative pseudorapidity ($\eta$) at small relative azimuth were observed. Phenomenological fits of the correlation data are presented where three models of the long-range $\eta$ correlation are studied: (i) non-Gaussian jet-like correlation, (ii) a 1D Gaussian ``ridge'' on azimuth, and (iii) a quadrupole on azimuth. Each corresponds respectively to mechanisms which might account for the long-range structure: e.g. transverse jet fragmentation along the beam direction, longitudinal correlations promptly induced at the partonic stage, and final-state correlations associated with the eccentricity of the transverse, coordinate space distribution of colliding partons. The quadrupole correlation is well known in high energy heavy ion collisions. The analysis indicates that models (ii) and (iii) are competitive implying that the long-range structure is either caused by early time, longitudinal correlations or is a consequence of the anisotropic distribution of colliding partons. \\[4pt] [1] CMS Collaboration, JHEP {\bf 1009}, 091 (2010), arXiv:1009.4122. [Preview Abstract] |
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