Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 58, Number 12
Friday–Saturday, October 18–19, 2013; Denver, Colorado
Session C6: Particle Physics I: Theory |
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Chair: Shufang Su, University of Arizona Room: 251 |
Friday, October 18, 2013 11:00AM - 11:24AM |
C6.00001: Hunting Asymmetric Top Squark Decays Invited Speaker: Michael Graesser In the irreducible natural supersymmetric spectrum, top squarks have comparable branching fractions to chargino-bottom and neutralino-top final states in the vast bulk of parameter space, provided only that both decay modes are kinematically accessible. The total top squark pair branching fractions into tt$+$MET (MET$=$missing transverse energy) can therefore be reduced, thus limiting the reach of traditional top squark searches. A new top squark search targeting the asymmetric final state tb$+$MET, which can restore sensitivity to natural top squarks in the 7, 8 and 14 TeV LHC runs will be presented. A new variable, topness, will be introduced, which efficiently suppresses the dominant top backgrounds to semileptonic top partner searches. The utility of topness in both the asymmetric search channel and traditional tt$+$MET searches will be compared and be shown to match or outperform existing variables. [Preview Abstract] |
Friday, October 18, 2013 11:24AM - 11:48AM |
C6.00002: Lattice field theory: QCD and beyond Invited Speaker: Ethan Neil Lattice simulation is a numerical technique for the non-perturbative investigation of quantum field theories. It has been very successful in precise studies of the strong nuclear force (quantum chromodynamics, or QCD.) In this talk I will review the basic framework of lattice simulations, and then describe current and future applications in particle physics, including the study of heavy-quark decays and searches for new strongly-coupled physics at the Large Hadron Collider. [Preview Abstract] |
Friday, October 18, 2013 11:48AM - 12:00PM |
C6.00003: Higgs Assisted Stop Search Huanian Zhang, Shufang Su The discovery of the Standard Model (SM)-like Higgs boson is a great success of particle physics over the past 50 years. The existence of a light Higgs boson provides strong indications for new physics beyond the SM. In this project, we study the supersymmetric partner of the top quark, namely stop, which is the most relevant supersymmetric particles given its strong coupling to the Higgs sector. We study the pair production of stops at the 14 TeV Large Hadron Collider (LHC): $p p \rightarrow \tilde{t}_1 \tilde{t}_1$ followed by the decays: $\tilde{t}_1 \rightarrow b \tilde{\chi}^+_1 \rightarrow b W^+ \tilde{\chi}^0_1$ and $ \tilde{t}_1 \rightarrow t \tilde{\chi}^0_2 \rightarrow t h \tilde{\chi}^0_1 $. The final states include exact one lepton (e or $\mu$), $\geq$ 2 b-jets, $\geq$ 2 light flavor jets, and large missing energy. We find that with 100 ${\rm fb^{-1}}$ luminosity, a 5 $\sigma$ reach of the stop mass up to 500 GeV could be obtained. [Preview Abstract] |
Friday, October 18, 2013 12:00PM - 12:12PM |
C6.00004: Constraining Type II 2HDM in Light of LHC Higgs Searches Felix Kling, Baradhwaj Coleppa, Shufang Su The discovery of a resonance at 126 GeV with properties consistent with the Standard Model Higgs boson in both the ATLAS and CMS experiments is undoubtedly the most significant experimental triumph of the LHC to date. Though further data would undoubtedly point us in the right direction, at this point it is useful to explore the implication of the current Higgs search results on models beyond the Standard Model. One of the simplest extensions of the Standard Model is the Two Higgs-Doublet Model which contains an additional Higgs Doublet. We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions. We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We also investigate the correlation between different discovery channels. $\gamma\gamma$ and $VV$ channels are most likely to be highly correlated with $\gamma\gamma:VV \sim 1$ for the normalized cross sections. [Preview Abstract] |
Friday, October 18, 2013 12:12PM - 12:24PM |
C6.00005: Confinement in a 2 + 1 Dimensional Center Vortex Model of the Yang-Mills Vacuum Derar Altarawneh, Michael Engelhardt A promising picture of confinement in QCD can be obtained based on a condensate of thick vortices with fluxes in the center of the gauge group (center vortices). We have constructed a concrete realization of this picture. In our model, vortices are represented by closed random lines in 2+1 dimensional space-time. These random lines are modeled as being piece-wise linear and an ensemble is generated by Monte Carlo methods. The physical space on which the vortex lines are defined is a cube with periodic boundary conditions, and we have developed the necessary algorithms which implement those boundary conditions as the vortex lines evolve across the boundaries. When two vortices become close to each other, it is possible that they connect to one another. Also the inverse process, that a vortex separates at a bottleneck, is allowed. Our ensemble therefore will contain not a fixed, but a variable number of closed vortex lines. This is expected to be important for realizing the deconfining phase transition. Using the model, we can investigate both the confinement and the deconfinement phase. We were able to study the potential between quark and anti-quark as a function of vortex density, vortex seqment length, and as a function of temperature. [Preview Abstract] |
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