Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session K12: Higgs Searches I |
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Sponsoring Units: DPF Chair: Al Goshaw, Duke University Room: Virginia A |
Sunday, February 14, 2010 3:30PM - 3:42PM |
K12.00001: Measurement of the $WW+WZ$ diboson cross section in final states containing both leptonic and hadronic decays at CDF Martina Hurwitz We present a measurement of the $WW+WZ$ production cross section in 4.6fb$^{-1}$ of integrated luminosity collected by the CDF detector from $p\bar{p}$ collisions at $\sqrt{s} =$~1.96~TeV. The measurement is performed in final states resulting from semileptonic decays containing an identified lepton and two hadronic jets, an event topology also used in searches for the Higgs boson. Separation of the signal from the overwhelming $W$ + jets background is achieved using matrix element calculations. Modeling of the background processes are studied carefully to ensure that the inputs to the matrix element calculations are well-matched in data and simulation. The measured cross section is found to be in agreement with NLO predictions. [Preview Abstract] |
Sunday, February 14, 2010 3:42PM - 3:54PM |
K12.00002: Search for $WZ$ production in the $\ell \nu b\overline{b}$ final state at CDF Justin Keung An important search channel for the standard model (SM) Higgs boson comes from associated $WH$ production with subsequent decays of $W \rightarrow \ell \nu$ and $H \rightarrow b\overline{b}$. The resulting final state is shared with SM $WZ$ diboson production which as a significant background necessarily needs to be well-constrained. Thus, using the same techniques as those used in the Higgs search analysis to measure the $WZ$ contribution to our candidate sample serves as an important cross-check. The identification of jets originating from $b$-quarks is an important component of Higgs searches for mass values below 130~GeV/$c^2$. In the context of this search, we present results of an improved, artificial neural network algorithm used to identify $b$-quark jets. [Preview Abstract] |
Sunday, February 14, 2010 3:54PM - 4:06PM |
K12.00003: Search for diboson production in final states containing missing transverse energy and $b$-quark jets Stephen Poprocki Diboson production in hadronic final states has been recently observed at the Tevatron in several channels. The dominant contribution to this process is $WW$ production with lower cross section contributions from $WZ$ and $ZZ$. Imposing the additional requirement that the observed hadronic jets are consistent with having originating from $b$-quark decays drastically reduces the contribution from $WW$ and enhances $WZ/ZZ$ contributions. Here we present a search for $WZ/ZZ$ in events with missing transverse energy and $b$-quark jets at CDF. The final state being measured is very similar to that obtained from associated Higgs production where the Higgs decays to two $b$-quarks and evidence for it is an important step towards a potential Higgs discovery. [Preview Abstract] |
Sunday, February 14, 2010 4:06PM - 4:18PM |
K12.00004: Search for $WZ/ZZ$ diboson production in the dilepton $+$ dijet final state at CDF Wesley Ketchum We present the results of studies aimed at an experimental measurement of $WZ/ZZ$ diboson production in the dilepton $+$ dijet final state using data recorded with the CDF detector at the Fermilab Tevatron collider. We select events by identifying those that contain two charged leptons with a reconstructed invariant mass near the mass of the Z boson, two hadronic jets, and low transverse missing energy. To distinguish our desired signal from the dominant background, $Z$ + jets production, we use an artificial neural network trained on variables related to the reconstructed jets including a new variable that reflects the spatial spread of the energy contained within a jet that offers some discrimination between hadronic jets originating from quarks and gluons. [Preview Abstract] |
Sunday, February 14, 2010 4:18PM - 4:30PM |
K12.00005: Search for Associated Production of W and Higgs Bosons in $l \nu bb$ Final States in ppbar Collisions at sqrt(s)=1.96 TeV with Neural Networks Jonathan Brown We present a search for a low mass Standard Model Higgs boson produced in association with a $W$ boson at a center-of-mass energy of $\sqrt{s}=$1.96~TeV with the D0 detector at the Fermilab Tevatron collider. The search is performed in events containing one lepton (electron, muon or tau), an imbalance in the transverse energy, and one or two $b$-tagged jets with up to 5~fb$^{-1}$ of data. The separation of signal and background events was done using Neural Networks. This channel is one of the most powerful in the search for a low mass Higgs at the Tevatron. Recent improvements to the sensitivity will be discussed. [Preview Abstract] |
Sunday, February 14, 2010 4:30PM - 4:42PM |
K12.00006: Search for SM Higgs production in association with a $W$ boson using a neural network technique at CDF Martin Frank We present a search for a standard model (SM) Higgs boson produced in association with a $W$ boson from data collected with the CDF detector in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$~TeV. The search is performed in the $WH \rightarrow \ell \nu b\bar{b}$ final state using a data sample corresponding to an integrated luminosity of 4.3 fb$^{-1}$. A Bayesian neural network is used to improve separation of signal and background. In the absence of an excess in data, we set an upper limit on the production rate times branching ratio as a function of the potential mass of the Higgs boson. [Preview Abstract] |
Sunday, February 14, 2010 4:42PM - 4:54PM |
K12.00007: Search for Associated Production of W and Higgs Bosons in the $ \ell \nu bb$ Final State in ppbar Collisions at sqrt(s)=1.96 TeV with the Boosted Decision Tree technique Hatim Hegab A search for $WH$ production in $p\overline{p}$ collisions performed by the D0 collaboration at a center of mass energy of $\sqrt{s}=$1.96 TeV is presented. Events selected for this analysis required to have one lepton, missing transverse energy, and one or two $b$-tagged jets. The separation of signal and background events was done using Boosted Decision Trees method. Using this technique we expect to improve the sensitivity of the D0 experiment to the standard model Higgs boson search. [Preview Abstract] |
Sunday, February 14, 2010 4:54PM - 5:06PM |
K12.00008: New techniques for reducing backgrounds originating from fake missing transverse energy in SM Higgs searches at CDF Philip Hebda We consider associated production of a standard model (SM) Higgs boson and a $W$ or $Z$ boson in conjunction with the subsequent decay of the Higgs into two $b$-quark jets and the decay of the $Z$ boson into neutrinos or the $W$ boson into a lepton that escapes detection and a neutrino, which results in both cases in a detector signature of large missing transverse energy. For these channels mis-measurement of jet energies in multi-jet events is one of the primary sources of background to a potenital Higgs signal. We use data-driven modeling of the multi-jet background to predict the shape of the distribution for fake missing transverse energy and fit this shape to remove background contributions to our candidate samples. The data was collected at the Fermilab Tevatron collider with the CDF detector. We present studies on the performance of this technique and its expected contribution to improvements in the sensitivity of the analysis. [Preview Abstract] |
Sunday, February 14, 2010 5:06PM - 5:18PM |
K12.00009: New techniques for improving SM Higgs search in the transverse missing energy plus jets final state at CDF Qiuguang Liu We present new techniques for improving standard Model (SM) Higgs searches in the transverse missing energy plus jets final state. These searches are performed with data collected by the CDF detector from $p\overline{p}$ collisions at $\sqrt{s} =$ 1.96~TeV at the Fermilab Tevatron Collider. A data-driven model for modeling the multi-jet background, a background reduction method based on a tracking-related measure of the missing energy, and other advanced analysis techniques designed to increase search sensitivity will be shown. [Preview Abstract] |
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