Session L12: Higgs I

Search for Higgs Bosons in $WW^{(*)}\to l^+l'^-$ Decays

The process $H\to WW^{(*)}\to l^+l'^-$ ($l$,$l'$ = $e$,$\mu$) is studied in $p\bar{p}$ collisions at the center of mass energy $\sqrt{s} =$1.96~TeV with the D0 detector at Fermilab. A Higgs particle with a mass greater than 140 GeV primarily decays into a pair of W-bosons and the semi-leptonic decay channels of the W provide a clear signature. The analysed data correspond to 2~fb$^{-1}$ of integrated luminosity.   

Search for H Decays to WW* at CDF

We present a search for Standard Model Higgs production in proton-antiproton collisions at sqrt(s)=1.96 TeV using approximately 2.4 $fb^{-1}$ of data collected with the CDF II detector. We consider the diboson decay channel, H$\rightarrow$WW*, which is the dominant decay mode for Higgs masses above 140 $GeV/c^2$. We further require both W bosons to decay leptonically. Both single and associated Higgs production modes are considered. In order to maximize sensitivity, a combined Matrix Element method and Neural Network approach is utilized to distinguish signal from background processes. Cross-section limits are presented for Higgs mass hypotheses between 110 $GeV/c^2$ and 200 $GeV/c^2$.   

Search for WH to WWW Using Like Sign Dileptons at CDF

We present a search for the Higgs boson production in association with a W boson using isolated high-pT like-sign dilepton events in ppbar collisions at sqrt(s) = 1.96 TeV. The data were collected with the CDFII detector at the Tevatron ppbar collider in Fermilab and correspond to an integrated luminosity 1.9 fb-1. This process has a good sensitivity to high mass Higgs ($>$160 GeV/c2), and if we assume the so-called ``fermiohobic Higgs'' which only couples to fermion such as the one in the 2HDM-TypeI, this process also has a good sensitivity to low mass Higgs.   

Search for Associated Production of W and Higgs Bosons in lnu bb Final States

We present a search for the Higgs boson through its associated production with W for masses between 105 and 155 GeV in ppbar collisions at $\sqrt{s} =$~1.96 TeV. The search is performed in events containing one lepton (electron or muon), an imbalance in the transverse energy, and two b-tagged jets in 2 fb$^{-1}$ of integrated luminosity accumulated by the D0 experiment at Fermilab.   

Search for Associated Production of Z and Higgs Bosons in nunu bb Final States

We present a search for a light Standard Model Higgs Boson produced in association with a Z boson decaying invisibly into a pair of neutrinos. The final state is characterised by a presence of two b-tagged jets from the Higgs Boson decay and a large imbalance in the transverse energy of the event. The search has been performed using data corresponding to 2 fb$^{-1}$ of integrated luminosity collected by the D0 experiment at Fermilab. This channel is challenging as the decay signatures are common in QCD and instrumental backgrounds.   

Search for SM Higgs Boson Produced in Association with a Z or a W Boson at CDF

We present a search for the Standard Model Higgs boson produced in association with a Z or a W boson in $p\overline{p}$ collisions at 1.96 TeV center of mass energy. The data were collected with the CDF II detector at the Tevatron collider at Fermilab, and correspond to an integrated luminosity of 1.7 $fb^{-1}$. We consider a scenario where the Z decays into neutrinos or the lepton originating from the W-decay escapes detection and the Higgs decays into a $b\overline{b}$ pair. Therefore the expected signature is missing transverse energy, no leptons, and two b-jets. We present the preliminary results as well as ongoing efforts in this search, such as new approaches of modeling QCD backgrounds and new techniques to increase sensitivity.   

Evolutionary Neural Network Based Analysis of the ZH to ll bb channel

We present a new technique for the standard model Higgs search in the $ZH\rightarrow l \bar l b \bar b$ decay channel using a genetically-evolved artificial neural network to optimize for sensitivity on 2 fb$^{-1}$ of CDF II data. Our method is based on a maximum-likelihood fit for the $ZH$ fraction in the data sample, using the standard model matrix-element probabilities to construct a likelihood function. This method is augmented with evolved neural networks to maximize the sensitivity to the $ZH$ signal. We will present the methodology and illustrate the gains from the use of the evolved neural network.   

On-Shell Methods Applied to Higgs Production with Heavy Quarks at NLO in QCD Physics

We calculate the production of a pair of heavy quarks ($Q\bar{Q}$) with a pseudoscalar ($A$) Higgs boson at hadron colliders, including NLO QCD corrections. The amplitude for $q\bar{q},gg\rightarrow Q\bar{Q} A$ is caculated both with a traditional Feynman-diagram approach and with more recently proposed on-shell methods. We use this process as a testing ground for the new on-shell methods in a case where several massive particles are involved.