Search For Higgs Boson Production Research Articles

Search for Higgs Boson Production via Vector Boson Fusion Process with Subsequent $$H \to b\bar {b}$$ Decay with CMS Experiment at LHC

Search for Higgs Boson Production via Vector Boson Fusion Process with Subsequent $$H \to b\bar {b}$$ Decay with CMS Experiment at LHC

Search for Higgs boson production in association with a high-energy photon via vector-boson fusion with decay into bottom quark pairs at sqrt{s} = 13 TeV with the ATLAS detector

A search is presented for the production of the Standard Model Higgs boson in association with a high-energy photon. With a focus on the vector-boson fusion process and the dominant Higgs boson decay into b-quark pairs, the search benefits from a large reduction of multijet background compared to more inclusive searches. Results are reported from the analysis of 132 fb−1 of pp collision data at sqrt{s} = 13 TeV collected with the ATLAS detector at the LHC. The measured Higgs boson signal yield in this final-state signature is 1.3 ± 1.0 times the Standard Model prediction. The observed significance of the Higgs boson signal above the background is 1.3 standard deviations, compared to an expected significance of 1.0 standard deviations.

Search for the Standard Model Higgs boson decaying into b b ¯ $$ b\overline{b} $$ produced in association with top quarks decaying hadronically in pp collisions at s = 8 $$ \sqrt{s}=8 $$ TeV with the ATLAS detector

A search for Higgs boson production in association with a pair of top quarks ($t\bar{t}H$) is performed, where the Higgs boson decays to $b\bar{b}$, and both top quarks decay hadronically. The data used correspond to an integrated luminosity of 20.3 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=8$ TeV collected with the ATLAS detector at the Large Hadron Collider. The search selects events with at least six energetic jets and uses a boosted decision tree algorithm to discriminate between signal and Standard Model background. The dominant multijet background is estimated using a dedicated data-driven technique. For a Higgs boson mass of 125 GeV, an upper limit of 6.4 (5.4) times the Standard Model cross section is observed (expected) at 95% confidence level. The best-fit value for the signal strength is $\mu = 1.6 \pm 2.6$ times the Standard Model expectation for $m_{H} = 125$ GeV. Combining all $t\bar{t}H$ searches carried out by ATLAS at $\sqrt{s}=8$ and 7 TeV, an observed (expected) upper limit of 3.1 (1.4) times the Standard Model expectation is obtained at 95% confidence level, with a signal strength $\mu = 1.7 \pm 0.8$.

Study of (W/Z)H production and Higgs boson couplings using H→ W W ∗ decays with the ATLAS detector

A search for Higgs boson production in association with a $W$ or $Z$ boson, in the $H \rightarrow WW^{\ast}$ decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies $\sqrt{s}=7$ TeV and 8 TeV, corresponding to integrated luminosities of 4.5 ${\rm fb}^{-1}$ and 20.3 ${\rm fb}^{-1}$, respectively. The $WH$ production mode is studied in two-lepton and three-lepton final states, while two-lepton and four-lepton final states are used to search for the $ZH$ production mode. The observed significance, for the combined $WH$ and $ZH$ production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined $WH$ and $ZH$ signal yield to the Standard Model expectation, $\mu_{VH}$, is found to be $\mu_{VH} =3.0^{+1.3}_{-1.1}{\, {(\rm stat.)}}^{+1.0}_{-0.7}{\,{(\rm sys.)}}$ for the Higgs boson mass of 125.36 GeV. The $WH$ and $ZH$ production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the $H \to WW^* \to \ell \nu \ell \nu$ decay channel, resulting in an overall observed significance of 6.5 standard deviations and $\mu_{\rm ggF+VBF+VH} = 1.16^{+0.16}_{-0.15} {\rm (stat.)}^{+0.18}_{-0.15} {\rm (sys.)}$. The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons ($\kappa_V$) and fermions ($\kappa_F$); the combined results are: $|\kappa_V| = 1.06^{+0.10}_{-0.10}$, $|\kappa_F| = 0.85^{+0.26}_{-0.20}$.

Search for Higgs boson production in trilepton and like-charge electron-muon final states with the D0 detector

We present a search for Higgs bosons in multilepton final states in pp-bar collisions at sqrt(s)=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider, using the full Run II data set with integrated luminosities of up to 9.7 fb-1. The multilepton states considered are two electron plus muon, electron with two muons, muon with two hadronic tau leptons, and like-charge electron-muon pairs. These channels directly probe the HVV (V=W,Z) coupling of the Higgs boson in production and decay. The muon with two hadronic tau lepton channel is also sensitive to H to tau lepton pair decays. Upper limits at the 95% C.L on the rate of standard model Higgs boson production are derived in the mass range 100 <= M_H <= 200 GeV. The expected and observed limits are a factor of 6.3 and 8.4 above the predicted standard model cross section at M_H=125 GeV. We also interpret the data in a fermiophobic Higgs boson model.

Search for Higgs boson production in oppositely charged dilepton and missing energy final states in9.7 fb−1ofpp¯collisions ats=1.96 TeV

We present a search for Higgs boson in final states with two oppositely charged leptons and large missing transverse energy as expected in H -> WW -> lvlv decays. The events are selected from the full Run II data sample of 9.7 fb-1 of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt s = 1.96 TeV. To validate our search methodology, we measure the non-resonant W W production cross section and find sigma_WW = 11.6 +/- 0.7 pb, in agreement with the standard model prediction. In the Higgs boson search, no significant excess above the background expectation is observed. Upper limits at the 95% confidence level on the Higgs boson production cross section are therefore derived. Within the standard model, the Higgs boson mass range 159 < MH < 176 GeV is excluded while the expected exclusion sensitivity is 156 < MH < 172 GeV. For a mass hypothesis of MH = 125 GeV, we exclude Higgs boson production cross sections 4.1 times larger than the standard model expectation, which is compatible with the presence of a Higgs boson at this mass. Within a theoretical framework with a fourth generation of fermions, the mass range 125 < MH < 218 GeV is excluded. The search results are also interpreted in the context of fermiophobic Higgs boson couplings, which yields an exclusion of fermiophobic Higgs boson production cross sections 3.1 times larger than the expectation for MH = 125 GeV.

Search for Higgs boson production in association with a top quark pair in pp collisions

We present a search for the standard model Higgs boson produced in association with a top quark pair in 5 fb−1 of 7 TeV pp collision data. We look for events where the Higgs boson decays to bb̄ and the top quark pair decays to either lepton plus jets (tt̄ → ℓνjjbb̄) or dileptons (tt̄ → ℓνℓνbb̄), where ℓ is an electron or muon. The major background to our signal is top pair production. We use artificial neural networks to discriminate between background and signal events. We perform a simultaneous fit for signal and background fractions using the neural network output distributions. Our expected limit on Higgs boson production cross section times H → bb̄ branching ratio for a Higgs boson mass of 125 GeV/c2 is 4.6 times the standard model expectation, while the observed limit is 3.8 times the standard model expectation.

Search for Higgs boson production in oppositely charged dilepton and missing energy events inpp¯collisions ats=1.96 TeV

We present a search for the standard model Higgs boson using events with two oppositely charged leptons and large missing transverse energy as expected in $H\rightarrow WW$ decays. The events are selected from data corresponding to 8.6 \ifb\ of integrated luminosity in $p \bar{p}$ collisions at $\sqrt{s}=1.96$ TeV collected with the D0 detector at the Fermilab Tevatron Collider. No significant excess above the standard model background expectation in the Higgs boson mass range this search is sensitive to is observed, and upper limits on the Higgs boson production cross section are derived.