Higgs Boson Mass Range Research Articles

A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

A search for heavy Higgs bosons produced in association with a vector boson and decaying into a pair of vector bosons is performed in final states with two leptons (electrons or muons) of the same electric charge, missing transverse momentum and jets. A data sample of proton–proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb−1. The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher-dimensional operators in an effective field theory. Upper limits on the production cross-section are calculated at 95% confidence level as a function of the heavy Higgs boson’s mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass range from 300 to 1500 GeV, and depend on the assumed couplings. The highest excluded mass for a heavy Higgs boson with the coupling combinations explored is 900 GeV. Limits on coupling strengths are also provided.

Search for heavy neutral Higgs bosons produced in association with b -quarks and decaying into b -quarks at s=13 TeV with the ATLAS detector

A search for heavy neutral Higgs bosons produced in association with one or two $b$-quarks and decaying to $b$-quark pairs is presented using 27.8 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. No evidence of a signal is found. Upper limits on the heavy neutral Higgs boson production cross-section times its branching ratio to $b\bar{b}$ are set, ranging from 4.0 to 0.6 pb at 95% confidence level over a Higgs boson mass range of 450 to 1400 GeV. Results are interpreted within the two-Higgs-doublet model and the minimal supersymmetric Standard Model.

Model-independent search strategy for the lepton-flavor-violating heavy Higgs boson decay to {tau mu } at the LHC

In this work we present a model-independent search strategy at the LHC for heavy Higgs bosons decaying into a tau and a muon, H/A rightarrow tau mu , showing a plausible tendency to improve the sensitivity obtained by the present experimental limits. This search strategy is performed for the Higgs boson mass range 1–5 TeV and uses as the most relevant kinematical variables, in order to discriminate signal against background, the transverse momenta of the muon and the tau together with the missing transverse energy. We estimate the exclusion limits at 95% CL and the significances for evidence and discovery at sqrt{s} = 14 TeV with mathcal {L} = 300 fb^{-1}, observing a growth in the sensitivities for high Higgs boson masses. Moreover, since the Higgs boson decay into a tau-lepton pair may mimic our LFV signal, we also study the impact of the ditau channel on the exclusion limits and the significances for evidence and discovery. In particular, the impact on the exclusion limits of LFV heavy Higgs boson decays is significant when the ditau rate begins to compete with the corresponding to the H/A rightarrow tau mu decay.

Search for a charged Higgs boson decaying to charm and bottom quarks in proton-proton collisions at sqrt{s}=8 TeV

A search for charged Higgs boson decaying to a charm and a bottom quark ( {mathrm{H}}^{+}to mathrm{c}overline{mathrm{b}} ) is performed using 19.7 fb−1 of pp collision data at sqrt{s}=8 TeV. The production mechanism investigated in this search is mathrm{t}overline{mathrm{t}} pair production in which one top quark decays to a charged Higgs boson and a bottom quark and the other decays to a charged lepton, a neutrino, and a bottom quark. Charged Higgs boson decays to mathrm{c}overline{mathrm{b}} are searched for, resulting in a final state containing at least four jets, a charged lepton (muon or electron), and missing transverse momentum. A kinematic fit is performed to identify the pair of jets least likely to be the bottom quarks originating from direct top quark decays and the invariant mass of this pair is used as the final observable in the search. No evidence for the presence of a charged Higgs boson is observed and upper limits at 95% confidence level of 0.8–0.5% are set on the branching fraction ℬ(t → H+b), assuming ℬ(H+ → mathrm{c}overline{mathrm{b}} ) = 1.0 and ℬ(t → H+b) + ℬ(t → Wb) = 1.0, for the charged Higgs boson mass range 90–150 GeV.

Search for an additional, heavy Higgs boson in the [Formula: see text] decay channel at [Formula: see text] in [Formula: see text] collision data with the ATLAS detector.

A search is presented for a high-mass Higgs boson in the Hrightarrow ZZrightarrow ell ^+ell ^-ell ^+ell ^-, Hrightarrow ZZrightarrow ell ^+ell ^-nu bar{nu }, Hrightarrow ZZrightarrow ell ^+ell ^- q bar{q}, and Hrightarrow ZZrightarrow nu bar{nu } q bar{q} decay modes using the ATLAS detector at the CERN Large Hadron Collider. The search uses proton–proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb^{-1}. The results of the search are interpreted in the scenario of a heavy Higgs boson with a width that is small compared with the experimental mass resolution. The Higgs boson mass range considered extends up to 1~mathrm{TeV} for all four decay modes and down to as low as 140 mathrm{GeV}, depending on the decay mode. No significant excess of events over the Standard Model prediction is found. A simultaneous fit to the four decay modes yields upper limits on the production cross-section of a heavy Higgs boson times the branching ratio to Z boson pairs. 95 % confidence level upper limits range from 0.53 pb at m_{H} =195 GeV to 0.008 pb at m_{H} =950 GeV for the gluon-fusion production mode and from 0.31 pb at m_{H} =195 GeV to 0.009 pb at m_{H} =950 GeV for the vector-boson-fusion production mode. The results are also interpreted in the context of Type-I and Type-II two-Higgs-doublet models.

Search for exotic decays of a Higgs boson into undetectable particles and one or more photons

A search is presented for exotic decays of a Higgs boson into undetectable particles and one or two isolated photons in pp collisions at a center-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of up to 19.4 fb−1 collected with the CMS detector at the LHC. Higgs bosons produced in gluon–gluon fusion and in association with a Z boson are investigated, using models in which the Higgs boson decays into a gravitino and a neutralino or a pair of neutralinos, followed by the decay of the neutralino to a gravitino and a photon. The selected events are consistent with the background-only hypothesis, and limits are placed on the product of cross sections and branching fractions. Assuming a standard model Higgs boson production cross section, a 95% confidence level upper limit is set on the branching fraction of a 125 GeV Higgs boson decaying into undetectable particles and one or two isolated photons as a function of the neutralino mass. For this class of models and neutralino masses from 1 to 120 GeV an upper limit in the range of 7 to 13% is obtained. Further results are given as a function of the neutralino lifetime, and also for a range of Higgs boson masses.

Search for a Higgs Boson decaying to γγ⁎ → γℓ+ℓ− in pp collision at [formula omitted] at the CMS experiment

The results of the Standard Model Higgs boson decay into a real photon and a virtual photon (γγ⁎) are presented. The analysis is performed using proton-proton collision data recorded by the CMS detector at the LHC. The events were collected at 8 TeV center-of-mass energy. No excess of events above background is found in the 120–150 GeV Higgs boson mass range.

Search for invisible decays of the Higgs boson produced in association with a hadronically decaying vector boson in pp collisions at [Formula: see text] TeV with the ATLAS detector.

A search for Higgs boson decays to invisible particles is performed using 20.3 {{mathrm {fb}}^{-1}} of pp collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the Large Hadron Collider. The process considered is Higgs boson production in association with a vector boson (V = W or Z) that decays hadronically, resulting in events with two or more jets and large missing transverse momentum. No excess of candidates is observed in the data over the background expectation. The results are used to constrain VH production followed by H decaying to invisible particles for the Higgs boson mass range 115<m_H<300 GeV. The 95 % confidence-level observed upper limit on sigma _{VH} times text {BR}(Hrightarrow text {inv.}) varies from 1.6 pb at 115 GeV to 0.13 pb at 300 GeV. Assuming Standard Model production and including the ggrightarrow H contribution as signal, the results also lead to an observed upper limit of 78 % at 95 % confidence level on the branching ratio of Higgs bosons decays to invisible particles at a mass of 125 GeV.

Search for a Charged Higgs Boson Produced in the Vector-Boson Fusion Mode with Decay H(±)→W(±)Z using pp Collisions at √s=8 TeV with the ATLAS Experiment.

A search for a charged Higgs boson, H(±), decaying to a W(±) boson and a Z boson is presented. The search is based on 20.3 fb(-1) of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The H(±) boson is assumed to be produced via vector-boson fusion and the decays W(±)→qq' and Z→e(+)e(-)/μ(+)μ(-) are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an H(±) boson is observed. Upper limits of 31-1020 fb at 95% C.L. are placed on the cross section for vector-boson fusion production of an H(±) boson times its branching fraction to W(±)Z. The limits are compared with predictions from the Georgi-Machacek Higgs triplet model.

Search for the Standard Model Higgs Boson in the H to [formula omitted] to lepton-hadron and hadron-hadron Decay Modes with the ATLAS Detector

In this proceeding, a search for a Higgs boson in the H to τ+τ− decay mode, where both taus decay hadronically or one decay hadronically and one leptonically. The analysis is based on a data sample of proton-proton collision collected by the ATLAS detector at the Large Hadron Collider (LHC) at centre-of-mass energies of 7 TeV during 2011, corresponding to an integrated luminosity of 4.7fb−1. No significant excess is observed in the Higgs boson mass range of 100–150 GeV. The observed (expected) limits on the cross-section times branching ratio for H to τ+τ− at mH=125 GeV are 6.2(5.9) and 6.3(6.5) for lepton-hadron and hadron-hadron decay modes, respectively.

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.

Updated search for the standard model Higgs boson in events with jets and missing transverse energy using the full CDF data set

We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclusion of a $b$-jet identification algorithm specifically optimized for $H\to b\bar{b}$ searches. Across the Higgs boson mass range $90 \le m_H \le 150$ GeV$/c^2$, the expected 95% credibility level upper limits on the $V H$ production cross section times the $H\to b\bar{b}$ branching fraction are improved by an average of 14% relative to the previous analysis. At a Higgs boson mass of 125 GeV$/c^2$, the observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state.

Search for a SM Higgs boson in theH→Z*Z→ ℓ+ℓ−qq̅channel in the mass range 120 - 180 GeV with the ATLAS Detector at √s= 7 TeV

A summary of the first study is given for the decay channel H ! Z ⇤ Z ! ` + `q¯ q (` = e,µ) in the Higgs boson mass range 120 - 180 GeV, using the pp collision data collected by the ATLAS experiment at p s = 7 TeV at the LHC. Data driven methods to estimate the background and new techniques to improve the mass resolution of the hadronic Z boson decay are used. Events with 0 or 1 b-jets and events with 2 b-jets are treated as separated channels. No significant excess of events above the estimated background is observed; upper limits at 95% C.L. on the Higgs production cross section are derived.

Standard Model Higgs boson searches in pp collisions at = 7 TeV with the ATLAS detector

We report on searches for the Standard Model Higgs boson with the ATLAS detector at the LHC. Several production mechanisms and decay channels are considered and a wide range of hypothetical Higgs boson masses explored. The datasets correspond to integrated luminosities ranging from 4.6 fb−1 to 4.9 fb−1 of proton-proton collisions collected at = 7 TeV in 2011. At the 95% confidence level the excluded Higgs boson mass ranges are 111.4 GeV to 116.6 GeV, 119.4 GeV to 122.1 GeV, and 129.2 GeV to 541 GeV, while the mass range from 120 GeV to 560 GeV is expected to be excluded in the absence of a signal. An excess of events is observed at a Higgs boson mass around 126 GeV with a local significance of 2.9σ The global probability for the background to produce an excess at least as significant anywhere in the mass range explored corresponds to a significance of approximately lσ.

Search for neutral Higgs bosons in events with multiple bottom quarks at the Tevatron

The combination of searches performed by the CDF and D0 collaborations at the Fermilab Tevatron Collider for neutral Higgs bosons produced in association with b quarks is reported. The data, corresponding to 2.6 fb-1 of integrated luminosity at CDF and 5.2 fb-1 at D0, have been collected in final states containing three or more b jets. Upper limits are set on the cross section multiplied by the branching ratio varying between 44 pb and 0.7 pb in the Higgs boson mass range 90 to 300 GeV, assuming production of a narrow scalar boson. Significant enhancements to the production of Higgs bosons can be found in theories beyond the standard model, for example in supersymmetry. The results are interpreted as upper limits in the parameter space of the minimal supersymmetric standard model in a benchmark scenario favoring this decay mode.

Search for the Standard Model Higgs boson in the H → τ + τ − decay mode in $ \sqrt {s} = 7\,{\mathrm{TeV}} $ pp collisions with ATLAS

Abstract A search for the Standard Model Higgs boson decaying into a pair of τ leptons is reported. The analysis is based on a data sample of proton-proton collisions collected by the ATLAS experiment at the LHC and corresponding to an integrated luminosity of 4.7 fb−1. No significant excess over the expected background is observed in the Higgs boson mass range of 100–150 GeV. The observed (expected) upper limits on the cross section times the branching ratio for H → τ + τ − are found to be between 2.9 (3.4) and 11.7 (8.2) times the Standard Model prediction for this mass range.

Search for a fermiophobic Higgs boson in pp collisions at $ \sqrt {s} = 7 $ TeV

AbstractCombined results are reported from searches for a fermiophobic Higgs boson in the γγ, WW, and ZZ decay modes in proton-proton collisions at$ \sqrt {s} = 7 $TeV. The explored Higgs boson mass range is 110–300 GeV. The data sample corresponds to an integrated luminosity of 4.9–5.1 fb−1. A fermiophobic Higgs boson is excluded at 95% confidence level in the mass range 110–194 GeV, and at 99% confidence level in the mass ranges 110–124.5 GeV, 127–147.5 GeV, and 155–180 GeV.

Search for the standard model Higgs boson produced in association with aW±boson with7.5 fb−1integrated luminosity at CDF

We present a search for the standard model Higgs boson produced in association with a $W^{\pm}$ boson. This search uses data corresponding to an integrated luminosity of 7.5 fb$^{-1}$ collected by the CDF detector at the Tevatron. We select $WH \to \ell\nu b \bar{b}$ candidate events with two jets, large missing transverse energy, and exactly one charged lepton. We further require that at least one jet be identified to originate from a bottom quark. Discrimination between the signal and the large background is achieved through the use of a Bayesian artificial neural network. The number of tagged events and their distributions are consistent with the standard model expectations. We observe no evidence for a Higgs boson signal and set 95% C.L. upper limits on the $WH$ production cross section times the branching ratio to decay to $b\bar b$ pairs, $\sigma(p\bar p \rightarrow W^{\pm} H) \times {\cal B}(H\rightarrow b\bar b)$, relative to the rate predicted by the standard model. For the Higgs boson mass range of 100 GeV/c$^2$ to 150 GeV/c$^2$ we set observed (expected) upper limits from 1.34 (1.83) to 38.8 (23.4). For 115 GeV/c$^2$ the upper limit is 3.64 (2.78). The combination of the present search with an independent analysis that selects events with three jets yields more stringent limits ranging from 1.12 (1.79) to 34.4 (21.6) in the same mass range. For 115 GeV/c$^2$ the upper limit is 2.65 (2.60).

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.

Combined search for the Standard Model Higgs boson inppcollisions ats=7 TeVwith the ATLAS detector

A combined search for the Standard Model Higgs boson with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities from 4.6 fb^-1 to 4.9 fb^-1 of proton-proton collisions collected at sqrt(s) = 7 TeV in 2011. The Higgs boson mass ranges of 111.4 GeV to 116.6 GeV, 119.4 GeV to 122.1 GeV, and 129.2 GeV to 541 GeV are excluded at the 95% confidence level, while the range 120 GeV to 560 GeV is expected to be excluded in the absence of a signal. An excess of events is observed at Higgs boson mass hypotheses around 126 GeV with a local significance of 2.9 standard deviations (sigma). The global probability for the background to produce an excess at least as significant anywhere in the entire explored Higgs boson mass range of 110-600 GeV is estimated to be ~15%, corresponding to a significance of approximately one sigma.