Search for the Higgs Boson Decaying to Two Tau Leptons in $p\bar{p}$ Collisions at a Center of Mass Energy of 1.96 Tev
Search for the Higgs Boson Decaying to Two Tau Leptons in $p\bar{p}$ Collisions at a Center of Mass Energy of 1.96 Tev

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Published: 2011

Total Pages: 166

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A search for the Higgs boson decaying to $ au au$ using 7.8f̃b${̂-1}$ of $par{p}$ collisions at 1.96T̃eV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of $ au au$ pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At $M_H$$=$120G̃eV/$c2̂$ observed limit is 14.9$ imessigma_{SM} imes Br (H → ??)$.

Search for the Higgs Boson Decaying to Two Tau Leptons in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV
Search for the Higgs Boson Decaying to Two Tau Leptons in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV

Author: Andrey Elagin

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Published: 2012

Total Pages:

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A search for the Higgs boson decaying to tau tau using 7.8 fb^-1 of pp collisions at 1.96 TeV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of tau tau pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At M_H=120 GeV/c^2 observed limit is 14.9 x sigma_SM x Br(H -> tau tau).

Search for a Neutral Higgs Boson Decaying to Tau Leptons Using CMS at the LHC
Search for a Neutral Higgs Boson Decaying to Tau Leptons Using CMS at the LHC

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Published: 2013

Total Pages: 0

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This thesis presents a search for the standard model Higgs boson decaying to a [tau tau] pair using CMS data recorded at the LHC with 7 TeV and 8 TeV center of mass energy during 2011 and 2012 respectively. The search is performed using two channels [tau mu tau eta] and [tau epsilon tau eta] where [tau epsilon, tau mu] represent a [tau] decay to an electron or muon and [tau eta] represents a [tau] decay to hadron(s). The search is performed in the range 100 GeV

Search for Lepton-flavour-violating H 2![mu][tau] Decays of the Higgs Boson with the ATLAS Detector
Search for Lepton-flavour-violating H 2![mu][tau] Decays of the Higgs Boson with the ATLAS Detector

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Published: 2015

Total Pages: 33

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A direct search for lepton-flavour-violating H → [mu][tau] decays of the recently discovered Higgs boson with the ATLAS detector at the LHC is presented. The analysis is performed in the H → [mu][tau] had channel, where [tau] had is a hadronically decaying [tau] -lepton. The search is based on the data sample of proton-proton collisions collected by the ATLAS experiment corresponding to an integrated luminosity of 20.3 fb-1 at a centre-of-mass energy of √s = 8 TeV. No statistically significant excess of data over the predicted background is observed. As a result, the observed (expected) 95% confidence-level upper limit on the branching fraction, Br( H → [mu][tau] ), is 1.85% (1.24%).

Search for Lepton-flavour-violating Decays of the Higgs Boson
Search for Lepton-flavour-violating Decays of the Higgs Boson

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Publisher:

Published: 2015

Total Pages: 26

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The first direct search for lepton-flavour-violating decays of the recently discovered Higgs boson (H) is described. The search is performed in the H 2![mu][tau]e and H2!mu][tau]h channels, where [tau]e and [tau]h are tau leptons reconstructed in the electronic and hadronic decay channels, respectively. The data sample used in this search was collected in pp collisions at a centre-of-mass energy of [arrow]" = 8 TeV with the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 19.7 fb−1. The sensitivity of the search is an order of magnitude better than the existing indirect limits. A slight excess of signal events with a significance of 2.4 standard deviations is observed. The p-value of this excess at MH=125 GeV is 0.010. The best fit branching fraction is [Beta](H 2![mu][tau])=(0.84+0.39-0.37)%. A constraint on the branching fraction, [Beta](H 2![mu][tau])

Search for the Higgs Boson in Its Decay Into Tau Leptons at CMS
Search for the Higgs Boson in Its Decay Into Tau Leptons at CMS

Author: Matthew Hans Chan

Publisher:

Published: 2013

Total Pages: 204

ISBN-13:

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A search for the Standard Model Higgs boson in the H --> rr channel is presented. The search is performed on proton collision data collected by the Compact Muon Solenoid at the Large Hadron Collider. The data corresponds to 4.9 fb-1 of proton collisions at [square root of]s = 7 TeV and 19.5 fb-1 at [square root of]s = 8 TeV. The search is based on di-tau events in which one tau decays into an electron or muon, and the other tau decays into hadrons. The search focuses on Higgs masses between 110 GeV and 145 GeV. The analysis reveals no statistically significant excess in the data over the Standard Model backgrounds. Upper limits on the Higgs production cross section at the 95% confidence level are established. The observed limit is statistically consistent with the expected limit in the background-only hypothesis but does not exclude any Higgs mass.

Evidence for the 125 GeV Higgs Boson Decaying to a Pair of $\tau$ Leptons
Evidence for the 125 GeV Higgs Boson Decaying to a Pair of $\tau$ Leptons

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Publisher:

Published: 2014

Total Pages: 72

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A search for a standard model Higgs boson decaying into a pair of tau leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9 inverse femtobarns at a centre-of-mass energy of 7 TeV and 19.7 inverse femtobarns at 8 TeV. Each tau lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the tau-lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for m[H] values between 115 and 130 GeV. The best fit of the observed H to tau tau signal cross section for m[H] = 125 GeV is 0.78 +- 0.27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons.

Search for a Higgs Boson Decaying Into $\gamma*̂\gamma\to\ell\ell\gamma$ with Low Dilepton Mass in Pp Collisions at $\sqrt{s}
Search for a Higgs Boson Decaying Into $\gamma*̂\gamma\to\ell\ell\gamma$ with Low Dilepton Mass in Pp Collisions at $\sqrt{s}

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Published: 2015

Total Pages: 22

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Our search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ll?). The analysis is performed using proton–proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120 mll? 150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H → ?*? → ll?, where the dilepton invariant mass is less than 20 GeV. A Higgs boson with mH=125 GeV has a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9sup+2.8/supsub-1.8/sub ) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H → (J/?)? for the 125 GeV Higgs boson is set at 1.5 × 10

Search for Higgs Bosons Decaying to Aa in the [mu][mu][tau][tau] Final State in Pp Collisions at [arrow]"
Search for Higgs Bosons Decaying to Aa in the [mu][mu][tau][tau] Final State in Pp Collisions at [arrow]

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Publisher:

Published: 2015

Total Pages:

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A search for the decay to a pair of new particles of either the 125 GeV Higgs boson (h) or a second charge parity (CP)-even Higgs boson (H) is presented. The data set corresponds to an integrated luminosity of 20.3 fb-1 of pp collisions at [arrow]" = 8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (a). One of the two a bosons is required to decay to two muons while the other is required to decay to two [tau] leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 to 50 GeV. Upper limits are placed on the production of h 2!aa relative to the standard model gg 2!h production, assuming no coupling of the a boson to quarks. The most stringent limit is placed at 3.5% for ma = 3.75 GeV. The upper limits are also placed on the production cross section of H 2!aa from 2.33 to 0.72 pb, for fixed ma = 5 GeV with mH ranging from 100 to 500 GeV.