Precise determination of the mass of the Higgs boson and tests of compatibility of its couplings with the standard model predictions using proton collisions at 7 and 8 TeV (original) (raw)
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The European physical journal. C, Particles and fields
Properties of the Higgs boson with mass near 125[Formula: see text] are measured in proton-proton collisions with the CMS experiment at the LHC. Comprehensive sets of production and decay measurements are combined. The decay channels include [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] pairs. The data samples were collected in 2011 and 2012 and correspond to integrated luminosities of up to 5.1[Formula: see text] at 7[Formula: see text] and up to 19.7[Formula: see text] at 8[Formula: see text]. From the high-resolution [Formula: see text] and [Formula: see text] channels, the mass of the Higgs boson is determined to be [Formula: see text]. For this mass value, the event yields obtained in the different analyses tagging specific decay channels and production mechanisms are consistent with those expected for the standard model Higgs boson. The combined best-fit signal relative to the standard model exp...
The European physical journal. C, Particles and fields
Combined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the [Formula: see text] and [Formula: see text] decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 [Formula: see text] at [Formula: see text] TeV and 20.3 [Formula: see text] at [Formula: see text] TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is [Formula: see text]. The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions...
The European Physical Journal C, 2019
Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at √ s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb −1. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quarkantiquark pair) and the following decay modes: H → γ γ , ZZ, WW, τ τ , bb, and μμ. Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be μ = 1.17 ± 0.10, assuming a Higgs boson mass of 125.09 GeV. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
A measurement of the Higgs boson mass in the diphoton decay channel
Physics Letters B
A measurement of the mass of the Higgs boson in the diphoton decay channel is presented. This analysis is based on 35.9 fb −1 of proton-proton collision data collected during the 2016 LHC running period, with the CMS detector at a center-of-mass energy of 13 TeV. A refined detector calibration and new analysis techniques have been used to improve the precision of this measurement. The Higgs boson mass is measured to be m H = 125.78 ± 0.26 GeV. This is combined with a measurement of m H already performed in the H → ZZ → 4 decay channel using the same data set, giving m H = 125.46 ± 0.16 GeV. This result, when further combined with an earlier measurement of m H using data collected in 2011 and 2012 with the CMS detector, gives a value for the Higgs boson mass of m H = 125.38 ± 0.14 GeV. This is currently the most precise measurement of the mass of the Higgs boson.
Measurements of Higgs boson production and properties in the ZZ decay channel using the CMS detector
Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016), 2017
Properties of the Higgs boson are measured in the H → ZZ → 4 (= e, µ) decay channel. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 41.5 fb −1 recorded in 2017 by the CMS detector at the LHC. The signalstrength modifier µ, defined as the ratio of the observed Higgs boson rate in the H → ZZ → 4 decay channel to the standard model expectation, is measured to be µ = 1.10 +0.19 −0.17 at m H = 125.09 GeV, the combined ATLAS and CMS measurement of the Higgs boson mass. The signal-strength modifiers for the main Higgs boson production modes are also constrained. Combination with data recorded in 2016 by the CMS detector at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb −1 is reported. All results are found to be compatible with the standard model predictions.
2018
This thesis presents the measurements of Higgs (H) boson properties in the four-lepton decay channel in proton-proton collisions at a centre-of-mass energy of 13 TeV with the CMS detector. The discovery of the Higgs boson is considered as the ultimate verification of the Standard Model. It solves the problem of the origin of elementary particles mass and provides unitarization at high energy. After the discovery was announced by the ATLAS and CMS Collaborations further studies of the properties of the Higgs boson were performed exploiting Run I data at collision energies of 7 and 8 TeV. While the discovery relied on a combination of studies in five different decay channels, two of them provided most of the sensitivity and a measurement of the H boson mass: it’s decay to a pair of photons and the decay to a pair of Z bosons that both decay into pairs of electrons or muons. For the Run II at 13 TeV, significant improvements in many aspects of the H → ZZ* → 4ℓ analysis are introduced w...
Higgs boson mass measurement using H → ZZ → 4` decays at CMS
2019
A summary of the methods used to make a precision measurement of the Higgs boson mass is presented. The final mass value for the Higgs boson is measured to be mH = 125.26 ± 0.21 GeV. This analysis considers the H → ZZ → 4` channel (` = e, μ), using protonproton collision data collected in 2016 corresponding to an integrated luminosity of 35.9 fb−1 at √ s = 13 TeV by the CMS experiment at the LHC. A mass constraint is imposed on the invariant mass of the two leptons coming from the mostly on-shell Z boson to refit the lepton momenta and, hence, improve the measurement of the Higgs boson mass, per-event. The mass of the Higgs boson is extracted using a three-dimensional likelihood fit, which uses three observables per-event: (1) the refitted four-lepton invariant mass (m4`), (2) the refitted four-lepton mass uncertainty (D′ mass), and (3) a matrix element-based kinematic discriminant (Dkin bkg). Talk presented at the 2019 Meeting of the Division of Particles and Fields of the American...
A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s = 8 TeV in 2012. Individual searches in the channels H→ ZZ (*) → 4ℓ, H→ γγ and H→ WW (*) → eνµν in the 8 TeV data are combined with previously published results of searches for H→ ZZ (*) , WW (*) , b ¯ b and τ + τ − in the 7 TeV data and results from improved analyses of the H→ ZZ (*) → 4ℓ and H→ γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7 × 10 −9 , is compatible with the production and decay of the Standard Model Higgs boson. Abstract A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s = 8 TeV in 2012. Individual searches in the channels H→ ZZ (*) → 4ℓ, H→ γγ and H→ WW (*) → eνµν in the 8 TeV data are combined with previously published results of searches for H→ ZZ (*) , WW (*) , b ¯ b and τ + τ − in the 7 TeV data and results from improved analyses of the H→ ZZ (*) → 4ℓ and H→ γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations , corresponding to a background fluctuation probability of 1.7 × 10 −9 , is compatible with the production and decay of the Standard Model Higgs boson.
Physical Review Letters, 2012
Search for the Standard Model Higgs boson in the decay channel H → Z Z ( * ) → 4 with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t A search for the Standard Model Higgs boson in the decay channel H → Z Z ( * ) → + − + − , where = e, μ, is presented. Proton-proton collision data at √ s = 7 TeV recorded with the ATLAS detector and corresponding to an average integrated luminosity of 2.1 fb −1 are compared to the Standard Model expectations. Upper limits on the production cross section of a Standard Model Higgs boson with a mass between 110 and 600 GeV are derived. The observed (expected) 95% confidence level upper limit on the production cross section for a Higgs boson with a mass of 194 GeV, the region with the best expected sensitivity for this search, is 0.99 (1.01) times the Standard Model prediction. The Standard Model Higgs boson is excluded at 95% confidence level in the mass ranges 191-197, 199-200 and 214-224 GeV.