1,868 research outputs found
A measurement of the Higgs boson mass in the diphoton decay channel
No full textA 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 centre-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 +/- 0.26GeV. This is combined with a measurement of m(H) already performed in the H -> ZZ -> 4l decay channel using the same data set, giving m(H) = 125.46 +/- 0.16GeV. 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 +/- 0.14GeV. This is currently the most precise measurement of the mass of the Higgs boson. (C) 2020 The Author(s). Published by Elsevier B.V
Measurement of the t t ¯ H and tH production rates in the H → b b ¯ decay channel using proton-proton collision data at s = 13 TeV
No full textAbstract An analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair ( t t ¯ H ) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H → b b ¯ ) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at s = 13 TeV in 2016–2018, which correspond to an integrated luminosity of 138 fb −1. The observed t t ¯ H production rate relative to the standard model expectation is 0.33 ± 0.26 = 0.33 ± 0.17(stat) ± 0.21(syst). Additionally, the t t ¯ H production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of 19.3 − 6.0 + 9.2 . Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the t t ¯ H and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels
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Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textCorrection to: Nature Published online 4 July 2022 In the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the article
Search for CP violation in tH and tH production in multilepton channels in proton-proton collisions at = 13 TeV
No full textThe charge-parity (CP) structure of the Yukawa interaction between the Higgs (H) boson and the top quark is measured in a data sample enriched in the tt¯
H and tH associated production, using 138 fb−1 of data collected in proton-proton collisions at s√
= 13 TeV by the CMS experiment at the CERN LHC. The study targets events where the H boson decays via H → WW or H → ττ and the top quarks decay via t → Wb: the W bosons decay either leptonically or hadronically, and final states characterized by the presence of at least two leptons are studied. Machine learning techniques are applied to these final states to enhance the separation of CP -even from CP -odd scenarios. Two-dimensional confidence regions are set on κt and κ∼
t, which are respectively defined as the CP -even and CP -odd top-Higgs Yukawa coupling modifiers. No significant fractional CP -odd contributions, parameterized by the quantity |fHttCP
| are observed; the parameter is determined to be |fHttCP
| = 0.59 with an interval of (0.24, 0.81) at 68% confidence level. The results are combined with previous results covering the H → ZZ and H → γγ decay modes, yielding two- and one-dimensional confidence regions on κt and κ∼
t, while |fHttCP
| is determined to be |fHttCP
| = 0.28 with an interval of |fHttCP
| < 0.55 at 68% confidence level, in agreement with the standard model CP -even prediction of |fHttCP
| = 0
Search for MSSM Higgs bosons decaying to mu(+)mu(-) in proton-proton collisions at root s=13TeV
No full textA search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13 TeV were used, corresponding to an integrated luminosity of 35.9 fb(-1). The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a b (b) over bar quark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the m(h)(mod+) and phenomenological MSSM scenarios on the parameter tan beta as a function of the mass of the pseudoscalar A boson, in the range from 130 to 600 GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with b quarks, in the mass range from 130 to 1000 GeV. (C) 2019 The Author(s). Published by Elsevier B.V
Search for γ H production and constraints on the Yukawa couplings of light quarks to the Higgs boson
No full textA search for γH production is performed with data from the CMS experiment at the LHC corresponding to an integrated luminosity of 138 fb−1 at a proton-proton center-of-mass collision energy of 13 TeV. The analysis focuses on the topology of a boosted Higgs boson recoiling against a high-energy photon. The final states of H →b ̄b
and H →4l are analyzed. This study examines effective HZγ and Hγγ anomalous couplings within the context of an effective field theory. In this approach, the production cross section is constrained to be σγH <16.4 fb
at 95% confidence level (CL). Simultaneous constraints on four anomalous couplings involving HZγ and Hγγ
are provided. Additionally, the production rate for H →4l is examined to assess potential enhancements in the Yukawa couplings between light quarks and the Higgs boson. Assuming the standard model values for the Yukawa couplings of the bottom and top quarks, the following simultaneous constraints are obtained: κu =(0.0 ±1.5) ×103, κd =(0.0+6.7
−6.8) ×102, κs =0+30−32 , and κc =0.0+2.3 −2.8. This rules out the hypothesis that up- or down-type quarks in the first or second generation have the same Yukawa couplings as those in the third generation, with a CL greater than 95%
Search for a light pseudoscalar Higgs boson in the boosted mu mu tau tau final state in proton-proton collisions at root s=13 TeV
No full textA search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> mu mu tau tau, and considers pseudoscalar masses in the range 3.6 < m(a) < 21 GeV. Because of the large mass difference between the H and the a bosons and the small masses of the a boson decay products, both the mu mu and the tau tau pairs have high Lorentz boost and are collimated. The tau tau reconstruction efficiency is increased by modifying the standard technique for hadronic tau lepton decay reconstruction to account for a nearby muon. No significant signal is observed. Model-independent limits are set at 95% confidence level, as a function of m(a), on the branching fraction (B) for H -> aa -> mu mu tau tau, down to 1.5 (2.0)x10(-4) for m(H) = 125 (300) GeV. Model-dependent limits on B(H -> aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV
Search for CP violation in t t ¯ H and tH production in multilepton channels in proton-proton collisions at √<i>s</i> = 13 TeV
No full textA preprint version of the article is available at arXiv:2208.02686v2 [hep-ex], https://arxiv.org/abs/2208.02686v2 . Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at this http URL (CMS Public Pages). Report number: CMS-HIG-21-006, CERN-EP-2022-157.The charge-parity (CP) structure of the Yukawa interaction between the Higgs (H) boson and the top quark is measured in a data sample enriched in the tt¯ and tH associated production, using 138 fb^{−1} of data collected in proton-proton collisions at s√ = 13 TeV by the CMS experiment at the CERN LHC. The study targets events where the H boson decays via H → WW or H → ττ and the top quarks decay via t → Wb: the W bosons decay either leptonically or hadronically, and final states characterized by the presence of at least two leptons are studied. Machine learning techniques are applied to these final states to enhance the separation of CP-even from CP-odd scenarios. Two-dimensional confidence regions are set on κt and κ~t, which are respectively defined as the CP-even and CP-odd top-Higgs Yukawa coupling modifiers. No significant fractional CP-odd contributions, parameterized by the quantity |fHttCP| are observed; the parameter is determined to be |fHttCP| = 0.59 with an interval of (0.24, 0.81) at 68% confidence level. The results are combined with previous results covering the H → ZZ and H → γγ decay modes, yielding two- and one-dimensional confidence regions on κt and κ~t, while |fHttCP| is determined to be |fHttCP| = 0.28 with an interval of |fHttCP| < 0.55 at 68% confidence level, in agreement with the standard model CP-even prediction of |fHttCP| = 0.SCOAP3
Search for a heavy Higgs boson decaying into two lighter Higgs bosons in the ττbb final state at 13 TeV
No full textA bstract A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h S is presented. The h and h S bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb −1 . Mass ranges of 240–3000 GeV for m H and 60–2800 GeV for m h S are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for m H = 240 GeV) to 2 . 7 fb (for m H = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery (Nature, (2022), 607, 7917, (60-68), 10.1038/s41586-022-04892-x)
No full textCorrection to: Nature Published online 4 July 2022 In the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the article.SCOAP
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