scholarly journals Evidence for Higgs boson decay to a pair of muons

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Top Quark ◽  
Vector Boson ◽  
Gluon Fusion ◽  
Measured Signal ◽  
Proton Collision ◽  
Proton Proton ◽  
Back Ground ◽  
Proton Proton Collision ◽  
8 Tev

Abstract Evidence for Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a vector boson, and in association with a top quark-antiquark pair. The analysis is performed using proton-proton collision data at $$ \sqrt{s} $$ s = 13 TeV, corresponding to an integrated luminosity of 137 fb−1, recorded by the CMS experiment at the CERN LHC. An excess of events over the back- ground expectation is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with mass of 125.38 GeV is 2.5. The combination of this result with that from data recorded at $$ \sqrt{s} $$ s = 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 fb−1, respectively, increases both the expected and observed significances by 1%. The measured signal strength, relative to the SM prediction, is $$ {1.19}_{-0.39}^{+0.40}{\left(\mathrm{stat}\right)}_{-0.14}^{+0.15}\left(\mathrm{syst}\right) $$ 1.19 − 0.39 + 0.40 stat − 0.14 + 0.15 syst . This result constitutes the first evidence for the decay of the Higgs boson to second generation fermions and is the most precise measurement of the Higgs boson coupling to muons reported to date.

scholarly journals Search for a light pseudoscalar Higgs boson in the boosted μμττ final state in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Branching Fraction ◽  
Vector Boson ◽  
Mass Difference ◽  
Standard Technique ◽  
Gluon Fusion ◽  
Large Mass ◽  
Proton Collision ◽  
Final State ◽  
Proton Proton

Abstract A 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 $$ \sqrt{s} $$ 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 → μμττ, and considers pseudoscalar masses in the range 3.6 < ma< 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 μμ and the ττ pairs have high Lorentz boost and are collimated. The ττ reconstruction efficiency is increased by modifying the standard technique for hadronic τ 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 ma, on the branching fraction (ℬ) for H → aa → μμττ, down to 1.5 (2.0) × 10−4 for mH = 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.

scholarly journals Search for rare and exotic Higgs Boson decay modes

2018 ◽  
Vol 182 ◽  
pp. 02123
Author(s):  
Junquan Tao
Keyword(s):  
Higgs Boson ◽  
New Physics ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Higgs Decay ◽  
Proton Proton Collision ◽  
8 Tev ◽  
Invisible Decays ◽  
Lepton Flavour

The latest results in the search for rare and exotic Higgs boson decays in proton-proton collision events collected with the CMS detector at the LHC are presented. The searches are performed for several decay modes of Higgs boson including H → X(X → 2ℓ)γ (X = Z, γ* and ℓ = e, μ), H → μμ=ee, invisible decays, lepton flavour violating decays and Higgs decay to light scalars or pseudo-scalars. No hint for new physics has been found from the analyzed results with the full LHC run-1 data collected during 2011 and 2012 at √s = 7-8 TeV and with the run-2 data at √s = 13 TeV collected during 2015 and 2016. Limits are set for all the searches which have been performed by CMS.

Review of combined measurements of Higgs boson production and decay using up to 80 fb−1 of proton–proton collision data at s = 13 TeV collected with the ATLAS experiment

2020 ◽  
pp. 2030023
Author(s):  
Hongtao Yang
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Vector Boson ◽  
Proton Collision ◽  
Boson Production ◽  
Proton Proton ◽  
Associated Production ◽  
The Standard Model ◽  
Proton Proton Collision ◽  
Combined Measurements

The combined measurements of Higgs boson production and decay are performed based on up to 80 fb[Formula: see text] of proton–proton collision data collected at [Formula: see text] = 13 TeV by the ATLAS detector. The overall signal strength, defined as measured signal yield divided by the Standard Model prediction, is [Formula: see text]. The inclusive and differential cross-sections of gluon–gluon fusion, vector-boson fusion, associated production with vector boson, and associated production with top quarks processes are also measured. The measurements are interpreted with leading-order motivated coupling strength modifiers. No significant deviations from the Standard Model predictions are observed.

scholarly journals Reconstruction and identification of boosted di-τ systems in a search for Higgs boson pairs using 13 TeV proton-proton collision data in ATLAS

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Hadron Collider ◽  
Gluon Fusion ◽  
Mass Range ◽  
Proton Collision ◽  
Final State ◽  
Proton Proton ◽  
Scalar Resonance ◽  
Proton Proton Collision ◽  
A New Technique

Abstract In this paper, a new technique for reconstructing and identifying hadronically decaying τ+τ− pairs with a large Lorentz boost, referred to as the di-τ tagger, is developed and used for the first time in the ATLAS experiment at the Large Hadron Collider. A benchmark di-τ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted $$ b\overline{b} $$ b b ¯ pair and the other into a boosted τ+τ− pair, with two hadronically decaying τ-leptons in the final state. Using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di-τ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di-τ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon-gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1–3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model.

scholarly journals Measurement of cross sections and couplings of the Higgs boson in fermionic decay modes with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02119
Author(s):  
Liaoshan Shi
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
The Cross

In this report, we present the latest ATLAS results on the measurement of the cross sections and couplings of the Higgs boson in the fermionic decay modes, H → μ+μ-, H → τ+τ- and H → bb. The searches are performed with proton-proton collision data delivered by the Large Hadron Collider during Run 1 and the first two years of Run 2 at √s = 7, 8 and 13 TeV.

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