scholarly journals Search for the 125 GeV Higgs Boson at 13 TeV in the diboson decay channels, by the ATLAS collaboration

2016 ◽  
Author(s):  
Maria Alconada Verzini
Keyword(s):  
Higgs Boson ◽  
Atlas Collaboration ◽  
Decay Channels

scholarly journals Measurement of cross sections and couplings of the Higgs Boson in bosonic decay channels with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02013
Author(s):  
Nikita Belyaev
Keyword(s):  
Higgs Boson ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Atlas Collaboration ◽  
Standard Model Higgs Boson ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Decay Channels ◽  
The Standard Model

After the discovery of the Higgs boson, the measurement of its properties are of particular importance. In this paper, measurement of the cross sections and couplings of the Higgs boson in bosonic decay channels with the ATLAS detector are presented. Previous measurements of the spin and parity of this new particle, as well as the investigation of its couplings to other SM particles, revealed no significant deviations from the corresponding predictions for the Standard Model Higgs boson. In the years 2015-2017, the centre-of-mass energy √s and the integrated luminosity of the Large Hadron Collider was increased up to 13 TeV and 36.1 fb-1, respectively. With this improvements of the LHC, the properties of recently discovered Higgs boson can be studied in more details. In this paper, latest updates on cross sections and couplings analyses of the Higgs Boson are presented. The discussion will focus on the recent results obtained by the ATLAS collaboration in γγ and 4l Higgs boson decay channels as well as their combination.

scholarly journals Search for decays of the 125 GeV Higgs boson into a Z boson and a ρ or ϕ meson

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Z Boson ◽  
Branching Fractions ◽  
Proton Collision ◽  
Data Set ◽  
Proton Proton ◽  
Decay Channels ◽  
Decay Products ◽  
Upper Limits ◽  
Z Boson Decays

Abstract Decays of the 125 GeV Higgs boson into a Z boson and a ρ0(770) or ϕ(1020) meson are searched for using proton-proton collision data collected by the CMS experiment at the LHC at $$ \sqrt{s} $$ s = 13 TeV. The analysed data set corresponds to an integrated luminosity of 137 fb−1. Events are selected in which the Z boson decays into a pair of electrons or a pair of muons, and the ρ and ϕ mesons decay into pairs of pions and kaons, respectively. No significant excess above the background model is observed. As different polarization states are possible for the decay products of the Z boson and ρ or ϕ mesons, affecting the signal acceptance, scenarios in which the decays are longitudinally or transversely polarized are considered. Upper limits at the 95% confidence level on the Higgs boson branching fractions into Zρ and Zϕ are determined to be 1.04–1.31% and 0.31–0.40%, respectively, where the ranges reflect the considered polarization scenarios; these values are 740–940 and 730–950 times larger than the respective standard model expectations. These results constitute the first experimental limits on the two decay channels.

scholarly journals Search for Heavy Higgs Bosons in Fermionic Decay Channels with CMS

2018 ◽  
Vol 46 ◽  
pp. 1860058
Author(s):  
Ye Chen
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Higgs Bosons ◽  
Final States ◽  
Centre Of Mass ◽  
Decay Channels ◽  
Upper Limits ◽  
The Standard Model ◽  
Cms Detector

Latest results of searches for heavy Higgs bosons in fermionic final states are presented using the CMS detector at the LHC. Results are based on pp collision data collected at centre-of-mass energies of 8 and 13 TeV which have been interpreted according to different extensions of the Standard Model such as MSSM, 2HDM, and NMSSM. These searches look for evidence of other scalar or pseudoscalar bosons, in addition to the observed SM-like 125 GeV Higgs boson, and set 95% confidence level upper limits in fermionic final states and benchmark models explored. The talk reviews briefly the major results obtained by the CMS Collaboration during Run I, and presents the most recent searches performed during Run II.

Scientists and Students from Hong Kong Join a Top Particle Physics Experiment

2014 ◽  
Vol 03 (02) ◽  
pp. 23-24
Author(s):  
Keyword(s):  
Hong Kong ◽  
Higgs Boson ◽  
Particle Physics ◽  
Hadron Collider ◽  
New Physics ◽  
Particle Accelerator ◽  
Atlas Collaboration ◽  
Particle Detectors ◽  
The World ◽  
Physics Experiment

A team of physicists from Hong Kong has now formally joined one of the most prestigious physics experiments in the world. Following a unanimous vote of approval today by its Collaboration Board, ATLAS has admitted the Hong Kong team as a member. The ATLAS Collaboration operates one of the largest particle detectors in the world, located at the Large Hadron Collider (LHC), the world's highest energy particle accelerator at CERN, Switzerland. In 2012, the ATLAS team — along with the CMS Collaboration — co-discovered the Higgs boson, or so-called 'God Particle'. The gigantic but sensitive and precise ATLAS detector, together with the unprecedentedly high collision energy and luminosity of the LHC, make it possible to search for fundamentally new physics, such as dark matter, hidden extra dimensions, and supersymmetry — a proposed symmetry among elementary particles. The LHC is currently undergoing an upgrade, targeting a substantial increase in beam energy and intensity in a year's time. It is widely expected that the discovery of the Higgs boson is only the beginning of an era of new breakthroughs in fundamental physics. All these exciting opportunities are now opened up to scientists and students from Hong Kong.

Hong Kong Scientists and Students Joined ATLAS Team at LHC, CERN

2015 ◽  
Vol 04 (01) ◽  
pp. 48-49
Author(s):  
Keyword(s):  
Hong Kong ◽  
Higgs Boson ◽  
New Physics ◽  
Atlas Collaboration ◽  
Major Step ◽  
Fundamental Physics ◽  
Fundamental Structure ◽  
Structure Of Matter

A team of physicists from Hong Kong has formally joined the ATLAS Collaboration at CERN since June, 2014. In 2012, the ATLAS Collaboration – along with the CMS Collaboration – co-discovered the Higgs boson. The discovery of the Higgs boson is widely regarded as a major step towards understanding the fundamental structure of matter and other mysteries of our universe. The admission of the Hong Kong team into ATLAS means, all these exciting opportunities of unveiling an era of new breakthroughs in fundamental physics, are now opened up to scientists and students from Hong Kong. The Hong Kong team plans to take up both hardware and software tasks on the muon detecting system and analysis of data to look for new physics.

scholarly journals The second lightest CP-even Higgs boson signals in the NMSSM at the LHC

2018 ◽  
Vol 33 (10) ◽  
pp. 1850071
Author(s):  
M. M. Almarashi
Keyword(s):  
Higgs Boson ◽  
Parameter Space ◽  
Gluon Fusion ◽  
Top Quarks ◽  
Bottom Quarks ◽  
Final States ◽  
Production Rates ◽  
Decay Channels ◽  
Text Signals

We study the signal rates of the second lightest CP-even Higgs boson, [Formula: see text], of the NMSSM produced in gluon fusion, in association with bottom quarks and in association with top quarks, which is not the SM-like Higgs boson, at the LHC. We evaluate the production rates of [Formula: see text] in the SM fermionic and bosonic final states in addition to [Formula: see text], [Formula: see text] and [Formula: see text] final states. It is observed that the size of the signal rates in some regions of the NMSSM parameter space is quite large and that could help extracting [Formula: see text] signals at the LHC through a variety of decay channels.

scholarly journals Synthesis on Heavy Higgs from the Standard Model to 2HDM and Beyond

2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Sections ◽  
Particle Physics ◽  
Hadron Collider ◽  
Signal Strength ◽  
Beyond The Standard Model ◽  
Decay Channels ◽  
Higgs Decay ◽  
The Standard Model

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.

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