Session C12: The Study of the Higgs Particle

Live

A cross-section measurement of the Standard Model Higgs boson produced in association with the Z boson is presented, using the full Run 2 proton-proton dataset at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137.1 fb\textasciicircum -1, recorded with the CMS (Compact Muon Solenoid) detector. Candidate events are selected to have a Z boson decaying to a pair of charged leptons and a Higgs boson decaying to two W bosons. One of the W bosons decays to a lepton and neutrino and the other decays to a quark pair, increasing the signal event yield compared to the conventional approach of requiring both W bosons to decay leptonically, at the price of increased background. Techniques to estimate and reduce these backgrounds will be described, and the results will be presented in the context of the measurement of the associated production of vector bosons and a Higgs boson with all h-\textgreater WW channels combined.   

Live

Presented are the results of a study of the production of a Higgs boson in association with a vector boson, in the H$\rightarrow$ WW decay mode, using full Run 2 data collected at the LHC by CMS in pp collisions at $\sqrt{s}=13$ TeV. Included in the results are two new VH, H$\rightarrow$WW channels that were not previously included, the WHSS 2$\ell$ (WH same sign, 2-lepton) and ZH3$\ell$ channels. The recurring channels, ZH4$\ell$ and WH3$\ell$, use updated analysis methods and feature improved results from the previously published H$\rightarrow$WW analysis. While all VH leptonic channels will be discussed, special emphasis will be given to the WH SS 2-lepton channel in the scope of the full analysis. Combination and STXS measurements were also performed for the VH leptonic analysis and will be discussed.   

Live

Higgs boson pair production occurs at a low rate in the Standard Model, and deviations from this rate could provide hints of new physics. This presentation will describe the latest results in the search for two Higgs bosons decaying to a final state with two tau leptons and two bottom quarks, using $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector. It will include the latest results in the search for non-resonant SM production, as well as the search for heavy resonances decaying to Higgs boson pairs.   

Live

CLIC is a mature option for a future electron-positron collider operating at centre-of-mass energies of up to 3 TeV. CLIC will be built and operated in a staged approach with three centre-of-mass energy stages currently assumed to be 380 GeV, 1.5 TeV, and 3 TeV. This presentation focusses on unique opportunities at the multi-TeV stages in the area of Higgs physics. Two studies based on full detector simulations will be discussed: Higgsstrahlung (e$^+$e$^- \to$ ZH) and the extraction of the Higgs self-coupling from double Higgs production. The first is particularly interesting as contributions from BSM effects to ZH production grow with energy. Substructure information can be used to identify fully hadronic ZH events at 3 TeV. B-tagging in boosted Higgs boson decays was studied for the first time for CLIC. New projections for the ZH event rate and angular distributions will be shown. The Higgs self-coupling is of particular interest: for determining the shape of the Higgs potential, and due to its sensitivity to a variety of BSM physics scenarios. At the higher-energy stages CLIC will produce Higgs boson pairs both via double Higgsstrahlung and via vector-boson fusion. Measurements of these processes lead to a determination of the Higgs self-coupling with a precision around 10\%.   

Live

Muon collisions at multi-TeV center-of-mass energies are perfect for studying the Higgs-boson properties. The number of produced Higgs bosons will allow to measure its couplings to fermions and bosons with an unprecedented precision. At $\sqrt{s}$ of the order of or greater than 10 TeV and with an instantaneous luminosity of at least $10^{35}cm^{-2}s^{-1}$ the double (triple) Higgs-boson production rate will be sufficiently high to directly measure the parameters of trilinear (quadrilinear) self-couplings, enabling the precise determination of the Higgs boson potential. The studies presented here, performed with a full simulation of the detector and the beam-induced background, demonstrate that the use of novel detector technologies allows to keep the detector occupancy at a manageable level. By using a simple cut-based approach, the b-jet invariant mass is reconstructed to identify the Higgs-boson. A first conservative evaluation of its coupling sensitivity at $\sqrt{s}$ of 3 and 10 TeV will be presented using the detector performance evaluated at 1.5 TeV, demonstrating that high precision Higgs measurements are possible at muon collider.   

Live

Rare decays of the Higgs boson to $J/\psi$ mesons are a promising laboratory to study couplings to charm quarks and physics beyond the standard model. A search for decays of the Higgs boson to $J/\psi$ meson pairs and $Z$ boson plus $J/\psi$ meson, with the subsequent resonance decays to muon pairs is performed with the Compact Muon Solenoid detector at the Large Hadron Collider. A data sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV during the years 2016, 2017 and 2018 is used. I will present results of the searches and implications for future searches of beyond standard model signatures at high luminosity.   

Live

The recent discovery of the Higgs boson has led to a hunt for a confirmation on the properties of the Higgs, such as the rate of predicted decay mechanisms. This project is a study of the kinematic data recorded from truth-jet analysis generated in simulations of the final state $H^0 \rightarrow gg \rightarrow b\overline{b}b\overline{b}$, where a Higgs boson decays to a pair of gluons and each gluon produces a pair of bottom quarks via gluon splitting. The main background is $H^0 \rightarrow b\overline{b}g \rightarrow b\overline{b}b\overline{b}$, in which a Higgs boson decays to a pair of bottom quarks where one bottom quark radiates a gluon that decays to a pair of bottom quarks, which serves as the predominant background. The momentum, energies, angle of separation and other factors were recorded from a simulation and compared. This study is done primarily to show that the identification of a particular final state Higgs process is incredibly difficult when considering other background processes that could be interpreted as false-positives in an isolated analysis. From our analysis of the kinematics of these processes, we also explore the application of a machine-learning algorithm to distinguish Higgs processes based on the kinematic data available to a detection model.   

On Demand

Some extensions of the Standard Model predict that the Higgs boson can produce invisible dark matter candidates through its decay. I present the progress of a search for invisible decays of the Higgs boson produced through the VBF channel with an associated photon.   

On Demand

In the standard model of particle physics, the fermion masses arise from a Yukawa coupling to the Higgs field. The existence of the Higgs field was confirmed by the discovery of the Higgs boson by the CMS and ATLAS experiments, its mass was measured and found to be approximately 125 GeV. Previous measurements at CMS and ATLAS established that the Higgs boson couples to third generation fermions (bottom and top quarks, tau leptons). The study of the Higgs boson decaying to muons extends the investigation to its couplings to second generation fermions. A search for the standard model Higgs boson decaying into a pair of muons is presented. This search uses proton-proton collision data at sqrt(s) $=$ 13 TeV recorded by the CMS experiment at the CERN LHC in 2016, 2017, and 2018, corresponding to an integrated luminosity of 137.1 fb-1.