Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Abstract

IntroductionThe discovery of a new particle of mass about 125 GeV in the search for the Standard Model This Letter presents measurements of several properties of the newly observed particle, including its mass, production strengths and couplings to fermions and bosons, using diboson final states 1 : Monte Carlo (MC) samples used to model signal and background processes. The analyses of the three decay channels are presented in Sections 4-6. Measurements of the Higgs boson mass, production properties and couplings are discussed in Section 7. Section 8 is devoted to the conclusions. Data sample and event reconstructionAfter data quality requirements, the integrated luminosities of the samples used for the studies reported here are about 4.7 fb −1 in 2011 and 20.7 fb −1 in 2012, with uncertainties given in Table 1 (determined as described in Ref. [13]). Because of the high LHC peak luminosity (up to 7.7 × 10 33 cm −2 s −1 in 2012) and the 50 ns bunch spacing, the number of proton-proton interactions occurring in the same bunch crossing is large (on average 20.7, up to about 40). This "pile-up" of events requires the use of dedicated algorithms and corrections to mitigate its impact on the reconstruction of e.g. leptons, photons and jets. 0370-2693/

What is the machine learning?

“…(1) by uniformly binning the input events and inverting the histogram, which introduces some finite bin effects as will be apparent below. Note for a different purpose, the experimental collaborations frequently weight events to match the transverse momentum spectrum of different samples (e.g., [18][19][20]). Next, we train a new network on the planed input data.…”

Ingredients for a discovery: Theory, experiment and a lot of patience

“…CMS and ATLAS have compared a number of options for the spin-parity of this particle, and zero spin and positive parity clearly are favored by the data, as is expected for the SM Higgs [7]: As an example, ATLAS excludes the spin 1 and 2 options and favors positive parity at 97% confidence level, and similar statements apply for CMS. Also measurements of the particle's interactions with other elementary particles-i.e.…”

Study of the Electroweak Symmetry Breaking Sector for the LHC

“…1 M ATLAS h = 125.5 ± 0.6 GeV and M CMS h = 125.7 ± 0.4 GeV, according to [109] and [110], respectively. 2 See app.…”