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Title: Search for the Higgs boson in the ZH→v$$\bar{v}$$b$$\bar{b}$$ channel: Development of a b-tagging method based on soft muons (in French)

Thesis/Dissertation ·
DOI:https://doi.org/10.2172/1005354· OSTI ID:1005354
 [1]
  1. Univ. of the Mediterranean, Marseille (France)

In the Standard Model of particle physics, the Higgs boson generates elementary particle masses. Current theoretical and experimental constraints lead to a Higgs boson mass between 114.4 and 158 GeV with 95% confidence level. Moreover, Tevatron has recently excluded the mass ranges between 100 and 109 GeV, 158 and 175 GeV with 95% confidence level. These results gives a clear indication to search for a Higgs boson at low mass. The D0 detector is located near Chicago, at the Tevatron, a proton-antiproton collider with an energy in the center of mass of 1.96 TeV. The topic of this thesis is the search for a Higgs boson in association with a Z boson. This channel is sensitive to low mass Higgs boson (<135 GeV) which has a branching ratio H → bb varies between 50% and 90% in this mass range. The decay channel ZH → v$$\bar{v}$$b$$\bar{b}$$ studied has in the final state 2 heavy-flavor jets and some missing transverse energy due to escaping neutrinos. The heavy-flavor jets identification ('b-tagging') is done with a new algorithm (SLTNN) developed specifically for semi-leptonic decay of b quarks. The Higgs boson search analysis was performed with 3 fb-1 of data. The use of SLTNN increases by 10% the Higgs boson signal efficiency. The global analysis sensitivity improvement, however, is rather low (<1%) after taking into account the backgrounds and systematic uncertainties.

Research Organization:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC02-07CH11359
OSTI ID:
1005354
Report Number(s):
FERMILAB-THESIS-2010-57; TRN: US1101128
Country of Publication:
United States
Language:
French