Improvements in Sensitivity and Background Modeling in WH→ℓνbb Matrix Element Analysis
Session Number
R10
Advisor(s)
Ryuji Yamada, Fermi National Accelerator Laboratory
Location
A-121
Start Date
28-4-2016 12:45 PM
End Date
28-4-2016 1:10 PM
Abstract
In 2012, the 125 GeV Higgs boson was detected using high-energy (√s = 7 TeV) collisions at the ATLAS and CMS detectors. However in the lower- energy collisions of the Tevatron collider, the evidence of Higgs particles was shown at 3 sigma, but not discovery. We present a search for such a Higgs boson in proton-antiproton collisions (√s = 1.96 TeV) collected at the D0 detector. At these energies, WH→ℓνbb has the largest cross-section of any Higgs interaction, although it is minuscule compared to the background which includes look-alike single-top interactions such as Wt→ℓνbb. To effectively separate signal from background, we use an implementation of “Matrix Element” analysis, which uses leading order matrix elements to compute event probability densities for each possible interaction (both signal and background) and rate events with a “discriminant” based upon the likelihood of a signal. We pair these discriminants with cuts derived from known characteristics of the Higgs boson, such as its invariant mass, to isolate probable Higgs events. There are some promising events with a very high likelihood of being Higgs events; these results will be discussed in detail during our presentation. We hope that this novel approach may be useful to future measurements in identifying low-cross- section interactions in noisy situations
Improvements in Sensitivity and Background Modeling in WH→ℓνbb Matrix Element Analysis
A-121
In 2012, the 125 GeV Higgs boson was detected using high-energy (√s = 7 TeV) collisions at the ATLAS and CMS detectors. However in the lower- energy collisions of the Tevatron collider, the evidence of Higgs particles was shown at 3 sigma, but not discovery. We present a search for such a Higgs boson in proton-antiproton collisions (√s = 1.96 TeV) collected at the D0 detector. At these energies, WH→ℓνbb has the largest cross-section of any Higgs interaction, although it is minuscule compared to the background which includes look-alike single-top interactions such as Wt→ℓνbb. To effectively separate signal from background, we use an implementation of “Matrix Element” analysis, which uses leading order matrix elements to compute event probability densities for each possible interaction (both signal and background) and rate events with a “discriminant” based upon the likelihood of a signal. We pair these discriminants with cuts derived from known characteristics of the Higgs boson, such as its invariant mass, to isolate probable Higgs events. There are some promising events with a very high likelihood of being Higgs events; these results will be discussed in detail during our presentation. We hope that this novel approach may be useful to future measurements in identifying low-cross- section interactions in noisy situations