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SLAC Technical Note: SLAC-TN-12-015
SLAC Release Date: August 28, 2012
Extracting bb Higgs Decay Signals using Multivariate Techniques
Smith, W. Clarke.
For low-mass Higgs boson production at ATLAS at radials = 7 TeV, the hard subprocess gg rightwards arrow h^0 rightwards arrow bb dominates but is in turn drowned out by background. We seek to exploit the intrinsic few-MeV mass width of the Higgs boson to observe it above the background in bb-dijet mass plots. The mass resolution of existing mass-reconstruction algorithms is insufficient for this purpose due to jet combinatorics, that is, the algorithms cannot identify every jet that results from... Show Full Abstract
For low-mass Higgs boson production at ATLAS at radials = 7 TeV, the hard subprocess gg rightwards arrow h^0 rightwards arrow bb dominates but is in turn drowned out by background. We seek to exploit the intrinsic few-MeV mass width of the Higgs boson to observe it above the background in bb-dijet mass plots. The mass resolution of existing mass-reconstruction algorithms is insufficient for this purpose due to jet combinatorics, that is, the algorithms cannot identify every jet that results from bb Higgs decay. We combine these algorithms using the neural net (NN) and boosted regression tree (BDT) multivariate methods in attempt to improve the mass resolution. Events involving gg rightwards arrow h^0 rightwards arrow bb are generated using Monte Carlo methods with Pythia and then the Toolkit for Multivariate Analysis (TMVA) is used to train and test NNs and BDTs. For a 120 GeV Standard Model Higgs boson, the mh0-reconstruction width is reduced from 8.6 to 6.5 GeV. Most importantly, however, the methods used here allow for more advanced mh0-reconstructions to be created in the future using multivariate methods. Show Partial Abstract
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