Search for the Standard Model Higgs boson in the H > WW > lvjj decay channel

This is a condensed description with plots for the analysis CMS-HIG-12-003

Abstract

A search for the Standard Model Higgs boson decaying to two W bosons with the subsequent decay to a final state containing one lepton, one neutrino, and two or three jets is presented. The results are based on a data sample corresponding to an integrated luminosity of 5.0/fb of proton-proton collisions at sqrt(s) = 7 TeV and collected with the CMS detector at the CERN LHC. Selections to discriminate between the signal and background events are based on kinematic and topological quantities including the angular spin correlations of the decay products. No evidence for the Higgs boson is found, and at 95% confidence level the SM Higgs boson production in the mass range 327-415 GeV is excluded.

Limits

MVA-based analysis

Fit-based analysis

Figures from CMS-HIG-12-003

figure	label	description
	Figure 1 (a) png,pdf	The invariant mass of the di-jet system after the physics object selection but before optimization, for the case of muons 2-jets sample.
	Figure 1 (b) png,pdf	The invariant mass of the four-body system after the physics object selection but before optimization, for the case of muons 2-jets sample.
	Figure 2(a) png,pdf	Fit-based analysis: the observed four-body mass distribution, with background contribution superimposed, after a simple kinematic selection for muon data. The dashed lines represent the expected Higgs signal peak (the SM cross-section has been multiplied by a factor 20 to make it more visible.)
	Figure 2(b) png,pdf	Fit-based analysis: the observed four-body mass distribution, with background contribution superimposed, after a simple kinematic selection for electron data. The dashed lines represent the expected Higgs signal peak (the SM cross-section has been multiplied by a factor 20 to make it more visible.)
	Figure 3(top left) png,pdf	Variable Φ used as input for the likelihood discriminant.
	Figure 3(top middle) png,pdf	Variable Φ1 used as input for the likelihood discriminant.
	Figure 3(top right) png,pdf	Variable Θ1 used as input for the likelihood discriminant.
	Figure 3(middle left) png,pdf	Variable Θ2 used as input for the likelihood discriminant.
	Figure 3(middle middle) png,pdf	Variable Θ* used as input for the likelihood discriminant.
	Figure 3(middle right) png,pdf	Variable PT(WW) used as input for the likelihood discriminant.
	Figure 3(bottom left) png,pdf	Rapidity of the WW system used as input for the likelihood discriminant.
	Figure 3(bottom middle) png,pdf	Likelihood discriminant for muon plus 2 jet channel with selection optimized for Higgs mass hypothesis 190 GeV.
	Figure 3(bottom right) png,pdf	Likelihood discriminant for muon plus 2 jet channel with selection optimized for Higgs mass hypothesis 500 GeV.
	Figure 4(a) png pdf, Figure 4(b) png pdf, Figure 4(c) png pdf	The di-jet invariant mass distribution with the fit projections, for the muon 2-jet category, after selections optimized for the Higgs mass hypotheses of 190 GeV (a), 350 GeV (b), and 500 GeV (c). The fit doesn't include data points in the test region between the vertical lines.
	Figure 5(a) png pdf, Figure 5(b) png pdf, Figure 5(c) png pdf	The distribution of the extrapolated background shape in the signal region for the Higgs mass hypothesis of 190 GeV (a), 350 GeV (b), and 500 GeV (c), for muon 2-jets category. The black markers represent the extrapolated points, while the blue curve is the smooth parametrization using an exponential function. The dashed bands show the envelope of the systematic uncertainty in the shape extrapolation.
	Figure 6(a) png pdf, Figure 6(d) png pdf	The WW invariant mass distribution with the fit projections, for the muon 2-jet category, after selection optimized for the Higgs mass hypotheses of 190 GeV. (a) shows the distribution of the four-body invariant mass distribution in the signal region 65 GeV < mjj < 95 GeV. With the kinematic selection used, we expect about 55 signal events in the distribution. (d) shows pull distribution computed as [(Data - Background)/ Background uncertainty].
	Figure 6(b) png pdf, Figure 6(e) png pdf	The WW invariant mass distribution with the fit projections, for the muon 2-jet category, after selection optimized for the Higgs mass hypotheses of 350 GeV. (b) shows the distribution of the four-body invariant mass distribution in the signal region 65 GeV < mjj < 95 GeV. With the kinematic selection used, we expect about 79 signal events in the distribution. (e) shows pull distribution computed as [(Data - Background)/ Background uncertainty].
	Figure 6(c) png pdf, Figure 6(f) png pdf	The WW invariant mass distribution with the fit projections, for the muon 2-jet category, after selection optimized for the Higgs mass hypotheses of 500 GeV. (c) shows the distribution of the four-body invariant mass distribution in the signal region 65 GeV < mjj < 95 GeV. With the kinematic selection used, we expect about 27 signal events in the distribution. (f) shows pull distribution computed as [(Data - Background)/ Background uncertainty].
	Figure 7(a) png pdf	Observed (solid) and expected (dashed) 95% CL upper limit on the ratio of the production cross section to the SM expectation for the Higgs boson obtained using the asymptotic CLS technique. The 68% and 95% ranges of expectation for the background-only model are also shown with green and yellow bands, respectively. The solid line at 1 indicates the SM expectation. The fit-based limit is shown.
	Figure 7(b) png pdf	Observed (solid) and expected (dashed) 95% CL upper limit on the ratio of the production cross section to the SM expectation for the Higgs boson obtained using the asymptotic CLS technique. The 68% and 95% ranges of expectation for the background-only model are also shown with green and yellow bands, respectively. The solid line at 1 indicates the SM expectation. The likelihood-based limit is shown.

Tables from CMS-HIG-12-003

Table 1: Determination of the m_jj shape and normalization. External constraints are assumed Gaussian.

Table 2: Sources of signal systematics considered in the analysis, with the corresponding magnitude, for the limit extraction.

Additional plots for public talks

From Analysis Note AN-2011/110

figure	label	description
	Figure 2 (left) png pdf, Figure 2 (right) png pdf	Comparison of the leading jet (left) and the second jet (right) pT distributions from data and MC for the muon+jets selection.
	Figure 3 (left) png pdf	Comparison of the leading jet η distributions from data and MC for the muon+jets selection.
	Figure 4 (left) png pdf	Comparison of the muon pT distributions from data and MC for the muon+jets selection.
	Figure 4 (right) png pdf	Comparison of the muon η distributions from data and MC for the muon+jets selection.
	Figure 5 (left) png pdf	Comparison of the distributions from data and MC of the transverse mass of the muon / MET system for the muon+jets selection.
	Figure 5 (right) png pdf	Comparison of the distributions from data and MC of the MET for the muon+jets selection.
	Figure 11 png pdf	Comparison of the dijet mass (mJJ) distributions from data and MC for the electron+jets selection.
	Figure 16 png pdf	Comparison of the charge of the muon from data and MC for the muon+jets selection.
	Figure 24 (left) png pdf	Comparison of the four-body invariant mass from data and MC for the electron+jets selection.
	Figure 25 (c) png pdf	The four-body mass distributions obtained before and after the kinematic fit are reported for the Higgs mass hypothesis of 190 GeV. The mass range is constrained to that used for subsequent template modeling and limit setting.

From Analysis Note AN-2012/029

Figure 20 (left) png pdf

Higgs boson invariant mass shape, as obtained from the simulation, with all the proper weighting factors taken into account. The spectrum is fitted with a double Crystal-Ball function (i.e. a Gaussian core with power law tails on both sides). This smooth function is used as signal input for the limit extraction. A Higgs mass of 400 GeV is assumed.

-- PietroGovoni - 30-Apr-2012