Search for a Higgs boson produced in association with b quarks and decaying into a b-quark pair

Abstract

This paper presents a search for a neutral Higgs boson decaying to a pair of b quarks and produced in association with at least one additional b quark. We study multijet final states with three b-tagged jets, one of which may include a non-isolated muon. The data used correspond to 2.7- 4.8 $ fb^{-1}$ collected by the CMS experiment in proton-proton collisions at the LHC at a centre of mass energy of 7 TeV. This search is particularly sensitive to Higgs bosons in MSSM scenarios with large values of tan b. No signal is observed. Stringent upper limits on the $ pp \rightarrow bH + X, H \rightarrow b\bar{b} $ cross section are derived, and interpreted as bounds in the MSSM $tan\beta$ and $M_A$ parameters space, with observed upper limits ranging as low as $tan\beta\approx18$ for $M_A\approx100 GeV/c^{2}$ in the $m^{max}_h$ scenario.

Documentation

CADI HIG-12-033 (restricted)

Main Results

Measurements of this search are the 95% CL limits on the MSSM $\sigma(pp\rightarrow b\Phi + X)*BR(\Phi\rightarrow b\bar{b})$ and $tan\beta$.

Cross section limit table: $\sigma(pp\rightarrow b\Phi+X)*BR(\Phi\rightarrow b\bar{b})$

Mass [GeV] Observed limit [pb] Expected limit [pb]
90 312 .4 486.3
100 163.2 365.1
120 115.2 172.1
130 104.5 128.1
140 67.8 92.0
160 38.3 52.7
180 45.5 34.4
200 19.8 21.1
250 16.5 13.5
300 10.9 8.4
350 3.9 5.8

MSSM Higgs boson limit table: $tan \beta$ ($m_h^{max}$ scenario at $\mu=+200GeV$ )

Mass [GeV] Observed limit Expected limit
90 21.8 28.2
100 17.7 28.2
120 20.5 25.7
130 21.9 24.8
140 21.2 25.1
160 19.5 23.2
180 27.8 23.5
200 21.6 22.2
250 32.6 29.1
300 42.2 35.7
350 35.5 44.0

MSSM Higgs boson limit table: $tan \beta$ ($m_h^{max}$ scenario at $\mu=-200GeV$ )

Mass [GeV] Observed limit Expected limit
90 18.7 23.4
100 15.7 23.5
120 18.1 22.0
130 19.1 21.2
140 18.4 21.3
160 17.0 19.8
180 23.0 19.9
200 18.5 19.0
250 26.1 23.7
300 31.8 27.9
350 28.0 33.0

Plots/Tables from CMS Paper HIG-12-033 (click on plot to get .pdf)

Figure Abbreviated Caption
https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/templates_m12_projection_csvt.png https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/templates_evtbtag_projection_csvt.pdf Figure 1: The $M_{12}$ (top) and EventBTag (bottom) projections of five templates, $(Bb)b$, $(Cb)b$, $(Qb)b$, $bbB$ and $bbX$ for the low-mass scenario.
Minv01_Le200.png Minv01_Gt200.png Figure2: Invariant mass of the two leading jets, for Data in the control regions, for low (top) and medium (bottom) mass regions . Prediction with B-tag Matrix (blue histogram), with Hyperball method (green histogram), data (red dots) are overlaid. The predictions are normalized to data.
https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/BkgdOnlyFit_M12_CSVT_Low.png (a) https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/BkgdOnlyFit_EvtBtag_CSVT_Low.png (b) https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/BkgdOnlyFit_M12_CSVT_Medium.png (c) https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/mH_0200_templateFitStacked_CSVT_X.png (d) Figure3: All-hadronic results. Plots (a), (b) are results of the background-only fit in the triple b-tag samples.The plot (a) shows the distribution of the di-jet mass, the plot (b) the distribution of the EventBTag in the low-mass scenario. The cyan-shaded area corresponds to the template uncertainties. Plots (c), (d) correspond to medium mass scenario. Di-jet mass distribution in the medium-mass scenario, (c) with only background templates, and (d) including a signal template for a Higgs boson with a mass of $200 GeV/c^{2}$
Minv01_SignalRegion_Le200.png (a) Minv01_SignalRegion_Gt200.png (b) Figure 4: Semi-leptonic results. Data (red) and predicted background (blue) in the signal region, for (a) low mass range (used for $M_A \leq 180 GeV/c^{2}$) and medium mass range (used for $M_A > 180 GeV/c^2$; the expected signal for different $M_A$ and for $\tan\beta=30$ is also plotted. The difference between data and predicted background is also shown.
xsec_mA_comb.png (a) xsec_mA_log_comb.png (b) Figure 5: Observed and expected upper limits for the cross section times branching ratio at 95% confidence level, with linear and logarithmic scales, including statistical and systematic uncertainties for the combined all-hadronic and semi-leptonic results.
tanb_mA_bands_mu_plus_200_comb_individual.png (a) tanb_mA_bands_mu-200_comb_individual.png (b) Figure 6: Observed upper limits at 95% CL on $tan\beta$ as a function of $M_A$ , including the statistical and systematic uncertainties, in the $m^{max}_h$ benchmark scenario, both for $\mu=+200 GeV/c^2$ (top) and $\mu=-200GeV/c^2$ (bottom), for the combined all-hadronic and semileptonic results. One- and two-standard deviation ranges for the expected upper limit are represented by the color bands. The expected upper limits for each of the two signatures are also shown (dashed and dotted lines).
ExclusionMinus200.png Figure 7: Observed upper limits at 95% confidence level on $tan\beta$ as a function of $M_A$, including the statistical and systematic uncertainties, in the $m_h^{max}$ benchmark scenario with $\mu=-200GeV/c^2$ for the combined all-hadronic and semileptonic results. One- and two-standard deviation ranges for the expected upper limit are represented by the gray bands. Previous exclusion regions from LEP and Tevatron in the multi-b jet channel are overlaid.

Systematics.PNG
Table 1: Systematic uncertainties on the signal yield from various sources are listed in the first column. The following two columns list the resulting uncertainties in the all-hadronic and semi-leptonic analysis. The first group is for signal, the second for the model-dependent limits. A range indicates the variation across the probed Higgs mass values. The source with + affects also the background, while those with * affect only the model-dependent results in the space of the MSSM parameters $M_A$ and $tan\beta$

Additional Plots/Tables for public presentation

Figure Abbreviated Caption
finalCLs_Xsec_Logy_FULL_newBM_HB_bjj_bjb.png Observed and expected upper limits for the cross section times branching ratio at 95% confidence level, with linear and logarithmic scales, including statistical and systematic uncertainties for the semi-leptonic results.

finalCLs_Xsec_Logy_FULL_newBM_HB_bjj_bjb.png:
finalCLs_Xsec_Logy_FULL_newBM_HB_bjj_bjb.pdf:
CLs_SignalStrengh_FULL_newBM_HB_bjj_bjb.png The best fit signal strength, in terms of the MSSM Higgs boson cross section with $tan\beta=30$ as a function of $M_A$ for the semi-leptonic analisys. The band corresponds to 1σ uncertainties on the μ̂ value

CLs_SignalStrengh_FULL_newBM_HB_bjj_bjb.png
CLs_SignalStrengh_FULL_newBM_HB_bjj_bjb.pdf
finalCLs_Tanb_FULL_newBM_HB_bjj_bjb.png Observed and expected upper limits at 95\% confidence level in the MSSM plane $(tan\beta,M_A)$, including the statistical and systematic uncertainties, in the $m_h^{max}$ benchmark scenario, $\mu = +200GeV$ for the semi-leptonic results.

finalCLs_Tanb_FULL_newBM_HB_bjj_bjb.png
finalCLs_Tanb_FULL_newBM_HB_bjj_bjb.pdf
finalCLs_Tanb_FULL_newBM_HB_bjj_bjb_mu-200.png Observed and expected upper limits at 95\% confidence level in the MSSM plane $(tan\beta,M_A)$, including the statistical and systematic uncertainties, in the $m_h^{max}$ benchmark scenario, for $\mu = -200GeV$ for the semi-leptonic results.

finalCLs_Tanb_FULL_newBM_HB_bjj_bjb_mu-200.png
finalCLs_Tanb_FULL_newBM_HB_bjj_bjb_mu-200.pdf
https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/SignalTemplates_mjjEvBTagTW_CSVT.png https://twiki.cern.ch/twiki/pub/CMSPublic/Hig12033TWiki/SignalTemplates_mjjEvBTagTW_CSVT_EvBTag.png Figure: The $M_{12}$ (top) and EventBTag (bottom) projections of signal templates for three different masses of the Higgs boson, $M_A = 120 GeV, M_A = 180 GeV, M_A = 250 GeV$ with the low-mass selection in the all-hadronic analysis.
tanb_mA_bands.mu200_had.png (a) tanb_mA_bands.mu-200_had.png (b) Figure: Observed and expected upper limits at 95% confidence level in the MSSM plane $(tan\beta,M_A),$ including the statistical and systematic uncertainties, in the $m_h^{max}$ benchmark scenario,both for $\mu=+200GeV$ (a) and $\mu=-200GeV$ (b) for the all-hadronic results.
Topic attachments
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PDFpdf BkgdOnlyFit_EvtBtag_CSVT_Low.pdf r2 r1 manage 154.7 K 2013-04-15 - 15:49 IgorMarfin Mass and evbtag spectra from all-had analysis
PNGpng BkgdOnlyFit_EvtBtag_CSVT_Low.png r2 r1 manage 29.9 K 2013-04-15 - 15:49 IgorMarfin Mass and evbtag spectra from all-had analysis
PDFpdf BkgdOnlyFit_M12_CSVT_Low.pdf r2 r1 manage 172.0 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PNGpng BkgdOnlyFit_M12_CSVT_Low.png r2 r1 manage 36.4 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PDFpdf BkgdOnlyFit_M12_CSVT_Medium.pdf r2 r1 manage 250.4 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PNGpng BkgdOnlyFit_M12_CSVT_Medium.png r2 r1 manage 35.6 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PDFpdf CLs_SignalStrengh_FULL_newBM_HB_bjj_bjb.pdf r1 manage 14.2 K 2012-11-08 - 15:48 StefanoLacaprara  
PNGpng CLs_SignalStrengh_FULL_newBM_HB_bjj_bjb.png r1 manage 29.7 K 2012-11-08 - 15:48 StefanoLacaprara  
PDFpdf ExclusionMinus200.pdf r1 manage 16.2 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PNGpng ExclusionMinus200.png r1 manage 63.8 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PDFpdf Minv01_Gt200.pdf r2 r1 manage 18.8 K 2013-04-15 - 15:34 IgorMarfin  
PNGpng Minv01_Gt200.png r2 r1 manage 39.6 K 2013-04-15 - 15:35 IgorMarfin  
PDFpdf Minv01_Le200.pdf r2 r1 manage 19.3 K 2013-04-15 - 15:36 IgorMarfin  
PNGpng Minv01_Le200.png r2 r1 manage 39.3 K 2013-04-15 - 15:36 IgorMarfin  
PDFpdf Minv01_SignalRegion_Gt200.pdf r2 r1 manage 25.7 K 2013-04-15 - 15:46 IgorMarfin  
PNGpng Minv01_SignalRegion_Gt200.png r2 r1 manage 46.1 K 2013-04-15 - 15:47 IgorMarfin  
PDFpdf Minv01_SignalRegion_Le200.pdf r2 r1 manage 25.7 K 2013-04-15 - 15:48 IgorMarfin  
PNGpng Minv01_SignalRegion_Le200.png r2 r1 manage 47.9 K 2013-04-15 - 15:48 IgorMarfin  
PDFpdf SignalTemplates_mjjEvBTagTW_CSVT.pdf r1 manage 14.4 K 2012-11-08 - 13:44 IgorMarfin  
PNGpng SignalTemplates_mjjEvBTagTW_CSVT.png r1 manage 15.6 K 2012-11-08 - 13:44 IgorMarfin  
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PNGpng SignalTemplates_mjjEvBTagTW_CSVT_EvBTag.png r1 manage 13.4 K 2012-11-08 - 13:44 IgorMarfin  
PNGpng Systematics.PNG r1 manage 68.4 K 2012-11-09 - 19:52 IgorMarfin  
PDFpdf finalCLs_Tanb_FULL_newBM_HB_bjj_bjb.pdf r1 manage 14.9 K 2012-11-08 - 15:48 StefanoLacaprara  
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PDFpdf finalCLs_Tanb_FULL_newBM_HB_bjj_bjb_mu-200.pdf r1 manage 14.9 K 2012-11-08 - 15:48 StefanoLacaprara  
PNGpng finalCLs_Tanb_FULL_newBM_HB_bjj_bjb_mu-200.png r1 manage 34.0 K 2012-11-08 - 15:48 StefanoLacaprara  
PDFpdf finalCLs_Xsec_Logy_FULL_newBM_HB_bjj_bjb.pdf r1 manage 15.0 K 2012-11-08 - 15:48 StefanoLacaprara  
PNGpng finalCLs_Xsec_Logy_FULL_newBM_HB_bjj_bjb.png r1 manage 35.2 K 2012-11-08 - 15:48 StefanoLacaprara  
PDFpdf mH_0200_templateFitStacked_CSVT_X.pdf r2 r1 manage 177.1 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PNGpng mH_0200_templateFitStacked_CSVT_X.png r2 r1 manage 37.5 K 2013-04-15 - 15:51 IgorMarfin Mass and evbtag spectra from all-had analysis
PNGpng tanb_mA_bands.mu-200_had.png r1 manage 20.8 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PNGpng tanb_mA_bands.mu200_had.png r1 manage 22.4 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PDFpdf tanb_mA_bands_mu-200_comb_individual.pdf r1 manage 14.9 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PNGpng tanb_mA_bands_mu-200_comb_individual.png r1 manage 49.2 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PDFpdf tanb_mA_bands_mu-200_had.pdf r1 manage 14.5 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PDFpdf tanb_mA_bands_mu200_had.pdf r1 manage 14.5 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PDFpdf tanb_mA_bands_mu_plus_200_comb_individual.pdf r1 manage 14.9 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PNGpng tanb_mA_bands_mu_plus_200_comb_individual.png r1 manage 52.1 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PDFpdf templates_evtbtag_projection_csvt.pdf r2 r1 manage 14.2 K 2013-04-15 - 15:05 IgorMarfin Templates for all-had analysis
PNGpng templates_evtbtag_projection_csvt.png r2 r1 manage 40.1 K 2013-04-15 - 15:32 IgorMarfin Templates for all-had analysis
PDFpdf templates_m12_projection_csvt.pdf r2 r1 manage 15.1 K 2013-04-15 - 15:33 IgorMarfin Templates for all-had analysis
PNGpng templates_m12_projection_csvt.png r2 r1 manage 46.9 K 2013-04-15 - 15:34 IgorMarfin Templates for all-had analysis
PDFpdf xsec_mA_comb.pdf r2 r1 manage 14.7 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PNGpng xsec_mA_comb.png r2 r1 manage 45.9 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PDFpdf xsec_mA_had.pdf r1 manage 14.8 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PNGpng xsec_mA_had.png r1 manage 23.8 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
PDFpdf xsec_mA_log_comb.pdf r2 r1 manage 14.6 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PNGpng xsec_mA_log_comb.png r2 r1 manage 44.1 K 2013-04-15 - 15:58 IgorMarfin XSec and tanBeta Upper Limits (combination)
PDFpdf xsec_mA_log_had.pdf r1 manage 14.6 K 2012-11-09 - 17:30 RainerMankel XSec and tanBeta Upper Limits (all-had)
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