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Search for the neutral MSSM Higgs bosons in the decay channel A/H/h -> μ+μ-

This page contains approved plots and results in the order as they appear in the CSC note. Only the CSC note contains all the relevant information and should thus be consulted if one of the plots is used.

Figure 1: Tree-level Feynman diagrams of the dominant background processes with two isolated muons in the final state: a) Drell-Yan Z boson production, b) Z boson production in association with jets, c) tt production and d) ZZ and WW production. q is a general symbol for u and d quarks, while Q stands for the b and c quarks.

Figure 2: Dimuon mass distribution for the bbA and gg -> A signal samples with an A boson mass of 200 GeV and tanβ=30. The distributions are fitted by the Gauss function.

fig03-a. fig03-b.
Figure 3: a) Transverse momentum pT of the b-jets in the bbA signal and the dominant background processes and b) the number of reconstructed b-jets per event. The selection criteria for the b-jets are described in the text.

Figure 4: Distribution of the b-tagging weight for the b-jets and the light jets in the bbA signal and t t background sample, obtained by the IP3DSV1 b-tagging algorithm. The arrow indicates the optimum cut value of 4, which is used for the selection of the b-jets in the analyses.

Figure 5: B-tagging efficiency in dependence of b-jet transverse energy ET (a) and pseudorapidity η (b), evaluated for the bbA signal sample at mA=200 GeV and tanβ=30. IP3DSV1 b-tagging weight cut of >4 has been applied.

Figure 6: Efficiency and the fake rate (left) and resolution (middle) of the muon reconstruction as a function of the |η| (for pT >20 GeV), with and without the pile-up contribution in the bbA signal sample with mA=200GeV. The right plot shows the corresponding dimuon mass distribution.

Figure 7: Missing transverse energy distribution for the bbA signal at 200 GeV (left) and the tt background (right), with and without pile-up.

Figure 8: Total number of jets per event (left) and the number of b-jets (right) in the Zbb background sample, with and without the pile-up contribution.

Figure 9: Distribution of the muon transverse momentum pT for the muons in the signal and background events.

fig10-a. fig10-b.
Figure 10: (left) Muon isolation variable ETcone0.4 /pT (μ), shown for different signal and background processes. Here, the ETcone0.4 is the energy measured in the calorimeters in cone ΔR = 0.4 around a given muon. (right) Rejection of the non-isolated muons originating from the b-quarks in tt events as a function of the selection efficiency for isolated muons, shown for the two isolation variables described in the text. The filled circle indicates the working point with the isolation cut at ETcone0.4 /pT(μ)<0.2 .

fig11-a. fig11-b. fig11-c.
Figure 11: (Left) Missing transverse energy, (middle) distribution of the b-tagging IP3DSV1 weight after requiring pT >20 GeV and |η| <2.5 and (right) the multiplicity of reconstructed b-jets per event, after applying the pT - and η-cuts and requiring the b-tagging IP3DSV1 weight greater than 4. Distributions for the bbA signal (mA =200 GeV) and for the major background processes are shown. Arrows indicate the cuts applied in the analysis.

fig12-a. fig12-b. fig12-c.
Figure 12: Discriminating variables against the tt background: a) | sinΔφ| shown for the bbA signal (mA =200 GeV) and for the major background processes, b) the maximum pT of the b-jet, and c) Sum pTjets -distribution for the signal and background processes. Arrows indicate the cuts applied in the analysis.

Figure 13: Invariant dimuon mass distributions of the main backgrounds and the A boson signal at masses mA =150, 200 and 300 GeV and tanβ=30, obtained for the integrated luminosity of 30 fb-1 . B-tagging has been applied for the event selection. The production rates of H and A bosons have been added together. a) for the 0 b-jet final state and b) for the final state with at least 1 b-jet.

Figure 14: Trigger selection efficiency of the bbA signal events (mA =200 GeV) in dependence on the offline analysis selection. Different curves show the results obtained for different trigger thresholds.

Figure 15: Fraction of events σ1b with exactly one b-quark with pT >15 GeV and |η| <2.5, relative to the total inclusive cross-section σtotal, shown in dependence on the Higgs boson mass MH. The lines show the theory prediction as the ratio between the MCFM bg->Hb and bb->H cross-sections. Solid line: MRST2004 pdf set, dashed line: MRST2002 pdf set. Circles: result from SHERPA 1.0.9. Triangles: PYTHIA 6.4 gg->bbH process

Figure 16: Differential pT and η distribution of the leading b-quark, obtained by SHERPA (gray histogram) and by the PYTHIA gg->bbH calculation (solid line). All histograms have been normalized to unity.

Figure 17: The μ+μ- invariant mass distribution (stars) of the tt background, and its estimates obtained from the e+ e- (triangles) and μ+/- e-/+ (full circles) final states. (b) Corresponding ratios of estimated and actual μ+μ- invariant mass distributions.

Figure 18: Invariant dimuon mass as in Figure 13(b), after the subtraction of the tt background estimated in the μ+/- e-/+ final state. The distributions correspond to an integrated luminosity of L =30 fb-1 .

Figure 19: (a) tt control sample (stacked histogram) obtained as described in text. Full circles indicate the actually measured μ+ μ- invariant mass distribution for the tt background, after applying the standard analysis selection cuts. (b) The measured (full circles) and the control tt distributions (open squares), normalized to the same number of events. (c) The ratio of normalized distributions from (b).

Figure 20: Fit (full line) of the background function fbkg (see Eq. 1) on the background distribution (full circles) resulting from the analysis with at least one b-jet in the final state. The dashed lines represent the shape variations given by the errors on the a2 and a3 parameters, from the fit on the e+ e- data.

fig21-a. fig21-b.
Figure 21: Normalized difference of the expected number of background events (BKG expected ) in the mass window from 188-212 GeV, and the number (BKG fitted ) obtained from the fit method described in the text (left) for an integrated luminosity of 15 fb-1 and (b) 3 fb-1.

fig22-a. fig22-b.
Figure 22: (left) Signal significance obtained in the fixed-mass approach for the signal at mA =200 GeV and tanβ=30, as a function of integrated luminosity. The full line corresponds to the results obtained by the profile likelihood method using the average number of expected signal and background events, while the dots show the results obtained from the Type-II error probability from a large amount of pseudoexperiments. Both estimations include the background uncertainty from the fSB-fit. (right) Ratio of signal significances obtained with the floating- and the fixed-mass approach, as a function of the integrated luminosity.

fig23-a. fig23-b.
Figure 23: Signal significance as a function of tanβ for the integrated luminosity of 10 fb-1 and mA=150 GeV (left) and mA=300 GeV (right). The dotted curves are obtained assuming a negligible error of the background determination. The dashed curves show the result once the background uncertainty is taken into account, as obtained from the fit to the data. The solid curves additionally include the systematic uncertainties. The width of the solid curves indicates the errors in the background shape parametrization.

fig24-a. fig24-b.
Figure 24: tanβ values needed for the 5σ-discovery (left) and for the 95% CL exclusion of the signal hypothesis (right), shown in dependence on the A boson mass.

fig25-a. fig25-b.
Figure 25: Combined analyses results: (left) tanβ values needed for the 5σ-discovery at L=10 fb-1 and L =30 fb-1, shown in dependence on the A boson mass and (right) combined 95% CL exlucion limits.

Major updates:
-- WolfgangMader - 27 Jan 2009

Responsible: CalebLampen
Last reviewed by: Never reviewed

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Topic revision: r14 - 2010-12-20 - PeterJones
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