Search for Neutral MSSM Higgs Bosons in the μ+μ- final state with the CMS experiment in pp Collisions at √s = 7 TeV

This is a condensed description with plots for the analysis CMS-HIG-12-011

Abstract

This paper presents a search for production of neutral Higgs bosons predicted by Supersymmetry using the μμ decay channel. The data from proton-proton collisions at √s = 7 TeV were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 4.96 fb-1. The search is sensitive to SUSY Higgs boson production in association with a b quark pair. and via gluon-gluon fusion process. In the mh max scenario, this analysis excludes values of tan β between 16 and 26, at the 95% CL, for Higgs masses from 115 to 175 GeV/c^2. Less stringent limits in terms of tan β (between 26 and 40) are determined for higher values of the Higgs mass up to 300 GeV/c^2.

Details

A detailed description of the event selection can be found here. After a preselection of two isolated, well reconstructed and high energetic muons and low missing transverse energy the events are split into three exclusive event categories. The first category is focused on the enhanced b-associated production by looking for a tagged b-jet. The second category tries to recover events were the b-tagging fails and looks for an additional muon in the event from a b decay. This category has the lowest statistics and therefore the lowest sensitivity. The third category recovers all events not falling in the first two categories, focussing on the gluon-gluon fusion component of the MSSM. This category is sensitive due to the high statistics.

The background shape for the limit calculations is determined by a simultaneous fit of signal and background hypothesis to data. The signal shape is fitted to the simulation, using a linear combination of three Breit-Wigner peaks, representing the three Higgs bosons h0, H0 and A0, convoluted with a common detector resolution, and is fixed for each tested mass point. The background shape consists a linear combination of a Breit Wigner peak for the Z -> mu mu contributon and a term proportional to m_μμ^-2 representing the γ*, multiplied with a falling exponential distribution representing the effect of the falling parton density function. For a detailed description check chapter 6 here.

Figures from CMS-HIG-12-011

Figure	Label	Description
	Figure 5-a pdf, eps, png	The μ+μ- invariant mass distribution for category 1. The expected di-muon invariant mass distribution for the decay Φ→μ+μ-, with m_A = 150 GeV/c^2 and tanβ = 30 is superimposed.
	Figure 5-b pdf, eps, png	The μ+μ- invariant mass distribution for category 2. The expected di-muon invariant mass distribution for the decay Φ→μ+μ-, with m_A = 150 GeV/c^2 and tanβ = 30 is superimposed.
	Figure 5-c pdf, eps, png	The μ+μ- invariant mass distribution for category 3. The expected di-muon invariant mass distribution for the decay Φ→μ+μ-, with m_A = 150 GeV/c^2 and tanβ = 30 is superimposed.
	Figure 5-d pdf, eps, png	The μ+μ- invariant mass distribution for the sum of all categories. The expected di-muon invariant mass distribution for the decay Φ→μ+μ-, with m_A = 150 GeV/c^2 and tanβ = 30 is superimposed.
	Figure 8-a pdf, eps, png	The exclusion limit for the MSSM production cross-section times the B.R. at 95% CL for category 1.
	Figure 8-b pdf, eps, png	The exclusion limit projection int the (m_A, tanβ)-plane for category 1.
	Figure 9-a pdf, eps, png	The exclusion limit for the MSSM production cross-section times the B.R. at 95% CL for category 2.
	Figure 9-b pdf, eps, png	The exclusion limit projection int the (m_A, tanβ)-plane for category 2.
	Figure 10-a pdf, eps, png	The exclusion limit for the MSSM production cross-section times the B.R. at 95% CL for category 3.
	Figure 10-b pdf, eps, png	The exclusion limit projection int the (m_A, tanβ)-plane for category 3.
	Figure 11-a pdf, eps, png	The combined exclusion limit for the MSSM production cross-section times the B.R. at 95% CL.
	Figure 11-b pdf, eps, png	The combined exclusion limit projection int the (m_A, tanβ)-plane.

Additional plots for public talks

Figure	Label	Description
	Figure 1-a pdf, eps, png	The Higgs bosons masses in the MSSM mh max scenario.
	Figure 1-b pdf, eps, png	The A0 width, ΓA, as a function of mA for various tanβ values.
	Figure 2-a pdf, eps, png	The Higgs bosons production process in the MSSM: bb-associated production.
	Figure 2-b pdf, eps, png	The Higgs bosons production process in the MSSM: gluon-gluon fusion.
	Figure 3-a pdf, eps, png	The A0 production cross section times the Φ&rightarrowμ+μ- branching ratio in the (m_A,tanβ)-plane for the bbA process.
	Figure 3-b pdf, eps, png	The A0 production cross section times the Φ&rightarrowμ+μ- branching ratio in the (m_A,tanβ)-plane for the ggA process.
	Figure 4 pdf, eps, png	Distribution of the b-tag discriminator variable, d_b-tag, of the jet with highest transverse momentum in the event. Data and background simulation are superposed. The expected d_b-tag distribution for the signal process is also shown.
	Figure 6-a pdf, eps, png	The overall selection efficiency for simulated signal events bbA, A→μ+μ- in the (tanβ,m_A)-plane for category 1.
	Figure 6-b pdf, eps, png	The overall selection efficiency for simulated signal events bbA, A→μ+μ- in the (tanβ,m_A)-plane for category 2.
	Figure 6-c pdf, eps, png	The overall selection efficiency for simulated signal events bbA, A→μ+μ- in the (tanβ,m_A)-plane for category 3.
	Figure 7-a pdf, eps, png	Fit of the invariant mass distribution of the expected signal for mA = 140 GeV/c^2 and tanβ = 50.
	Figure 7-b pdf, eps, png	Fit of the di-muon invariant mass around the Z peak to determine the mass and width of the BW function, for events of category 1.
	Figure 7-c pdf, eps, png	Fit of the di-muon spectrum of data from category 1.
	Figure 7-d pdf, eps, png	A test of the fit procedure where the expected Monte Carlo signal is artificially added to the data. The term f_Signalêxpected is an estimation of the expected signal calculated as the ratio between the number of selected MC signal events and the number of events in data with 100 < M_μμ < 300 GeV/c^2. For all distributions the difference between the fit results and data is shown in the ΔN distribution.