Projected sensitivity for Higgs boson searches for 7 TeV and 1 fb^-1

Main Results

Projections are presented for three SM Higgs signatures, H→WW→2l2v, H→ZZ→4l, H→γγ, their combination, and the MSSM Higgs channel pp→bbΦ→bb(ττ). SM Higgs searches are expected to reach a discovery level sensitivity for m_H=160-170 GeV and an exclusion level sensitivity for m_H=145-190 GeV. Higgs boson mass m_H<400 GeV can be excluded in models with four generations of quarks, regardless of how heavy their masses might be. Fermiophobic Higgs can be excluded for m_H<110 GeV. The expected discovery/exclusion sensitivities for the neutral MSSM Higgs bosons are given as contours in the (m_A,tanβ)-plane. At low m_A~90 GeV, the discovery can be possible for tanβ>20 and the exclusion limit is expected to reach down to tanβ~15

Public Note: NOTE-2010/008 The CMS physics reach in searches at 7 TeV

How these projections were obtained

The presented projections are NOT new analyses done with 7 TeV MC samples and new detector simulation/reconstruction software. The following describes the work flow for deriving these projections.

• Start out from public results at 14 TeV (int. luminosity from 1-30 fb-1)
• Re-scale signal and bkgd event counts by the ratio of 7 and 14 TeV cross sections and project for the integrated luminosity of 1 fb-1
• No corrections for higher acceptance at smaller sqrt(s), up to ~20%
• No corrections for improvements in reconstruction (efficiencies, resolution)
• Modify systematic errors:
  • for backgrounds derived from control samples, scale as 1/sqrt(N)
  • other errors: assess whether to keep as is (e.g. theoretical errors) or inflate to correspond to a smaller data set
  • take into account error correlations
• Statistical analysis:
  • Use re-scaled event counts and re-evaluated systematic errors
  • Exclusions (95%CL): Modified Frequentist method (Bayesian limits are very similar)
  • Significance: Profile Likelihood method

Public plots recommended for conferences:

The plot on the left (eps format) shows the projected exclusion limits for a search for H→WW→2l2v. The expected exclusion mass range is 150<mH<185 GeV. Projection is derived using results published in PAS HIG-08/006 (a pair of isolated leptons, MET, jet veto in the central region; event counting above a cut on the MVA output variable).

The plot on the left (eps format) shows significance of a projected excess of events in a search for H→WW→2l2v, should the SM Higgs have a mass corresponding to the points in the plot. The discovery level sensitivity (~5σ) is expected for the mass range is 160<mH<170 GeV. Projection is derived using results published in PAS HIG-08/006 (a pair of isolated leptons, MET, jet veto in the central region; event counting above a cut on either the MVA output variable or after applying a small set of sequential cuts).

The plots on the left (eps format left and right) shows the projected exclusion limits for a search for H→ZZ→4l. The SM Higgs boson cannot be excluded anywhere in the entire mass range. However, the Higgs boson with a mass mH<400 GeV would be excluded, should a fourth generation of quarks exist (an extra doublet of quarks would make the gg→H production rate 9 times larger, regardless of how massive the the two extra quarks might be). Projection is derived using results published in PAS HIG-08/003 and NOTEs 2006/115, 2006/122, 2006/136 (four isolated leptons, no significant impact parameter for any of them; event counting in a sliding 4l-mass window).

The plot on the left (eps format) shows the projected exclusion limits for a search for H→γγ. The SM Higgs boson cannot be excluded anywhere in the entire mass range. The limit on the anomalous production is expected to be about 4 times σ(pp→HSM)xBR(HSM→γγ). Hence, a fermio-phobic Higgs boson with a mass mh<110 GeV would be excluded, since the yield σ(pp→hfph)xBR(hfph→γγ) for the fermio-phobic Higgs boson at 7 TeV is >4 for mh<110 GeV. Projection is derived using results published in NOTE-2006/122 (two isolated photons, no photon reconstruction categorization is used; event counting in a sliding γγ-mass window).

The plot on the left (eps format) shows the projected exclusion limits for a SM Higgs by combining results of the H→WW→2l2v, H→ZZ→4l, and H→γγ. The expected exclusion mass range is 145<mH<190 GeV. Projection is obtained by combing results shown above.

2xCMS : The plots on the left (eps format left and right) shows the projected exclusion limits for a SM Higgs by combining results of the H→WW→2l2v, H→ZZ→4l, and H→γγ, assuming twice amount of data. This plot is intended to indicate what ATLAS + CMS combined sensitivity might be at 1fb-1. The expected exclusion mass range for the SM Higgs is 140<mH<200 GeV. The Higgs boson with a mass mH<500 GeV would be excluded, should a fourth generation of heavy quarks exist.

The plot on the left (eps format) shows the projected discovery and exclusion contours in the MSSM (mA,tanβ)-plane for a search for a neutral MSSM Higgs bosons in the pp→bbΦ→bbττ channel. At low mA~90 GeV, the discovery can be possible for tanβ>20 and the exclusion limit is expected to reach down to tanβ~15. Projection is derived using results published in NOTEs 2006/075, 2006/101, 2006/105 (one b-tagged jet, 2 τ-candidates (τhadτμ, τhadτe, τμτe), MET, extra-jet veto; event counting in a sliding ττ-mass window).

-- AndreyKorytov - 11-Apr-2010