Search for Doubly Charged Higgs

This is the condensed description with plots for the analysis HIG-12-005.

Abstract

A search for the doubly charged Higgs boson in pp collisions at √s = 7 TeV is presented. The data correspond to an integrated luminosity of 4.63 fb−1 collected by the CMS experiment at the LHC. The doubly charged Higgs is a member of SU(2)L scalar triplet Φ in extensions of the Standard Model which include the seesaw mechanism of type II. The search is inclusive and is performed in events with three or more isolated charged leptons of all flavors originating from the decays of pair produced triplet components Φ++Φ−− and Φ++Φ−. No signal is observed and new lower limits at the 95% confidence level are set on the Φ±± mass, under specific assumption on the Φ++ branching fraction. An upper bound of 457 GeV in the μμ channel, of 455 GeV in eμ channel, of 445 GeV in the ee channel, of 369 GeV in the μτ channel, of 352 GeV in the eτ channel, of 198 GeV in the ττ channel and between 380 GeV and 410 GeV in four chosen benchmark points is set for the type-II see-saw model.

Main results

No significant excess is observed so new world limits are set in ten model specific assumptions of branching ratios. The limits are:

Model assumption	Combined limit on all production mechanisms	Limit on pair-production only
BR(Φ++ -> e+e+) = 100%	445 GeV	387 GeV
BR(Φ++ -> e+μ+) = 100%	455 GeV	389 GeV
BR(Φ++ -> e+τ+) = 100%	352 GeV	300 GeV
BR(Φ++ -> μ+μ+) = 100%	457 GeV	391 GeV
BR(Φ++ -> μ+τ+) = 100%	369 GeV	313 GeV
BR(Φ++ -> τ+τ+) = 100%	198 GeV	165 GeV
Benchmark point 1 (Normal hierarchy)	380 GeV	326 GeV
Benchmark point 2 (Inverse hierarchy)	410 GeV	361 GeV
Benchmark point 3 (Degenerate masses)	406 GeV	350 GeV
Benchmark point 4 (Equal branching ratios)	399 GeV	353 GeV

Figures from HIG-12-005

Figure	Label	Description
	Figure 1a: pdf png	Feynman diagram of associated production.
	Figure 1b: pdf png	Feynman diagram of pair production.
	Figure 2: pdf png	Cross sections of both pair and associated production processes.
	Figure 3a: pdf png	Invariant mass distribution from three lepton final state for backgrounds and data. We also show the expected contribution of a Φ++ with a mass of 350 GeV for the benchmark point BP4. The plot is after pre-selection.
	Figure 3b: pdf png	Cut flow for three lepton final state for backgrounds and data. We also show the expected contribution of a Φ++ with a mass of 350 GeV for the benchmark point BP4.
	Figure 4a: pdf png	Invariant mass distribution from four lepton final state for backgrounds and data. We also show the expected contribution of a Φ++ with a mass of 350 GeV for the benchmark point BP4. The plot is after pre-selection.
	Figure 4b: pdf png	Cut flow for four lepton final state for backgrounds and data. We also show the expected contribution of a Φ++ with a mass of 350 GeV for the benchmark point BP4.
	Figure 5: pdf png	Summary plot of results.
	Figure 6: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to ee channel.
	Figure 7: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to eμ channel.
	Figure 8: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to eτ channel.
	Figure 9: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to μμ channel.
	Figure 10: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to μτ channel.
	Figure 11: pdf png	Observed Φ++ mass limits at 95% C.L. for 100% branching fraction to ττ channel.
	Figure 12: pdf png	Observed Φ++ mass limits at 95% C.L. for benchmark point BP1.
	Figure 13: pdf png	Observed Φ++ mass limits at 95% C.L. for benchmark point BP2.
	Figure 14: pdf png	Observed Φ++ mass limits at 95% C.L. for benchmark point BP3.
	Figure 15: pdf png	Observed Φ++ mass limits at 95% C.L. for benchmark point BP4.