The 28 GeV dimuon excess in lepton specific THDM

Abstract

We explore the Higgs mass spectrum in a class of Two Higgs Doublet Models (THDMs) in which a scalar SU(2)L doublet interacts only with quarks, while the second one interacts only with leptons. The spectrum includes two CP-even Higgs bosons, either of which can account for the SM-like Higgs boson, and the spectra involving light Higgs bosons receive strong impacts from the LEP results and the current collider analyses. We find that a consistent spectrum can involve a CP-odd Higgs boson as light as about 10 GeV, while the lightest CP-even Higgs boson cannot be lighter than about 55 GeV when mA∼28 GeV. These analyses can rather bound the low tan⁡β region which can also accommodate an observed excess in dimuon events at mμμ∼28 GeV. A lepton-specific class of THDMs (LS-THDM) can predict such an excess through A→μμ decays, while the solutions can be constrained by the A→ττ mode. After constraining the solutions with the consistent ranges of σ(pp→bbA→bbττ), a largest excess at about 1.5σ at 8 TeV center of mass (COM) energy and 2σ at 13 TeV COM is observed for tan⁡β∼12 and mA∼28 GeV in the σ(pp→bbA→bbμμ) events.