Charged Higgs in Models with Singlet Neutrino in Large Extra Dimensions

Models with extra dimensions postulate the existence of δ additional spatial dimensions of size R where gravity and perhaps other fields freely propagate while the SM degrees of freedom are confined to (3+1)-dimensional wall (4D) of the higher dimensional space. The true scale of gravity, or fundamental Planck scale M∗, of the (4 + δ)D space time is related to the reduced 4D Planck scale MP l, by M 2 P l = R M δ+2 ∗ , where MP l = 2.4 × 10 GeV is related to the usual Planck mass 1.2 × 10 GeV = √ 8πMP l. Since no experimental deviations from Newtonian gravity are observed at distances above 0.2 mm , the extra dimensions must be smaller or equal to the sub-millimeter scale with M∗ as low as few TeV and δ ≥ 2. The spectrum of many extensions of the SM includes a charged Higgs state. H decays to the right handed τ through the τ Yukawa coupling: H → τ R ν̄. The H decay to left handed τ is completely suppressed in the Minimal Supersymmetric Standard Model (MSSM). However, in the scenario of singlet neutrino in large extra dimensions, H can decay to both right handed and left handed τ depending on the parameters M∗, mD, δ, mH± and tan β: H → τ R ν̄ + τ L ψ, where ψ is a bulk neutrino and ν is dominantly a light neutrino with a small admixture of the Kaluza-Klein modes 2 of the order mR/|n|. The measurement of the