Radiative corrections to the decay H+→W+A0H^+ \to W^+ A^0

Full one-loop electroweak corrections to the on-shell decay $H^+ \to W^+A^0$ are computed in the framework of models with two Higgs doublets (THDM). Such a decay may be dominant for $H^{\pm}$ over a wide range of parameter space relevant at present and future colliders. We show that the corrections may approach 40% and in particular are sensitive to $\lambda_5$, which parametrizes the discrete symmetry breaking term. We suggest that a measurement of the branching ratio of $H^+ \to W^+A^0$ may offer a possibility of measuring the magnitude of $\lambda_5$.Comment: 27 pages, LaTex, 6 figures, one figure added, appendix shortened. To be published in Eur. Phys. Jour.

h \gamma \gamma Coupling in Higgs Triplet Model

We investigate Higgs boson decay into two photons in the type-II seesaw model. The rate of $h\to \gamma\gamma$ gets suppressed/enhanced in this model compared to the Standard Model (SM) due to the presence of the singly and doubly charged Higgs $H^\pm$ and $H^{\pm\pm}$.Comment: Latex, 7 pages, 2 Figures. The 2011 International Workshop on Future Linear Colliders (LCWS11), Granada, Spai

Inverse Seesaw Neutrino Mass from Lepton Triplets in the U(1)_Sigma Model

The inverse seesaw mechanism of neutrino mass, i.e. m_nu = (m_D^2/m_N^2)epsilon_L where epsilon_L is small, is discussed in the context of the U(1)_Sigma model. This is a gauge extension of the Standard Model of particle interactions with lepton triplets (Sigma^+,Sigma^),Sigma^-) as (Type III) seesaw anchors for obtaining small Majorana neutrino masses.Comment: 7 pages, no figur

Branching Ratio and CP-asymmetry for B-> 1^{1}P_{1}gamma decays

We calculate the branching ratios for B_{d}^{0}->(b_{1},h_{1})gamma at next-to-leading order (NLO) of alpha_{s} where b_{1} and h_{1} are the corresponding radially excited axial vector mesons of rho and omega respectively. Using the SU(3)symmetry for the form factor, the branching ratio for B_{d}^{0}->(b_{1},h_{1})gamma is expressed in terms of the branching ratio of the B_{d}^{0}-> K_{1}gamma and it is found to be B(B_{d}^{0}->b_{1}gamma)=0.71* 10^{-6} and B(B_{d}^{0}-> h_{1}gamma) =0.74*10^{-6}. We also calculate direct CP asymmetry for these decays and find, in confirmity with the observations made in the literature, that the hard spectator contributions significantely reduces the asymmetry arising from the vertex corrections alone. The value of CP-asymmetry is 10% and is negative like rho and omega in the Standard Model.Comment: 10 pages, 2 figure