Related papers: Constraints on Trilinear Coupling Constant A_0 in …
Bounds of the neutral current sector parameters of the left-right symmetric model are investigated taking into account the low-energy data, LEP-data and CDF-result for the top mass $m_t=174\pm 10^{+13}_{-12}$. It is found that in the case…
The triviality and vacuum stability bounds on the Higgs-boson mass ($\mh$) were revisited in presence of weakly-coupled new interactions parameterized in a model-independent way by effective operators of dimension 6. The constraints from…
Some new physics beyond the Standard Model of particle physics, like Supersymmetry, Extra-dimensions etc., and their effect on the nature of different standard model phenomena are explored in this thesis. We discuss the power law scaling of…
The amplitudes for $2\rightarrow 2$ scattering processes involving longitudinally polarized gauge bosons $( W_L^\pm, Z_L )$ and the Higgs boson are analyzed up to two loops. Assuming $M_H >> M_W$, the trilinear Higgs coupling, $\lambda v$,…
We study bounds on Higgs boson masses from perturbative unitarity in the Georgi-Machacek model, whose Higgs sector is composed of a scalar isospin doublet, a real and a complex isospin triplet fields. This model can be compatible with the…
We consider the Kaluza-Klein scenario in which gravity propagates in the $4+n$ dimensional bulk of spacetime and the Standard Model particles are confined to a 3-brane. We calculate the gauge boson self-energy corrections arising from the…
An elementary Higgs boson, which is the remnant of the spontaneous symmetry breaking mechanism in the Standard Model, remains one of the most elusive particles. If a Higgs boson candidate is found at future accelerators, it becomes…
On the evaluation of $\tan{\beta}$ is revisited by the method of the renormalization group with the criteria of the bottom-tau unification in the SUSY SU(5) GUT model. Among the conventional supersymmetric theories, an energy-scale constant…
We analize the structure of models with unbroken and spontaneously broken U(1)_a x U(1)_b gauge symmetry. We show that the quantum corrections to the 2N gauge charges, with N = #fermions + #scalars, can be absorbed in the redefinition of…
We review the constraints on Higgs boson properties from effective potential methods. In the Standard Model, the requirement of stability (or metastability) of the standard electroweak minimum puts an upper bound on the scale of new physics…
The minimal supersymmetric extension of the Standard Model (SM) is a well motivated scenario for physics beyond the SM, which allows a perturbative description of the theory up to scales of the order of the Grand Unification scale, where…
We calculate a full set of one-loop corrections to the Higgs boson coupling constants as well as the electroweak parameters. We compute the decay rate of the standard model (SM)-like Higgs boson ($h$) into diphoton. Renormalized Higgs…
In a generic Grand Unified Theory with a relatively small dispersion of the spectrum around the $Z$-boson and the unification masses, a connection is established, exact at one loop level, between $M_Z$, $G_{\rm F}$, $\alpha(M_Z)$ and the…
Renormalization group analyses show that the three running gauge coupling constants of the Standard Model do not become equal at any energy scale. These analyses have not included any effects of the Higgs boson's self-interaction. In this…
We investigate the effect of supersymmetric CP violating phases on the $B\to X_s \gamma$ and $B\to X_s l^+l^-$ decays in the minimal supergravity model. We show that the phase of the trilinear scalar coupling constant for top squarks is…
The status of coupling constant unification in the standard model and its supersymmetric extension are discussed. Uncertainties associated with the input coupling constants, $m_{t}$, threshold corrections at the low and high scales, and…
We reanalyze precision LEP data and coupling constant unification in the minimal supersymmetric $SU(5)$ model including the evolution of the gaugino masses. We derive general bounds on the primordial gaugino supersymmetry-breaking…
Spectra, triple and quartic gauge couplings of the Higgsless model with gauge group $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ defined in warped space are explored with numerical method. We extend the equation of motions, boundary conditions…
The maximal SO(5) gauged D=7 supergravity is dimensionally reduced to six dimensions yielding a new SO(5) gauged D=6 model. It is shown that, unlike in D=7, the SO(5) gauge coupling constant can be taken to zero to yield the maximally…
It was shown recently that, in two Higgs doublet models without $Z_2$ symmetry, extra Yukawa couplings such as $\rho_{tc}$, $\rho_{tt}$ can fuel enough $CP$ violation for electroweak baryogenesis (EWBG). We revisit an old proposal where a…