Fermion mass hierarchy and new physics at the TeV scale

In this talk, I present a new framework to understand the long-standing fermion mass hierarchy puzzle. We extend the Standard Model gauge symmetry by an extra local U(1)_S symmetry, broken spontaneously at the electroweak scale. All the SM particles are singlet with respect to this U(1)_S. We also introduce additional flavor symmetries, U(1)_F's, with flavon scalars F_i, as well as vectorlike quarks and leptons at the TeV scale. The flavon scalars have VEV in the TeV scale. Only the top quark has the usual dimension four Yukawa coupling. EW symmetry breaking to all other quarks and leptons are propagated through the messenger field, S through their interactions involving the heavy vector-like fermions and S, as well as through their interactions involving the vector-like fermions and F_i. In addition the explaining the hierarchy of the charged fermion masses and mixings, the model has several interesting predictions for Higgs decays, flavor changing neutral current processes in the top and the b quark decays, decays of the new singlet scalars to the new Z' boson, as well as productions of the new vectorlike quarks. These predictions can be tested at the LHC.Comment: 10 pages, 2 figures; Plenary talk presented at the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY09) at Northeastern University, Boston, MA, 5-10 June, 200

Natural fermion mass hierarchy and new signals for the Higgs boson

We suggest a novel approach towards resolving the fermion mass hierarchy problem within the framework of the Standard Model. It is shown that the observed masses and mixings can be explained with order one couplings using successive higher dimensional operators involving the SM Higgs doublet field. This scenario predicts flavor-dependent enhancement in the the Higgs boson coupling to the fermions (by a factor of 3 to the b-quark and \tau and by a factor of 5 to \mu relative to the SM). It also predicts flavor changing \bar{t}ch^0 interaction with a strength comparable to that of \bar{b}bh^0. This opens up a new discovery channel for the Higgs boson at the upgraded Tevatron and the LHC through t -> ch^0 or h^0 -> \bar{t}c + \bar{c}t. Additional tests of the framework include D^0-\bar{D^0} mixing which is predicted to be near the current experimental limit and a host of new phenomena associated with flavor physics at the TeV scale.Comment: 10 pages in RevTe

'Constraint consistency' at all orders in Cosmological perturbation theory

We study the equivalence of two - order-by-order Einstein's equation and Reduced action - approaches to cosmological perturbation theory at all orders for different models of inflation. We point out a crucial consistency check which we refer to as 'Constraint consistency' that needs to be satisfied. We propose a quick and efficient method to check the consistency for any model including modified gravity models. Our analysis points out an important feature which is crucial for inflationary model building i.e., all `constraint' inconsistent models have higher order Ostrogradsky's instabilities but the reverse is not true. In other words, one can have models with constraint lapse function and shift vector, though it may have Ostrogradsky's instabilities. We also obtain the single variable equation for non-canonical scalar field in the limit of power-law inflation for the second-order perturbed variables.Comment: 25 page

Vector Galileon and inflationary magnetogenesis

Cosmological inflation provides the initial conditions for the structure formation. However, the origin of large-scale magnetic fields cannot be addressed in this framework. The key issue for this long-standing problem is the conformal invariance of the electromagnetic (EM) field in 4-D. While many approaches have been proposed in the literature for breaking conformal invariance of the EM action, here, we provide a completely new way of looking at the modifications to the EM action and generation of primordial magnetic fields during inflation. We explicitly construct a higher derivative EM action that breaks conformal invariance by demanding three conditions - theory be described by vector potential $A_\mu$ and its derivatives, Gauge invariance be satisfied, and equations of motion be linear in second derivatives of vector potential. The unique feature of our model is that appreciable magnetic fields are generated at small wavelengths while tiny magnetic fields are generated at large wavelengths that are consistent with current observations.Comment: 20 pages, 0 figure, updated references, published in JCA