Ashok Goyal

Lepton flavor violation in the little Higgs model with T parity

Little Higgs models with T-parity may provide us with a new source of lepton flavor violation, as such, in this paper we consider the anomalous magnetic moment of the muon (g-2){sub {mu}} and the lepton flavor violating decays {mu}{yields}e{gamma} and {tau}{yields}{mu}{gamma} in the little Higgs model with T-parity [A. Goyal, hep-ph/0609095.]. Our results show that the present experimental constraints of {mu}{yields}e{gamma} are a much more useful tool for constraining the new sources of flavor violation, than from the other processes considered here, which are present in T-parity models.

Bd–B¯d mass difference in little Higgs model

Abstract An alternate solution of hierarchy problem in the Standard Model namely, the little Higgs model, has been proposed lately. In this work B d 0 – B ¯ d 0 mass difference in the framework of the little Higgs model is evaluated. The experimental limits on the mass difference is shown to provide meaningful constraints on the parameter space of the model.

Burning of Two-Flavor Quark Matter into Strange Matter in Neutron Stars and in Supernova Cores

Assuming a first-order phase transition from nuclear to quark matter in neutron stars and in supernova cores, we have studied the phase transition from two-flavor quark matter to strange matter. This transition has bearing on the cooling of neutron stars and may lead to observable signals in the form of a second neutrino burst. In the case of transition occurring in a supernova core, it has the effect of raising the core temperature and the energy of the shock wave and thus affecting the evolution of the core. In this study we have systematically taken into account the effect of strong interactions perturbatively to order ?c and the effect of finite temperature and strange quark mass.

Lepton number violation in a little Higgs model

The Standard Model (SM) has been remarkably successful in explaining experimental data upto the highest energies available at present. The precision electroweak data suggests that the Higgs boson remains light [1], mH < 219 GeV at 95% CL, upto the Planck’s scale. In SM, the Higgs boson however, gets quadratically divergent contribution to its mass and requires fine tuning of parameters which are sensitive to new physics that may be present at scales much higher than electroweak scale. Fine tuning and naturalness requires this new physics to be at the TeV scale. Supersymmetry (SUSY) provides a particularly elegant solution to the Hierarchy problem where quadratic divergences in Higgs mass are canceled between contributions of SM particles and their superpartners. This has the desired effect of stabilizing the electro-weak scale. In Technicolor theories, the hierarchy problem is deferred by introducing new dynamics at a scale not too much above electroweak scale. Theories of large extra dimensions resolve the hierarchy problem by lowering the Planck’s scale and modifying quantum gravity at the TeV scale. Phenomenological consequences of these theories have been studied in the literature and constraints obtained [2]. Recently there has been a proposal to consider Higgs fields as pseudo-Nambu-Goldstone boson of a Global symmetry which is spontaneously broken at some high scale [3]. The Higgs fields acquire mass through electroweak symmetry breaking triggered by radiative corrections leading to Coleman-Weinberg type of potential. Since the Higgs is protected by approximate global symmetry, it remains light and the quadratic divergent contributions to its mass are canceled by the contributions of heavy gauge bosons and a heavy Fermionic state that are introduced in the model. The Littlest Higgs (LH) [3, 4, 5] model is a minimal model of this class which accomplishes this task to one loop order within a minimal matter content. The LH model consists of an SU(5) non-linear sigma model which is spontaneously broken to its subgroup SO(5) by vacuum expectation value (VEV) of order f. The gauged group [SU(2) � U(1)] 2 is broken at the same time to its diagonal electroweak SM sub

Neutrinos as the source of ultrahigh energy cosmic rays in extra dimensions

If the neutrinos are to be identified with the primary source of ultra-high energy cosmic rays(UHECR), their interaction on relic neutrinos is of great importance in understanding their long intergalactic journey. In theories with large compact dimensions, the exchange of a tower of massive spin-2 gravitons (Kaluza-Klein excitations) gives extra contribution to

Dynamical evolution of the Universe in the quark-hadron phase transition and nugget formation

\nu\bar{\nu} \longrightarrow f\bar{f}

Bounds on the neutrino magnetic moment from SN 1987 A

and

ELECTRICAL CONDUCTIVITY AT THE CORE OF A MAGNETAR

\gamma\gamma

Eigenfrequencies of radial pulsations of strange quark stars

processes along with the opening of a new channel for the neutrinos to annihilate with the relic cosmic neutrino background

Effect of a magnetic field on the electron neutrino sphere in pulsars

\nu\bar{\nu} \longrightarrow G_{kk}