nan Mamta

Unparticles and Muon Decay

Abstract Recently Georgi has discussed the possible existence of ‘Unparticles’ describable by operators having non-integral scaling dimensions. With the interaction of these with the Standard Model particles being constrained only by gauge and Lorentz symmetries, it affords a new source for lepton flavour violation. Current and future muon decay experiments are shown to be very sensitive to such scenarios.

Role of polarization in probing anomalous gauge interactions of the Higgs boson

We explore the use of polarized e(+)/e(-) beams and/or the information on final state decay lepton polarizations in probing the interaction of the Higgs boson with a pair of vector bosons. A model independent analysis of the process e(+)e(-) -> f (f) over barH, where f is any light fermion, is carried out through the construction of observables having identical properties under the discrete symmetry transformations as different individual anomalous interactions. This allows us to probe an individual anomalous term independent of the others. We find that initial state beam polarization can significantly improve the sensitivity to CP-odd couplings of the Z boson with the Higgs boson (ZZH). Moreover, an ability to isolate events with a particular tau helicity, with even 40% efficiency, can improve sensitivities to certain ZZH couplings by as much as a factor of 3. In addition, the contamination from the ZZH vertex contributions present in the measurement of the trilinear Higgs-W (WWH) couplings can be reduced to a great extent by employing polarized beams. The effects of initial state radiation and beamstrahlung, which can be relevant for higher values of the beam energy are also included in the analysis.

Anomalous Higgs couplings at an eγ collider

We examine the sensitivity of e{gamma} colliders (based on e{sup +}e{sup -} linear colliders of c.m. energy 500 GeV) to the anomalous couplings of the Higgs to W-boson via the process e{sup -}{gamma}{yields}{nu}WH. This has the advantage over e{sup +}e{sup -} collider in being able to dissociate WWH vertex from ZZH. We are able to construct several dynamical variables which may be used to constrain the various couplings in the WWH vert0008.

Variational Approach to Higgs Mass Bound

We present a variational study of the Higgs sector of the standard model (with a single doublet Higgs) regarding it as an effective field theory with an ultraviolet cutoff. Our results yield a maximum value of the Higgs mass about 10.8 times the W-mass.

New Physics Contribution to Neutral Trilinear Gauge Boson Couplings

We study the one-loop new physics effects to the CP even triple neutral gauge boson vertices γ⋆γZ, γ⋆ZZ, Z⋆Zγ and Z⋆ZZ in the context of Little Higgs models. We compute the contribution of the additional fermions in Little Higgs models in the framework of direct product groups where [SU(2)×U(1)]2 gauge symmetry is embedded in SU(5) global symmetry and also in the framework of the simple group where SU(N)×U(1) gauge symmetry breaks down to SU(2)L×U(1). We calculate the contribution of the fermions to these couplings when T parity is invoked. In addition, we re-examine the MSSM contribution at the chosen point of SPS1a′ and compare with the SM and Little Higgs models.

TRIVIALITY BOUND ON LIGHTEST HIGGS MASS IN NEXT TO MINIMAL SUPERSYMMETRIC MODEL

We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that the mass of the lightest Higgs boson in NMSSM has an upper bound ∼10MW which is of the same order as that in the standard model.We study the implication of triviality on Higgs sector in next to minimal su-persymmetric model (NMSSM) using variational field theory. It is shown that mass of the lightest Higgs boson in NMSSM has an upper bound ∼ 10 M W which is of the same order as that in standard model.

QUARK MODEL ANALYSIS OF RADIATIVE PION DECAY

We present a relativistic quark model analysis of radiative pion decay using a systematic application of Low’s bremsstrahlung theorem. Our findings agree reasonably with recent definitive experimental results by the Russian group on the structure-dependent components of the πγA and πγV amplitudes, with the latter agreeing remarkably well with the CVC prediction. Finally we analyze between the quark model calculation and the current algebra prediction and establish the equivalence of the two within the limit of a local πqq interaction.

Pion electromagnetic form-factor in a BS model

The electromagnetic form factor of the pion is studied using a simple relativistic quark model based on a dynamical picture of the pion as a bound state of the constituent q system.