ash B. Pal

Dirac, Majorana, and Weyl fermions

We discuss the Dirac, Majorana, and Weyl fermion fields. The definitions and motivations for introducing each kind of field is discussed, along with the connections between them. It is pointed out that these definitions have to do with the proper Lorentz group and not with any discrete symmetry. The action of discrete symmetries, such as charge conjugation and CP on various types of fermion fields, which are particularly important for Majorana fermions, is also clarified.

The Strong CP question in SU(3)(C) x SU(3)(L) x U(1)(N) models

We analyze two recent models based on the gauge group SU(3)

Scalar sector properties of two-Higgs-doublet models with a global U(1) symmetry

_c\times

Constraints on a Muon - Neutrino Mass Around 100-kev

SU(3)

Induced charge of neutrinos in a medium

_L\times

Generalized Fierz identities

U(1)

Nothing but relativity

_N

Rephasing-invariant CP violating parameters with Majorana neutrinos

where each generation is not anomaly-free, but anomaly cancels when three generations are taken into account. We show that the most general Yukawa couplings of these models admit of a Peccei-Quinn symmetry. This symmetry can be extended to the entire Lagrangian by using extra fields in a very elegant way so that the resulting axion can be made invisible.

Modified Higgs couplings and unitarity violation

A bstractWe analyze the scalar sector properties of a general class of two-Higgs-doublet models which has a global U(1) symmetry in the quartic terms. We find constraints on the parameters of the potential from the considerations of unitarity of scattering amplitudes, the global stability of the potential and the ρ-parameter. We concentrate on the spectrum of the non-standard scalar masses in the decoupling limit which is preferred by the Higgs data at the LHC. We exhibit charged-Higgs induced contributions to the diphoton decay width of the 125 GeV Higgs boson and its correlation with the corresponding Zγ width.

Third electromagnetic constant of an isotropic medium

Abstract In the context of left-right symmetric models, we examine the possibility of a neutrino ν 2 with mass around 100 keV that is essentially the muon neutrino. To meet cosmological constraints, ν 2 must decay into three lighter neutrinos; within the SU(2) L ×SU(2) R ×U(1) model we discuss the relation of this decay to the decay μ →3e.