Comment on "PT Symmetry as a Generalization of Hermiticity" [arXiv:1002.2676]

We notice that the general PT-symmetric Hamiltonian matrix(N=2) having 6-real parameters fails to reproduce one parameter PT-symmetric matrix.Comment: Title unchanged ,one ref [5] added . Abstract changed . All the previous matrices have been changed consideing the ref[5

Neutrino mass generation in the SO(4) model

Generation of neutrino mass in SO(4) model is proposed here. The algebraic structure of SO(4) is same as to that of $SU(2)_{L}\times SU(2)_{R}$. It is shown that the spontaneous symmetry breaking results three massive as well as three massless gauge bosons. The standard model theory according to which there exist three massive gauge bosons and a massless one is emerged from this model. In the framework of $SU(2)_{L}\times SU(2)_{R}$ a small Dirac neutrino mass is derived. It is also shown that such mass term may vanish with a special choice. The Majorana mass term is not considered here and thus in this model the neutrino mass does not follow seesaw structure.Comment: 7 pages, no figur

Neutrino Mass and New Physics

We review the present state of and future outlook for our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and what may have the most promise to throw light on the flavor problem of quarks and leptons. We focus on the seesaw mechanism which fits into the big picture of particle physics such as supersymmetry and grand unification providing a unified approach to flavor problem of quarks and leptons. We argue that in combination with family symmetries, this may be at the heart of a unified understanding of flavor puzzle. We also discuss other new physics ideas such as neutrinos in models with extra dimensions and possible theoretical implications of sterile neutrinos. We outline some tests for the various schemes.Comment: 90 pages and 9 figures; With permission from the Annual Review of Nuclear and Particle Science. Final version of this material is scheduled to appear in the Annual Review of Nuclear and Particle Science Vol. 56, to be published in November 2006 by Annual Reviews (http://www.annualreviews.org); some references and parts of text update

Minimal Pati-Salam Model from String Theory Unification

We provide what we believe is the minimal three family ${\cal N} = 1$ SUSY and conformal Pati-Salam Model from type IIB superstring theory. This $Z_3$ orbifolded AdS$\otimes S^5$ model has long lived protons and has potential phenomenological consequences for LHC.Comment: 8 page

On Neutrino Masses and Family Replication

The old issue of why there are more than one family of quarks and leptons is reinvestigated with an eye towards the use of anomaly as a tool for constraining the number of families. It is found that, by assuming the existence of right-handed neutrinos (which would imply that neutrinos will have a mass) and a new chiral SU(2) gauge theory, strong constraints on the number of families can be obtained. In addition, a model, based on that extra SU(2), is constructed where it is natural to have one "very heavy" fourth neutrino and three almost degenerate light neutrinos whose masses are all of the Dirac type.Comment: RevTex, 12 pages with 1 figure, minor changes to the text and added acknowledgment

THE DYNAMIC EFFECTS OF U.S. FOOD AID

Food Security and Poverty, International Development,