Implications of μ−τ\mu-\tau Flavored CP Symmetry of Leptons

We discuss gauge models incorporating $\mu-\tau$ flavored CP symmetry (called CP$^{\mu\tau}$ in the text) in combination with $L_\mu-L_\tau$ invariance to understand neutrino mixings and discuss their phenomenological implications. We show that viable leptogenesis in this setting requires that the lightest right-handed neutrino mass must be between $10^9-10^{12}$ GeV and for effective two hierarchical right-handed neutrinos, leptogenesis takes place only in a narrower range of $5\times 10^{10}-10^{12}$ GeV. A multi-Higgs realization of this idea implies that there must be a pseudoscalar Higgs boson with mass less than 300 GeV. Generically, the vev alignment problem can be naturally avoided in our setting.Comment: 34pp. v3: matches journal versio

New vector-scalar contributions to neutrinoless double beta decay and constraints on R-parity violation

We show that in minimal supersymmetric standard model (MSSM) with R-parity breaking as well as in the left-right symmetric model, there are new observable contributions to neutrinoless double beta decay arising from hitherto overlooked diagrams involving the exchange of one W boson and one scalar boson. In particular, in the case of MSSM, the present experimental bounds on neutrinoless double beta decay lifetime improves the limits on certain R-parity violating couplings by about two orders of magnitude. It is shown that similar diagrams also lead to enhanced rates for $\mu^-\rightarrow e^+$ conversion in nuclei, which are in the range accessible to ongoing experiments.Comment: Latex file; 9 pages; 3 figures available on reques

CHANGING WRINKLES TO SMILES WITH PALLIATIVE CARE FOR THE ELDERLY!

Over the past years, the conscious and collaborative efforts of Peoples and Planners world-wide have shown a reduction in mortality and increase in the life expectancy at birth. Thus, the world will be over loaded with aged people one century ahead; on the other hand, we in India have cheated this particular group for last 65 years by not providing any special care package for them – the Elderly: presenting them the “geriatric care”! The then Director-General of the World Health Organization, Gro Harlem Brundtland in 1999 had said “Population ageing is, rst and foremost, a success story for public health policies as well as social and economic development”. Thus, the WHO has aptly chosen the theme “Ageing and health: Good health adds life to years” for 2012. The focus is how good health throughout life can help older men and women lead full and productive lives and be a resource for their families and communities.[1] It is predicted that within the next five years, the number of adults aged 65 years and over will outnumber children under the age of 5 and by 2050, all children under the age of 14. Between 2000 and 2050, the proportion of the world’s population over 60 years will double from about 11% to 22% with the most rapid and dramatic demographic changes being seen in low and middle income countries.[2

The coupling constants for an electroweak model with a SU(4)PS⊗SU(4)EWSU(4)_{PS} \otimes SU(4)_{EW} unification symmetry

We introduce the sequence of spontaneous symmetry breaking of a coupling between Pati-Salam and electroweak symmetries $SU(4)_{PS} \otimes SU(4)_{EW}$ in order to establish a mathematically consistent relation among the coupling constants at grand unification energy scale. With the values of baryon minus lepton quantum numbers of known quarks and leptons, by including right-handed neutrinos, we can find the mixing angle relations at different energy levels up to the electromagnetic $U(1)_{EM}$ scale.Comment: 8 page

Cosmology of Brane-Bulk Models in Five Dimensions

We study the cosmology of models with four space and one time dimension where our universe is a 3-brane and report a few results which extend existing work in several directions. Assuming a stable fifth dimension, we obtain a solution for the metric, which does not depend on any arbitrary parameters. We discuss some implications of this result.Comment: Minor changes: brane energy conservation law and some typos corrected. All main results unchanged. 11 pages, no figures, LaTeX fil

Implications of the Superkamiokande result on the nature of new physics

It is remarked that the SuperKamiokande (SK) discovery of $\nu_\mu$ to $\nu_\tau$ (or $\nu_X$)-oscillation, with a $\delta m^2 \approx 10^{-2}-10^{-3} eV^2$ and $sin^2 2 \theta > 0.8$, provides a clear need for the right-handed (RH) neutrinos. This in turn reinforces the ideas of the left-right symmetric gauge structure $SU(2)_L \times SU(2)_R$ as well as SU(4)-color, for which the RH neutrinos are a compelling feature. It is noted that by assuming (a) that B-L and $I_{3R}$, contained in a string-derived $G(224) = SU(2)_L \times SU(2)_R \times SU(4)^c$ or SO(10), break near the GUT-scale, as opposed to an intermediate scale, (b) the see-saw mechanism, and (c) the SU(4)-color relation between the Dirac mass of the tau neutrino and $m_{top}$, one obtains a mass for $\nu^\tau_L$ which is just about what is observed. This is assuming that the SK group is actually seeing $\nu^\mu_L - \nu^\tau_L$ (rather than $\nu_L^\mu - \nu_X$) oscillation. Following a very recent work by Babu, Wilczek and myself, it is furthermore noted that one can quite plausibly obtain a large $\nu_L^\mu-\nu_L^\tau$ oscillation angle, as observed, in spite of highly non-degenerate masses of the light neutrinos: e.g. with $m(\nu_L^\mu)/m(\nu_L^\tau)\approx 1/10-1/20$. Such non-degeneracy is of course natural to see-saw. In this case, $\nu^e_L - \nu^\mu_L$ oscillation can be relevant to the small angle MSW explanation of the solar neutrino puzzle. Implications of the mass of $\nu^\tau_L$ suggested by the SK result, on proton decay are noted. Comments are made at the end on how the SuperKamiokande result supplements the LEP result in selecting out the route to higher unification.Comment: Based on the talk presented at the Neutrino-98 Conference, Takayama, Japan, June 4-9, 199