R-Parity Violation and the HERA Events

The excess in high-Q^2 events at HERA is introduced and possible explanations within the framework of R-parity violating supersymmetry are discussed.Comment: LaTeX, 5 pages, 2 figures. Talk presented at the International Workshop on Physics "Beyond the Standard Model: from Theory to Experiment", Valencia, Spain (October 13 - 17, 1997), to appear in the Proceeding

A New Type of Singularity Theorem

A new type of singularity theorem, based on spatial averages of physical quantities, is presented and discussed. Alternatively, the results inform us of when a spacetime can be singularity-free. This theorem provides a decisive observational difference between singular and non-singular, globally hyperbolic, open cosmological models.Comment: 6 pages, no figures. Contribution to appear in the Proceedings of the Spanish Relativity Meeting ERE-07, "Relativistic Astrophysics and Cosmology

The Unforeseen Developments Clause in Safeguards under the WTO: Confusions in Compliance

In this article the author explores in detail the “unforeseen developments†requirement in the Agreement on Safeguards under the WTO. The author seeks to answer questions such as whether the requirement (i.e., unforeseen developments must be demonstrated in order for safeguard measures to be justified) is an integral part of the Agreement on Safeguards, and how the subjectivity associated with this requirement contributes to the difficulty of constructing a reasoned and adequate account of the causal chain. The article also includes within its scope a brief analysis of larger issues such as the political and economic rationale behind safeguard measures, and how ambiguities in the Agreement on Safeguards can destabilize the discipline of safeguards and defeat one of its major purposes - to help countries nurture their infant industries. Finally, the article reflects upon how India, being one of the leading users of safeguard measures as of 2008, is likely to be affected by unclear areas in the present legislation such as the unforeseen developments clause.India, international trade, safeguards, unforeseen developments, WTO, Industrial Organization, Institutional and Behavioral Economics, International Development, International Relations/Trade, Political Economy,

Solar neutrino: Flux, cosmic rays and the 11 year solar cycle

It is shown that the results of maximum likelihood treatment of Monte Carlo simulation with constant production rate of 7.6 SNU and 1.Epsilon SNU are consistent with the constant production rate when the tests of hypotheses (e.g., t-test, sigma squared-test, Wilcoxon-Mann-Whitney test, run test, etc.) are applied to the two groups of data formed from sunspot minimum range and sunspot maximum range, whereas the real data pulsates with the solar activity cycle. It is shown that SN flux-change is in opposition phase to the solar activity cycle and lags behind the latter by about one year. A correlation between SN flux and the cosmic rays is suggested

Next to Minimal Higgs : Mass Bounds and Search Prospects

The Standard Model of electroweak interactions has one scalar doublet. The minimal extension of this sector is effected by adding a neutral, singlet scalar field. Depending on whether the singlet field has a non-zero vacuum expectation value, x, or not, the scenario has quite distinctive predictions. In particular, x unequal to 0 produces a mixing between the usual SU(2) doublet and the singlet, giving rise to two physical states and a goldstone boson with non-vanishing coupling to these. Presence of this coupling modifies the 2 jets + missing energy signal of the Bjorken process at LEP. We update the bounds on the Higgs mass using the LEP-1 data. We then explore, using parton-level Monte Carlo event generators, the production of these scalars at the LHC via gluon-gluon fusion and subsequent detection. We compare the signals with the expected backgrounds.Comment: 16 pages and 7 Postscript figures, Late

Three-Higgs-doublet model under A4 symmetry implies alignment

A model with three scalar doublets can be conveniently accommodated within an A4 symmetric framework. The A4 symmetry permits only a restricted form for the scalar potential. We show that for the global minima of this potential alignment follows as a natural consequence. We also verify that in every case positivity and unitarity constraints are satisfactorily met.Comment: 17 pages, v2: References added, some changes in text, to appear in JHE

A4-based see-saw model for realistic neutrino masses and mixing

We present an $A4$-based model where neutrino masses arise from a combination of see-saw mechanisms. The model is motivated by several small mixing and mass parameters indicated by the data. These are $\theta_{13}$, the solar mass splitting, and the small deviation of $\theta_{23}$ from maximal mixing (= $\pi/4$). We take the above as indications that at some level the small quantities are well-approximated by zero. In particular the mixing angles, to a zero order, should be either 0 or $\pi/4$. Accordingly, in this model the Type-II see-saw dominates and generates the larger atmospheric mass splitting and sets $\theta_{23} = \pi/4$. The other mixing angles are vanishing as is the solar splitting. We show how the $A4$ assignment for the lepton doublets leads to this form. We also specify the $A4$ properties of the right-handed neutrinos which result in a smaller Type-I see-saw contribution that acts as a perturbation and shifts the angles $\theta_{12}$ and $\theta_{13}$ into the correct range and the desired value of $\Delta m^2_{solar}$ is produced. The $A4$ symmetry results in relationships between these quantities as well as with a small deviation of $\theta_{23}$ from $\pi/4$. If the right-handed neutrino mass matrix, $M_R$, is chosen real then there is no leptonic CP-violation and only Normal Ordering is admissible. If $M_R$ is complex then Inverted Ordering is also allowed with the proviso that the CP-phase, $\delta$, is large, i.e., $\sim \pi/2$ or $-\pi/2$. The preliminary results from NO$\nu$A favouring Normal Ordering and $\delta$ near $-\pi/2$ imply quasi-degenerate neutrino masses in this model.Comment: v2: 23 pages, 3 figures, Appendix on scalar potential minimization added, Matches with the published versio