Discrete symmetries for electroweak natural type-I seesaw mechanism

The naturalness of electroweak scale in the models of type-I seesaw mechanism with ${\cal O}(1)$ Yukawa couplings requires TeV scale masses for the fermion singlets. In this case, the tiny neutrino masses have to arise from the cancellations within the seesaw formula which are arranged by fine-tuned correlations between the Yukawa couplings and the masses of fermion singlets. We motivate such correlations through the framework of discrete symmetries. In the case of three Majorana fermion singlets, it is shown that the exact cancellation arranged by the discrete symmetries in seesaw formula necessarily leads to two mass degenerate fermion singlets. The remaining fermion singlet decouples completely from the standard model. We provide two candidate models based on the groups $A_4$ and $\Sigma(81)$ and discuss the generic perturbations to this approach which can lead to the viable neutrino masses.Comment: 26 pages, 4 figures; references added, matches published versio

REGULATION AND ENFORCEMENT OF INTELLECTUAL PROPERTY RIGHTS FOR AGRICULTURAL BIOTECHNOLOGY IN DEVELOPING COUNTRIES

Game theory and numerical simulation are used to analyze government's role in regulating IPRs for agricultural biotechnology in a developing country. An imported variety brings productivity gains and a negative externality. The relative effectiveness of corrective taxes or subsidies depends upon whether there is full enforcement of the IPRs.Research and Development/Tech Change/Emerging Technologies,

Implication of Higgs at 125 GeV within Stochastic Superspace Framework

We revisit the issue of considering stochasticity of Grassmannian coordinates in N=1 superspace, which was analyzed previously by Kobakhidze {\it et al}. In this stochastic supersymmetry(SUSY) framework, the soft SUSY breaking terms of the minimal supersymmetric Standard Model(MSSM) such as the bilinear Higgs mixing, trilinear coupling as well as the gaugino mass parameters are all proportional to a single mass parameter \xi, a measure of supersymmetry breaking arising out of stochasticity. While a nonvanishing trilinear coupling at the high scale is a natural outcome of the framework, a favorable signature for obtaining the lighter Higgs boson mass $m_h$ at 125 GeV, the model produces tachyonic sleptons or staus turning to be too light. The previous analyses took $\Lambda$, the scale at which input parameters are given, to be larger than the gauge coupling unification scale $M_G$ in order to generate acceptable scalar masses radiatively at the electroweak scale. Still this was inadequate for obtaining $m_h$ at 125 GeV. We find that Higgs at 125 GeV is highly achievable provided we are ready to accommodate a nonvanishing scalar mass soft SUSY breaking term similar to what is done in minimal anomaly mediated SUSY breaking (AMSB) in contrast to a pure AMSB setup. Thus, the model can easily accommodate Higgs data, LHC limits of squark masses, WMAP data for dark matter relic density, flavor physics constraints and XENON100 data. In contrast to the previous analyses we consider $\Lambda=M_G$, thus avoiding any ambiguities of a post-grand unified theory physics. The idea of stochastic superspace can easily be generalized to various scenarios beyond the MSSM . PACS Nos: 12.60.Jv, 04.65.+e, 95.30.Cq, 95.35.+dComment: LaTex, 35 pages, 7 figures. Minor changes in text. B-physics constraints updated with no change in conclusion. Version to be published in PR

A Meta-Analysis of Political Advertising

Political advertising is one of the dominant media for reaching voters. Previous metaanalyses (Allen & Burrell, 2002; Lau, Sigelman, Heldman, & Babbitt, 1999) found little or no net benefit to negative versus positive ads. However, this finding does not reveal whether ads have effects (both or neither could be persuasive). A meta-analysis revealed that political spots increased issue knowledge, influenced perceptions of the candidates’ character, altered attitudes, and affected candidate preference; influenced agenda-setting, and altered vote likelihood (turnout). One moderator variable was detected: The effect size for learning was larger for studies of students than non-students; however, the effect size for both sub-groups was significant. On the other hand, political ads had larger effects on attitudes for non-students than students

A six-parameter space to describe galaxy diversification

Galaxy diversification proceeds by transforming events like accretion, interaction or mergers. These explain the formation and evolution of galaxies that can now be described with many observables. Multivariate analyses are the obvious tools to tackle the datasets and understand the differences between different kinds of objects. However, depending on the method used, redundancies, incompatibilities or subjective choices of the parameters can void the usefulness of such analyses. The behaviour of the available parameters should be analysed before an objective reduction of dimensionality and subsequent clustering analyses can be undertaken, especially in an evolutionary context. We study a sample of 424 early-type galaxies described by 25 parameters, ten of which are Lick indices, to identify the most structuring parameters and determine an evolutionary classification of these objects. Four independent statistical methods are used to investigate the discriminant properties of the observables and the partitioning of the 424 galaxies: Principal Component Analysis, K-means cluster analysis, Minimum Contradiction Analysis and Cladistics. (abridged)Comment: Accepted for publicationin A\&

Contrasting the magnetic response between magnetic-glass and reentrant spin-glass

Magnetic-glass is a recently identified phenomenon in various classes of magnetic systems undergoing a first order magnetic phase transition. We shall highlight here a few experimentally determined characteristics of magnetic-glass and the relevant set of experiments, which will enable to distinguish a magnetic-glass unequivocally from the well known phenomena of spin-glass and reentrant spin-glass.Comment: 10 pages and 4 figures. The preprint has been amended after taking care of various typographical errors, some errors in Figs.2 and 4 and with the addition of some new references. This version has been accepted for publication in Physical Review

Ground state of a double-exchange system containing impurities: bounds of ferromagnetism

We study the boundary between ferromagnetic and non-ferromagnetic ground state of a double-exchange system with quenched disorder for arbitrary relation between Hund exchange coupling and electron band width. The boundary is found both from the solution of the Dynamical Mean Field Approximation equations and from the comparison of the energies of the saturated ferromagnetic and paramagnetic states. Both methods give very similar results. To explain the disappearance of ferromagnetism in part of the parameter space we derive from the double-exchange Hamiltonian with classical localized spins in the limit of large but finite Hund exchange coupling the $t-J$ model (with classical localized spins).Comment: 5 pages, 8 eps figures, latex; minor typos correcte