Up-Down Unification, Neutrino Masses and Rare Lepton Decays

In a recent paper, we showed that tree level up-down unification of fermion Yukawa couplings is a natural consequence of a large class of supersymmetric models. They can lead to viable quark masses and mixings for moderately large values of $\tan\beta$ with interesting and testable predictions for CP violation in the hadronic sector. In this letter, we extend our discussion to the leptonic sector focusing on one particular class of these models, the supersymmetric left-right model with the seesaw mechanism for neutrino masses. We show that fitting the solar and the atmospheric neutrino data considerably restricts the Majorana-Yukawa couplings of the leptons in this model and leads to predictions for the decay $\tau\to \mu +\gamma$, which is found to be accessible to the next generation of rare decay searches. We also show that the resulting parameter space of the model is consistent with the requirements of generating adequate baryon asymmetry through lepton-number violating decays of the right-handed neutrino.Comment: 16 pages, latex, 6 figures, typos correcte

Matter induced charge symmetry breaking and pion form factor in nuclear medium

Medium modification of pion form factor has been evaluated in asymmetric nuclear matter. It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with $\rho$-$\omega$ mixing. This is due to the density and asymmetry dependent $\rho$-$\omega$ mixing which could even dominate over its vacuum counterpart in matter. Effect of the in-medium pion factor on experimental observables {\it e.g.}, invariant mass distribution of lepton pairs has been demonstrated.Comment: Final Version to appear in Jour. Phys.

India’s Nuclear Doctrine : Context and Constraints

Ever since India achieved independence in 1947, its response to global nuclear non-proliferation measures has been a dominant theme in the country’s overall evolution of nuclear policy. However, India conducted a nuclear test in 1974, which it termed a ‘peaceful nuclear explosion’ and in 1998, India conducted a full-scale nuclear test and subsequently claimed to have attained nuclear capability. The purpose of this article is to critically evaluate key elements of India’s draft nuclear doctrine. The draft was presented to the Prime Minister and the Cabinet in August 1999 and released later for public debate by the National Security Advisory Board

TYPES OF QUESTIONS TEACHERS ASK TO ENGAGE STUDENTS IN MAKING SENSE OF A STUDENT CONTRIBUTION

In the student-centered classroom, a teacher’s interpretation and response to student mathematical contributions plays an important role to shape and direct students’ opportunities for sense-making. This research used a scenario-based survey questionnaire to examine what types of questions middle and high school mathematics teachers indicate they would ask to engage students in making sense of a high-leverage student mathematical contribution and their reasoning about why particular questions are or are not productive. From the results, it could be concluded that teachers asked more productive questions after seeing a set of possible questions. Their beliefs about the productivity of the questions related to a variety of factors, including the specificity of the question, student participation, student ability and whether incorrect solutions should be discussed. The results could inform future work with teachers to productively use student thinking in their teaching

Quenching of light hadrons at RHIC in a collisional energy loss scenario

We evaluate the nuclear suppression factor, $R_{AA}(p_T)$ for light hadrons by taking into account the collisional energy loss. We show that in the measured $p_T$ domain of RHIC the elastic process is the dominant mechanism for the partonic energy loss.Comment: 4 pages with 3 figures, Quark Matter 2008 Proceeding