New magic number for neutron rich Sn isotopes

The variation of E(2+_1) of (134-140)Sn calculated with empirical SMPN interaction has striking similarity with that of experimental E(2+_1) of even-even (18-22)O and (42-48)Ca, showing clearly that N=84-88 spectra exhibit the effect of gradual filling up of \nu(2f_{7/2}) orbital which finally culminates in a new shell closure at N=90. Realistic two-body interaction CWG does not show this feature. Spin-tensor decomposition of SMPN and CWG interactions and variation of their components with valence neutron number reveals that the origin of the shell closure at 140Sn lies in the three body effects. Calculations with CWG3, which is obtained by including a simple three-body monopole term in the CWG interaction, predict decreasing E(2+_1) for (134-138)Sn and a shell closure at 140Sn.Comment: 4 pages, 5 figure

Spontaneous Left-Right Symmetry Breaking in Supersymmetric Models with only Higgs Doublets

We studied the question of parity breaking in a supersymmetric left-right model, in which the left-right symmetry is broken with Higgs doublets (carrying $B-L=\pm 1$). Unlike the left-right symmetric models with triplet Higgs scalars (carrying $B-L=\pm 2$), in this model it is possible to break parity spontaneously by adding a parity odd singlet. We then discussed how neutrino mass of type III seesaw can be invoked in this model by adding extra fermion singlets. We considered simple forms of the mass matrices that are consistent with the unification scheme and demonstrate how they can reproduce the required neutrino mixing matrix. In this model, the baryon asymmetry of the universe is generated via leptogenesis. The required mass scales in the model is then found to be consistent with the gauge coupling unification.Comment: 19 pages, 1 eps figur

Debt and Corporate Governance in Emerging Economies - Evidence from India

We analyze the role of debt in corporate governance with respect to a large emerging economy, India, where debt has been an important source of external finance. First, we examine the extent to which debt acts as a disciplining device in those corporations where potential for over investment is present. We undertake a comparative evaluation of group-affiliated and non-affiliated companies to see if the governance role of debt is sensitive to ownership and control structures. Second, we examine the role of institutional change in strengthening the disciplining effect or mitigating the expropriating effect of debt. In doing so, we estimate, simultaneously, the relation between Tobins Q and leverage using a large cross-section of listed manufacturing firms in India for three years, 1996, 2000, and 2003. Our analyses indicate that while in the early years of institutional change, debt did not have any disciplinary effect on either standalone or group affiliated firms, the disciplinary effect appeared in the later years as institutions become more market oriented. We also find limited evidence of debt being used as an expropriation mechanism in group firms that are more vulnerable to such expropriation. However, the disciplining effect of debt is found to persist even after controlling for such expropriation possibilities. In general, our results highlight the role of ownership structures and institutions in debt governance.Debt, ownership structure, Corporate governance, institutional change.