We study Kaluza-Klein spectrum of type IIB string theory compactified on AdS5 Ã— T â€² in the context of AdS/CFT correspondence. We examine some of the modes of the complexified 2 form potential as anâ€¦ (More)

We propose a formula for the degeneracy of quarter BPS dyons in a class of CHL models. The formula uses a modular form of a subgroup of the genus two modular group Sp(2, ZZ). Our proposal isâ€¦ (More)

The interplay between gravitational couplings on branes and the occurrence of fractional flux in low dimensional orientifolds is examined. It is argued that gravitational couplings need to beâ€¦ (More)

We construct Nielsen-Olesen vortex solution in the noncommutative abelian Higgs model. We derive the quantized topological flux of the vortex solution. We find that the flux is integral by explicitâ€¦ (More)

A formula for the exact partition function of 1/4 BPS dyons in a class of CHL models has been proposed earlier. The formula involves inverse of Siegel modular forms of subgroups of Sp(2, ZZ). In thisâ€¦ (More)

We study various aspects of power suppressed as well as exponentially suppressed corrections in the asymptotic expansion of the degeneracy of quarter BPS dyons in N = 4 supersymmetric stringâ€¦ (More)

We compute the spectrum of quarter BPS dyons in freely acting ZZ2 and ZZ3 orbifolds of type II string theory compactified on a six dimensional torus. For large charges the result for statisticalâ€¦ (More)

We analyse of the effective action of the tachyon field on a D-brane, of both bosonic as well as superstring theory. We find that the non-standard kinetic term of the tachyon field requires aâ€¦ (More)

We study the dynamics of fuzzy two-spheres in a matrix model which represents string theory in the presence of RR flux. We analyze the stability of the known static solutions of such a theory whichâ€¦ (More)

We investigate the nature of the ground ring of c = 1 string theory at the special A-D-E points in the c = 1 moduli space associated to discrete subgroups of SU(2). The chiral ground rings at theseâ€¦ (More)