Modern Physics Letters A

A general method of constructing canonical gauge-invariant actions is used to establish the equivalence between 2-D induced gravity and a WZNW system, defined by a difference of two simple WZNW actions for the SL(2, R) group. The diffeomorphism invariance of the induced gravity is generated by the SL(2, R) Kac–Moody structure of the WZNW system.

We study a configuration of a parallel F- (fundamental) and D-string in IIB string theory by considering its T-dual configuration in the matrix model description of M-theory. We show that certain nonperturbative features of string theory such as O(e^-1/g_s) effects due to soliton loops, the existence of bound state (1,1) strings and manifest S-duality, can be seen in matrix models. We discuss certain subtleties that arise in the large-N limit when membranes are wrapped around compact dimensions.

Integrable deformations of two affine Toda field theories based on BC_n and non-simply laced algebras are studied. The proof of quantum integrability of the two theories is given and it is shown that the two theories are dual, corresponding respectively to the weak and strong coupling regimes of an intermediate theory. Perturbative calculations and the bootstrap principle permit the construction of the intermediate quantum field theory which flows from the first to the second with the coupling constant.

We consider a homogeneous and isotropic cosmological model in Weyl integrable space–time. A general non-singular solution is obtained which is consistent with the inflationary scenario.

In a recent paper¹ Euclidean wormhole solution has been obtained with a vacuum Brans–Dicke theory with parameter ω=0. These wormholes suffer from unphysical values of the gravitational constant. One can relate the various known wormholes by means of conformal transformations; although one should not transform them directly to the Einstein frame as the gravitational constant there is "forced" physical: so removing the wormholes.

However, by arguing for the existence of a fundamental minimum length scale such wormholes can now be considered as representative of quantum gravitational phenomena. One can also obtain wormholes as solutions of the quantum mechanical Wheeler–De Witt equation; now in Brans–Dicke for any ω>-3/2.

We show that the longitudinal polarization of the top quarks produced in the annihilation of e⁺e^- or μ⁺μ^- into at energies near the threshold is not affected by the large Coulomb-type corrections, which modify the total cross-section significantly. Thus the longitudinal polarization, though small, may give an independent information on the mass and the width of the top quark, largely independent of the uncertainty in α_s.

The supersymmetric version of the Miura and Bäcklund transformations associated with the supersymmetric Gelfand–Dickey bracket are investigated from the point of view of the Kupershmidt–Wilson theorem.

We investigate charged Bose liquid immersed in uniform background charge at zero temperature. Novel phenomena, such as oscillatory shielding of external localized electric charge, rotons and charge density waves (charge stripes in two dimensions), occur in any dimensions. Oscillatory shielding is caused by mixing between scalar boson exchange and Coulomb interactions, which mediate opposite forces. On the other hand, rotons and charge density waves are due to attractive local self-interaction of bosons. Rotons can be regarded as a finite size charge density wave packet without any back flow. We also comment on charge stripes observed recently in cuprates and nickelates.