The spherical symmetric dyonic black hole solutions of the effective action of heterotic string are studied perturbatively up to second order in the inverse string tension. An expression for the temperature in terms of the mass and the electric and magnetic charge of the black hole is derived and it is shown that its behaviour is qualitatively different in the two special cases where the electr...

Conformally invariant scalar waves in black hole spacetimes which are asymptotically anti-de Sitter are investigated. We consider both the (2 + 1)-dimensional black hole and (3 + 1)-dimensional Schwarzschild-anti-de Sitter spacetime as backgrounds. Analytical and numerical methods show that the waves decay exponentially in the (2 + 1) dimensional black hole background. However the falloff patte...

We discuss the role of thermal cyclo–synchrotron emission in a magnetically dominated corona above an accretion disk in an active galaxy or a galactic black hole candidate. The dissipation occurs in localized active regions around the central black hole. Cyclo– synchrotron radiation is found to be an important process. In the case of galactic black hole candidates, its emission can dominate the...

We have used resonant soft x-ray scattering to study the effects of discommensuration on the hole Wigner crystal (HC) in the spin ladder Sr(14-x)CaxCu24O41 (SCCO). As the hole density is varied the HC forms only with the commensurate wave vectors L(L) = 1/5 and L(L) = 1/3; for incommensurate values it "melts." A simple scaling between L(L) and temperature is observed, tau1/3/tau1/5 = 5/3, indic...

Several series of shallow large-size (l ≫ lattice spacing) two-hole bound states are found in the two-dimensional t−J model. Their binding energies depend exponentially on the inverse value of the hole-spin-wave coupling constant. Their parity is connected with the angular wave function in a nonstandard way. The possible role of these states in the formation of superconducting pairing is consid...

The entropy of a half-BPS black hole in N = 4 supersymmetric heterotic string compactification is independent of the details of the charge vector and is a function only of the norm of the charge vector calculated using the appropriate Lorenzian metric. Thus in order for this to agree with the degeneracy of the elementary string states, the latter must also be a function of the same invariant no...

We study analytically the initial value problem for a charged massless scalarfield on a Reissner-Nordström spacetime. Using the technique of spectral decomposition we extend recent results on this problem. Following the no-hair theorem we reveal the dynamical physical mechanism by which the charged hair is radiated away. We show that the charged perturbations decay according to an inverse power...

We study numerically the fully nonlinear spherically-symmetric collapse of a selfgravitating, minimally-coupled, massless scalar field. Our numerical code is based on double-null coordinates and on free evolution of the metric functions and the scalar field. The numerical code is stable and second-order accurate. We use this code to study the late-time asymptotic behavior at fixed r (outside th...