Modern Physics Letters A

The picture of S-wave scattering from a 4-D extremal dilatonic black hole is examined. Classically, a small matter shock wave will form a non-extremal black hole. In the “throat region” the r-t geometry is exactly that of a collapsing 2-D black hole. The 4-D Hawking radiation (in this classical background) gives the 2-D Hawking radiation exactly in the throat region. The 4-D geometry outside the throat region is almost the extremal one, and the deviations can be calculated using a linear approximation. Inclusion of the back-reaction changes this picture: the linear approximation is valid only at the beginning of the evaporating process. We give (explicitly) that linear 4-D solution. The linear approximation breaks down even before an apparent horizon is formed, which suggests that the 4-D semiclassical solution may be quite different from the 2-D one.

In order to understand the phase structure of d>1 strings we investigate the c=1 matrix model with g′(tr M(t)²)² interaction which is the simplest approximation of the large-N reduced model of odd-dimensional matrix field theory. We find three distinct phases: (i) an ordinary c=1 gravity phase, (ii) a branched polymer phase and (iii) an intermediate phase, and compute the disk and cylinder amplitudes in the phases (i) and (iii). Further we also analyze the model with slightly generalized interaction. As a result the multi-critical versions of the phase (ii) are found.

Methods developed for the analysis of integrable systems are used to study the problem of hyper-Kähler metrics building as formulated in D=2, N=4 supersymmetric harmonic superspace. We show in particular that the constraint equation

We discuss a long-standing problem of the global topological non-trivial properties of the four-dimensional space-times underlying black hole physics and observe that the standard space-time topology of the ℝ²×S² form for black hole physics admits topologically inequivalent configurations of a complex scalar field on black hole by virtue of the availability of non-trivial complex line bundles over S². Each configuration can be labeled by its Chern number n∈ℤ. For the Schwarzschild black hole we formulate an appropriate wave equation for these configurations in massless case and describe its solutions as a first step to study quantum effects for the above configurations within the framework of black hole physics.

In this article we obtain, by separation of variables, an exact solution to the Dirac equation with anomalous momentum for an electrically neutral massless particle in a Bertotti-Robinson universe. We discuss the phenomenon of particle creation in this model.

We investigate the representation theory of some recently constructed N=2 super -algebras with two generators. Except for the central charges in the unitary minimal series of the N=2 super Virasoro algebra we find no new rational models. However, from our results it is possible to arrange all known N=2 super -algebras with two generators and vanishing self-coupling constant into four classes. For the algebras existing for c≥3 which can be understood by the spectral flow of the N=2 super Virasoro algebra we find that the representations have quantized U(1) charge.

Up to 10 crossing numbers, there are two knots, 9₄₂ and 10₇₁ whose chirality is not detected by any of the known polynomials, namely, Jones invariants and their two variable generalizations, HOMFLY and Kauffman invariants. We show that the generalized knot invariants, obtained through SU(2) Chern-Simons topological field theory, which give the known polynomials as special cases, are indeed sensitive to the chirality of these knots.

Recently, we proposed a new front-form quantization which treated both the x⁺ and the x⁻ coordinates as front-form ‘times’. This quantization was found to preserve parity explicitly. In this letter we extend this construction to fermion fields in the context of the Yukawa theory. We quantize this theory using a method proposed originally by Faddeev and Jackiw. We find that P⁻ and P⁺ become dynamical and that the theory is manifestly invariant under parity.