Modern Physics Letters A

Quantum back reaction due to N massless fields may be worked out to a considerable detail in a variant of integrable dilaton gravity model in two dimensions. It is shown that there exists a critical mass of collapsing object of order ħN×(cosmological constant)^1/2, above which the end point of Hawking evaporation is two disconnected remnants of infinite extent, each separated by a mouth from the outside region. Deep inside the mouth there is a universal flux of radiation in all directions, in a form different from Hawking radiation. Below the critical mass no remnant is left behind, implying complete Hawking evaporation or even showing no sign of Hawking radiation.

The gravity field induced by the magnetic field in an infinite solenoid is found. Gravitational effects are studied, the most important of them being the radial acceleration of neutral particles. It becomes equal to the earth’s acceleration for magnetic fields with strength 2×10¹⁴ G.

We examine the possibility of contact interaction of anyons within the framework of a two-particle supersymmetric model. It is shown that anyons can be realized in a supersymmetric manner (except in two low lying states) and they do not feel contact interaction.

The path-integral method is applied to derive the chiral bosonized action and the minimal WZW action for chiral QCD₂. An interesting feature in our model is that the Poisson brackets of the new set of constraints, which is a recombination of the original ones, are field-independent on the constraint surface. The correct contribution from det {Ω_i, Ω_j} or δ(Ω^a) is considered, and it seems to affect the properties of the integration measure. Here Ωi are the original chiral constraints, Ω^a are linear combination of Ω_i. However, due to the determinants of L^ab(ɸ) and (the definition of Lab(ɸ) and can be seen from Eqs. (22) and (41)) being ±1, the right-invariant measure is equivalent to the left-invariant measure, which is quite unlike the case of the gauge quasigroup. As a result, we can identify the integration measure in our model with the Haar measure.

The string theory defined by gauging W_∞/2, the subalgebra of W_∞ generated by the currents of even spin, is discussed. The critical value of the central charge is calculated using zeta-function techniques and shown to be c=1. A critical string theory is constructed by coupling a free boson to W_∞/2-gravity and the physical states are analyzed.

The color coherence effects are studied for direct processes of γp interactions at high energies using PYTHIA Monte-Carlo simulation and perturbative QCD approach. Sub-processes of QED and QCD Compton scattering on quarks leading to jet topology of photoproduction events are considered. It is shown that the coherence leads to drag phenomenon in the interjet region.

The requirements of geodesic completeness and self-adjointness imply that the Hamiltonian for anyons is the Laplacian with respect to the Weil-Petersson metric. This metric is complete on the Deligne-Mumford compactification of moduli (configuration) space. The structure of this compactification fixes the possible anyon configurations. This allows us to identify anyons with singularities (elliptic points with ramification q⁻¹) in the Poincare metric implying that anyon spectrum is chaotic for n≥3. Furthermore, the bound on the holomorphic sectional curvature of moduli spaces implies a gap in the energy spectrum. For q=0 (punctures) anyons are infinitely separated in the Poincare metric (hard core). This indicates that the exclusion principle has a geometrical interpretation. Finally we give the differential equation satisfied by the generating function for volumes of the configuration space of anyons.

The issue of gauge invariances in the sigma model formalism is discussed at the free and interacting level. The problem of deriving gauge invariant interacting equations can be addressed using the proper time formalism. This formalism is discussed, both for point particles and strings. The covariant Klein-Gordon equation arises in a geometric way from the boundary terms. This formalism is similar to the background independent open string formalism introduced by Witten.

One discusses the tree-level unitarity and presents asymptotic behavior of scattering amplitudes for three-dimensional gauge-invariant models where complex Chern- Simons-Maxwell fields (with and without a Proca-like mass) are coupled to an Abelian gauge field.

In the standard model of electroweak interactions the Higgs doublet is replaced by a doublet of vector bosons and the gauge symmetry is broken dynamically. This generates masses for the gauge bosons and fermions as well as it fixes the interactions in the model. The model has a low momentum scale. In this note we show that the model survives the test of the ρ parameter, and to each momentum scale ρ chooses a possible range of vector boson masses.

The multilevel field-antifield formalism is constructed in a geometrically covariant way without imposing the unimodularity conditions on the hypergauge functions. Thus the version given in Refs. 1 and 2 can be extended to cover the most general case of Lagrangian surface bases. It is shown that the extra measure factors, required to enter the gauge-independent functional integrals, can be included naturally into the multilevel scheme by modifying the boundary conditions to the quantum master equation.