Modern Physics Letters A

The MAGIC telescope with its 17m diameter mirror is today the largest operating single-dish Imaging Air Cherenkov Telescope (IACT). It is located on the Canary Island La Palma, at an altitude of 2200 m above sea level, as part of the Roque de los Muchachos European Northern Observatory. The MAGIC telescope detects celestial very high energy γ-radiation in the energy band between about 50 GeV and 10 TeV. Since the autumn of 2004 MAGIC has been taking data routinely, observing various objects, like supernova remnants (SNRs), γ-ray binaries, Pulsars, Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRB). We briefly describe the observational strategy, the procedure implemented for the data analysis, and discuss the results of observations of Galactic Sources.

We study the mixing of excited states of a hydrogen atom in a cavity with de-excited states plus a confined photon as a model for the coupling of quark–antiquark and quark–antiquark–gluon hybrid states in QCD. For an interesting range of parameters, the results are analytic. We find a case for which wave functions (and hence decay patterns) may be at odds with mass with respect to identification of a state as hybrid or not.

We find a new type of nonlinear supersymmetries, called -fold parasupersymmetry, which is a generalization of both -fold supersymmetry and parasupersymmetry. We provide a general formulation of this new symmetry and then construct a second-order -fold parasupersymmetric quantum system where all the components of -fold parasupercharges are given by type A -fold supercharges. We show that this system exactly reduces to the Rubakov–Spiridonov model when and admits a generalized type C -fold superalgebra. We conjecture the existence of other "-fold generalizations" such as -fold fractional supersymmetry, -fold orthosupersymmetry, and so on.

Based on the decomposition of U(1) gauge potential theory and the ϕ-mapping topological current theory, the three-dimensional knot invariant and a four-dimensional new topological invariant are discussed in the U(1) gauge field.

A study of Kantowski–Sachs and Bianchi type III spacetimes according to their proper projective symmetry is given by using the algebraic and direct integration techniques. It is shown that the above spacetimes do not admit proper projective collineations.

The Fubini's idea to introduce a fundamental scale of hadron phenomena by means of dilatation non-invariant vacuum state in the framework of a scale invariant Lagrangian field theory is recalled. The Fubini vacua is invariant under the de Sitter subgroup of the full conformal group. We obtain a finite entropy for the quantum state corresponding to the classical Fubini vacua in Euclidean spacetime resembling the entropy of the de Sitter vacua. In Minkowski spacetime it is shown that the Fubini vacua is mainly a bath of radiation with Rayleigh–Jeans distribution for the low energy radiation. In four dimensions, the critical scalar theory is shown to be equivalent to the Einstein field equation in the ansatz of conformally flat metrics and to the SU(2) Yang–Mills theory in the 't Hooft ansatz. In D dimensions, the Hitchin formula for the information geometry metric of the moduli space of instantons is used to obtain the information geometry of the free-parameter space of the Fubini vacua which is shown to be a (D+1)-dimensional AdS space. Considering the Fubini vacua as a de Sitter vacua, the corresponding cosmological constant is shown to be given by the coupling constant of the critical scalar theory. In Minkowski spacetime it is shown that the Fubini vacua are equivalent to an open FRW universe.