Modern Physics Letters A

A non-Abelian Born–Infeld theory is presented. Its construction does not require the square-root structure that characterizes the Dirac–Born–Infeld (DBI) action. The procedure is based on an Abelian theory proposed by Schrödinger that, as he showed, is equivalent to Born–Infeld theory. Various non-Abelian generalizations are possible. We focus our attention on one of them. For it, it is shown that instantons solutions exist. Our formalism could be of interest in connection with string theory and possible extensions of well-known physical results in the usual Born–Infeld Abelian case.

For the first time the expected pulse shapes to be observed for neutrinoless double beta events in a big ⁷⁶Ge detector have been calculated starting from their Monte Carlo calculated time history and spatial energy distribution. It is shown that with the spatial resolution of a large size Ge detector for the majority of 0νββ events it is not possible to differentiate between the contributions of different particle physics parameters entering into the 0νββ decay process — in the mass mechanism the effective neutrino mass and the right-handed weak current parameters λ, η. It is shown that on the other hand it is possible in a ⁷⁶Ge double beta decay experiment to reject a background of larger sizes (high multiplicity) gamma events by selecting low size (low multiplicity) events. First comparison of the theoretical ββ pulses to events from the line observed at^3,4Q_ββ shows very good agreement. It is shown further that a rather good radial position determination of ββ events in the detector is possible. By the same type of calculation it is shown that use of the pulse shapes of the 1592 keV double escape line of the 2614 keV γ-transition from ²²⁸Th for calibrating a neuronal net for search of events of neutrinoless double beta decay should be helpful.

It has been proposed that the Poincaré and some other symmetries of noncommutative field theories should be twisted. Here we extend this idea to gauge transformations and find that twisted gauge symmetries close for arbitrary gauge group. We also analyse twisted-invariant actions in noncommutative theories.

We construct a quantum theory of free scalar field in (1+1) dimensions based on the deformed Heisenberg algebra where β is a deformation parameter. Both canonical and path integral formalisms are employed. A higher dimensional extension is easily performed in the path integral formalism.

We investigate the a₀ωγ vertex and estimate the coupling constant g_a0ωγ in the framework of the light-cone QCD sum rules. We compare our result with the value of the coupling constant calculated in the QCD sum rules.

The statefinder parameters were introduced recently to differentiate different dark energy models. In this paper we perform a statefinder diagnostic to the phantom dark energy model with two different phantom field potentials. Our results show that the statefinder diagnostic is rather robust in differentiating not only different dark energy models but also the same kind of models with different potentials which lead to different fate of the universe.

The Shishkin's solutions of the Dirac equation in spherical moving frames of the de Sitter spacetime are investigated pointing out the set of commuting operators whose eigenvalues determine the integration constants. It is shown that these depend on the usual angular quantum numbers and, in addition, on the value of the scalar momentum. With these elements a new result is obtained finding the system of solutions normalized (in generalized sense) in the scale of scalar momentum.