Modern Physics Letters A

By analytically continuing QCD scattering amplitudes through specific complexified momenta, one can study and learn about the nature and the consequences of factorization and unitarity. In some cases, when coupled with the largest time equation and gauge invariance requirement, this approach leads to recursion relations, which greatly simplify the construction of multi-gluon scattering amplitudes. The setting for this discussion is in the space-cone gauge.

We point out that the theoretical predictions for the inflationary observables may be generically altered by the presence of fields which are heavier than the Hubble rate during inflation and whose dynamics is usually neglected. They introduce corrections which may be easily larger than both the second-order contributions in the slow-roll parameters and the accuracy expected in the forthcoming experiments.

The famous formula for the emission angle of Cherenkov radiation should be modified when applied to hadronic reactions because of recoil effects and the color nature of the participants. They impose an upper limit on the energy of the gluon emitted at a given angle. Also, it leads to essential corrections to the nuclear refractive index value as determined from the angular position of Cherenkov rings.

We derive a system of cosmological equations for a braneworld with induced curvature which is a junction between several bulk spaces. The permutation symmetry of the bulk spaces is not imposed, and the values of the fundamental constants, and even the signatures of the extra dimension, may be different on different sides of the brane. We then consider the usual partial case of two asymmetric bulk spaces and derive an exact closed system of scalar equations on the brane. We apply this result to the cosmological evolution on such a brane and describe its various partial cases.

In this paper we study the statefinder parameters for the coupled tachyon dark energy model which has two types of stable scaling solutions. It is found that the evolving trajectories of the solutions are different in the statefinder parameters plane. These trajectories lie in the two regions r > 1, s < 0 and r < 1, s > 0, and pass through the LCDM fixed point. So, through the statefinder diagnostic, we not only characterize the properties of the coupled tachyon dark energy model, but also show the difference from other dark energy model.

We consider a Moyal plane and propose to make the noncommutativity parameter Θ^μν bifermionic, i.e. composed of two fermionic (Grassmann odd) parameters. The Moyal product then contains a finite number of derivatives, which avoid the difficulties of the standard approach. As an example, we construct a two-dimensional noncommutative field theory model based on the Moyal product with a bifermionic parameter and show that it has a locally conserved energy–momentum tensor. The model has no problem with the canonical quantization and appears to be renormalizable.

We construct supersymmetric (SUSY) generalized MIC–Kepler system and show that the systems with half integral Dirac quantization condition belong to an SUSY family (hierarchy of Hamiltonian) with same spectrum between the respective partner Hamiltonians except for the ground state. Similarly, the systems with integral Dirac quantization condition μ=±1,±2,±3,… belong to another family. We show that, it is necessary to introduce additional potential to MIC–Kepler system in order to unify the two families into one. We also reproduce the results of the (supersymmetric) Hydrogenic problem in our study.