32 research outputs found
On the unitarity of higher-dervative and nonlocal theories
We consider two simple models of higher-derivative and nonlocal quantu
systems.It is shown that, contrary to some claims found in literature, they can
be made unitary.Comment: 8 pages, no figure
Remarks on quantization of Pais-Uhlenbeck oscillators
This work is concerned with a quantization of the Pais-Uhlenbeck oscillators
from the point of view of their multi-Hamiltonian structures. It is shown that
the 2n-th order oscillator with a simple spectrum is equivalent to the usual
anisotropic n - dimensional oscillator
Poincare covariant mechanics on noncommutative space
The Dirac approach to constrained systems can be adapted to construct
relativistic invariant theories on a noncommutative (NC) space. As an example,
we propose and discuss relativistic invariant NC particle coupled to
electromagnetic field by means of the standard term . Poincare
invariance implies deformation of the free particle NC algebra in the
interaction theory. The corresponding corrections survive in the
nonrelativistic limit.Comment: 7 pages, JHEP style, final versio