375,844 research outputs found
(Re-)Inventing the Relativistic Wheel: Gravity, Cosets, and Spinning Objects
Space-time symmetries are a crucial ingredient of any theoretical model in
physics. Unlike internal symmetries, which may or may not be gauged and/or
spontaneously broken, space-time symmetries do not admit any ambiguity: they
are gauged by gravity, and any conceivable physical system (other than the
vacuum) is bound to break at least some of them. Motivated by this observation,
we study how to couple gravity with the Goldstone fields that non-linearly
realize spontaneously broken space-time symmetries. This can be done in
complete generality by weakly gauging the Poincare symmetry group in the
context of the coset construction. To illustrate the power of this method, we
consider three kinds of physical systems coupled to gravity: superfluids,
relativistic membranes embedded in a higher dimensional space, and rotating
point-like objects. This last system is of particular importance as it can be
used to model spinning astrophysical objects like neutron stars and black
holes. Our approach provides a systematic and unambiguous parametrization of
the degrees of freedom of these systems.Comment: 30 page
Spin-charge rotating local reference frames: a unified U(2)=U(1)xSU(2) approach to the interacting electrons
A spin-charge unifying description for the Hubbard model based on the time
dependent local gauge transformations is developed. The collective variables
for charge and spin are isolated in the form of the space-time fluctuating U(1)
phase field and rotating spin quantization axis governed by the SU(2) symmetry,
respectively. As a result interacting electrons appear as a composite objects
consisting of bare fermions with attached U(1) and SU(2) gauge fields. We
elaborate on the microscopic origins of the effective action with the Coulomb
interaction that contain topological theta terms. Furthermore, we unravel the
link between non-trivial multiply-connected topological structure of the
U(2)=U(1)SU(2) configurational space for gauge fields and the
instanton contribution to the statistical sum.Comment: 5 pages, Proceedings of the XXX International Conference of
Theoretical Physics: Electron Correlations in nano- and macrosystems (ECNM06
Ustron, Poland); to be published in Phys. Stat. Solidi
- …