141 research outputs found
The excitation spectrum of rotating strings with masses at the ends
We compute the spectrum of excitations of the rotating Nambu-Goto string with
masses at the ends. We find interesting quasi-massless modes in the limit of
slow rotation and comment on the nontrivial relation between world-sheet and
target space energy.Comment: 13 pages, 1 figure, v2: Typos corrected, v3: fina
Divergences in QFT on the Noncommutative Minkowski Space with Grosse-Wulkenhaar potential
We study quantum field theory on the two-dimensional Noncommutative Minkoswki
space with a Grosse-Wulkenhaar potential. We explicitly construct the retarded
propagator and show that it is not a tempered distribution. This leads to
problems when trying to define planar products of such distributions, as they
appear in the Yang-Feldman series. At and above the self-dual point, these can
no longer be defined, not even at different points. This shows that we do not
deal with an ordinary ultraviolet divergence.Comment: 8 pages, Contribution to the proceedings of the Corfu Summer
Institute on Elementary Particles and Physics 201
Locally covariant chiral fermions and anomalies
We define chiral fermions in the presence of non-trivial gravitational and
gauge background fields in the framework of locally covariant field theory.
This allows to straightforwardly compute the chiral anomalies on non-compact
Lorentzian space-times, without recourse to a weak field approximation.Comment: 19 page
Dispersion relations in the noncommutative \phi^3 and Wess-Zumino model in the Yang-Feldman formalism
We study dispersion relations in the noncommutative \phi^3 and Wess-Zumino
model in the Yang-Feldman formalism at one-loop order. Nonplanar graphs lead to
a distortion of the dispersion relation. We find that the strength of this
effect is moderate if the scale of noncommutativity is identified with the
Planck scale and parameters typical for a Higgs field are employed. The
contribution of the nonplanar graphs is calculated rigorously using the
framework of oscillatory integrals.Comment: 23 pages, 2 figures. v2: Minor corrections and changes in the
presentatio
- …