A Gauge Field Theory for Continuous Spin Tachyons

We present a gauge field theory for unitary infinite dimensional tachyonic representations of the Poincar\'e group. It was obtained by a dimensional reduction from the gauge field theory for continuous spin particles in a cotangent bundle over Minkowski space-time. We discuss its BRST formulation and compute the partition function. Some cubic vertices are also presented and their properties discussed. In the massless limit the gauge theory for continuous spin tachyons reduces to the gauge theory for continuous spin particles.Comment: 22 pages, typos correcte

Noncommutative Supersymmetric Field Theories

We discuss some properties of noncommutative supersymmetric field theories which do not involve gauge fields. We concentrate on the renormalizability issue of these theories.Comment: 12 pages, updated version of a talk presented at the XXI Brazilian National Meeting on Particles and Fields, Sao Lorenco, MG, Oct. 23 - 26, 200

Duality in Noncommutative Maxwell-Chern-Simons Theory

Applying a master action technique we obtain the dual of the noncommutative Maxwell-Chern-Simons theory. The equivalence between the Maxwell-Chern-Simons theory and the self-dual model in commutative space-time does not survive in the non-commutative setting. We also point out an ambiguity in the Seiberg-Witten map.Comment: 10 pages; Fifth International Conference on Mathematical Methods in Physics, Rio de Janeiro, April 24-28, 2006; PoS documentclas

Remarks on a Gauge Theory for Continuous Spin Particles

We discuss in a systematic way the gauge theory for a continuous spin particle proposed by Schuster and Toro. We show that it is naturally formulated in a cotangent bundle over Minkowski spacetime where the gauge field depends on the spacetime coordinate ${x^\mu}$ and on a covector $\eta_\mu$. We discuss how fields can be expanded in $\eta_\mu$ in different ways and how these expansions are related to each other. The field equation has a derivative of a Dirac delta function with support on the $\eta$-hyperboloid $\eta^2+1=0$ and we show how it restricts the dynamics of the gauge field to the $\eta$-hyperboloid. We then show that on-shell the field carries one single irreducible unitary representation of the Poincar\'e group for a continuous spin particle. We also show how the field can be used to build a set of covariant equations found by Wigner describing the wave function of one-particle states for a continuous spin particle. Finally we show that it is not possible to couple minimally a continuous spin particle to a background abelian gauge field, and make some comments about the coupling to gravity.Comment: 21 pages, typos corrected, improved presentation of section VI, final versio

Tunnelling of Pulsating Strings in Deformed Minkowski Spacetime

Using the WKB approximation we analyse the tunnelling of a pulsating string in deformed Minkowski spacetime

Non Abelian Fields in Very Special Relativity

We study non-Abelian fields in the context of very special relativity (VSR). For this we define the covariant derivative and the gauge field gauge transformations, both of them involving a fixed null vector $n_{\mu}$, related to the VSR breaking of the Lorentz group to the Hom(2) or Sim(2) subgroups. As in the Abelian case the gauge field becomes massive. Moreover we show that the VSR gauge transformations form a closed algebra. We then write actions coupling the gauge field to various matter fields (bosonic and fermionic). We mention how we can use the spontaneous symmetry breaking mechanism to give a flavor dependent VSR mass to the gauge bosons. Finally, we quantize the model using the BRST formalism to fix the gauge. The model is renormalizable and unitary and for non abelian groups, asymptotically free.Comment: 11 pages, late