15105689
Effective Electric and Magnetic Local Actions for Electromagnetism with two Gauge Fields
A simple mechanism of dynamical symmetry breaking of electromagnetism with two gauge fields (U(1) × U(1)) is considered. By considering the action variations with respect to the gauge connections F = dA and G = dC we obtain an electric and a magnetic effective actions (U(1)) that have an extra coupling to the magnetic and electric currents (respectivelly) that decouple from the classical theory, meaning that it does not contribute to the standard equations of motion obtained by varying A and C, i.e. Maxwell equations. The extra gauge field C(or A) effectivelly is fixed by the physical effective field A(or C) constituting a non-trivial configuration C = C(A) (or A = A(C)) such that the field discontinuities (Dirac string or WuYang non-trivial fiber-bundle) are encoded in the extra gauge field C (or A). Our construction is only compactible with local current densities. work supported by SFRH/BPD/17683/2004 and POCTI P-FIS-57547/2004; also at Centra
18433177
Electro-Magnetic Space-Time Duality for 2+1 D Stationary Classical Solutions
We extend a space-time duality suggested by Kogan for 2+1-dimensional static classical solutions of Einstein Maxwell Chern-Simons theories to stationary rotating space-times. We also extend the original duality to other possible dualities of the same kind that constitute a close duality web. In 3+1-dimensions these dualities are only possible for systems which exhibit non-projected cylindrical symmetry and are not related to the usual electromagnetic duality of Maxwell equations. Generalization to $N$-form theories in higher dimensional space-times is briefly addressed.
119098673
Pseudo-Photon Radiative Corrections in Non-Regular Backgrounds
Extended $U_e(1)\times U_g(1)$ electromagnetism containing both a photon and a pseudo-photon is introduced at variational level and is justified by the violation of the Bianchi identities in conceptual systems, either in the presence of magnetic monopoles or non-regular external fields, not being accounted by the standard Maxwell action. It is shown that in the perturbative quantum field theory regimes there are observable consequences both for the magnetic momenta and second order vacuum polarization radiative corrections in the presence of non-regular strong electromagnetic fields (e.g. rotating magnetic fields).
119410476
Why Randall-Sundrum Scenarious are not Compatible with an Orbifolded Fifth Dimension
We show the (already known) fact that Randall-Sundrum scenarious although compatible with a ${\mathbb{Z}}_2$ orbifold symmetry cannot hold regularity of the fields at the orbifold planes in the absence of boundary actions and respective jumps of the fields. This makes the models mathematical inconsistence and invalidate the inclusion of such models in a higher dimensional theory such as string theory. For completeness we point out some directions already in the literature and in progress.
118869835
Heterotic, Open and Unoriented String Theories from Topological Membrane
In this work are consider several topics in the Topological Membrane (TM) approach to string theory. The string dynamics is generated from the bulk physics, namely from the 3D Topologically Massive Gauge Theory (TMGT) and Topologically Massive Gravity (TMG). Both (equivalent) path integral and canonical methods of quantizing TMGT are studied. It is shown that Narain constraints on toroidal compactification (integer, even, self-dual momentum lattice) have a natural interpretation in purely three dimensional terms. The Heterotic string and the block structure of c=1 RCFT are derived from the point of view of three dimensional field theory. Open and unoriented strings in TM(GT) theory are also studied through orbifolds of the bulk 3D space. This is achieved by gauging discrete symmetries of the theory. Open and unoriented strings can be obtained from all possible realizations of C, P and T symmetries. The important role of C symmetry to distinguish between Dirichlet and Neumann boundary conditions is discussed in detail. Future directions of research in this field are also suggested and discussed.
6355453
Rotating Electric Classical Solutions of 2+1 D U(1) Einstein Maxwell Chern-Simons
We study electric stationary radial symmetric classical solutions of the U(1) Einstein Maxwell Chern-Simons theory coupled to a gravitational massless scalar field with a cosmological constant in 2+1 dimensions. Generic aspects of the theory are discussed at an introductory level. We study solutions for both negative sign (standard) and positive sign (ghost) of the gauge sector concluding that although the expressions for the solutions are the same, the constants as well as the physics change significantly. It is found a rotating electric point particle. For the standard sign and specific values of the parameters corresponding to solutions with positive mass the singularity is dressed (in the sense that itself constitutes an horizon). The space-time curvatures can be both positive or negative depending on the dominance of the scalar or topologically massive matter. The Chern-Simons term is responsible for interesting features, besides only allowing for rotating solutions, it imposes restrictive bounds on the cosmological constant $\Lambda$ such that it belongs to a positive interval and is switch on and off by the topological mass $m^2$. Furthermore the charge, angular momentum and mass of the particle solution are expressed uniquely as functions of the ratio between the cosmological constant and the topological mass squared $x=\Lambda/m^2$. The main drawback of our particle solution is that the mass is divergent. Our background is a rotating flat space without angular deficit. We briefly discuss parity and time-inversion violation by the Chern-Simons term which is explicit in the solutions obtained, their angular momentum only depends on the relative sign between the Chern-Simons term and the Maxwell term. Trivial solutions are briefly studied holding non-singular extended configurations.
119052706
Constraints on a primordial magnetic field
We derive an upper limit of B{sub 0}{lt}3.4{times}10{sup -9}({Omega}{sub 0}h{sup 2}{sub 50}){sup 1/2} G on the present strength of any primordial homogeneous magnetic field. The microwave background anisotropy created by cosmological magnetic fields is calculated in the most general flat and open anisotropic cosmologies containing expansion-rate and 3-curvature anisotropies. Our limit is derived from a statistical analysis of the 4-year Cosmic Background Explorer (COBE) data for anisotropy patterns characteristic of homogeneous anisotropy averaged over all possible sky orientations with respect to the COBE receiver. The limits we obtain on homogeneous magnetic fields are stronger than those imposed by nucleosynthesis. {copyright} {ital 1997} {ital The American Physical Society}
85524781
Contributions from flavour changing effective operators to the physics of the top quark at LHC
We consider all relevant dimension six operators to perform a model independent analysis of flavour changing single top production at the LHC.
55409487
Errors in Estimating Omega_Lambda due to the Fluid Approximation
The matter content of the Universe is strongly inhomogeneous on small scales. Motivated by this fact, we consider a model of the Universe that has regularly spaced discrete masses, rather than a continuous fluid. The optical properties of such space-times can differ considerably from the continuous fluid case, even if the 'average' dynamics are the same. We show that these differences have consequences for cosmological parameter estimation, and that fitting to recent supernovae observations gives a correction to the inferred value of Omega_Lambda of ~10%.
118632718
Constraining primordial magnetic fields with CMB polarization experiments
We calculate the effect that a primordial homogeneous magnetic field, B{sub 0}, will have on the different CMB power spectra due to Faraday rotation. Concentrating on the TB, EB, and BB correlations, we forecast the ability for future CMB polarization experiments to constrain B{sub 0}. Our results depend on how well the foregrounds can be subtracted from the CMB maps, but we find a predicted error between {sigma}{sub B{sub 0}}=4x10{sup -11} G (for the QUIET experiment with foregrounds perfectly subtracted) and 3x10{sup -10} G (with the Clover experiment with no foreground subtraction). These constraints are two orders of magnitude better than the present limits on B{sub 0}.
9840308
Polarization-temperature correlation from a primordial magnetic field
We propose a new method for constraining a primordial homogeneous magnetic field with the cosmic microwave background. Such a field will induce an observable parity odd cross correlation between the polarization anisotropy and the temperature anisotropy by Faraday rotation. We analyze the necessary experimental features to match, and improve, current constraints of such a field by measuring this correlation.