16,211 research outputs found
Closed Expressions for Lie Algebra Invariants and Finite Transformations
A simple procedure to obtain complete, closed expressions for Lie algebra
invariants is presented. The invariants are ultimately polynomials in the group
parameters. The construction of finite group elements require the use of
projectors, whose coefficients are invariant polynomials. The detailed general
forms of these projectors are given. Closed expressions for finite Lorentz
transformations, both homogeneous and inhomogeneous, as well as for Galilei
transformations, are found as examples.Comment: 34 pages, ps file, no figure
QCD and QED Corrections to Light-by-Light Scattering
We present the QCD and QED corrections to the fermion-loop contributions to
light-by-light scattering, gamma gamma to gamma gamma, in the ultrarelativistic
limit where the kinematic invariants are much larger than the masses of the
charged fermions.Comment: 17 pages, 3 figure files, JHEP styl
Universal Aspects of Gauge Field Localization on Branes in -dimensions
In this work, we study the general properties of the -vector field
localization on -brane with co-dimension . We consider a
conformally flat metric with the warp factor depending only on the transverse
extra dimensions. We employ the geometrical coupling mechanism and find an
analytical solution for the gauge field valid for any warp factor. Using
this solution we find that the only condition necessary for localization is
that the bulk geometry is asymptotically AdS. Therefore, our solution has an
universal validity for any warp factor and is independent of the particular
model considered. We also show that the model has no tachyonic modes. Finally,
we study the scalar components of the -vector field. As a general result, we
show that if we consider the coupling with the tensor and the Ricci scalar in
higher co-dimensions, there is an indication that both sectors will be
localized. As a concrete example, the above techniques are applied for the
intersecting brane model. We obtain that the branes introduce boundary
conditions that fix all parameters of the model in such a way that both
sectors, gauge and scalar fields, are confined.Comment: 26 pages, 5 figures, Accepted version for publication in JHE
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