37,429 research outputs found
Inhomogeneous de Sitter Solution with Scalar Field and Perturbations Spectrum
We provide an inhomogeneous solution concerning the dynamics of a real self
interacting scalar field minimally coupled to gravity in a region of the
configuration space where it performs a slow rolling on a plateau of its
potential. During the inhomogeneous de Sitter phase the scalar field dominant
term is a function of the spatial coordinates only. This solution specialized
nearby the FLRW model allows a classical origin for the inhomogeneous
perturbations spectrum.Comment: 9 pages, no figures, to appear on Mod.Phys.Lett.
Proposal of a second generation of quantum-gravity-motivated Lorentz-symmetry tests: sensitivity to effects suppressed quadratically by the Planck scale
Over the last few years the study of possible Planck-scale departures from
classical Lorentz symmetry has been one of the most active areas of
quantum-gravity research. We now have a satisfactory description of the fate of
Lorentz symmetry in the most popular noncommutative spacetimes and several
studies have been devoted to the fate of Lorentz symmetry in loop quantum
gravity. Remarkably there are planned experiments with enough sensitivity to
reveal these quantum-spacetime effects, if their magnitude is only linearly
suppressed by the Planck length. Unfortunately, in some quantum-gravity
scenarios even the strongest quantum-spacetime effects are suppressed by at
least two powers of the Planck length, and many authors have argued that it
would be impossible to test these quadratically-suppressed effects. I here
observe that advanced cosmic-ray observatories and neutrino observatories can
provide the first elements of an experimental programme testing the possibility
of departures from Lorentz symmetry that are quadratically Planck-length
suppressed.Comment: version to appear in a GRF2003 Special Issue of IntJournModPHysD
(minor editing and some additional refs
Rapidity evolution of Wilson lines at the next-to-leading order
At high energies particles move very fast so the proper degrees of freedom
for the fast gluons moving along the straight lines are Wilson-line operators -
infinite gauge factors ordered along the line. In the framework of operator
expansion in Wilson lines the energy dependence of the amplitudes is determined
by the rapidity evolution of Wilson lines. We present the next-to-leading order
hierarchy of the evolution equations for Wilson-line operators.Comment: 5 pages and 2 figures, PRD version with typos correcte
High-energy amplitudes in N=4 SYM in the next-to-leading order
The high-energy behavior of the N=4 SYM amplitudes in the Regge limit can be
calculated order by order in perturbation theory using the high-energy operator
expansion in Wilson lines. At large , a typical four-point amplitude is
determined by a single BFKL pomeron. The conformal structure of the four-point
amplitude is fixed in terms of two functions: pomeron intercept and the
coefficient function in front of the pomeron (the product of two residues). The
pomeron intercept is universal while the coefficient function depends on the
correlator in question. The intercept is known in the first two orders in
coupling constant: BFKL intercept and NLO BFKL intercept calculated in Ref. 1.
As an example of using the Wilson-line OPE, we calculate the coefficient
function in front of the pomeron for the correlator of four currents in
the first two orders in perturbation theory.Comment: 10 pages, 3 figure
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