3,312 research outputs found
ALHEP symbolic algebra program for high-energy physics
ALHEP is the symbolic algebra program for high-energy physics. It deals with
amplitudes calculation, matrix element squaring, Wick theorem, dimensional
regularization, tensor reduction of loop integrals and simplification of final
expressions. The program output includes: Fortran code for differential cross
section, Mathematica files to view results and intermediate steps and TeX
source for Feynman diagrams. The PYTHIA interface is available. The project
website http://www.hep.by/alhep contains up-to-date executables, manual and
script examples.Comment: 33 pages, 4 figure
Accelerating cosmologies in Lovelock gravity with dilaton
For the description of the Universe expansion, compatible with observational
data, a model of modified gravity - Lovelock gravity with dilaton - is
investigated. D-dimensional space with 3- and (D-4)-dimensional maximally
symmetric subspaces is considered. Space without matter and space with perfect
fluid are under test. In various forms of the theory under way (third order
without dilaton and second order - Einstein-Gauss-Bonnet gravity - with dilaton
and without it) stationary, power-law, exponential and exponent-of-exponent
form cosmological solutions are obtained. Last two forms include solutions
which are clear to describe accelerating expansion of 3-dimensional subspace.
Also there is a set of solutions describing cosmological expansion which does
not tend to isotropization in the presence of matter.Comment: 23 page
- …