HIGH ENERGY THEORY / RELATIVITY / COSMOLOGY SEMINARS
Fall 2006
Monday September 18 Seminar :
Aharon Davidson (Ben-Gurion University)
Title : Dirac Relaxation of the Israel Junction Conditions
Abstract:
| Following Dirac's
brane variation prescription, the brane must not be
deformed during the variation process, or else
the linearity of the variation may be
lost. Alternatively, the variation of the brane is
done, in a special Dirac frame, by varying the
bulk coordinate system itself. Imposing
appropriate Dirac style boundary conditions on the
constrained 'sandwiched' gravitational action, we
show how Israel junction conditions get relaxed,
but remarkably, all solutions of the original Israel
equations are still respected. The Israel
junction conditions are traded, in
the $Z_2$-symmetric case, for a generalized
Regge-Teitelboim type equation (plus a local conservation
law), and in the generic case, for a pair of
coupled Regge-Teitelboim equations. The
Randall-Sundrum model and its derivatives, such as
the Dvali-Gabadadze-Porrati and the Collins-Holdom
models, get generalized accordingly. Furthermore,
Randall-Sundrum and Regge-Teitelboim brane theories
appear now to be two different faces of the one and
the same unified brane theory. Within the framework
of unified brane cosmology, we examine the dark
matter/energy interpretation of the effective
energy/momentum deviations from General Relativity. |
Host : Wali