2
votes
0answers
58 views

Gravity at large distances, the DGP model vs. compactification of dimensions

If we live in $4+n$ dimension and compactify the extra $n$ dimensions so that they are of typical size $R$, then on scales $r\gg R$ gravity is known to act in the normal manner. That is, the ...
3
votes
1answer
74 views

Must string models that describe 4d effective field theories always have D-branes that extend in the 4 non-compact spacetime dimensions?

In string theory the D-branes give those directions that the strings are allowed to move along. The string excitations give the fields that we detect. Is it correct to think of a particle propagating ...
6
votes
1answer
128 views

Disappearance of moduli for condensate of open strings

Consider a Dp-brane. Compactify $d$ spatial dimensions over a torus $T^d$. Suppose $d\geqslant p$, and that the Dp-brane is completely wrapped around the compactified dimensions. Look at the open ...