Hubble Law and Brane Matter after Ekpyrosis

We study brane matter in the ekpyrotic scenario and observe that in order to obtain standard gravity on the visible brane, the tension of the visible brane should be positive. If the sizes of both the fifth dimension and the Calabi-Yau threefold are fixed, the Israel junction conditions do not allow time-dependent brane matter. Relaxing this constraint, it is possible to obtain approximately standard cosmology on the visible brane, with small corrections due to possible time-dependence of the Calabi-Yau threefold.