The energy-carrying velocity and rolling of tachyons of unstable D-branes

It is shown that the tachyons which originate from unstable D-branes carry energy and momentum at the velocity $\beta = c^2/v,$ where $v$ is the phase velocity which is greater than $c.$ For an observer who moves with the velocity $\beta,$ tachyon is observed to be moving from one of the ground states of the tachyon potential to the poten...More