Strings, branes and two-time physics

We generalize the ideas and formalism of two-time physics from particle dyn amics to some specific examples of string and p-brane(p greater than or equ al to 1) dynamics. The two-time string or p-brane action can be gauge fixed to produce various one-time string or p-brane actions that are dual to eac h other under gauge transformations. We discuss the particular gauges that correspond to tensionless strings and p-branes in flat (d - 1) + 1 spacetim e, rigid strings and p-branes in flat (d - 1) + I spacetime, and tensionles s strings and p-branes propagating in the AdS(d-n) x S-n backgrounds. (C) 1 999 Published by Elsevier Science B.V. All rights reserved.