This review is concerned with the dynamics of low energy string theory, or M-theory, in the presence of brane degrees of freedom in a regime in which the full string (M-) theory effective action9 reduces to
More specifically, I will be concerned with the kinematical properties characterising when the latter describes a single brane, though in Section 7, the extension to many branes will also be briefly discussed. From the perspective of full string theory, it is important to establish the regime in which the full dynamics is governed by . This requires one to freeze the gravitational sector to its classical on-shell description and to neglect its backreaction into spacetime. Thus, one requires
Condition (18) is definitely necessary, but not sufficient, to guarantee the reliability of . I will postpone a more thorough discussion of this important point till Section 3.7, once the explicit details on the effective actions and the assumptions made for their derivations have been spelled out in Sections 3.1 – 3.6.
Below, I focus on the identification of the degrees of freedom and symmetries to describe brane physics. The distinction between world volume and spacetime symmetries and the preservation of spacetime covariance and supersymmetry will lead us, once again, to the necessity and existence of kappa symmetry.
Living Rev. Relativity 15, (2012), 3
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