M-theory superalgebra from the M-5-brane

The algebra of Noether supercharges of the M-5-brane effective action is shown to include both 2-form and 5-form central charges. Surprisingly, only the 5-form charge is entirely due to the Wess-Zumino term because the `naive' algebra is the M-2-brane supertranslation algebra. The full structure of central charges is shown to be directly related to the projector arising in the proof of $\kappa$-symmetry of the M-5-brane action. It is also shown to allow `mixed' M-brane configurations preserving 1/2 supersymmetry that include the (non-marginal) M-2-brane/M-5-brane `bound state' as a special case.