We formulate new gauge principles for n supersymmetric particles in a
worldline formalism with N supersymmetries. The models provide realiza
tions of the more general supersymmetries that are encountered in sect
ors of S-theory or Matrix theory, with a superalgebra of the form {Q(a
lpha)(A),Q(beta)(B)} = delta(AB)gamma(alpha beta)(mu 1...mu n)(p(mu 1)
(1)...p(mu n)(n)). Due to the local gauge and kappa symmetries the n s
uperparticle momenta p(i mu) and N supercharges Q(alpha)A are constrai
ned by p(i).p(j) = 0 and gamma.p(i)Q(A) = 0. The constraints have solu
tions only in a space with n timelike dimensions and SO(d+n-2,n) space
time symmetry. The cases SO(9,1), SO(10,2) and SO(10,3), with one, two
and three timelike dimensions respectively, are of special interest.
In each case, due to the constraints. the classical motion and quantum
theory of each superparticle are equivalent to the physics with a sin
gle time-like dimension in an effective 10D superspace with SO(9,1) Lo
rentz symmetry. (C) 1998 Elsevier Science B.V.