N-particle quantum mechanics described by a sigma model with an N-dimensional
target space with torsion is considered. It is shown that an SL(2,R) conformal
symmetry exists if and only if the geometry admits a homothetic Killing vector
Da whose associated one-form Da is closed. Further, the SL(2,R) can
always be extended to Osp(1|2) superconformal symmetry, with a suitable choice
of torsion, by the addition of N real fermions. Extension to SU(1,1|1) requires
a complex structure I and a holomorphic U(1) isometry DaIab∂b.
Conditions for extension to the superconformal group D(2,1;\alpha), which
involve a triplet of complex structures and SU(2) x SU(2) isometries, are
derived. Examples are given.Comment: 23 pages harvmac. Conventions simplified; typos corrected; references
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