BPS states on non-commutative tori and duality Original Research Article

We study gauge theories on non-commutative tori. It has been proved that Morita equivalence of non-commutative tori leads to a physical equivalence (SO(d, d/Z)-duality) of the corresponding gauge theories [Nucl. Phys. B 534 (1998) 720]. We calculate the energy spectrum of maximally supersymmetric BPS states in these theories and show that this spectrum agrees with the SO(d, d/Z)-duality. The relation of our results with those of recent calculations is discussed.