Orbifold string topology

It is well known that the category of orbifolds is equivalent to the category of proper etale groupoids modulo Morita equivalences. This allows one to talk about the classifying space of an orbifold or even the loop groupoid of a representing groupoid. Moreover in the case of a global quotien X = [M∕G], we can follow the methods of R. Cohen and J. Jones to define a Chas-Sullivan string product on the homology of the free loop space of the classifying space of an orbifold. The resulting ring is a BV algebra and realizes the Chas-Sullivan construction in the case in which the orbifold is a manifold. (PDF file)