Jens Marklof
Theta sums, Eisenstein series, and the semiclassical dynamics of a 
precessing spin
(2958K, postscript)

ABSTRACT.  Recent results on the asymptotic behaviour of theta sums are illustrated
with physical examples, such as the semiclassical time evolution of a
quantum spin, which has been previously discussed by Berry and Goldberg.
The second goal is to give a detailed account of the equidistribution of
closed horocycles on the metaplectic cover of the special linear group
SL(2,R) modulo a certain arithmetic subgroup, which in turn can be used to
calculate the limit distribution of the values of theta sums.