  The persistence exponents associated with the T=0 quenching dynamics of the
two dimensional XY model and a two dimensional uniaxial spin nematic model have
been evaluated using a numerical simulation. The site persistence or the
probability that the sign of a local spin component does not change starting
from initial time t=0 up to certain time t, is found to decay as L(t)^-theta,
(L(t) is the linear domain length scale), with theta =0.305 for the two
dimensional XY model and 0.199 for the two dimensional uniaxial spin nematic
model. We have also investigated the scaling (at the late time of phase
ordering) associated with the correlated persistent sites in both models. The
persistence correlation length was found to grow in same way as L(t).
