  We study the short time behavior of the order parameter coupled to a
conserved field in semi-infinite geometry. The short time exponent, obtained by
solving the one loop differential equations for the conserved density and the
order parameter, agrees with the prediction from a scaling argument based on
short distance expansion. The scaling analysis further shows that this exponent
satisfies a scaling relation similar to that known in the case of a
nonconserved order parameter without any coupling.
