  We study the adsorption-desorption phase transition of directed branched
polymer in $d+1$ dimensions in contact with a line by mapping it to a $d$
dimensional hard core lattice gas at negative activity. We solve the model
exactly in 1+1 dimensions, and calculate the crossover exponent related to
fraction of monomers adsorbed at the critical point of surface transition, and
we also determine the density profile of the polymer in different phases. We
also obtain the value of crossover exponent in 2+1 dimensions and give the
scaling function of the sticking fraction for 1+1 and 2+1 dimensional directed
branched polymer.
