  We study the static and dynamic behavior of the one dimensional pair contact
process with diffusion. Several critical exponents are found to vary with the
diffusion rate, while the order-parameter moment ratio m=\bar{rho^2}
/\bar{rho}^2 grows logarithmically with the system size. The anomalous behavior
of m is traced to a violation of scaling in the order parameter probability
density, which in turn reflects the presence of two distinct sectors, one
purely diffusive, the other reactive, within the active phase. Studies
restricted to the reactive sector yield precise estimates for exponents beta
and nu_perp, and confirm finite size scaling of the order parameter. In the
course of our study we determine, for the first time, the universal value m_c =
1.334 associated with the parity-conserving universality class in one
dimension.
