  The variance of the local density of the pair contact process with diffusion
(PCPD) is investigated in a bosonic description. At the critical point of the
absorbing phase transition (where the average particle number remains constant)
it is shown that for lattice dimension d>2 the variance exhibits a phase
transition: For high enough diffusion constants, it asymptotically approaches a
finite value, while for low diffusion constants the variance diverges
exponentially in time. This behavior appears also in the density correlation
function, implying that the correlation time is negative. Yet one has dynamical
scaling with a dynamical exponent calculated to be z=2.
