Description
The replica trick is widely used to calculate entanglement and R\'enyi entropies in conformal field theory, but its application to logarithmic and non-unitary theories is less understood. We study this problem in $c=-2$ logarithmic CFTs, using symplectic fermions and the continuum theory of the non-Hermitian SSH model as complementary realizations. We find an odd--even splitting of the R\'enyi moments arising from fermionic replica sewing, with odd and even replica numbers following distinct scaling sequences. On the odd branch connected to $n=1$, an infrared Grassmann zero mode produces an additional $\log(mL/v_F)$ contribution, accounting for the residual entropy observed in the lattice model. For two disjoint intervals, the twist-field four-point function contains an additional logarithmic contribution beyond the standard conformal dependence. Together, these results show that entanglement in c=-2 logarithmic critical theories contains universal information beyond the central charge.