  We analyze fermionic spectral function in the spin-density-wave (SDW) phase
of quasi-2D cuprates at small but finite T. We use a non-perturbative approach
and sum up infinite series of thermal self-energy terms, keeping at each order
nearly-divergent (T/J) |log epsilon| terms, where epsilon is a deviation from a
pure two-dimensionality, and neglecting regular T/J corrections. We show that,
as SDW order decreases, the spectral function in the antinodal region acquires
peak/hump structure: the coherent peak position scales with SDW order
parameter, while the incoherent hump remains roughly at the same scale as at
T=0 when SDW order is the strongest. We identify the hump with the pseudogap
observed in ARPES and argue that the presence of coherent excitations at low
energies gives rise to magneto-oscillations in an applied field. We show that
the same peak/hump structure appears in the density of states and in optical
conductivity.
