Temperature variation of the pseudogap in underdoped cuprates

We consider thermal evolution of the spectral function (Formula presented) in underdoped cuprates at (Formula presented) We find that in the strong-coupling limit, the fermionic Green’s function near (Formula presented) behaves as (Formula presented) in the whole frequency range relevant to photoemission experiments. The analysis of the pairing problem with this form of (Formula presented) yields a leading edge gap in (Formula presented) and a broad maximum at larger frequencies. We find that classical fluctuations predominantly add a frequency independent term to (Formula presented). This term destroys the leading edge gap at (Formula presented) which has a maximum value of about 200 K near (Formula presented).