Strong spin-fluctuation effects on the photoemission line shape in the normal state of high- T_C cuprates

We have studied the quasiboson model for photoemission from cuprates in the normal state, where quasiparticles are coupled to collective spin excitations strongly enhanced near momentum (π, π). The present model has a benefit to describe the observed crossover from the overdoped to the underdoped cases because it is in principle an infinite-order theory in the limit of narrow bandwidth. The anomalous dependences of the photoemission line shape on the momentum and hole concentration are consistently understood within the model with no adjustable parameter except for a doping-independent coupling constant.