Non-Fermi liquid behavior in two-dimensional metals at the onset of incommensurate density wave order

Quantum critical fluctuations at the onset of incommensurate 2k_F charge or spin density wave order strongly affect single-particle excitations in two-dimensional metals. The case of a single pair of hot spots at high symmetry positions on the Fermi surface needs to be distinguished from the case of two hot spot pairs. The energy dependence of the single-particle decay rate at the hot spots obeys non-Fermi liquid power laws, with an exponent 2/3 in the case of a single hot spot pair, and exponent one for two hot spot pairs – in leading order perturbation theory. The prefactors of the linear behavior obtained in the latter case exhibit a pronounced particle-hole asymmetry.