Locally critical umklapp scattering and holography

Understand

Efficient momentum relaxation through umklapp scattering, leading to a power law in temperature d.c.

• resistivity, requires a significant low energy spectral weight at finite momentum.
• One way to achieve this is via a Fermi surface structure, leading to the well-known relaxation rate Gamma ~ T^2.
• We observe that local criticality, in which energies scale but momenta do not, provides a distinct route to efficient umklapp scattering.