  Angle resolved photoemission (ARPES) experiments reveal the coherent
electronic excitation in the energy spectrum of under- and optimally doped
cuprates at temperatures above their temperature of transition into
superconducting state only near nodal points on the parts of the "bare" Fermi
surface known as the Fermi arcs. That raises questions about the meaning and
possible interpretations of the experimental data. Below we derive expressions
for the Hall coefficient for the Fermi arc model both in weak and strong
magnetic fields.
