  Many-body effects on quantum capacitance, compressibility, renormalized Fermi
velocity, kinetic and interaction energies of massless Dirac electrons in
graphene, induced by the Coulomb interactions, are analyzed theoretically in
the first-order, Hartree-Fock and random phase approximations. Recent
experimental data on quantum capacitance and renormalized Fermi velocity are
analyzed and compared with the theory. The bare Fermi velocity and the
effective dielectric constants are obtained from the experimental data. A
combined effect of Coulomb interactions and Gaussian fluctuations of disorder
potential is considered.
