Thermodynamic and other properties of a high-Tcexcitonic superconductor

We have calculated the isotope effect, the thermodynamics, and the gap (${\Delta }_0$) to critical temperature ($T_c$) ratio for an excitonic superconductor. We consider the possibility that some contribution to the pairing interaction is due to the electron-phonon interaction. As the amount of electron-phonon contribution is increased from zero, the thermodynamic ratios start deviating from Bardeen-Cooper-Schrieffer behavior, but in the opposite direction from conventional strong-coupling superconductors. The isotope effect increases very slowly from zero and $\frac{2{\Delta }_0}{k_B{T}_c}$ remains close to 3.54 for a significant range of phonon coupling strength.