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\sect{Heat capacity of He4}

The specific heat of He4 at low temperatures has the form ${Cv =
AT^{3} + B\left(T\right)exp\left(\frac{-\triangle}{T}\right)}$.
What
can you deduce about the excitations of the system? (assume that the
density of excitation modes has the form
${g\left(\omega\right)~\omega ^{p} 0}$.
What would be the form of
${Cv}$ for a similar system in a two dimensional world?





