q-deformation and instability of the phonon spectrum in 4He

We present an application of a q-deformed system to phonons in 4He. We show that a discrepancy between theory and experiments concerning the stability of phonon spectrum can be overcome when we treat the gas of phonon excitations in 4He as an ideal deformed bosonic gas in a ν0 inequivalent representation. Our results are compared with data from 4He specific heat measurements for T<1 K and we reproduce within 5% of accuracy the curves resulting from least-squares fits of those data.