  High frequency quasiperiodic oscillations (HF QPOs) detected in the power
spectra of low mass x-ray binaries (LMXBs) could unveil the fingerprints of
gravitation in strong field regime. Using the energy-momentum relation we
calculate the energy a clump of plasma orbiting in the accretion disk releases
during circularization of its slightly eccentric relativistic orbit. Following
previous works, we highlight the strong tidal force as mechanism to dissipate
such energy. We show that tides acting on the clump are able to reproduce the
observed coherence of the upper HF QPO seen in LMXBs with a neutron star (NS).
The quantity of energy released by the clump and relativistic boosting might
give a modulation amplitude in agreement with that observed in the upper HF
QPO. Both the amplitude and coherence of the upper HF QPO in NS LMXBs could
allow us to disclose, for the first time, the tidal circularization of
relativistic orbits occurring around a neutron star.
