  We present an energy-dependent analysis for the type-C quasi-periodic
oscillations (QPOs) observed in the black hole X-ray binary Swift J1727.8-1613
using Insight-HXMT observations. We find that the QPO fractional rms at
energies above 40 keV is significantly higher than that below 20 keV. This is
the first report of a high energy (HE)-rms excess in the rms spectrum of a
black hole X-ray binary. In the high energy band, an extra hard component is
observed in additional to the standard thermal Comptonization component at
similar energy band. The value of the QPO HE-rms excess is not only correlated
with the disk parameters and the photon index of the standard Comptonization
component, but also exhibits a moderate positive correlation with the flux of
the additional hard spectral component. No features in the QPO phase-lag
spectra are seen corresponding to the additional hard component. We propose
that the additional hard component in the spectrum may originate from jet
emission and the associated QPO HE-rms excess can be explained by the
precession of the jet base.
