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In this paper the effects of time-dependent Newton constant $G$ during inflation are studied.
We present the formalism of curvature perturbations in an inflationary system with time-dependent Newton constant.
As an example we consider a toy model in which $G$ undergoes a sudden change during inflation. By imposing the
appropriate matching conditions the imprints of this sharp change in $G$ on curvature perturbation power spectrum
are studied. We show that depending on whether $G$ increases (decreases) during the transition the amplitude of curvature perturbations on large scales decreases (increases). In our model with a sudden change in $G$ a continuous sinusoidal modulations of curvature power spectrum is induced which can be detected on CMB. In a realistic scenarioin which the change in $G$ has some finite time-scales, we expect this sinusoidal modulations to be damped on short scales.The generated feature may be used to explain the observed glitches on CMB power spectrum. This puts a bound on $\Delta G$ during inflation roughly the same order as current bounds on $\Delta G$ during entire observed age of the universe.
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