field would render super-Planckian VEV dependent mass to the matter field ( for a reasonable gauge or Yukawa coupling ≤ O (1)). The effective field theory prescrip- tion is bound to break down when super-heavy quanta is running in the loops of an inflaton field. For a gauge invariant inflaton, i.e. MSSM inflaton, it is impossible to consider VEVs above the cut-off, as the inflaton has SM gauge interactions. Similarly, embedding inflation in SUGRA or in string theory will always provide inflaton VEV below the Planck scale, this remains true for any realistic potential arising from the low energy effective theory [288–290]. In a limit when the inflaton coupling to matter vanishes, or in a free field theory case, it is possible to obtain VEVs above the cut-off maintaing the effective field theory arguments given in Refs. [4, 145, 283]. • Quantum initial conditions: If inflation lasts long enough, i.e. N ∼ 60 − 70 e-foldings, then it is inevitable that the present observable mode would originate from sub-Planckian length scales. Potentially quantum gravity corrections at those length scales can leave some imprint in the CMB perturbations, it is known as the trans-Planckian problem for an inflationary cosmology [291–296]. There are two pertinent questions, the first one is related to the choice of Bunch-Davies vacuum as an initial state [185, 297] in order to evolve the quantum perturbations. Second one has to do with an adiabatic evolution of the state throughout the dynamics of inflation. Both the questions have been raised in the literature. It was observed that if either the vacuum or the evolution of a state would violate Lorentz-invariance the corrections to the amplitude of the CMB perturbations would be as large as order one. Typically the corrections will be ∝ ( H$_{inf}$$^{/M}$∗ ), where $^{M}$∗ is the cut-off above which either the initial state is modified or the evolution. In Ref. [293], the initial state was chosen to be alpha-vacuum (a variant of Bunch-Davies vacuum with large excitations) and the modification to the amplitude of the CMB perturbations were found to be ( H$_{inf}$$^{/M}$∗ ) $^{2}$. It was argued in [298] that as long as the state evolves adiabatically and Lorentz-invariance is maintained, the trans-Planckian corrections would be small of order ∼ ( H$_{inf}$$^{/M}$∗ ) $^{2}$, which is a good news for any low scale inflation. The quantum corrections to the inflaton potential arising from trace-anomaly and light scalars yield similar corrections to the CMB perturbations [299, 300]. 35