• Stable KK modes and gravitons: • Breakdown of an effective description of a (MS)SM throat: • Reheating via tunneling: D 3- D 3 annihilation also excites massive KK modes and gravitons. The heavy KK modes can decay into the lightest KK mode and gravitons. The lightest KK mode can be absolutely stable at the bottom of the throat due to conserved angular mo- mentum [884]. The self annihilation of these KK modes is gravitationally suppressed, σ ∼ ( L/R ) $^{6}$(1 /M$_{P}$h $^{2}$), where L is linear size of the 6 d compactification volume and R is the size of the throat, h is the relative warping [884, 885], therefore once produced copiously during brane annihilation, these KK modes can overclose the universe. Due to the hierarchy between inflation and (MS)SM throat, during inflation the (MS)SM throat will also be sensitive to inflation-induced vacuum fluctuations. The curvature scalar of the (MS)SM throat will obtain corrections of order, R ∼ 12 H 2 $_{inf}$e − 2 $^{A$_{SM}$}$, with e − 2 A$_{SM}$ ∼ ( M$_{P}$/M$_{SM}$ ) 2 ≫ 1 during inflation [883], which will ren- der perturbative description of the (MS)SM throat ineffective. The (MS)SM throat will now be uplifted by warping given by e A$_{SM}$ ∼ H$_{inf}$/M$_{P}$ [883]. Once inflation ends, the geometry of (MS)SM throat will start relaxing gradually before settling down to its original value. The process of relaxation could give rise to a violent particle production and excitations of open and closed strings [883]. The massive KK modes can decay into the (MS)SM throat via quantum tunneling [931, 932]. There is a large uncertainty in the tunneling rate, for a range of parameters given by the RR flux, n$_{R}$ ∼ 10 − 100, 6 d compactified volume, e 4 $^{u}$/g$_{s}$ ∼ 1 − 10 3 and g$_{s}$ ∼ 1 / 10, the rate is roughly given by: Γ$_{t}$ ∼ O (10 − 10 $^{10}$)( H$_{inf}$/M$_{P}$ ) 3 / $^{2}$H$_{inf}$ [883]. With the above tunneling rate the reheat temperature of the (MS)SM throat, T$_{R}$ ∼ √$_{Γ}$$_{t}$$_{M}$$_{P}$$_{,}$ will exceed the fundamental scale M$_{SM}$ . This would lead to excitations of the KK modes and gravitons in the (MS)SM throat. Again the universe would be dominated a gas of non-relativistic KK particles. In all the cases, the reheating temperature is very close to the string scale, T$_{R}$ ∼ M$_{SM}$ , in the (MS)SM throat. This gives rise to thermal excitations of long open, and closed strings, into account of the hidden sectors along with the SM sector. 234