11 momentum k , denoted by χ$_{k}$ , is given by: where Γ is the rate for perturbative inflaton decay. This yields the following expression for the reheat temperature Let us freeze the expansion of the universe first. Includ- ing the expansion will not change our conclusions. For very large values of ϕ$_{0}$ , thermalization is consider- ably delayed, e.g. H$_{th}$ ≪ Γ, and hence T$_{R}$ ≪ (Γ m$_{pl}$ ) 1 / $^{2}$. This happens for We will now show that there is also a kinematic block- ing of preheating if the initial value of the flat direction fields is large. We consider the most efficient case for preheating, large field inflation, e.g. 〈 φ 〉 > m$_{pl}$ . Note that for g > 10 − $^{6}$, the inflaton induces a large mass g 〈 φ 〉 > H$_{inf}$ for χ during inflation. As a result, χ , quickly settles down to the minimum even if it is initially dis- placed, and remains there. Therefore, ϕ , does not re- ceive any mass corrections from its coupling to χ during inflation. As discussed in the previous subsection, in the in- terval m$_{ϕ}$ ≤ H ≤ m , the flat direction VEV slides very slowly because of the under damped motion due to large Hubble friction term - it is effectively frozen. Non-perturbative production of χ quanta will occur if there is a non-adiabatic time-variation in the energy, e.g. that dω$_{k}$/dt ≥ ω 2 $_{k}$. The inflaton oscillations result in a time-varying contribution to ω$_{k}$ , while the flat direction coupling to χ yields a virtually constant piece. This con- stant piece weakens the non-adiabaticity condition. In- deed time-variation of ω$_{k}$ will be adiabatic at all times, i.e. dω$_{k}$/dt < ω 2 $_{k}$, provided that h $^{2}$| ϕ | 2 > g Φ m , where Φ ∼ O ( m$_{pl}$ ) is the amplitude of the inflaton oscillations. Thus, there will be no resonant production of χ quanta if In the above discussions it has been assumed that the flat direction condensate does not decay non- perturbatively. One may think that non-perturbative ef- fects could also result in a fast decay of flat directions similar to preheating [36]. However, there is crucial dif- ference between a rotating and a radially oscillating con- densate. The F -term couplings do not lead to resonant particle production from a rotating condensate [70, 71]. It has been shown that D -term couplings of the flat di- rection can result in non-perturbative particle produc- tion [72]. However, unlike the case of a radially oscillat- ing field, the produced quanta have momenta that are less than the mass of the condensate in this case. Similar arguments lead to a kinematical blocking of fermionic preheating, as the symmetry between bosons and fermions implies similar equations for the momen- tum excitations, see Eq. (60). The flat direction VEV spontaneously breaks the SM gauge group. The gauge fields of the broken symme- tries then acquire a SUSY conserving mass of the order of α 1 / $^{2}$| ϕ | . This mass provides a physical infrared cut- off for scattering diagrams with gauge boson exchange in the t − channel. Thus the cross-section for inelastic scat- terings is now given by $^{σ$_{2}$}$→ 3 ∼ α $^{2}$| ϕ | − $^{2}$. For large values of | ϕ | the scattering rate is suppressed, which results in a delayed thermalization. It can be shown that the universe reaches thermal equilibrium when the Hubble expansion rate is (for details see Ref. [48]) The reason is that a rotating condensate has a U (1) global charge 7 that, in the case of MSSM flat direc- tions, is identified with the baryon and/or lepton num- ber [62, 63, 73]. Now, it is easy to show that the charge per particle in the rotating condensate is of O (1). Note also that the baryon and lepton number of MSSM fields, whether in the flat direction condensate or produced from the flat direction rotation, is ± 1 / 3 and ± 1 respectively. Hence preservation of the baryon/lepton number by the D -term interactions, along with the conservation of en- ergy density, implies that for an elliptic trajectory with O (1) eccentricity the number of produced quanta cannot be much smaller than the number of zero-mode quanta in the rotating condensate [69]. Therefore, the non- perturbative decay of a rotating flat direction does not change the thermalization picture described above. The reason for a delayed thermalization is due to in- ducing large masses to the gauge/gaugino fields from the VEV of the flat direction. The induced mass by the plasma is given by m 2 eff ∼ αn/ 〈 E 〉 , where 〈 E 〉 and n are the average energy and number density of quanta in the plasma respectively. Since they cannot be much dif- ferent from those in the condensate, the induced masses will also be comparable. E. Thermalization ω$_{k}$ = ( k 2 + 2 g $^{2}$φ2 $_{+}$√$_{2}$$_{gmφ}$$_{+ 2}$$_{h}$ $^{2}$| ϕ | 2 ) 1 / $^{2}$. (60) T$_{R}$ ∼ ( H$_{th}$m$_{pl}$ ) 1 / $^{2}$. (63) ϕ$_{0}$ > 3 α m$_{ϕ}$m$_{pl}$ ( m Γ) 1 / $_{2}$. (64) ϕ$_{0}$ $_{> h}$− $^{1}$( gm$_{pl}$m ) 1 / 2 , (61) H$_{th}$ = min [10 α 2 ( m$_{pl}$ ϕ$_{0}$ ) 2 m 2 ϕ m , (62) 10 α 2 ( m$_{pl}$ ϕ$_{0}$ ) $^{2}$( Γ m$_{ϕ}$ ) 1 / 2 m 2 ϕ m , Γ] , 7 This charge corresponds to the angular momentum of the rotat- ing condensate in field space.