content_image/363277.jpg content_image/363281.jpg content_image/363282.jpg
<img src='content_image/363277.jpg'>

approximately given $^{4}$, for x ≪ 1, by 

<img src='content_image/363281.jpg'>

As can be seen in Eqs. (44,45), since the lepton asymmetries in µ and τ flavors are equal but opposite in sign to the first order, i.e. ε µ 3 ≈ − ε τ $_{3}$, satisfying ε µ 3 + ε τ 3 = − ε e $_{3}$, and the wash-out parameters in µ and τ are almost equal K µ 3 ≈ K τ 3 ≫ K e $_{3}$, the effects of wash-out factor related with N$_{3}$ can play a crucial role in a successful leptogenesis according to the size of δ$_{N}$$_{3}$$_{η}$ . In strong wash-out regime K α 3 > 1 ( α = e, µ, τ ), given the initial thermal abundance of N$_{3}$ and the condition for K α $_{3}$, the resulting baryon-to-photon ratio η$_{B}$ including lepton flavor effects can be approximately given as 

<img src='content_image/363282.jpg'>

