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They are normalized to Tr T $^{α}$T β = δ $^{αβ}$. In this basis 5 , which decomposes into ( 2 , 2 ) ⊕ ( 1 , 1 ) under SU (2)$_{L}$ × SU (2)$_{R}$, reads 

where the first (second) subscript ± , 0 corresponds to T 3 L = ± 1 $_{2}$, 0 ( T 3 R = ± 1 $_{2}$, 0), respectively. 

<img src='content_image/350588.jpg'>

## Appendix B: KK expansion in the presence of boundary Majorana masses 

Let us consider the effect on the KK expansion of a bulk fermion ψ with a UV localized Majorana mass term 

and then satisfying the UV boundary condition 

The corresponding KK expansion can be written 

where the 4D fields are assumed to obey a Majorana equation 

<img src='content_image/350583.jpg'>

<img src='content_image/350584.jpg'>

<img src='content_image/350582.jpg'>

<img src='content_image/350581.jpg'>

If we insert these expansions in the 5D equations of motion and use the 4D Majorana equations, we get a system of coupled differential equations 

<img src='content_image/350585.jpg'>

The solution of this system of equations can be obtained using standard techniques (decou- pling by iteration and use of the first order equation to obtain the second solution), 

<img src='content_image/350586.jpg'>

