20.3. L-channel for Majorana fermions Consider the Dirac action of a Majorana massive fermion on a finite volume S =  dt 

R2

−R2 dx ¯ψ i γ μ ∂μ −m ψ.

Quantize this system in the canonical way and show that the finite volume ground state energy E0(R) can be written as E0(R) = −π c−(r)

6R

, where the scaling function c−(r) coincides with the expression given by the TBA.