  We provide a comprehensive theoretical description of low-energy quantum
transport for a Coulomb-Majorana junction, where several helical Luttinger
liquid nanowires are coupled to a joint mesoscopic superconductor with finite
charging energy. Including the Majorana bound states formed near the ends of
superconducting wire parts, we derive and analyze the Keldysh phase action
describing nonequilibrium charge transport properties of the junction. The
low-energy physics corresponds to a two-channel Kondo model with symmetry group
SO(M), where M is the number of leads connected to the superconductor.
Transport observables, such as the conductance tensor or current noise
correlations, display non-trivial temperature or voltage dependences reflecting
non-Fermi liquid behavior.
