feynlag.vacuum.masses.seesaw_mass_matrix¶

feynlag.vacuum.masses.seesaw_mass_matrix(m_D, M_R)[source]¶

The type-I-seesaw neutral-fermion Majorana mass matrix.

In the left-handed basis n = (ν_L, ν_R^c) the mass term is −½ nᵀ C M n + h.c. with the symmetric block matrix

M = [[ 0 , m_D ],
[ m_Dᵀ, M_R ]]

where m_D (n_L × n_R) is the Dirac mass (= Y_ν v/√2, e.g. from fermion_mass_matrix() on the L̄ H̃ ν_R Yukawa) and M_R (n_R × n_R, symmetric) the right-handed Majorana mass (from majorana_mass_matrix()). The result is symmetric and ready for diagonalize_takagi().