Fig. 7: Feynman diagrams of G2κκ′ (τ,s,t) for the second–order peaks of dG/dVb.
The solid lines with right and left arrows represent the propagations of electrons moving forward and backward in the time domain in the conduction band, respectively. The backward propagation appears as a complex conjugation of the probability amplitude in the forward propagation. Colored wavy lines denote the exchange of phonons between electrons and holes, while different colors refer to different phonon modes such as LA and LO. Two different tunneling processes via intermediate states of \({\kappa }_{{{{{{\rm{A}}}}}}}\) and \({\kappa }_{{{{{{\rm{B}}}}}}}\) exhibit quantum interference when those processes involve two phonons with a reversed order. The interaction strength of each term is presented before the parentheses. We highlight that quantum interference occurs as the intermediate states \({\kappa }_{{{{{{\rm{A}}}}}}}\) and \({\kappa }_{{{{{{\rm{B}}}}}}}\) are distinct in 2D SC-TMDs.
