Effect of hybridization parity on multiband superconductors properties

We investigated the influence that hybridization parity has on the so-called multiband superconductors, where we proposed a model with two bands [Formula: see text] and [Formula: see text]. Thus, we observe the behavior of intra-band superconductivity, the one whose coupling occurs between carriers that belong to the same band [Formula: see text] or [Formula: see text], and inter-bands, when the coupling occurs between carriers of different bands [Formula: see text] with [Formula: see text] — from graphs of the order parameter as a function of hybridization and the order parameter as a function of temperature, for null temperature in the first case and for finite temperature in the second, as well as intraband phase diagrams. In this sense, the study of the influence that hybridization has on superconductivity is fundamental for understanding unconventional superconductors, such as heavy fermions and high-temperature superconductors.

Integrating out new fermions at one loop

We present the fermionic universal one-loop effective action obtained by integrating out heavy vector-like fermions at one loop using functional techniques. Even though previous approaches are able to handle integrating out heavy fermions with non-chiral interactions, i.e. vanishing γ5 interaction terms, the computations proceed in a tedious manner that obscures a physical interpretation. We show how directly tackling the fermionic functional determinant not only allows for a much simpler and transparent computation, but is also able to account for chiral interaction terms in a simple, algorithmic way. Finally, we apply the obtained results to integrate out at one loop the vector-like fermions appearing in a toy model and in a fermionic model that exhibits strong cosmological phase transitions.