# Consistent two-lifetime model for spectral functions of superconductors

## TL;DR

This paper compares two models with two lifetimes for analyzing spectral functions in superconductors, demonstrating that the Dynes superconductor model is consistent and fits experimental data well, unlike a previously used phenomenological model.

## Contribution

It introduces and validates the Dynes superconductor model as a consistent two-lifetime framework for spectral functions in superconductors, improving analysis of ARPES data.

## Key findings

- The phenomenological model violates the occupation number sum rule.
- The Dynes superconductor model aligns with exact results.
- Spectral functions in cuprates fit well with the Dynes model.

## Abstract

Recently it has been found that models with at least two lifetimes have to be considered when analyzing the angle resolved photoemission data in the nodal region of the cuprates [T. Kondo et al., Nat. Commun. 6, 7699 (2015)]. In this paper we compare two such models. First we show that the phenomenological model used by Kondo et al. violates the sum rule for the occupation number. Next we consider the recently proposed model of the so-called Dynes superconductors, wherein the two lifetimes measure the strengths of pair-conserving and pair-breaking processes. We demonstrate that the model of the Dynes superconductors is fully consistent with known exact results and we study in detail the resulting spectral functions. Finally, we show that the spectral functions in the nodal region of the cuprates can be fitted well by the model of the Dynes superconductors.