# On Convergence of Spectral Expansions of Dirac Operators with Regular Boundary Conditions

## TL;DR

This paper investigates the spectral properties of Dirac operators with regular boundary conditions and complex potentials, aiming to establish conditions for the root functions to form a Riesz basis without parentheses.

## Contribution

It provides new criteria ensuring the root function system of Dirac operators forms a standard Riesz basis under regular boundary conditions.

## Key findings

- Identifies conditions for Riesz basis formation
- Distinguishes between usual and parentheses Riesz bases
- Advances understanding of spectral expansions for Dirac operators

## Abstract

Spectral problem for the Dirac operator with regular but not strongly regular boundary conditions and complex-valued potential summable over a finite interval is considered. The purpose of this paper is to find conditions under which the root function system forms a usual Riesz basis rather than a Riesz basis with parentheses.