English

Koplienko-Neidhardt trace formula for unitaries $-$ A new proof

Functional Analysis 2020-10-09 v1

Abstract

Koplienko \cite{Ko} found a trace formula for perturbations of self-adjoint operators by operators of Hilbert-Schmidt class B2(H)\mathcal{B}_2(\mathcal{H}). Later in 1988, a similar formula was obtained by Neidhardt \cite{NH} in the case of unitary operators. In this article, we give a still another proof of Koplienko-Neidhardt trace formula in the case of unitary operators by reducing the problem to a finite dimensional one as in the proof of Krein's trace formula by Voiculescu \cite{Voi}, Sinha and Mohapatra \cite{MoSi94,MoSi96}.

Keywords

Cite

@article{arxiv.2010.04039,
  title  = {Koplienko-Neidhardt trace formula for unitaries $-$ A new proof},
  author = {Arup Chattopadhyay and Soma Das and Chandan Pradhan},
  journal= {arXiv preprint arXiv:2010.04039},
  year   = {2020}
}

Comments

20 pages

R2 v1 2026-06-23T19:10:39.622Z