The core results of the Kreı̆n-Višik-Birman theory of self-adjoint extensions of semi-
bounded symmetric operators are reproduced, both in their original and in a more modern …

We consider a Dirac operator in three space dimensions, with an electrostatic (ie, real-
valued) potential V (x), having a strong Coulomb-type singularity at the origin. This operator …

We describe the self-adjoint realizations of the operator H:=-i α ⋅ ∇+ m β+ V (x) H:=-i α·∇+
m β+ V (x), for m ∈ R m∈ R, and V (x)=| x|^-1 (ν I _4+ μ β-i λ α ⋅ x/| x|\, β) V (x)=| x|-1 (ν I 4+ …

Semibounded symmetric operators have a distinguished self-adjoint extension, the
Friedrichs extension. The eigenvalues of the Friedrichs extension are given by a variational …

We prove a sharp Hardy-type inequality for the Dirac operator. We exploit this inequality to
obtain spectral properties of the Dirac operator perturbed with Hermitian matrix-valued …

The one-particle Dirac Hamiltonian with Coulomb interaction is known to be realised, in a
regime of large (critical) couplings, by an infinite multiplicity of distinct self-adjoint operators …

A square-integrable spinor solution to non-interacting Dirac equations | AIP Advances | AIP
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Observables in quantum mechanics are represented by self-adjoint operators on Hilbert
space. Such ubiquitous, well-known, and very foundational fact, however, is traditionally …

We investigate the properties of self-adjointness of a two-dimensional Dirac operator on an
infinite sector with infinite mass boundary conditions and in the presence of a Coulomb-type …

We determine explicitly a boundary triple for the Dirac operator H≔− i α⋅∇+ m β+ V (x) in R
3⁠, for m∈ R and V (x)=| x|− 1 (ν I 4+ μ β− i λ α⋅ x/| x| β)⁠, with ν, μ, λ∈ R⁠. Consequently …