From the 1 of 9 linked papers with an AI index.
9 papers
Metric completion of the Bender--Brody--Müller Hamiltonian: dilation spectrum and missing eigenstates
Kejun Liu
The Bender--Brody--Müller (BBM) Hamiltonian was proposed as a non-Hermitian Hilbert--Pólya operator. We analyze the Hilbert completion induced, on the standard half-line co…
Paraparticles intrinsically exhibit Hardy-space breakdown
Kejun Liu
The paper shows that particles with non‑unitary exchange statistics (paraparticles) inherently violate the Hardy‑space analyticity required for Kramers–Kronig relations in the memo…
Operator-Valued Hardy Spaces and Kramers--Kronig Relations for Non-Markovian Quantum Memory Kernels
Kejun Liu
Retarded support, upper-half-plane holomorphy, and Hardy boundary control are distinct properties of a memory kernel. We give sufficient conditions linking them for the Nakajima--Z…
A real-space exceptional ring mediates an eigenframe-charge transition in a non-Hermitian skyrmion
Kejun Liu
The integer topological charge of a skyrmion is the standard example of topological protection. We ask what happens to that protection when the local generator is made non-Hermitia…
Dispersion Relations Across the Unitarity Boundary
Kejun Liu
Kramers-Kronig (KK) relations rest on a binary premise: a response function is either analytic in the upper half-plane or it is not. We show that a single reduced-state transform o…
Exceptional Points as Manifestations of Analyticity Breakdown in the 't Hooft Model
Kejun Liu
We use the exactly-solvable t Hooft model of 1+1D large-N_c QCD as a rigorous laboratory for the breakdown of analyticity of a causal response function, the meson two-point functio…