Spin and Pseudospin Dynamics of the Anderson Model

Manne Stenberg, A.A. Alastalo, M.M. Salomaa

Rachel Wortis, Malcolm P. Kennett

Canio Noce, Mario Cuoco

It is shown that the ground state of the symmetric one-dimensional periodic Anderson model on a bipartite lattice with periodic boundary conditions is a pseudospin singlet and has total momentum equal to zero. \textcopyright{} 1996 The American Physical Society.

Vinayak M. Kulkarni

We construct an interacting integrable realization of many-body exceptional-point amplification in the static equal-velocity linearized finite-$U$ Anderson impurity. Two spin-orbit branches are linearized about counterpropagating Fermi points and folded into equal-velocity chiral components. The impurity carries the constant pseudo-Hermitian matrix $M=γσ_x+iβσ_z$, while the hybridization is a component scalar. A canonical $GL(2,\mathbb C)$ transformation preserves the Anderson interaction, and a position-dependent version maps the model to the conventional Anderson Hamiltonian plus a conserved complexified pseudospin charge with boundary twist $G=\exp(iML/v)$. The exact two-electron Anderson $R$-matrix is rational in the dressed rapidity $u(p)=p(p-2ε_d-U)/(2UΓ_A)$ and yields YBE, RLL, and twisted RTT relations for arbitrary particle number. At $β^2=γ^2$, $G$ is nontrivial unipotent. On every pseudospin-$S$ multiplet, the deformed Hamiltonian is similar to a single Jordan block of order $2S+1$; finite $U$ shifts its energy but does not split it. Approaching the unipotent point through a singularly conjugated diagonal twist, the descendant spin roots contract to $λ=\infty$ with scaled positions fixed by $L_r^{(-2S-1)}(2x)$. For the maximal descendant at large $S$, their normalized zeros converge to the Szego curve. Curvature, unequal velocities, and nonscalar channel couplings lie outside the theorem.

N. S. Vidhyadhiraja, David E. Logan

Paul B. Wiegmann