The open supersymmetric Haldane-Shastry spin chain and its associated motifs

Oct 16, 2020
51 pages
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20202021202201
Abstract: (arXiv)
We study the open version of the su(mn)(m|n) supersymmetric Haldane-Shastry spin chain associated to the BCNBC_N extended root system. We first evaluate the model's partition function by modding out the dynamical degrees of freedom of the su(mn)(m|n) supersymmetric spin Sutherland model of BCNBC_N type, whose spectrum we fully determine. We then construct a generalized partition function depending polynomially on two sets of variables, which yields the standard one when evaluated at a suitable point. We show that this generalized partition function can be written in terms of two variants of the classical skew super Schur polynomials, which admit a combinatorial definition in terms of a new type of skew Young tableaux and border strips (or, equivalently, extended motifs). In this way we derive a remarkable description of the spectrum in terms of this new class of extended motifs, reminiscent of the analogous one for the closed Haldane-Shastry chain. We provide several concretes examples of this description, and in particular study in detail the su(11)(1|1) model finding an analytic expression for its Helmholtz free energy in the thermodynamic limit.
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  • 51 pages, typeset with LaTeX