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Fermionic expressions for minimal model Virasoro characters

Combinatorics 2009-12-10 v3 Mathematical Physics math.MP

Abstract

Fermionic expressions for all minimal model Virasoro characters χr,sp,p\chi^{p, p'}_{r, s} are stated and proved. Each such expression is a sum of terms of fundamental fermionic form type. In most cases, all these terms are written down using certain trees which are constructed for ss and rr from the Takahashi lengths and truncated Takahashi lengths associated with the continued fraction of p/pp'/p. In the remaining cases, in addition to such terms, the fermionic expression for χr,sp,p\chi^{p, p'}_{r, s} contains a different character χr^,s^p^,p^\chi^{\hat p, \hat p'}_{\hat r,\hat s}, and is thus recursive in nature. Bosonic-fermionic qq-series identities for all characters χr,sp,p\chi^{p, p'}_{r, s} result from equating these fermionic expressions with known bosonic expressions. In the cases for which p=2rp=2r, p=3rp=3r, p=2sp'=2s or p=3sp'=3s, Rogers-Ramanujan type identities result from equating these fermionic expressions with known product expressions for χr,sp,p\chi^{p, p'}_{r, s}. The fermionic expressions are proved by first obtaining fermionic expressions for the generating functions χa,b,cp,p(L)\chi^{p, p'}_{a, b, c}(L) of length LL Forrester-Baxter paths, using various combinatorial transforms. In the LL\to\infty limit, the fermionic expressions for χr,sp,p\chi^{p, p'}_{r, s} emerge after mapping between the trees that are constructed for bb and rr from the Takahashi and truncated Takahashi lengths respectively.

Cite

@article{arxiv.math/0212154,
  title  = {Fermionic expressions for minimal model Virasoro characters},
  author = {Trevor A. Welsh},
  journal= {arXiv preprint arXiv:math/0212154},
  year   = {2009}
}

Comments

153 pages, includes eps figures. v2: exceptional cases clarified, (1.45/6) corrected for d=1, Section 7.5 rewritten, reference added. v3: minor typos and clarifications. To appear in Memoirs of the American Mathematical Society