Refined asymptotic formula for representation counts

Derive an improved asymptotic formula for the number p_r(n) of n-dimensional representations of \(\mathfrak{sl}_{r+1}(\mathbb{C})\), generalizing Romik’s asymptotic formula for \(r=2\), by computing the saddle-point parameter \(q_n\) to sufficient accuracy and conducting a more precise analysis of the associated Witten zeta functions or of the expansion in Proposition 1.1.

Background

The paper relates the enumeration function pr(n)p_r(n) to the Boltzmann model and, using equivalence of ensembles, obtains the asymptotic pr(n)nr+2r+3(2πDr,var)1/2qnnkNr(1qna(k))1p_r(n) \sim n^{-\frac{r+2}{r+3}}(2\pi D_{r,\mathrm{var}})^{-1/2}q_n^{-n}\prod_{k\in\mathbb{N}^r}(1-q_n^{a(k)})^{-1}. The authors explain that a more accurate evaluation of the saddle-point parameter qnq_n would permit this estimate to be sharpened into an asymptotic formula with further terms.

The proposed refinement is intended to extend the known result of Romik for r=2r=2 to the general family of representation-counting functions. The authors identify the likely technical requirements as a more careful study of Witten zeta functions or additional terms in the asymptotic expansion established in Proposition 1.1. The problem is explicitly left unresolved.

References

If qn is computed to enough accuracy, then the above may be improved to an asymptotic formula that generalizes Romik’s asymptotic formula for r = 2 in [22]. As this would likely require a more careful study of the Witten zeta functions or more terms in the expansion in Proposition 1.1, we leave this as an open problem.

Statistics for random representations of Lie algebras  (2503.02822 - Bridges et al., 4 Mar 2025) in Remark following Proposition 4.4, Section 4.2, p. 14