English

Blobbed topological recursion from extended loop equations

Mathematical Physics 2025-04-08 v2 Algebraic Geometry math.MP

Abstract

We consider the N×NN\times N Hermitian matrix model with measure dμE,λ(M)=1Zexp(λN4tr(M4))dμE,0(M)d\mu_{E,\lambda}(M)=\frac{1}{Z} \exp(-\frac{\lambda N}{4} \mathrm{tr}(M^4)) d\mu_{E,0}(M), where dμE,0d\mu_{E,0} is the Gaussian measure with covariance MklMmn=δknδlmN(Ek+El)\langle M_{kl}M_{mn}\rangle=\frac{\delta_{kn}\delta_{lm}}{N(E_k+E_l)} for given E1,...,EN>0E_1,...,E_N>0. It was previously understood that this setting gives rise to two ramified coverings x,yx,y of the Riemann sphere strongly tied by y(z)=x(z)y(z)=-x(-z) and a family ωn(g)\omega^{(g)}_{n} of meromorphic differentials conjectured to obey blobbed topological recursion due to Borot and Shadrin. We develop a new approach to this problem via a system of six meromorphic functions which satisfy extended loop equations. Two of these functions are symmetric in the preimages of xx and can be determined from their consistency relations. An expansion at \infty gives global linear and quadratic loop equations for the ωn(g)\omega^{(g)}_{n}. These global equations provide the ωn(g)\omega^{(g)}_{n} not only in the vicinity of the ramification points of xx but also in the vicinity of all other poles located at opposite diagonals zi+zj=0z_i+z_j=0 and at zi=0z_i=0. We deduce a recursion kernel representation valid at least for g1g\leq 1.

Keywords

Cite

@article{arxiv.2301.04068,
  title  = {Blobbed topological recursion from extended loop equations},
  author = {Alexander Hock and Raimar Wulkenhaar},
  journal= {arXiv preprint arXiv:2301.04068},
  year   = {2025}
}

Comments

49 pages. v2: discussion of the loop insertion operator and of symmetry of the \omega^{(g)}_n added; references updated and expanded; minor corrections

R2 v1 2026-06-28T08:08:41.019Z