We present a topological recursion formula for calculating the intersection
numbers defined on the moduli space of open Riemann surfaces. The spectral
curve is x=21y2, the same as spectral curve used to calculate
intersection numbers for closed Riemann surfaces, but the formula itself is a
variation of the usual Eynard-Orantin recursion. It looks like the recursion
formula used for spectral curves of degree 3, and also includes features
present in β-deformed models. The recursion formula suggests a
conjectural refinement to the generating function that allows for
distinguishing intersection numbers on moduli spaces with different numbers of
boundary components.Comment: 17 page