Heegaard Floer theory and pseudo-Anosov flows I: Generators and categorification of the zeta function

We bring to light a new connection between dynamics and Heegaard Floer homology. On a closed 3-manifold $Y$ we consider a pseudo-Anosov flow $\phi$ with no perfect fits with respect to its singularity locus $L\subset Y$, or perhaps a larger collection of closed orbits. Using work of Agol and Guéritaud on veering branched surfaces we produce a chain complex computing the link Floer homology of $L$ in the framing specified by the degeneracy curves of the flow. Using work of Landry, Minsky, and Taylor we show that the generators of the chain complex correspond to certain closed multi-orbits of $\phi$. We prove that two canonical generators ${\mathbf{x}}^{\mathrm{t}\mathrm{o}\mathrm{p}}$ and ${\mathbf{x}}^{\mathrm{b}\mathrm{o}\mathrm{t}}$ determine non-trivial homology classes located in the ${\text{spin}}^{\text{c}}$-grading of the flow, and its opposite. Finally, we observe that our specific model of the chain complex for link Floer homology naturally supports a grading with dynamical significance. This grading, a modification of the regular Maslov grading, is shown to categorify a suitable normalization of the zeta function associated to $\phi$.