$c_2$ invariants of hourglass chains via quadratic denominator reduction

Abstract

We introduce families of four-regular graphs consisting of chains of hourglasses which are attached to a finite kernel. We prove a formula for the $c_2$ invariant of these hourglass chains which only depends on the kernel. For different kernels these hourglass chains typically give rise to different $c_2$ invariants. An exhaustive search for the $c_2$ invariants of hourglass chains with kernels that have a maximum of ten vertices provides Calabi-Yau manifolds with point-counts which match the Fourier coefficients of modular forms whose weights and levels are [4,8], [4,16], [6,4], and [9,4]. Assuming the completion conjecture, we show that no modular form of weight 2 and level $\le 1000$ corresponds to the $c_2$ of such hourglass chains. This provides further evidence in favour of the conjecture that curves are absent in $c_2$ invariants of ${\varphi }^4$ quantum field theory.

References in corpus (4)

• Algorithms for the symbolic integration of hyperlogarithms with applications to Feynman integrals
• Graphical functions in even dimensions
• An Introduction to Motivic Feynman Integrals
• Further investigations into the graph theory of ${\varphi }^4$-periods and the $c_2$ invariant