Degree-4 Sum-of-Squares improvement for Paley clique number

Show that there exists ε > 0 such that the degree-4 Sum-of-Squares relaxation for the clique number of the Paley graph yields an O(p^{1/2 − ε}) upper bound.

Background

The Lovasz theta (degree-2 SoS) yields at best √p-type bounds for Paley graphs. Numerical evidence suggests that degree-4 SoS could achieve better-than-√p scaling, potentially polynomially better, though lower bounds limit improvements to Ω(p{1/3}).

Proving an O(p{1/2−ε}) bound would demonstrate a concrete advantage of low-degree SoS over classical SDP relaxations for Paley graphs.

References

Conjecture There exists $\varepsilon>0$ such that the Sum-of-Squares relaxation of degree 4 for the clique number of the Paley graph gives a bound of $O(p{\frac12-\varepsilon})$.

Randomstrasse101: Open Problems of 2025  (2603.29571 - Bandeira et al., 31 Mar 2026) in Conjecture, Section “On the clique number of the Paley Graph (ASB)” (Entry 12)