Point evaluation for polynomials on the circle

Abstract: We study the constant $\mathscr{C}{d,p}$ defined as the smallest constant $C$ such that $|P|\infty^p \leq C|P|p^p$ holds for every polynomial $P$ of degree $d$, where we consider the $L^p$ norm on the unit circle. We conjecture that $\mathscr{C}{d,p} \leq dp/2+1$ for all $p \geq 2$ and all degrees $d$. We show that the conjecture holds for all $p \geq 2$ when $d \leq 4$ and for all $d$ when $p \geq 6.8$.