New family of hyperbolic knots whose Upsilon invariants are convex

Keisuke Himeno

Published 2024-03-20Version 1

The Upsilon invariant of a knot is a concordance invariant derived from knot Floer homology theory. It is a piecewise linear continuous function defined on the interval $[0,2]$. Borodzik and Hedden gave a question asking for which knots the Upsilon invariant is a convex function. It is known that the Upsilon invariant of any $L$-space knot, and a Floer thin knot after taking its mirror image, if necessary, as well, is convex. Also, we can make infinitely many knots whose Upsilon invariants are convex by the connected sum operation. In this paper, we construct infinitely many mutually non-concordant hyperbolic knots whose Upsilon invariants are convex. To calculate the full knot Floer complex, we make use of a combinatorial method for $(1,1)$-knots.