An Alexander Polynomial Obstruction to Cosmetic Crossing Changes

Abstract: The cosmetic crossing conjecture posits that switching a non-trivial crossing in a knot diagram always changes the knot type. Generalizing work of Balm, Friedl, Kalfagianni and Powell, and of Lidman and Moore, we give an Alexander polynomial condition that obstructs cosmetic crossing changes for knots with $L$-space branched double covers, a family that includes all alternating knots. As an application, we prove the cosmetic crossing conjecture for a five-parameter infinite family of pretzel knots. We also discuss the state of the conjecture for alternating knots with eleven crossings.