A new invariant of equivariant concordance and results on 2-bridge knots

We study the equivariant concordance classes of 2-bridge knots and we prove that no 2-bridge knot is equivariantly slice. Finally, we introduce a new equivariant concordance invariant for strongly invertible knots. Using this invariant as an obstruction we strengthen the result on 2-bridge knots, proving that every 2-bridge knot has infinite order in the equivariant concordance group.