A1-CONNECTEDNESS OF MODULI OF VECTOR BUNDLES ON A CURVE

Abstract

In this note, we prove that the moduli stack of vector bundles on a curve with a fixed determinant is A(1)-connected. We obtain this result by classifying vector bundles on a curve up to A(1) concordance. Consequently, we classify P-n-bundles on a curve up to A(1)-weak equivalence, extending a result in [3] of Asok-Morel. We also give an explicit example of a variety which is A(1)-h-cobordant to a projective bundle over P-2 but does not have the structure of a projective bundle over P-2, thus answering a question of Asok-Kebekus-Wendt [2].