2021/02/17 by Biswas, Indranil, Parameswaran, A. J. · 1 citation
#14E20 #14H30 #14H60 #Algebraic Geometry (math.AG) #FOS: Mathematics
paper · doi:10.48550/arxiv.2102.08744
Let f:C→ D be a nonconstant separable morphism between irreducible smooth projective curves defined over an algebraically closed field. We say that f is genuinely ramified if \mathcal OD is the maximal semistable subbundle of f_*\mathcal OC (equivalently, the homomorphism of etale fundamental groups is surjective). We prove that the pullback f^*E→ C is stable for every stable vector bundle E on D if and only if f is genuinely ramified.