Non-invariance of weak approximation with Brauer-Manin obstruction for surfaces

In this paper, we study the property of weak approximation with Brauer-Manin obstruction for surfaces with respect to field extensions of number fields. For any nontrivial extension of number fields L/K, assuming a conjecture of M. Stoll, we construct a smooth, projective, and geometrically connected surface over K such that it satisfies weak approximation with Brauer-Manin obstruction off all archimedean places, while its base change to L fails. Then we illustrate this construction with an explicit unconditional example.Comment: This is a part of our paper "Non-invariance of the Brauer-Manin obstruction for surfaces" arXiv:2103.0178