On Brauer $p$-dimensions and index-exponent relations over finitely-generated field extensions

Abstract: Let $E$ be a field of absolute Brauer dimension abrd$(E)$, and $F/E$ a transcendental finitely-generated extension. This paper shows that the Brauer dimension Brd$(F)$ is infinite, if abrd$(E) = \infty $. When the absolute Brauer $p$-dimension abrd${p}(E)$ is infinite, for some prime number $p$, it proves that for each pair $(n, m)$ of integers with $n \ge m > 0$, there is a central division $F$-algebra of Schur index $p ^{n}$ and exponent $p ^{m}$. Lower bounds on the Brauer $p$-dimension Brd${p}(F)$ are obtained in some important special cases where abrd$_{p}(E) < \infty $. These results solve negatively a problem posed by Auel et al. (Transf. Groups {\bf 16}: 219-264, 2011).