## The $a$-theorem at large N$_f$

Preprint number: CP3-Origins-2018-28 DNRF90
Authors: Oleg Antipin (Rudjer Boskovic Institute), Nicola Andrea Dondi (CP3-Origins), Francesco Sannino (CP3-Origins & DIAS), and Anders Eller Thomsen (CP3-Origins)

We determine the Jack and Osborn $a$-function and related metric for gauge-fermion theories to leading order in the large number of fermions and to all orders in the gauge coupling, thus demonstrating that the strong version of the $a$-theorem is violated.