Safe and free instantons

Preprint number: CP3-Origins-2018-8 DNRF90
Authors: Francesco Sannino (CP3-Origins & DIAS) and Vedran Skrinjar (SISSA)
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We investigate the instanton dynamics of asymptotically safe and free quantum field theories featuring respectively controllable ultraviolet and infrared fixed points. We start by briefly reviewing the salient points about the instanton calculus for pure Yang Mills (YM) and QCD. We then move on to determine the role of instantons within the controllable regime of the QCD conformal window. In this region we add a fermion-mass operator and determine the density of instantons per unit volume as function of the fermion mass. Finally, for the first time, we extend the instanton calculus to asymptotically safe theories.