Special Lunch String Phenomenology Seminar: Runaway Relaxion Monodromy

Monday 28 Nov 2016, 12:00 → 12:30 Europe/Berlin

DESY Hamburg

Speaker: John Stout (Cornell U.) Abstract: Technical naturalness has long been used to ensure that predictions are robust to quantum effects; if a symmetry is restored in the limit some parameter g vanishes, then quantum corrections forbidden by that symmetry must appear in powers of g. However, we will show that this logic can be spoiled by quantum gravitational effects in systems undergoing monodromy. We will argue that a physical charge must account for the monodromy, and backreaction of this charge can lead to corrections independent of g. String theoretic realizations of the relaxion mechanism---a technically natural solution to the Higgs hierarchy problem---provide an illustrative example of this backreaction effect. In particular, we will show that this backreaction leads to an exponential suppression of the relaxion stopping potential. In the absence of a dramatic fine tuning, this correction leads to a runaway which renders the relaxion mechanism ineffective. Technical naturalness is not sufficient to forbid large quantum corrections in systems undergoing monodromy.