# Naturalness, Hierarchy, and Fine Tuning

28 February 2018 to 2 March 2018
Aachen
Europe/Zurich timezone

## Two Notions of Naturalness

28 Feb 2018, 11:50
40m

### Speaker

Porter Williams (Univ. Pittsburgh)

### Description

My aim will be to distinguish two notions of naturalness in use in BSM physics. One way of understanding naturalness is as a prohibition on sensitive dependencies of a theory's description of low-energy physics on details of the theory's description of high-energy physics. I will argue that considerations from the general structure of effective field theory provide motivation for this notion of naturalness. A second way of understanding naturalness is as a requirement that the values of the parameters in a quantum field theory, such as the Higgs mass, be likely'' (for some appropriate measure) in some appropriately circumscribed space of models. The two notions are clearly related but strike me as motivated by distinct theoretical considerations and, furthermore, may admit of distinct kinds of solution.

### Primary author

Porter Williams (Univ. Pittsburgh)