Naturalness made easy: two-loop naturalness bounds on minimal SM extensions

Understand

The main result of this paper is a collection of conservative naturalness bounds on minimal extensions of the standard model by (vector-like) fermionic or scalar gauge multiplets.

• Within, we advocate for an intuitive and physical concept of naturalness built upon the renormalisation group equations.
• In the effective field theory of the standard model plus a gauge multiplet with mass $M$, the low scale Higgs mass parameter is a calculable function of $\overline{\rm MS}$ input parameters defined at some high scale $\Lambda_h > M$.
• If the Higgs mass is very sensitive to these input parameters, then this signifies a naturalness problem.