Flavoured Naturalness

TL;DR

This paper explores how mixing between right-handed charm and top squarks affects collider signatures, relaxes stop mass bounds, and offers new experimental search channels at the LHC.

Contribution

It demonstrates that significant charm-top squark mixing is compatible with flavor constraints and impacts collider phenomenology in novel ways.

Findings

Large charm-top squark mixing is allowed by flavor constraints.

Mixing reduces the experimental lower bound on the stop mass.

New collider signatures, such as t anti-c (c anti-t) + missing E_T, are promising for LHC searches.

Abstract

We show that a large mixing between the right-handed charm and top squarks (i) is allowed by low-energy flavour constraints; (ii) reduces the experimental bound on the stop mass; (iii) has a mild, but beneficial, effect on fine-tuning; (iv) leads to interesting signatures at the LHC not presently investigated by experiments. We estimate the current bound on the stop mass, in presence of flavour mixing, and discuss the new collider signatures. The signal in the t anti-c (c anti-t) + missing E_T channel is large enough that it can be immediately searched for experimentally, while the signature with same-sign tops and missing E_T requires a luminosity upgrade of the LHC.