# The Other Fermion Compositeness

## TL;DR

This paper explores two main models of fermion compositeness, constructs an effective theory for Goldstini, and derives experimental bounds, finding that certain compositeness scales are compatible with current collider and low-energy data.

## Contribution

It introduces a calculable effective field theory for Goldstino-based fermion compositeness and derives new experimental bounds on these models.

## Key findings

- Goldstino-like electrons have a compositeness scale around 2 TeV.
- Goldstino-like first-generation quarks have a compositeness scale around 10 TeV.
- Predicted exotic particles could be within LHC detection reach.

## Abstract

We discuss the only two viable realizations of fermion compositeness described by a calculable relativistic effective field theory consistent with unitarity, crossing symmetry and analyticity: chiral-compositeness vs goldstino-compositeness. We construct the effective theory of $\mathcal{N}$ Goldstini and show how the Standard Model can emerge from this dynamics. We present new bounds on either type of compositeness, for quarks and leptons, using dilepton searches at LEP, dijets at the LHC, as well as low-energy observables and precision measurements. Remarkably, a scale of compositeness for Goldstino-like electrons in the 2 TeV range is compatible with present data, and so are Goldstino-like first generation quarks with a compositeness scale in the 10 TeV range. Moreover, assuming maximal $R$-symmetry, goldstino-compositeness of both right- and left-handed quarks predicts exotic spin-1/2 colored sextet particles that are potentially within the reach of the LHC.