Light bound states of heavy fermions

TL;DR

This paper explores the theoretical possibility of multi-fermion bound states involving heavy fermions, predicting their masses and suggesting experimental searches in the 2-3 TeV range could reveal or constrain new physics beyond the Standard Model.

Contribution

It introduces a mean field approximation to predict multi-fermion bound states with specific mass scaling, extending the understanding of heavy fermion interactions and potential new particles.

Findings

Multi-fermion states with masses ~1.2 N^{1/2} TeV are predicted.

Experimental searches in the 2-3 TeV range could confirm or rule out these states.

Implications for multi-top states and baryogenesis are discussed.

Abstract

In the Standard Model, a group of heavy fermions, e.g. top quarks, can collectively strongly affect the Higgs field and create relatively long-lived bound states. If there exist new generations of fermions with masses beyond 1 TeV, strong binding of several of them can make them lighter than even a single heavy fermion. Using the mean field approximation we find multi-fermion states with masses M ~ 5 v N^{1/2} ~ 1.2 N^{1/2} TeV, with N=2,3... being the total number of heavy fermions bound together, and v=246 GeV the Higgs VEV. The experimental search for multi-fermions within the range of energies 2-3 Tev would either discover them, or suggest absence of new Standard Model fermions with larger masses. Possible implications related to multi-top states and baryonic asymmetry of the Universe are discussed.