Composite states occur over vast scales and play an important role in various domains of particle physics. In the first part I report on the recent development and application of non-relativistic QCD for the study of hadrons and multi-hadron systems in QCD and beyond. In particular, I will demonstrate how we obtain quantities such as binding energies, mass spectra and color scaling for heavy bound states. The techniques we employ are highly computationally efficient and thus can provide reliable estimates of properties of heavy baryons and multi-hadron systems, as well as dark baryons without the need for computationally intensive lattice QCD calculations. In the second part I introduce a chiral SU(15) gauge theory in which the SM quarks and leptons emerge as bound states of massless preons below a large confining scale. We show how under certain assumptions di-prebaryon bound states behave as Higgs fields and that proton-decay operators are likely induced at the compositeness scale. We find dominant exotic proton decay modes involving heavy right-handed neutrinos which could be observed using the Super-K or DUNE detectors.
