LIGHT OR MASSLESS SPIN 2 PARTICLE (GRAVITONS) Amati and Veneziano proposed that a graviton might emerge from a NJL type model in A Unified Gauge and Gravity Theory With Only Matter Fields D. Amati, G. Veneziano (Nov, 1981) Published in: Nucl.Phys.B 204 (1982) 451-476 but typically such models have too many degrees of freedom because they have the spin states of a massive graviton with the mass then tuned to zero - there is not the gauge conditions to eliminate some of the degrees of freedom. This was already formalised by Witten and Weinberg who proved that a composite particle could not be a graviton in Limits on Massless Particles Steven Weinberg, Edward Witten (Aug, 1980) Published in: Phys.Lett.B 96 (1980) 59-62 However, there are now ghost free effective theories of massive gravitons such as Resummation of Massive Gravity Claudia de Rham, Gregory Gabadadze, Andrew J. Tolley (Nov, 2010) Published in: Phys.Rev.Lett. 106 (2011) 231101; e-Print: 1011.1232 [hep-th] so there is still an interesting question of whether theories can produce light massive gravitons and what the low energy effective theory and phenomenology is. Here is a recent talk by Peter Orland (Southampton, March 2021) on the topic based on his paper A unitary renormalizable model of composite gravitons Peter Orland (Nov, 2010) Published in: e-Print: 2101.02236 [hep-th] Raman Sundrum pointed out a potential link of graviton compositeness to the dark energy problem in Fat gravitons, the cosmological constant and submillimeter tests Raman Sundrum (June, 2003) Published in: Phys.Rev.D 69 (2004) 044014 • e-Print: hep-th/0306106 [hep-th] work which led onto the Randall/Sundrum brane world model (which holds some of the elements of a holographic description of a composite graviton) in A Large mass hierarchy from a small extra dimension Lisa Randall, Raman Sundrum (May 1999) Published in: Phys.Rev.Lett. 83 (1999) 3370-3373 • e-Print: hep-ph/9905221 [hep-ph]