TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.10.3.075
TI  - On non-canonical degrees of freedom
PY  - 2021/03/25
UR  - https://www.scipost.org/SciPostPhys.10.3.075
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 10
IS  - 3
SP  - 075
A1  - Quinn, Eoin
AB  - Non-canonical degrees of freedom provide one of the most promising routes towards characterising a range of important phenomena in condensed matter physics. Potential candidates include the pseudogap regime of the cuprates, heavy-fermion behaviour, and also indeed magnetically ordered systems. Nevertheless it remains an open question whether non-canonical algebras can in fact provide legitimate quantum degrees of freedom. In this paper we survey progress made on this topic, complementing distinct approaches so as to obtain a unified description. In particular we obtain a novel exact representation for a self-energy-like object for non-canonical degrees of freedom. We further make a resummation of density correlations to obtain analogues of the RPA and GW approximations commonly employed for canonical degrees of freedom. We discuss difficulties related to generating higher-order approximations which are consistent with conservation laws, which represents an outstanding issue. We also discuss how the interplay between canonical and non-canonical degrees of freedom offers a useful paradigm for organising the phase diagram of correlated electronic behaviour.
ER  -

@Article{10.21468/SciPostPhys.10.3.075,
	title={{On non-canonical degrees of freedom}},
	author={Eoin Quinn},
	journal={SciPost Phys.},
	volume={10},
	pages={075},
	year={2021},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.10.3.075},
	url={https://scipost.org/10.21468/SciPostPhys.10.3.075},
}