TY - JOUR

T1 - Gravity as the square of gauge theory

T2 - a review

AU - Borsten, L.

N1 - Publisher Copyright:
© 2020, Società Italiana di Fisica.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - We briefly review the manifold incarnations and facets of the notion that gravity, in certain regards, can be re-conceived as the product of two gauge theories. We begin with a short history of the relationship between gauge and gravity theories in the context of “gravity = gauge × gauge ”. This is followed by modern approaches to gauge/gravity scattering amplitude relations, focussing on the Bern–Carrasco–Johansson colour-kinematic duality and double-copy construction of gravitational amplitudes from gauge amplitudes. This includes a partial characterisation of what gravity theories admit a gauge theory squared origin. We then consider classical and off-shell perspectives on “gravity = gauge × gauge ”. First we review field theoretic approaches to understanding the colour-kinematic duality and the double-copy prescription, including kinematic algebras and colour-kinematic duality and double-copy manifesting Lagrangians. We then consider classical double-copy-like methods for constructing gravitational solutions from gauge theory solutions. To close, we consider a purely field theoretic take on “gravity = gauge × gauge ”. This framework centres on a convolutive product of gauge theories, at the level of spacetime fields themselves, that yields gravitational theories.

AB - We briefly review the manifold incarnations and facets of the notion that gravity, in certain regards, can be re-conceived as the product of two gauge theories. We begin with a short history of the relationship between gauge and gravity theories in the context of “gravity = gauge × gauge ”. This is followed by modern approaches to gauge/gravity scattering amplitude relations, focussing on the Bern–Carrasco–Johansson colour-kinematic duality and double-copy construction of gravitational amplitudes from gauge amplitudes. This includes a partial characterisation of what gravity theories admit a gauge theory squared origin. We then consider classical and off-shell perspectives on “gravity = gauge × gauge ”. First we review field theoretic approaches to understanding the colour-kinematic duality and the double-copy prescription, including kinematic algebras and colour-kinematic duality and double-copy manifesting Lagrangians. We then consider classical double-copy-like methods for constructing gravitational solutions from gauge theory solutions. To close, we consider a purely field theoretic take on “gravity = gauge × gauge ”. This framework centres on a convolutive product of gauge theories, at the level of spacetime fields themselves, that yields gravitational theories.

UR - http://www.scopus.com/inward/record.url?scp=85081907975&partnerID=8YFLogxK

U2 - 10.1007/s40766-020-00003-6

DO - 10.1007/s40766-020-00003-6

M3 - Review article

AN - SCOPUS:85081907975

SN - 0393-697X

VL - 43

SP - 97

EP - 186

JO - Rivista del Nuovo Cimento

JF - Rivista del Nuovo Cimento

IS - 3

ER -