Wilson loop


\infty-Chern-Weil theory

Differential cohomology



A Wilson loop or Wilson line is an observable in (both classical and quantum) gauge theory obtained from the holonomy of the gauge connection.

Hence if the gauge connection is given by a globally defined 1-form AA, then the Wilson loop along a closed loop CC is the trace of the time-ordered exponential?

W C=Tr(𝒫exp(i CA μdx μ)) W_C = Tr(\mathcal{P}exp(i\oint_C A_\mu d x^\mu))

where 𝒫\mathcal{P} is the “time-ordering operator” and A μA_\mu are the components of the connection.


Relation to 1d Chern-Simons theory

For GG a suitable Lie group (compact, semi-simple and simply connected) the Wilson loops of GG-principal connections are equivalently the partition functions of a 1-dimensional Chern-Simons theory.

This appears famously in the formulation of Chern-Simons theory with Wilson lines. More detailes are at orbit method.

Relation to defects

Wilson loop insertions may be thought of or at least related to defects in the sense of QFT with defects.

Duality with ’t Hooft operators under S-duality and geometric Langlands

S-duality of 4d super Yang-Mills theory may exchange Wilson loop operators with ’t Hooft operators, in an incarnation of the geometric Langlands correspondence (Kapustin-Witten 06)

geometric Langlands correspondenceS-duality in N=4 D=4 super Yang-Mills theory
Hecke transformation’t Hooft operator
local system/flat connectionelectric eigenbrane (eigenbrane of Wilson operator)
Hecke eigensheafmagnetic eigenbrane (eigenbrane of ’t Hooft operator )

(Kapustin-Witten 06)


In Chern-Simons theory

In SU(3)SU(3)-Chern-Simons theory the Wilson line observables compute the Jones polynomial of the given curve. See there for more details.



  • Kenneth Wilson, Confinement of quarks, Physical Review D 10 (8): 2445. doi (1974)

  • Yuri Makeenko, Methods of contemporary gauge theory, Cambridge Monographs on Math. Physics, gBooks

  • wikipedia Wilson loop

  • R. Giles, Reconstruction of gauge potentials from Wilson loops, Physical Review D 24 (8): 2160, doi

  • A. Andrasi, J. C. Taylor, Renormalization of Wilson operators in Minkowski space, Nucl. Phys. B516 (1998) 417, hep-th/9601122

  • Amit Sever, Pedro Vieira, Luis F. Alday, Juan Maldacena, Davide Gaiotto, An Operator product expansion for polygonal null Wilson loops,

In Chern-Simons theory

The Poisson bracket of Wilson line observables in 3d Chern-Simons theory was obtained in

  • W. Goldman, Invariant functions on Lie groups and Hamiltonian flow of surface group representations, Inventiones Math., 85 (1986), 263–302.

For more see

In QFT with defects

Relation to QFT with defects is discussed in

slide 17 of

slide 5 of

As partition functions of 1d Chern-Simons theory

Expression of Wilson loops as partition functions of 1-dimensional Chern-Simons theories by the orbit method (as used notably in Chern-Simons theory) is in section 4 of

  • Chris Beasley, Localization for Wilson Loops in Chern-Simons Theory, in J. Andersen, H. Boden, A. Hahn, and B. Himpel (eds.) Chern-Simons Gauge Theory: 20 Years After, AMS/IP Studies in Adv. Math., Vol. 50, AMS, Providence, RI, 2011. (arXiv:0911.2687)

referring to

  • S. Elitzur, Greg Moore, A. Schwimmer, and Nathan Seiberg, Remarks on the Canonical Quantization of the Chern-Simons-Witten Theory, Nucl. Phys. B 326 (1989) 108–134.

in the context of Chern-Simons theory and in more general gauge theory to

  • A. P. Balachandran, S. Borchardt, and A. Stern, Lagrangian And Hamiltonian Descriptions of Yang-Mills Particles, Phys. Rev. D 17 (1978) 3247–3256

In S-duality and relation to t Hoofts operators

Revised on July 18, 2015 10:09:30 by Urs Schreiber (