nLab graviton

Idea

The graviton is the (hypothetical) quantum of the field of gravity, i.e., the quanta of the theory of quantum gravity.

Details

In first-order formulation of gravity a field configuration is locally a Lie algebra-valued form

$$(E, \Omega) : T X \to \mathfrak{iso}(d)$$

with values in the Poincare Lie algebra.

This is a vielbein $E$ and a spin connection $\Omega$. This together is the graviton field.

A graviton has spin $2$, and is massless. We can see that it has spin $2$ from the fact that the source of gravity is $T$, the energy-momentum tensor, which is a second-rank tensor. It can be shown that a massless spin-$2$ particle has to be a graviton. The basic concept behind this is that massless particles have to couple to conserved currents - the stress-energy tensor $T$, the source of gravity.

In supergravity this is accompanied by the gravitino.

Related concepts

• soft graviton theorem

• boson

  • gauge boson

    • photon, gluon,

    • graviton,

      • dual graviton

      • giant graviton

• fermion

  • electron, quark,

  • gravitino, gaugino , dilatino

References

General

See the references at quantum gravity – and an effective perturbative field theory

On potential experiments detecting gravitons:

• Freeman Dyson, Is the graviton detectable?, International Journal of Modern Physics A 28 25 (2013) 1330041 [doi:10.1142/S0217751X1330041X]

• Tony Rothman, Stephen Boughn, Can Gravitons be Detected?, Foundations of Physics 36 (2006) 1801–1825 [doi:10.1007/s10701-006-9081-9]

• Tony Rothman, Stephen Boughn, Aspects of graviton detection: graviton emission and absorption by atomic hydrogen, Classical and Quantum Gravity 23 20 (2006) 5839 [doi:10.1088/0264-9381/23/20/006]

• Daniel Carney, Valerie Domcke, Nicholas L. Rodd, Graviton detection and the quantization of gravity [arXiv:2308.12988]

• Jen-Tsung Hsiang, Hing-Tong Cho, Bei-Lok Hu, Graviton physics: Quantum field theory of gravitons, graviton noise and gravitational decoherence – a concise tutorial [arXiv:2405.11790]

Classification of long-range forces

Classification of possible long-range forces, hence of scattering processes of massless fields, by classification of suitably factorizing and decaying Poincaré-invariant S-matrices depending on particle spin, leading to uniqueness statements about Maxwell/photon-, Yang-Mills/gluon-, gravity/graviton- and supergravity/gravitino-interactions:

• Steven Weinberg, Feynman Rules for Any Spin. 2. Massless Particles, Phys. Rev. 134 (1964) B882 (doi:10.1103/PhysRev.134.B882)

• Steven Weinberg, Photons and Gravitons in $S$-Matrix Theory: Derivation of Charge Conservationand Equality of Gravitational and Inertial Mass, Phys. Rev. 135 (1964) B1049 (doi:10.1103/PhysRev.135.B1049)

• Steven Weinberg, Photons and Gravitons in Perturbation Theory: Derivation of Maxwell’s and Einstein’s Equations,” Phys. Rev. 138 (1965) B988 (doi:10.1103/PhysRev.138.B988)

• Paolo Benincasa, Freddy Cachazo, Consistency Conditions on the S-Matrix of Massless Particles (arXiv:0705.4305)

• David A. McGady, Laurentiu Rodina, Higher-spin massless S-matrices in four-dimensions, Phys. Rev. D 90, 084048 (2014) (arXiv:1311.2938, doi:10.1103/PhysRevD.90.084048)

Review:

• Claus Kiefer, section 2.1.3 of: Quantum Gravity, Oxford University Press 2007 (doi:10.1093/acprof:oso/9780199585205.001.0001, cds:1509512)

• Daniel Baumann, What long-range forces are allowed?, 2019 (pdf)