# nLab graviton

### Context

#### Gravity

gravity, supergravity

# Contents

## 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.

Revised on May 24, 2014 05:14:56 by Urs Schreiber (89.204.135.120)