### Abstract

We compare form factors in sine-Gordon theory, obtained via the bootstrap, to finite volume matrix elements computed using the truncated conformal space approach. For breather form factors, this is essentially a straightforward application of a previously developed formalism that describes the volume dependence of operator matrix elements up to corrections exponentially decaying with the volume. In the case of solitons, it is necessary to generalize the formalism to include effects of non-diagonal scattering. In some cases it is also necessary to take into account some of the exponential corrections (so-called μ-terms) to get agreement with the numerical data. For almost all matrix elements the comparison is a success, with the puzzling exception of some breather matrix elements that contain disconnected pieces. We also give a short discussion of the implications of the observed behavior of μ-terms on the determination of operator matrix elements from finite volume data, as occurs e.g. in the context of lattice field theory.

Original language | English |
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Pages (from-to) | 441-467 |

Number of pages | 27 |

Journal | Nuclear Physics B |

Volume | 852 |

Issue number | 2 |

DOIs | |

Publication status | Published - Nov 11 2011 |

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### Keywords

- Finite size effects
- Form factors
- Integrable models
- Sine-Gordon model

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Nuclear Physics B*,

*852*(2), 441-467. https://doi.org/10.1016/j.nuclphysb.2011.06.020