### Abstract

Original language | English |
---|---|

Article number | 084011 |

Pages (from-to) | 1-11 |

Number of pages | 11 |

Journal | Physical Review D |

Volume | 96 |

Issue number | 8 |

Early online date | 5 Oct 2017 |

DOIs | |

Publication status | Published - 15 Oct 2017 |

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### Cite this

*Physical Review D*,

*96*(8), 1-11. [084011]. https://doi.org/10.1103/PhysRevD.96.084011

**Immirzi parameter without Immirzi ambiguity : Conformal loop quantization of scalar-tensor gravity.** / Veraguth, Olivier Jacques; Wang, Charles H.-T.

Research output: Contribution to journal › Article

*Physical Review D*, vol. 96, no. 8, 084011, pp. 1-11. https://doi.org/10.1103/PhysRevD.96.084011

}

TY - JOUR

T1 - Immirzi parameter without Immirzi ambiguity

T2 - Conformal loop quantization of scalar-tensor gravity

AU - Veraguth, Olivier Jacques

AU - Wang, Charles H.-T.

N1 - C.W. wishes to thank G. Immirzi and C. Rovelli for early discussions and brief correspondence respectively, and appreciates the EPSRC GG-Top Project and the Cruickshank Trust for financial support. O.V. is grateful to the Aberdeen University College of Physical Sciences for a research studentship.

PY - 2017/10/15

Y1 - 2017/10/15

N2 - Conformal loop quantum gravity provides an approach to loop quantization through an underlying conformal structure i.e. conformally equivalent class of metrics. The property that general relativity itself has no conformal invariance is reinstated with a constrained scalar field setting the physical scale. Conformally equivalent metrics have recently been shown to be amenable to loop quantization including matter coupling. It has been suggested that conformal geometry may provide an extended symmetry to allow a reformulated Immirzi parameter necessary for loop quantization to behave like an arbitrary group parameter that requires no further fixing as its present standard form does. Here, we find that this can be naturally realized via conformal frame transformations in scalar-tensor gravity. Such a theory generally incorporates a dynamical scalar gravitational field and reduces to general relativity when the scalar field becomes a pure gauge. In particular, we introduce a conformal Einstein frame in which loop quantization is implemented. We then discuss how different Immirzi parameters under this description may be related by conformal frame transformations and yet share the same quantization having, for example, the same area gaps, modulated by the scalar gravitational field.

AB - Conformal loop quantum gravity provides an approach to loop quantization through an underlying conformal structure i.e. conformally equivalent class of metrics. The property that general relativity itself has no conformal invariance is reinstated with a constrained scalar field setting the physical scale. Conformally equivalent metrics have recently been shown to be amenable to loop quantization including matter coupling. It has been suggested that conformal geometry may provide an extended symmetry to allow a reformulated Immirzi parameter necessary for loop quantization to behave like an arbitrary group parameter that requires no further fixing as its present standard form does. Here, we find that this can be naturally realized via conformal frame transformations in scalar-tensor gravity. Such a theory generally incorporates a dynamical scalar gravitational field and reduces to general relativity when the scalar field becomes a pure gauge. In particular, we introduce a conformal Einstein frame in which loop quantization is implemented. We then discuss how different Immirzi parameters under this description may be related by conformal frame transformations and yet share the same quantization having, for example, the same area gaps, modulated by the scalar gravitational field.

U2 - 10.1103/PhysRevD.96.084011

DO - 10.1103/PhysRevD.96.084011

M3 - Article

VL - 96

SP - 1

EP - 11

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 8

M1 - 084011

ER -