On Quadratic Gravity

Donoghue, John F.; Menezes, G.

doi:10.48550/arxiv.2112.01974

Cited by 4 publications

(5 citation statements)

References 38 publications

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“…It is unclear whether traditional field-theory techniques agree in their results when applied to higher-derivative theories. For instance, the equivalence of Euclidean and Lorentzian formulations has been grounded in standard theories, and it is not clear how such a correspondence would be possible for higher-derivative theories, particularly bearing mind the unconventional analytic features such theories possess [61]. Perhaps the traditional representation of loop amplitudes in terms of Feynman diagrams might not be useful here.…”

Section: Discussionmentioning

confidence: 99%

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Leading Singularities in Higher-Derivative Yang–Mills Theory and Quadratic Gravity

Menezes

2022

Universe

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In this work, we explore general leading singularities of one-loop amplitudes in higher-derivative Yang–Mills and quadratic gravity. These theories are known to possess propagators which contain quadratic and quartic momentum dependence, which leads to the presence of an unstable ghostlike resonance. However, unitarity cuts are not to be taken through unstable particles and therefore unitarity is still satisfied. On the other hand, this could engender issues when calculating leading singularities which are generalizations of unitarity cuts. Nevertheless, we will show with explicit examples how leading singularities are still well defined and accordingly they are able to capture relevant information on the analytic structure of amplitudes in such higher-derivative theories. We discuss some simple one-loop amplitudes which clarify these features.

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Section: Discussionmentioning

confidence: 99%

“…We are particularly interested in a higher-derivative version of the Yang-Mills theory and also quadratic gravity. The latter still constitutes a potential UV completion for quantum gravity [60,61]. We will study one-loop scattering of gluons and gravitons as well as scattering of matter particles in such higher-derivative theories.…”

Section: Introductionmentioning

confidence: 99%

Leading Singularities in Higher-Derivative Yang–Mills Theory and Quadratic Gravity

Menezes

2022

Universe

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“…[28]. See also [14,29,30] for extensive reviews and comments about the problem of ghosts generically associated with this class of theories.…”

Section: Jhep10(2023)054mentioning

confidence: 99%

On the resilience of the gravitational variational principle under renormalization

Neri,

Liberati

2023

J. High Energ. Phys.

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A well-defined variational principle for gravitational actions typically requires to cancel boundary terms produced by the variation of the bulk action with a suitable set of boundary counterterms. This can be achieved by carefully balancing the coefficients multiplying the bulk operators with those multiplying the boundary ones. A typical example of this construction is the Gibbons-Hawking-York boundary action that needs to be added to the Einstein-Hilbert one in order to have a well-defined metric variation for General Relativity with Dirichlet boundary conditions. Quantum fluctuations of matter fields lead to a renormalization of these coefficients which may or may not preserve this balance. Indeed, already at the level of General Relativity, the resilience of the matching between bulk and boundary constants is far from obvious and it is anyway incomplete given that matter generically induces quadratic curvature operators. We investigate here the resilience of the matching of higher-order couplings upon renormalization by a non-minimally coupled scalar field and show that a problem is present. Even though we do not completely solve the latter, we show that it can be greatly ameliorated by a wise splitting between dynamical and topological contributions. Doing so, we find that the bulk-boundary matching is preserved up to a universal term (present for any Weyl invariant matter field content), whose nature and possible cancellation we shall discuss in the end.

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“…It is unclear whether traditional field-theory techniques agree in their results when applied to higher derivative theories. For instance, the equivalence of Euclidean and Lorentzian formulations has been grounded in standard theories and it is not clear how such correspondence would be possible for higher derivative theories, particularly bearing mind the unconventional analytic features such theories possess [61]. Perhaps the traditional representation of loop amplitudes in terms of Feynman diagrams might not be useful here.…”

Section: Scalar Scatteringmentioning

confidence: 99%

Leading singularities in higher-derivative Yang-Mills theory and quadratic gravity

Menezes

2022

Preprint

Self Cite

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In this work we explore general leading singularities of one-loop amplitudes in higher-derivative Yang-Mills and quadratic gravity. These theories are known to possess propagators which contain quadratic and quartic momentum dependence, which leads to the presence of an unstable ghostlike resonance. However, unitarity cuts are not to be taken through unstable particles and therefore unitarity is still satisfied. On the other hand, this could engender issues when calculating leading singularities which are generalizations of unitarity cuts. Nevertheless, we will show with explicit examples how leading singularities are still well defined and accordingly they are able to capture relevant information on the analytic structure of amplitudes in such higher-derivative theories. We discuss some simple one-loop amplitudes which clarify these features.

show abstract

On Quadratic Gravity

Cited by 4 publications

References 38 publications

Leading Singularities in Higher-Derivative Yang–Mills Theory and Quadratic Gravity

Leading Singularities in Higher-Derivative Yang–Mills Theory and Quadratic Gravity

On the resilience of the gravitational variational principle under renormalization

Leading singularities in higher-derivative Yang-Mills theory and quadratic gravity

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