Effective Action in Quantum Field Theory

Buchbinder, I. L.; Odintsov, S. D.; Shapiro, I. L.

doi:10.1201/9780203758922-2

Cited by 28 publications

(64 citation statements)

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“…Also, the conformal instability typical for the Euclidean quantum gravity is not presents in CG. A particularly pleasing aspect of the quadratic-curvature action (3) is its power-counting renormalisability [42] and asymptotic freedom (β-function for α c is negative) [43].…”

Section: Quantum Conformal Gravitymentioning

confidence: 99%

Inflationary cosmology from quantum conformal gravity

2015

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We analyze the functional integral for quantum conformal gravity and show that, with the help of a HubbardStratonovich transformation, the action can be broken into a local quadratic-curvature theory coupled to a scalar field. A one-loop effective-action calculation reveals that strong fluctuations of the metric field are capable of spontaneously generating a dimensionally transmuted parameter which, in the weak-field sector of the broken phase, induces a Starobinskytype f (R)-model with a gravi-cosmological constant. A resulting non-trivial relation between Starobinsky's parameter and the gravi-cosmological constant is highlighted and implications for cosmic inflation are briefly discussed and compared with the recent PLANCK and BICEP2 data.

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Section: Quantum Conformal Gravitymentioning

confidence: 99%

Inflationary cosmology from quantum conformal gravity

2015

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“…As discussed in the literature, the spectrum of quadratic gravity can be considered as consisting of the graviton augmented by the presence of a heavy particle named a Merlin mode, whose mass obeys the relation [40,50]. Merlin modes are interesting in that they carry positive energy backwards in time.…”

Section: Causality Violation In Quadratic Gravitymentioning

confidence: 99%

“…In any case, one can also embark upon an interesting exploration of quantum-gravity signatures from the perspective a UV-complete theory of gravity. In this respect, perhaps the framework of quadratic gravity would constitute the most conservative approach as it continues to use the metric as the fundamental dynamical variable and is renormalizable and unitary [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]. It is often overlooked in discussions of quantum gravity as it must violate some traditional aspect of our usual formulation of quantum field theory-the modern interpretation is that the usual notion of causality is blurred close to the Planck scale.…”

Section: Introductionmentioning

confidence: 99%

Quantum gravity phenomenology from the perspective of quantum general relativity and quadratic gravity

Menezes

2023

Class. Quantum Grav.

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Multi-messenger astronomy provides us with the possibility of discovering phenomenological signatures of quantum-gravity effects. This should be of paramount importance in the pursuit of an elusive quantum theory for the gravitational interactions. Here we discuss feasible explorations within the effective field theory treatment of general relativity. By exploring current techniques borrowed from modern amplitude methods, we calculate leading quantum corrections to the classical radiated momentum and spectral waveforms. The lessons drawn from these low-energy results are that phenomenological applications in gravitational-wave physics can be discussed in line with the effective field theory approach. In turn, we also examine possible phenomenological surveys from the perspective of a UV completion for quantum gravity which employs the metric as the fundamental dynamical variable, namely quadratic gravity. Being more specific, by resorting to the eikonal approximation, we compute the leading-order time delay/advance in the scattering of light by a heavy object and find a possible significant deviation from the standard general-relativity prediction. This allows us to probe causal uncertainty due to quantum fluctuations of the gravitational field as a genuine prediction from Planck-scale physics.

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“…Não apenas isso, mas o fato de que nossas equações de movimento não devem possuir mais de duas derivadas na variável dinâmica, que no caso são a métrica e o campo escalar essas variáveis, ou possuir os chamados campos "fantasma", também limita a forma de f [19]. Por fim, como cada teoria é em geral construída de forma a entender algum regime particular de energia, teorias que buscam explicar a aceleração cósmica precisam reproduzir o Universo observado [32], e teorias que buscam ser o limite de uma teoria quântica da gravidade [33] possuem cada uma complexidades e limitações particulares.…”

Section: Um Exemplo De Teoria Escalar-tensorialunclassified

Primeiro passo em direção à modificação da gravidade: Teorias Escalar-Tensoriais e f(R)

Bessa¹,

Ottoni²

2022

Cad. Astro.

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A relatividade geral, apesar de seus sucessos, é hoje entendida como uma teoria aberta a possibilidades de modificação. Neste artigo buscamos introduzir de maneira didática a base de uma classe de teorias que busca preencher algumas lacunas deixadas pela relatividade geral, as teorias f(R) e escalar-tensoriais. Construímos as teorias a partir de um princípio de ação e obtemos suas equações de campo. Mostramos a equivalência entre as duas teorias e comentamos sobre mecanismos de blindagem. Por fim, mostramos alguns resultados observacionais sobre modificações da relatividade geral dentro do contexto dessas teorias.

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Effective Action in Quantum Field Theory

Cited by 28 publications

References 0 publications

Inflationary cosmology from quantum conformal gravity

Inflationary cosmology from quantum conformal gravity

Quantum gravity phenomenology from the perspective of quantum general relativity and quadratic gravity

Primeiro passo em direção à modificação da gravidade: Teorias Escalar-Tensoriais e f(R)

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