Conformally invariant “massless” spin-2 field in the de Sitter universe

Dehghani, M.; Rouhani, S.; Takook, M. V.; Tanhayi, Mohammad Reza

doi:10.1103/physrevd.77.064028

Cited by 60 publications

(79 citation statements)

References 39 publications

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“…This is why it is called as the physical state. It has been discussed in [39], for the gauge-fixed value equal to zero, [41] for the gauge-fixed value equal to 2 5 and the extended discussions are given in [42].…”

Section: Jhep03(2016)203mentioning

confidence: 99%

“…In these cases, the two representations Π ± 2,2 , in the discrete series with p = q = 2, have a Minkowskian interpretation. It is important to note that the representations Π ± 2,1 do not have corresponding flat limit [39]. (More details can be found in [34] and references therein.…”

Section: Jhep03(2016)203mentioning

confidence: 99%

“…The reader how is not familiar to the ambient space notations is referred to [39] and references therein. The symmetric tensor field K αβ (x) is defined on dS space-time and satisfies the transversality condition [33,34] x · K(x) = 0, i.e.…”

Section: Jhep03(2016)203mentioning

confidence: 99%

“…Let us first introduce a traceless and transverse tensor field K in terms of a five-dimensional constant vector Z 1 = (Z 1α ) and a scalar field φ 1 and two vector fields K and K g by putting [34,39,41,42,48,49]…”

Section: Solution To the Conformal Field Equationmentioning

confidence: 99%

“…[37] and [38] respectively. The spin-2 tensor representations relevant to the present work are [39]:…”

Section: Jhep03(2016)203mentioning

confidence: 99%

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Group theoretical interpretation of the modified gravity in de Sitter space

Dehghani

2016

J. High Energ. Phys.

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A framework has been presented for theoretical interpretation of various modified gravitational models which is based on the group theoretical approach and unitary irreducible representations (UIR's) of de Sitter (dS) group. In order to illustrate the application of the proposed method, a model of modified gravity has been investigated. The background field method has been utilized and the linearized modified gravitational field equation has been obtained in the 4-dimensional dS space-time as the background. The field equation has been written as the eigne-value equation of the Casimir operators of dS space using the flat 5-dimensional ambient space notations. The Minkowskian correspondence of the theory has been obtained by taking the zero curvature limit. It has been shown that under some simple conditions, the linearized modified field equation transforms according to two of the UIR's of dS group labeled by Π ± 2,1 and Π ± 2,2 in the discrete series. It means that the proposed modified gravitational theory can be a suitable one to describe the quantum gravitational effects in its linear approximation on dS space. The field equation has been solved and the solution has been written as the multiplication of a symmetric rank-2 polarization tensor and a massless scalar field using the ambient space notations. Also the two-point function has been calculated in the ambient space formalism. It is dS invariant and free of any theoretical problems.

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Section: Jhep03(2016)203mentioning

confidence: 99%

Section: Jhep03(2016)203mentioning

confidence: 99%

Section: Jhep03(2016)203mentioning

confidence: 99%

Section: Solution To the Conformal Field Equationmentioning

confidence: 99%

“…[37] and [38] respectively. The spin-2 tensor representations relevant to the present work are [39]:…”

Section: Jhep03(2016)203mentioning

confidence: 99%

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Group theoretical interpretation of the modified gravity in de Sitter space

Dehghani

2016

J. High Energ. Phys.

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A brief review on the problem of divergence in Krein space quantization

Payandeh

Moghaddam

Fathi

2012

Fortschritte der Physik

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In this paper we have a brief review on the problem of divergence in quantum field theory and its elimination using the method of Krein space quantization. In this method, the auxiliary negative frequency states have been utilized, the modes of which do not interact with the physical states and are not affected by the physical boundary conditions. It is remarkable that Krein space quantization is similar to Pauli-Villars regularization, so we can call it the "Krein regularization". Considering the QED in Krein space quantization, it could be shown that the theory is automatically regularized. Calculation of the three primitive divergent integrals, the vacuum polarization, electron self energy and vertex function using Krein space method leads to finite values, since the infrared and ultraviolet divergencies do not appear. For another example, the Casimir stress on a spherical shell in de Sitter spacetime for a massless scalar field could be calculated using Krein space quantization. *

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