Spectrum of Gravitational Waves in Krein Space Quantization

Krein approach is used to study the particle creation during quasi-de Sitter inflation in different background space-times. In the conventional method for calculating the created particles spectrum, the background space-time is automatically considered flat. Selecting a flat background poses two fundamental problems: First, the method of calculating is not covariant relative to the curved space-time. Second, the number of created particles becomes negative. Krein approach can be considered as a covariant method to calculate two-point functions in curved space-time. So we extend this method for particle creation during early cosmic inflation. As a new proposal, we choose the background vacuum based on the smallest number of created particles in that space-time. The calculations in covariant approach will show that in order to solve the above second mentioned problem, the background space-time must be non-flat and the number of particles in the background must be minimum.

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“…The complete solution in the Krein approach is made up of a combination of two positive and negative norm states [25,32,33],…”

Section: Krein Approach In Cosmological Calculationsmentioning

confidence: 99%

A Covariant Approach for Particle Creation in Non-flat Background

2020

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“…The complete solution in the Krein approach is made up of a combination of two positive and negative norm states [23,31,32],…”

Section: Krein Approach In Cosmological Calculationsmentioning

confidence: 99%

A Covariant Approach for Particle Creation in Non-flat Background

Ziyaee,

Mohsenzadeh,

Yusofi

2020

Preprint

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Krein approach is used to study the particle creation during quasi-de Sitter inflation in different background space-times. In the conventional method for calculating the created particles spectrum, the background space-time is automatically considered flat. Selecting a flat background poses two fundamental problems: First, the method of calculating is not covariant relative to the curved space-time. Second, the number of created particles becomes negative. Krein approach can be considered as a covariant method to calculate two-point functions in curved space-time. So we extend this method for particle creation during early cosmic inflation. As a new proposal, we choose the background vacuum based on the smallest number of created particles in that space-time. The calculations will show that in order to solve the above mentioned problems, the background space-time must be non-flat and the number of particles in the background must be minimum.

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“…This technique means that one can remove the effects of the background space-time. This interpretation of removing the related effects of a spacetime, resembles Krein space approach [16,17], where the renormalization method is accomplished by the support of the negative norm solutions of the wave equation and therefore the minus sign in (III.10) appears because of the negative norm solutions. Also, in Krein space, the two-point function is defined by [1]:…”

Section: A Power Spectrummentioning

confidence: 99%

Particle creation with excited de Sitter modes

2015

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Recently, in Ref.[1], we introduced exited-de Sitter modes to study the power spectrum which was finite in Krein space quantization and the trans-Plankian corrections due to the exited modes were non-linear. It was shown that the de Sitter limit of corrections reduces to what obtained via the several previous conventional methods, moreover, with such modes the space-time symmetry becomes manifest. In this paper, inspired by Krein method and using exited-de Sitter modes as the fundamental initial states during the inflation, we calculate particle creation in the spatially flat Robertson-Walker space-time. It is shown that in de Sitter and Minkowski space-time in the far past time limit, our results coincides to the standard results.Pacs:04.62.+v, 98.80.Cq

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Spectrum of Gravitational Waves in Krein Space Quantization

Cited by 8 publications

References 12 publications

A Covariant Approach for Particle Creation in Non-flat Background

A Covariant Approach for Particle Creation in Non-flat Background

A Covariant Approach for Particle Creation in Non-flat Background

Particle creation with excited de Sitter modes

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