Alexei A Starobinsky | Joint Institute for Nuclear Research (original) (raw)
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Papers by Alexei A Starobinsky
Physical Review D
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Gravitation and Cosmology
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The European Physical Journal C
We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime.... more We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime. For the theory with a quartic self-interaction, the two-point function is calculated up to two loops. Comparing our results with the Hartree–Fock approximation and with the stochastic approach shows that the former resums only the cactus type diagrams, whereas the latter contains the sunset diagram as well and produces the correct result. We also demonstrate that the long-wavelength expectation value of the commutator of two fields is equal to zero both for spacelike and timelike separated points.
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Journal of Cosmology and Astroparticle Physics, 2021
We present constraints on inflationary dynamics and features in the primordial power spectrum of ... more We present constraints on inflationary dynamics and features in the primordial power spectrum of scalar perturbations using the Cosmic Microwave Background temperature, polarization data from Planck 2018 data release and updated likelihoods. We constrain the slow-roll dynamics using Hilltop Quartic Potential and Starobinsky R + R 2 model in the Einstein frame using the Planck 2018 binned Plik likelihood. Using the Hilltop as base potential, we construct Whipped Inflation potential to introduce suppression in the scalar power spectrum at large angular scales. We notice marginal (68% C.L.) preference of suppression from the large scale temperature angular power spectrum. However, large-scale E-mode likelihood based on high frequency instrument cross spectrum, does not support this suppression and in the combined data the preference towards the suppression becomes negligible. Based on the Hilltop and Starobinsky model, we construct the Wiggly Whipped Inflation potentials to introduce o...
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Motivated by the idea that inflation occurs at the GUT symmetry breaking scale, in this paper we ... more Motivated by the idea that inflation occurs at the GUT symmetry breaking scale, in this paper we construct a new class of large field inflaton potentials where the inflaton starts with a power law potential; after initial period of relative fast roll that lasts until after a few e-folds inside the horizon, it transits to the attractor of the slow roll part of the potential with a lower power. Due to the initial fast roll stages of inflation, we find a suppression in scalar primordial power at large scales and at the same time the choice of the potential can provide us a tensor primordial spectrum with high amplitude. This suppression in scalar power with a large tensor-to-scalar ratio helps us to reconcile the Planck and BICEP2 data in a single framework. We find that a transition from a cubic to quadratic form of inflaton potential generates an appropriate suppression in power of scalar primordial spectrum that provides significant improvement in fit compared to power law model whe...
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Journal of Cosmology and Astroparticle Physics, 2020
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International Journal of Modern Physics D, 2020
Emergence of [Formula: see text] inflation, which is the best fit framework for CMB observations ... more Emergence of [Formula: see text] inflation, which is the best fit framework for CMB observations till date, comes from the attempts to attack the problem of quantization of gravity which in turn have resulted in the trace anomaly discovery. Further developments in trace anomaly and different frameworks aiming to construct quantum gravity indicate an inevitability of nonlocality in fundamental physics at small time and length scales. A natural question would be to employ the [Formula: see text] inflation as a probe for signatures of nonlocality in the early Universe physics. Recent advances of embedding [Formula: see text] inflation in a string theory inspired nonlocal gravity modification provide very promising theoretical predictions connecting the nonlocal physics in the early Universe and the forthcoming CMB observations.
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Journal of Cosmology and Astroparticle Physics, 2020
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Journal of Cosmology and Astroparticle Physics, 2020
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Monthly Notices of the Royal Astronomical Society, 2018
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Journal of High Energy Physics, 2016
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Journal of Cosmology and Astroparticle Physics, 2016
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Journal of Cosmology and Astroparticle Physics, 2016
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A novel class of exact solutions of inflationary dynamics with a specific form of a scalar potent... more A novel class of exact solutions of inflationary dynamics with a specific form of a scalar potential is given based on a "fast-roll" ansatz, where the even-order slow-roll parameters approach to a nonnegligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime. Due to the rapid evolution of the background dynamics, the would-be decaying mode of the linear curvature perturbation may behave as a growing mode depending on the value of the model parameter, while the other mode remains constant. For the parameters giving a slightly red-tilted primordial power spectrum, the unwanted anomalous growth of the curvature perturbation is inevitable, which is similar to the case of the so-called ultra-slow-roll inflation.
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The Astrophysical Journal, 2001
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The Astrophysical Journal, 1999
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The Astrophysical Journal, 1999
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Journal of Experimental and Theoretical Physics Letters, 1997
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Astronomy & Astrophysics, 2011
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Journal of Cosmology and Astroparticle Physics, 2014
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Physical Review D
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Gravitation and Cosmology
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The European Physical Journal C
We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime.... more We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime. For the theory with a quartic self-interaction, the two-point function is calculated up to two loops. Comparing our results with the Hartree–Fock approximation and with the stochastic approach shows that the former resums only the cactus type diagrams, whereas the latter contains the sunset diagram as well and produces the correct result. We also demonstrate that the long-wavelength expectation value of the commutator of two fields is equal to zero both for spacelike and timelike separated points.
Bookmarks Related papers MentionsView impact
Journal of Cosmology and Astroparticle Physics, 2021
We present constraints on inflationary dynamics and features in the primordial power spectrum of ... more We present constraints on inflationary dynamics and features in the primordial power spectrum of scalar perturbations using the Cosmic Microwave Background temperature, polarization data from Planck 2018 data release and updated likelihoods. We constrain the slow-roll dynamics using Hilltop Quartic Potential and Starobinsky R + R 2 model in the Einstein frame using the Planck 2018 binned Plik likelihood. Using the Hilltop as base potential, we construct Whipped Inflation potential to introduce suppression in the scalar power spectrum at large angular scales. We notice marginal (68% C.L.) preference of suppression from the large scale temperature angular power spectrum. However, large-scale E-mode likelihood based on high frequency instrument cross spectrum, does not support this suppression and in the combined data the preference towards the suppression becomes negligible. Based on the Hilltop and Starobinsky model, we construct the Wiggly Whipped Inflation potentials to introduce o...
Bookmarks Related papers MentionsView impact
Motivated by the idea that inflation occurs at the GUT symmetry breaking scale, in this paper we ... more Motivated by the idea that inflation occurs at the GUT symmetry breaking scale, in this paper we construct a new class of large field inflaton potentials where the inflaton starts with a power law potential; after initial period of relative fast roll that lasts until after a few e-folds inside the horizon, it transits to the attractor of the slow roll part of the potential with a lower power. Due to the initial fast roll stages of inflation, we find a suppression in scalar primordial power at large scales and at the same time the choice of the potential can provide us a tensor primordial spectrum with high amplitude. This suppression in scalar power with a large tensor-to-scalar ratio helps us to reconcile the Planck and BICEP2 data in a single framework. We find that a transition from a cubic to quadratic form of inflaton potential generates an appropriate suppression in power of scalar primordial spectrum that provides significant improvement in fit compared to power law model whe...
Bookmarks Related papers MentionsView impact
Journal of Cosmology and Astroparticle Physics, 2020
Bookmarks Related papers MentionsView impact
International Journal of Modern Physics D, 2020
Emergence of [Formula: see text] inflation, which is the best fit framework for CMB observations ... more Emergence of [Formula: see text] inflation, which is the best fit framework for CMB observations till date, comes from the attempts to attack the problem of quantization of gravity which in turn have resulted in the trace anomaly discovery. Further developments in trace anomaly and different frameworks aiming to construct quantum gravity indicate an inevitability of nonlocality in fundamental physics at small time and length scales. A natural question would be to employ the [Formula: see text] inflation as a probe for signatures of nonlocality in the early Universe physics. Recent advances of embedding [Formula: see text] inflation in a string theory inspired nonlocal gravity modification provide very promising theoretical predictions connecting the nonlocal physics in the early Universe and the forthcoming CMB observations.
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Journal of Cosmology and Astroparticle Physics, 2020
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Journal of Cosmology and Astroparticle Physics, 2020
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Monthly Notices of the Royal Astronomical Society, 2018
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Journal of High Energy Physics, 2016
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Journal of Cosmology and Astroparticle Physics, 2016
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Journal of Cosmology and Astroparticle Physics, 2016
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A novel class of exact solutions of inflationary dynamics with a specific form of a scalar potent... more A novel class of exact solutions of inflationary dynamics with a specific form of a scalar potential is given based on a "fast-roll" ansatz, where the even-order slow-roll parameters approach to a nonnegligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime. Due to the rapid evolution of the background dynamics, the would-be decaying mode of the linear curvature perturbation may behave as a growing mode depending on the value of the model parameter, while the other mode remains constant. For the parameters giving a slightly red-tilted primordial power spectrum, the unwanted anomalous growth of the curvature perturbation is inevitable, which is similar to the case of the so-called ultra-slow-roll inflation.
Bookmarks Related papers MentionsView impact
The Astrophysical Journal, 2001
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The Astrophysical Journal, 1999
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The Astrophysical Journal, 1999
Bookmarks Related papers MentionsView impact
Journal of Experimental and Theoretical Physics Letters, 1997
Bookmarks Related papers MentionsView impact
Astronomy & Astrophysics, 2011
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Journal of Cosmology and Astroparticle Physics, 2014
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