scholarly journals de Sitter vacua in N=8 supergravity and slow-roll conditions

2013 ◽  
Vol 718 (3) ◽  
pp. 1132-1136 ◽  
Author(s):  
G. DallʼAgata ◽  
G. Inverso
Keyword(s):  
De Sitter ◽  
Slow Roll ◽  
De Sitter Vacua

scholarly journals A stringy perspective on the coincidence problem

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Francesc Cunillera ◽  
Antonio Padilla
Keyword(s):  
Phase Transition ◽  
Dark Energy ◽  
Early Universe ◽  
Low Energy ◽  
De Sitter ◽  
Coincidence Problem ◽  
String Compactifications ◽  
Slow Roll ◽  
De Sitter Vacua ◽  
Quintessence Field

Abstract We argue that, for string compactifications broadly consistent with swampland constraints, dark energy is likely to signal the beginning of the end of our universe as we know it, perhaps even through decompactification, with possible implications for the cosmological coincidence problem. Thanks to the scarcity (absence?) of stable de Sitter vacua, dark energy in string theory is assumed to take the form of a quintessence field in slow roll. As it rolls, a tower of heavy states will generically descend, triggering an apocalyptic phase transition in the low energy cosmological dynamics after at most a few hundred Hubble times. As a result, dark energy domination cannot continue indefinitely and there is at least a percentage chance that we find ourselves in the first Hubble epoch. We use a toy model of quintessence coupled to a tower of heavy states to explicitly demonstrate the breakdown in the cosmological dynamics as the tower becomes light. This occurs through a large number of corresponding particles being produced after a certain time, overwhelming quintessence. We also discuss some implications for early universe inflation.

scholarly journals Unimodular vs nilpotent superfield approach to pure dS supergravity

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Sukruti Bansal ◽  
Silvia Nagy ◽  
Antonio Padilla ◽  
Ivonne Zavala
Keyword(s):  
String Theory ◽  
General Framework ◽  
Recent Progress ◽  
High Energy ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
New Approach ◽  
Sitter Spacetime ◽  
Novel Approach ◽  
De Sitter Vacua

Abstract Recent progress in understanding de Sitter spacetime in supergravity and string theory has led to the development of a four dimensional supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua, also called de Sitter supergravity. One approach makes use of constrained (nilpotent) superfields, while an alternative one couples supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action. These two approaches have been shown to give rise to the same 4D action. A novel approach to de Sitter vacua in supergravity involves the generalisation of unimodular gravity to supergravity using a super-Stückelberg mechanism. In this paper, we make a connection between this new approach and the previous two which are in the context of nilpotent superfields and the goldstino brane. We show that upon appropriate field redefinitions, the 4D actions match up to the cubic order in the fields. This points at the possible existence of a more general framework to obtain de Sitter spacetimes from high-energy theories.

scholarly journals Logarithmic loop corrections, moduli stabilisation and de Sitter vacua in string theory

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Ignatios Antoniadis ◽  
Yifan Chen ◽  
George K. Leontaris
Keyword(s):  
String Theory ◽  
De Sitter ◽  
De Sitter Vacua

scholarly journals Interacting quantum field theory in de Sitter vacua

2003 ◽  
Vol 67 (2) ◽  
Author(s):  
Martin B. Einhorn ◽  
Finn Larsen
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Field ◽  
De Sitter ◽  
De Sitter Vacua

scholarly journals Inflationary cosmology in unimodular F(T) gravity

2017 ◽  
Vol 32 (21) ◽  
pp. 1750114 ◽  
Author(s):  
Kazuharu Bamba ◽  
Sergei D. Odintsov ◽  
Emmanuel N. Saridakis
Keyword(s):  
Spectral Index ◽  
Teleparallel Gravity ◽  
Specific Model ◽  
Inflationary Cosmology ◽  
Model Parameters ◽  
De Sitter ◽  
Reconstruction Procedure ◽  
Additional Advantage ◽  
Slow Roll ◽  
Good Agreement

We investigate the inflationary realization in the context of unimodular F(T) gravity, which is based on the F(T) modification of teleparallel gravity, in which one imposes the unimodular condition through the use of Lagrange multipliers. We develop the general reconstruction procedure of the F(T) form that can give rise to a given scale-factor evolution, and then we apply it in the inflationary regime. We extract the Hubble slow-roll parameters that allow us to calculate various inflation-related observables, such as the scalar spectral index and its running, the tensor-to-scalar ratio, and the tensor spectral index. Then, we examine the particular cases of de Sitter and power-law inflation, of Starobinsky inflation, as well as inflation in a specific model of unimodular F(T) gravity. As we show, in all cases the predictions of our scenarios are in a very good agreement with Planck observational data. Finally, inflation in unimodular F(T) gravity has the additional advantage that it always allows for a graceful exit for specific regions of the model parameters.

scholarly journals Cosmological model favored by the holographic principle

2016 ◽  
Vol 41 ◽  
pp. 1660127
Author(s):  
Irina Dymnikova ◽  
Anna Dobosz ◽  
Bożena Sołtysek
Keyword(s):  
Cosmological Model ◽  
Cosmological Constant ◽  
Space Time ◽  
Holographic Principle ◽  
Einstein Equations ◽  
Energy Tensor ◽  
De Sitter ◽  
Quantum Evaporation ◽  
Stress Energy ◽  
De Sitter Vacua

We present a regular spherically symmetric cosmological model of the Lemaitre class distinguished by the holographic principle as the thermodynamically stable end-point of quantum evaporation of the cosmological horizon. A source term in the Einstein equations connects smoothly two de Sitter vacua with different values of cosmological constant and corresponds to anisotropic vacuum dark fluid defined by symmetry of its stress-energy tensor which is invariant under the radial boosts. Global structure of space-time is the same as for the de Sitter space-time. Cosmological evolution goes from a big initial value of the cosmological constant towards its presently observed value.

scholarly journals Gauge R-symmetry and de Sitter vacua in supergravity and string theory

2014 ◽  
Vol 886 ◽  
pp. 43-62 ◽  
Author(s):  
Ignatios Antoniadis ◽  
Rob Knoops
Keyword(s):  
String Theory ◽  
De Sitter ◽  
De Sitter Vacua ◽  
R Symmetry

scholarly journals A new class of de Sitter vacua in type IIB large volume compactifications

2017 ◽  
Vol 2017 (10) ◽  
Author(s):  
Diego Gallego ◽  
M. C. David Marsh ◽  
Bert Vercnocke ◽  
Timm Wrase
Keyword(s):  
Large Volume ◽  
De Sitter ◽  
New Class ◽  
De Sitter Vacua

scholarly journals Tachyon effective dynamics and de Sitter vacua

2004 ◽  
Vol 70 (6) ◽  
Author(s):  
Bruno Carneiro da Cunha
Keyword(s):  
De Sitter ◽  
Effective Dynamics ◽  
De Sitter Vacua
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