scholarly journals Cosmological singularities and 2-dimensional dilaton gravity

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Ritabrata Bhattacharya ◽  
K. Narayan ◽  
Partha Paul
Keyword(s):  
Field Theory ◽  
Dimensional Reduction ◽  
Flat Space ◽  
Big Bang ◽  
Point Of View ◽  
Time Behaviour ◽  
Dilaton Gravity ◽  
Cosmological Singularity ◽  
Higher Dimensional ◽  
Scalar Theories

Abstract We study Big-Bang or -Crunch cosmological singularities in 2-dimensional dilaton-gravity-scalar theories, in general obtained by dimensional reduction of higher dimensional theories. The dilaton potential encodes information about the asymptotic data defining the theories, and encompasses various families such as flat space, AdS, conformally AdS as arising from nonconformal branes, and more general nonrelativistic theories. We find a kind of universal near singularity behaviour independent of the dilaton potential, giving universal interrelations between the exponents defining the time behaviour near the cosmological singularity. More detailed analysis using a scaling ansatz enables finding various classes of cosmological backgrounds, recovering known examples such as the AdS Kasner singularity as well finding as new ones. We give some comments on the dual field theory from this point of view.

scholarly journals Testing a Dilaton Gravity Model Using Nucleosynthesis

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Boran ◽  
E. O. Kahya
Keyword(s):  
Steady State ◽  
Gravity Model ◽  
Big Bang ◽  
Universe Model ◽  
Light Elements ◽  
Dilaton Gravity ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Higher Dimensional ◽  
State Universe

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for theΛ-CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D,3He,4He, T, and7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model andΛ-CDM in the light of the astrophysical observations.

scholarly journals Revisiting Coleman-de Luccia transitions in the AdS regime using holography

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Jewel K. Ghosh ◽  
Elias Kiritsis ◽  
Francesco Nitti ◽  
Lukas T. Witkowski
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Scalar Field ◽  
Flat Space ◽  
Field Theories ◽  
Quantum Field ◽  
De Sitter ◽  
Thin Walled ◽  
Scalar Theories ◽  
Scalar Potentials

Abstract Coleman-de Luccia processes for AdS to AdS decays in Einstein-scalar theories are studied. Such tunnelling processes are interpreted as vev-driven holographic RG flows of a quantum field theory on de Sitter space-time. These flows do not exist for generic scalar potentials, which is the holographic formulation of the fact that gravity can act to stabilise false AdS vacua. The existence of Coleman-de Luccia tunnelling solutions in a potential with a false AdS vacuum is found to be tied to the existence of exotic RG flows in the same potential. Such flows are solutions where the flow skips possible fixed points or reverses direction in the coupling. This connection is employed to construct explicit potentials that admit Coleman-de Luccia instantons in AdS and to study the associated tunnelling solutions. Thin-walled instantons are observed to correspond to dual field theories with a parametrically large value of the dimension ∆ for the operator dual to the scalar field, casting doubt on the attainability of this regime in holography. From the boundary perspective, maximally symmetric instantons describe the probability of symmetry breaking of the dual QFT in de Sitter. It is argued that, even when such instantons exist, they do not imply an instability of the same theory on flat space or on R × S3.

scholarly journals Chiral correlators in $$ \mathcal{N} $$ = 2 superconformal quivers

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Francesco Galvagno ◽  
Michelangelo Preti
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Flat Space ◽  
Field Theories ◽  
Superconformal Field Theories ◽  
Four Dimensions ◽  
Yang Mills ◽  
The Matrix ◽  
Superspace Formalism ◽  
Model Approach

Abstract We consider a family of $$ \mathcal{N} $$ N = 2 superconformal field theories in four dimensions, defined as ℤq orbifolds of $$ \mathcal{N} $$ N = 4 Super Yang-Mills theory. We compute the chiral/anti-chiral correlation functions at a perturbative level, using both the matrix model approach arising from supersymmetric localisation on the four-sphere and explicit field theory calculations on the flat space using the $$ \mathcal{N} $$ N = 1 superspace formalism. We implement a highly efficient algorithm to produce a large number of results for finite values of N , exploiting the symmetries of the quiver to reduce the complexity of the mixing between the operators. Finally the interplay with the field theory calculations allows to isolate special observables which deviate from $$ \mathcal{N} $$ N = 4 only at high orders in perturbation theory.

STOCHASTIC FIELD THEORY AND RENORMALIZATION GROUP APPROACH TO CRITICAL BEHAVIORS IN THERMO FIELD DYNAMICS

1989 ◽  
Vol 04 (09) ◽  
pp. 2185-2210
Author(s):  
B. BHATTACHARYA
Keyword(s):  
Field Theory ◽  
Renormalization Group ◽  
Finite Temperature ◽  
Internal Field ◽  
Point Of View ◽  
Internal Space ◽  
Theoretic Approach ◽  
Stochastic Field ◽  
Stochastic Fields ◽  
Renormalization Group Approach

We have studied here the critical behaviors in a simple model from the point of view of the renormalization group at finite temperature utilizing the Stochastic field theoretic approach towards a finite temperature field theory. To this end, thermofield dynamics has been formulated in terms of Stochastic fields in the external and internal space and the thermal average of the two-point correlation function of the internal field functions is related with the order parameter. The thermodynamical functions and the critical phenomena are then studied constructing the generating functionals involving Stochastic fields.

scholarly journals Lifshitz hydrodynamics at generic z from a moving black brane

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Aruna Rajagopal ◽  
Larus Thorlacius
Keyword(s):  
Field Theory ◽  
Steady State ◽  
Critical Exponent ◽  
Stress Tensor ◽  
Perfect Fluid ◽  
Scale Invariance ◽  
Linear Momentum ◽  
Black Brane ◽  
Dilaton Gravity ◽  
Non Equilibrium

Abstract A Lifshitz black brane at generic dynamical critical exponent z > 1, with non-zero linear momentum along the boundary, provides a holographic dual description of a non-equilibrium steady state in a quantum critical fluid, with Lifshitz scale invariance but without boost symmetry. We consider moving Lifshitz branes in Einstein-Maxwell-Dilaton gravity and obtain the non-relativistic stress tensor complex of the dual field theory via a suitable holographic renormalisation procedure. The resulting black brane hydrodynamics and thermodynamics are a concrete holographic realization of a Lifshitz perfect fluid with a generic dynamical critical exponent.

GRAVITATIONAL BAG EFFECTS ON KALUZA KLEIN AND STRING EXCITATIONS

1989 ◽  
Vol 04 (19) ◽  
pp. 5119-5131 ◽  
Author(s):  
E. I. GUENDELMAN
Keyword(s):  
Extra Dimensions ◽  
Blow Up ◽  
Point Of View ◽  
Spherically Symmetric ◽  
Massive String ◽  
Free Objects ◽  
Higher Dimensional ◽  
Central Regions ◽  
The Masses ◽  
Kaluza Klein

Gravitational Bags are spherically symmetric solutions of higher-dimensional Kaluza Klein (K – K) theories, where the compact dimensions become very large near the center of the geometry, although they are small elsewhere. The K – K excitations therefore become very light when located near the center of this geometry and this appears to affect drastically the naive tower of the masses spectrum of K – K theories. In the context of string theories, string excitations can be enclosed by Gravitational Bags, making them not only lighter, but also localized, as observed by somebody, that does not probe the central regions. Strings, however, can still have divergent sizes, as quantum mechanics seems to demand, since the extra dimensions blow up at the center of the geometry. From a projected 4-D point of view, very massive string bits may lie inside their Schwarzschild radii, as pointed out by Casher, Gravitational Bags however are horizon free objects, so no conflict with macroscopic causality arises if the string excitations are enclosed by Gravitational Bags.

scholarly journals The Use of Idioms and Wordplay in The Big Bang Theory Sitcom

Tertium ◽  
2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Lendita Kryeziu
Keyword(s):  
Age Groups ◽  
Pop Culture ◽  
Big Bang ◽  
Point Of View ◽  
Communication Tool ◽  
Vast Number ◽  
Big Bang Theory ◽  
Public Speakers ◽  
The Big Bang

Language is a powerful communication tool. A skilful person uses words and manipulates them for different purposes; be that for persuading clients in buying different products or joining a congregation; soothing aggravated patients and consoling people who lost their loved ones. Language is used for teaching, informing, entertaining and making people laugh. Many public speakers, teachers, politicians and leaders use humour for breaking the ice and engaging the audience into listening. Moreover, nowadays a vast number of sitcoms are popular among different age groups based on the topics, genre and the audience’s field of interest. One such series which has caught the interest of a broader audience on Netflix is The Big Bang Theory. The usage of idioms, wordplays, puns, rhyming structures, pop culture language and scientific jargon, permeated with humour, are widely spread into the characters’ daily conversations through entire episodes. From the linguistic point of view, the corpus of The Big Bang Theory episodes will be thoroughly analysed for finding the relevance of using idioms, wordplays, puns and other structures in transmitting humorous messages to the audience.

scholarly journals The structure of the big bang from higher-dimensional embeddings

2002 ◽  
Vol 19 (6) ◽  
pp. 1139-1155 ◽  
Author(s):  
Sanjeev S Seahra ◽  
Paul S Wesson
Keyword(s):  
Big Bang ◽  
Higher Dimensional ◽  
The Big Bang

Primal Emergence

2017 ◽  
Author(s):  
John L. Culliney ◽  
David Jones
Keyword(s):  
Background Radiation ◽  
Quantum Turbulence ◽  
Big Bang ◽  
Point Of View ◽  
Microwave Background ◽  
Creation Story ◽  
Catalytic Potential ◽  
Microwave Background Radiation ◽  
Nuclear Synthesis ◽  
The Big Bang

Since the Big Bang, the universe’s inflation and its aftermath might be called the “creation story” according to science, in which tremendously variegated order and deterministic pattern propagated from a cosmic seed of perfect uniformity and smoothness. The formative properties of matter and energy were forged through initial quantum turbulence and an emergent principle of attraction that seems to pervade all of nature. As it emerged out of simplicity, the universe adopted a modus operandi that we call the cooperative constant, initially manifested in physical forces, especially gravity, and progressively complemented by chemistry. From an evolutionary point of view, an emergent catalytic potential, an attraction to cooperate, or participate in heterogeneity—which becomes a sine qua non for the existence of life—is widely characteristic of matter in our universe. This tendency is now found at the heart of the most progressive systems of which we are aware. Chapter One weaves its cosmological story through leading theories and revelations in astrophysics including primordial quantum turbulence, the multiverse, recombination, and the origin of the cosmic microwave background radiation (CMB), also the enigmas of dark matter and dark energy, and nuclear synthesis of the elements of life within stars.

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