scholarly journals THE GRACEFUL EXIT FROM THE ANOMALY-INDUCED INFLATION: SUPERSYMMETRY AS A KEY

2002 ◽  
Vol 11 (08) ◽  
pp. 1159-1169 ◽  
Author(s):  
I. L. SHAPIRO
Keyword(s):  
Supersymmetry Breaking ◽  
Low Energy ◽  
Fine Tuning ◽  
Starobinsky Model ◽  
Expansion Of The Universe ◽  
Soft Supersymmetry Breaking ◽  
The Universe

The stable version of the anomaly-induced inflation does not need a fine tuning to induce sufficient expansion of the Universe. The non-stable version (Starobinsky model) provides the graceful exit to the FRW phase. Here, we indicate the possibility of the inflation which is stable at the beginning and unstable at the end. The effect is due to the soft supersymmetry breaking and the decoupling of the massive sparticles at low energy.

scholarly journals Explicit soft supersymmetry breaking in the heterotic M-theory B − L MSSM

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Anthony Ashmore ◽  
Sebastian Dumitru ◽  
Burt A. Ovrut
Keyword(s):  
Line Bundle ◽  
Supersymmetry Breaking ◽  
Moduli Space ◽  
Initial Conditions ◽  
Low Energy ◽  
Strongly Coupled ◽  
Hidden Sector ◽  
Effective Lagrangian ◽  
Soft Supersymmetry Breaking ◽  
M Theory

Abstract The strongly coupled heterotic M-theory vacuum for both the observable and hidden sectors of the B − L MSSM theory is reviewed, including a discussion of the “bundle” constraints that both the observable sector SU(4) vector bundle and the hidden sector bundle induced from a single line bundle must satisfy. Gaugino condensation is then introduced within this context, and the hidden sector bundles that exhibit gaugino condensation are presented. The condensation scale is computed, singling out one line bundle whose associated condensation scale is low enough to be compatible with the energy scales available at the LHC. The corresponding region of Kähler moduli space where all bundle constraints are satisfied is presented. The generic form of the moduli dependent F-terms due to a gaugino superpotential — which spontaneously break N = 1 supersymmetry in this sector — is presented and then given explicitly for the unique line bundle associated with the low condensation scale. The moduli-dependent coefficients for each of the gaugino and scalar field soft supersymmetry breaking terms are computed leading to a low-energy effective Lagrangian for the observable sector matter fields. We then show that at a large number of points in Kähler moduli space that satisfy all “bundle” constraints, these coefficients are initial conditions for the renormalization group equations which, at low energy, lead to completely realistic physics satisfying all phenomenological constraints. Finally, we show that a substantial number of these initial points also satisfy a final constraint arising from the quadratic Higgs-Higgs conjugate soft supersymmetry breaking term.

scholarly journals Scale hierarchies in particle physics and cosmology

2018 ◽  
Vol 182 ◽  
pp. 02005
Author(s):  
I. Antoniadis
Keyword(s):  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Particle Physics ◽  
Scalar Potential ◽  
Low Energy ◽  
Chiral Multiplet ◽  
Positive Cosmological Constant ◽  
Shift Symmetry ◽  
Kähler Potential ◽  
Soft Supersymmetry Breaking

I describe the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tuneable) positive cosmological constant. It utilises a single chiral multiplet with a gauged shift symmetry, that can be identified with the string dilaton (or an appropriate compactification modulus). The model is coupled to the MSSM, leading to calculable soft supersymmetry breaking masses and a distinct low energy phenomenology that allows to differentiate it from other models of supersymmetry breaking and mediation mechanisms. We also study the question if this model can lead to inflation by identifying the dilaton with the inflaton. We find that this is possible if the Kähler potential is modified by a term that has the form of NS5-brane instantons, leading to an appropriate inflationary plateau around the maximum of the scalar potential, depending on two extra parameters.

scholarly journals THE ACCELERATING EXPANSION OF THE UNIVERSE AND TORSION ENERGY

2007 ◽  
Vol 22 (31) ◽  
pp. 5709-5716 ◽  
Author(s):  
M. I. WANAS
Keyword(s):  
Geometric Structure ◽  
Repulsive Force ◽  
Fine Tuning ◽  
Tuning Parameter ◽  
Absolute Parallelism ◽  
Accelerating Expansion ◽  
Torsion Energy ◽  
Expansion Of The Universe ◽  
Curvature And Torsion ◽  
The Universe

In the present work, it is shown that the problem of the accelerating expansion of the Universe can be directly solved by applying Einstein geometrization philosophy in a wider geometry. The geometric structure used to fulfil the aim of the work is a version of Absolute Parallelism geometry in which curvature and torsion are simultaneously non vanishing objects. It is shown that, while the energy corresponding to the curvature of space- time gives rise to an attractive force, the energy corresponding to the torsion indicates the presence of a repulsive force. A fine tuning parameter can be adjusted to give the observed phenomena.

Soft supersymmetry breaking in superstring-based low-energy supergravity

1988 ◽  
Vol 203 (4) ◽  
pp. 400-402 ◽  
Author(s):  
Parthasarathi Majumdar ◽  
Soumitra Sengupta
Keyword(s):  
Supersymmetry Breaking ◽  
Low Energy ◽  
Soft Supersymmetry Breaking

scholarly journals IR quantum gravity solves naturally cosmic acceleration and its coincidence problem

2019 ◽  
Vol 28 (14) ◽  
pp. 1944013
Author(s):  
Fotios K. Anagnostopoulos ◽  
Georgios Kofinas ◽  
Vasilios Zarikas
Keyword(s):  
Quantum Gravity ◽  
Cosmic Acceleration ◽  
Fine Tuning ◽  
Accelerated Expansion ◽  
The Novel ◽  
Positive Cosmological Constant ◽  
Coincidence Problem ◽  
Expansion Of The Universe ◽  
Free Parameters ◽  
The Universe

The novel idea is that the undergoing accelerated expansion of the universe happens due to infrared quantum gravity modifications at intermediate astrophysical scales of galaxies or galaxy clusters, within the framework of Asymptotically Safe gravity. The reason is that structures of matter are associated with a scale-dependent positive cosmological constant of quantum origin. In this context, no extra unproven energy scales or fine-tuning are used. Furthermore, this model was confronted with the most recent observational data from a variety of probes, and with the aid of Bayesian analysis, the most probable values of the free parameters were extracted. Finally, the model proved to be statistically equivalent with [Formula: see text]CDM, and thus being able to resolve naturally the concept of dark energy and its associated cosmic coincidence problem.

scholarly journals COSMOLOGICAL DYNAMICS OF f(R) GRAVITY SCALAR DEGREE OF FREEDOM IN EINSTEIN FRAME

2013 ◽  
Vol 22 (14) ◽  
pp. 1350083 ◽  
Author(s):  
UMANANDA DEV GOSWAMI ◽  
KABITA DEKA
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Einstein Frame ◽  
Degree Of Freedom ◽  
Gravity Models ◽  
Accelerated Expansion ◽  
Power Law Model ◽  
Starobinsky Model ◽  
Expansion Of The Universe ◽  
The Universe

f(R) gravity models belong to an important class of modified gravity models where the late time cosmic accelerated expansion is considered as a manifestation of the large scale modification of the force of gravity. f(R) gravity models can be expressed in terms of a scalar degree of freedom by redefinition of model's variable. The conformal transformation of the action from Jordan frame to Einstein frame makes the scalar degree of freedom more explicit and can be studied conveniently. We have investigated the features of the scalar degree of freedoms and the consequent cosmological implications of the power-law (ξRn) and the Starobinsky (disappearing cosmological constant) f(R) gravity models numerically in the Einstein frame. Both the models show interesting behavior of their scalar degree of freedom and could produce the accelerated expansion of the universe in the Einstein frame with the negative equation of state of the scalar field. However, the scalar field potential for the power-law model is the well-behaved function of the field, whereas the potential becomes flat for higher value of field in the case of the Starobinsky model. Moreover, the equation of state of the scalar field for the power-law model is always negative and less than -1/3, which corresponds to the behavior of the dark energy, that produces the accelerated expansion of the universe. This is not always the case for the Starobinsky model. At late times, the Starobinsky model behaves as cosmological constant Λ as behaves by power-law model for the values of n → 2 at all times.

scholarly journals A Cosmological Scenario from the Starobinsky Model within the f(R,T) Formalism

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
P. H. R. S. Moraes ◽  
P. K. Sahoo ◽  
G. Ribeiro ◽  
R. A. C. Correa
Keyword(s):  
Functional Form ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Starobinsky Model ◽  
Cosmological Scenario ◽  
Expansion Of The Universe ◽  
Theory Of Gravitation ◽  
Free Parameters ◽  
The Universe

In this paper we derive a novel cosmological model from the f(R,T) theory of gravitation, for which R is the Ricci scalar and T is the trace of the energy-momentum tensor. We consider the functional form f(R,T)=f(R)+f(T), with f(R) being the Starobinsky Model, named R+αR2, and f(T)=2γT, with α and γ being constants. We show that a hybrid expansion law form for the scale factor is a solution for the derived Friedmann-like equations. In this way, the model is able to predict both the decelerated and the accelerated regimes of expansion of the universe, with the transition redshift between these stages being in accordance with recent observations. We also apply the energy conditions to our material content solutions. Such an application makes us able to obtain the range of acceptability for the free parameters of the model, named α and γ.

STRINGY EFFECTS ON SUPERSYMMETRY BREAKING IN LOW ENERGY SUPERGRAVITY THEORIES

1991 ◽  
Vol 06 (01) ◽  
pp. 41-58
Author(s):  
SOUMITRA SENGUPTA ◽  
PARTHASARATHI MAJUMDAR
Keyword(s):  
Supersymmetry Breaking ◽  
Quantum Effects ◽  
Low Energy ◽  
Tree Level ◽  
World Sheet ◽  
Supergravity Theory ◽  
The World ◽  
String Loop ◽  
Mass Terms ◽  
Soft Supersymmetry Breaking

The possibility of soft supersymmetry breaking at the tree level of string-inspired low energy supergravity theory is investigated. It is shown that the stringy quantum effects like the world sheet instanton and string loop effects can induce soft supersymmetry breakings at the tree level of the observable sector. Generic mass terms and trilinear soft breaking terms that arise are calculated.

Scale hierarchies and string cosmology

2017 ◽  
Vol 32 (17) ◽  
pp. 1730012
Author(s):  
I. Antoniadis
Keyword(s):  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Scalar Potential ◽  
String Cosmology ◽  
Low Energy ◽  
Chiral Multiplet ◽  
Positive Cosmological Constant ◽  
Shift Symmetry ◽  
Kähler Potential ◽  
Soft Supersymmetry Breaking

I describe the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tuneable) positive cosmological constant. It utilizes a single chiral multiplet with a gauged shift symmetry, that can be identified with the string dilaton (or an appropriate compactification modulus). The model is coupled to the MSSM, leading to calculable soft supersymmetry breaking masses and a distinct low energy phenomenology that allows to differentiate it from other models of supersymmetry breaking and mediation mechanisms. We also study the question if this model can lead to inflation by identifying the dilaton with the inflaton. We find that this is possible if the Kähler potential is modified by a term that has the form of NS5-brane instantons, leading to an appropriate inflationary plateau around the maximum of the scalar potential, depending on two extra parameters.

ON THE CALCULATION OF THE LOW ENERGY SOFT SUPERSYMMETRY BREAKING TERMS

1993 ◽  
Vol 08 (27) ◽  
pp. 2579-2583 ◽  
Author(s):  
N.V. KRASNIKOV
Keyword(s):  
Renormalization Group ◽  
Supersymmetry Breaking ◽  
Low Energy ◽  
Planck Mass ◽  
Renormalization Group Equations ◽  
Soft Supersymmetry Breaking

We show that in supergravity theories with soft supersymmetry breaking it is necessary to take into account the terms in the Lagrangian which are suppressed by the inverse powers of the Planck mass in the calculation of the low energy soft supersymmetry breaking terms. Such terms are discarded in the standard calculations based on the use of the renormalization group equations.

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