Study of some cosmological parameters in logarithmic corrected f(R) gravitational model with swampland conjectures

2020 ◽  
pp. 2150027
Author(s):  
J. Sadeghi ◽  
E. Naghd Mezerji ◽  
S. Noori Gashti
Keyword(s):  
Polynomial Function ◽  
Cosmological Parameters ◽  
Low Energy ◽  
Index Formula ◽  
Quantum Field ◽  
Logarithmic Term ◽  
Slow Roll ◽  
Gravitational Model ◽  
Energy Quantum ◽  
Lower Limits

In this paper, we use corrected [Formula: see text] gravitational model which is a polynomial function with a logarithmic term. We employ the slow-roll conditions and obtain the number of cosmological parameters. This helps us to verify the swampland conjectures which guarantees validation of low energy quantum field theory. The obtained results show that the corresponding model is consistent with the swampland conjectures. Also, the upper and lower limits of the parameter [Formula: see text] are, respectively, 0.15 and 0.0033. Finally, by using scalar spectrum index [Formula: see text] and tensor-to-scalar ratio [Formula: see text] relations and comparing with the Planck 2018 data, we obtain the coefficients [Formula: see text], [Formula: see text] and [Formula: see text]. Also, the corresponding results are constructed by several figures, literature and also Planck 2018 data.

scholarly journals Logarithmic corrected polynomial f(R) inflation mimicking a cosmological constant

2016 ◽  
Vol 25 (07) ◽  
pp. 1650077 ◽  
Author(s):  
J. Sadeghi ◽  
B. Pourhassan ◽  
A. S. Kubeka ◽  
M. Rostami
Keyword(s):  
Cosmological Constant ◽  
Critical Points ◽  
Cosmological Parameters ◽  
Polynomial Form ◽  
Inflationary Model ◽  
Logarithmic Term ◽  
Slow Roll ◽  
Viable Model

In this paper, we consider an inflationary model of [Formula: see text] gravity with polynomial form plus logarithmic term. We calculate some cosmological parameters and compare our results with the Planck 2015 data. We find that presence of both logarithmic and polynomial corrections is necessary to yield slow-roll condition. Also, we study critical points and stability of the model to find that it is a viable model.

scholarly journals Quantum Gravity Phenomenology from the Thermodynamics of Spacetime

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 50
Author(s):  
Ana Alonso-Serrano ◽  
Marek Liška
Keyword(s):  
Quantum Gravity ◽  
Big Bang ◽  
Einstein Equations ◽  
Logarithmic Term ◽  
Quantum Gravity Phenomenology ◽  
Gravity Effects ◽  
Energy Quantum ◽  
The Big Bang ◽  
Big Bang Singularity ◽  
Modified Dynamics

This work is based on the formalism developed in the study of the thermodynamics of spacetime used to derive Einstein equations from the proportionality of entropy within an area. When low-energy quantum gravity effects are considered, an extra logarithmic term in the area is added to the entropy expression. Here, we present the derivation of the quantum modified gravitational dynamics from this modified entropy expression and discuss its main features. Furthermore, we outline the application of the modified dynamics to cosmology, suggesting the replacement of the Big Bang singularity with a regular bounce.

scholarly journals Reheating constraints on Kähler moduli inflation

2019 ◽  
Vol 34 (15) ◽  
pp. 1950114 ◽  
Author(s):  
Rakesh Kabir ◽  
Amitabha Mukherjee ◽  
Daksh Lohiya
Keyword(s):  
Equation Of State ◽  
State Parameter ◽  
Index Formula ◽  
Planck Data ◽  
Slow Roll ◽  
Cosmological Scenario ◽  
Hubble Radius ◽  
The One ◽  
Potential Parameters ◽  
The Universe

The end of inflation is connected to the standard cosmological scenario through reheating. During reheating, the inflaton oscillates around the minimum of the potential and thus decays into the daughter particles that populate the Universe at later times. Using cosmological evolution for observable CMB scales from the time of Hubble crossing to the present time, we translate the constraint on the spectral index [Formula: see text] from Planck data to the constraint on the reheating scenario in the context of Kähler moduli inflation. We find that the equation of state parameter plays a crucial role in the reheating analysis, however the details of the one parameter potential are irrelevant if the analysis is done strictly within the slow-roll formalism. In addition, we extend the de facto analysis generally done only for the pivot scale to all the observable scales which crossed the Hubble radius during inflation, where we study how the maximum number of e-folds varies for different scales, and the effect of the equation of state and potential parameters.

Slow-roll inflation in loop quantum cosmology of scalar–tensor theories of gravity

2015 ◽  
Vol 30 (26) ◽  
pp. 1550127
Author(s):  
Yu Han
Keyword(s):  
Quantum Cosmology ◽  
Field Model ◽  
Equations Of Motion ◽  
Index Formula ◽  
Jordan Frame ◽  
Loop Quantum Cosmology ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Theories Of Gravity ◽  
Slow Roll Inflation

The slow-roll inflation of scalar–tensor theories (STTs) of gravity in the context of loop quantum cosmology (LQC) is investigated in this paper. After deriving the effective Hamiltonian, we obtain the semiclassical equations of motion for the background variables in both Jordan frame and Einstein frame of STTs. Then we apply these equations in the slow-roll limit and derive the LQC corrections to the scalar spectral index [Formula: see text] and the tensor-to-scalar ratio [Formula: see text] in the two frames of STTs. Finally, we take two special sectors of STTs as specific examples, namely the Starobinsky model and the non-minimally coupled scalar field model (with the coupling function [Formula: see text] and the potential [Formula: see text]). We derive the detailed expressions of the LQC corrections to [Formula: see text] and [Formula: see text] in terms of the [Formula: see text]-folding number for these two models in both frames.

scholarly journals Synthesis of Majorana mass terms in low-energy quantum systems

2018 ◽  
Vol 20 (6) ◽  
pp. 063032
Author(s):  
L Lepori ◽  
A Celi ◽  
A Trombettoni ◽  
M Mannarelli
Keyword(s):  
Quantum Systems ◽  
Low Energy ◽  
Majorana Mass ◽  
Mass Terms ◽  
Energy Quantum

scholarly journals Gauge and infrared properties of hadronic structure of nucleon in neutron beta decay to order O(α/π) in standard V − A effective theory with QED and linear sigma model of strong low-energy interactions

2019 ◽  
Vol 34 (02) ◽  
pp. 1950010 ◽  
Author(s):  
A. N. Ivanov ◽  
R. Höllwieser ◽  
N. I. Troitskaya ◽  
M. Wellenzohn ◽  
Ya. A. Berdnikov
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Electron Energy ◽  
Low Energy ◽  
Radiative Corrections ◽  
Quantum Field ◽  
Neutron Lifetime ◽  
Gauge Invariant ◽  
Hadronic Structure ◽  
Lepton Current

Within the standard [Formula: see text] theory of weak interactions, Quantum Electrodynamics (QED) and the linear [Formula: see text]-model [Formula: see text] of strong low-energy hadronic interactions we analyze gauge and infrared properties of hadronic structure of the neutron and proton in the neutron [Formula: see text]-decay to leading order in the large nucleon mass expansion. We show that the complete set of Feynman diagrams describing radiative corrections of order [Formula: see text], induced by hadronic structure of the nucleon, to the rate of the neutron [Formula: see text]-decay is gauge noninvariant and unrenormalizable. We show that a gauge noninvariant contribution does not depend on the electron energy in agreement with Sirlin’s analysis of contributions of strong low-energy interactions (Phys. Rev. 164, 1767 (1967)). We show that infrared divergent and dependent on the electron energy contributions from the neutron radiative [Formula: see text]-decay and neutron [Formula: see text]-decay, caused by hadronic structure of the nucleon, are canceled in the neutron lifetime. Nevertheless, we find that divergent contributions of virtual photon exchanges to the neutron lifetime, induced by hadronic structure of the nucleon, are unrenormalizable even formally. Such an unrenormalizability can be explained by the fact that the effective [Formula: see text] vertex of hadron–lepton current–current interactions is not a vertex of the combined quantum field theory including QED and [Formula: see text], which are renormalizable theories. We assert that for a consistent gauge invariant and renormalizable analysis of contributions of hadronic structure of the nucleon to the radiative corrections of any order to the neutron decays one has to use a gauge invariant and fully renormalizable quantum field theory including the Standard Electroweak Model (SEM) and the [Formula: see text], where the effective [Formula: see text] vertex of hadron–lepton current–current interactions is caused by the [Formula: see text]-electroweak-boson exchange.

Observational constraints on reheating in braneworld inflation

2019 ◽  
Vol 34 (27) ◽  
pp. 1950152
Author(s):  
Z. Sakhi ◽  
A. Safsafi ◽  
M. Ferricha-Alami ◽  
H. Chakir ◽  
M. Bennai
Keyword(s):  
Cosmological Parameters ◽  
High Energy ◽  
Observational Constraints ◽  
Brane Tension ◽  
Energy Limit ◽  
Polynomial Potential ◽  
High Energy Limit ◽  
Slow Roll ◽  
Braneworld Inflation ◽  
Best Fit

The reheating era after inflation is analyzed in the framework of the braneworld models. We study reheating by calculating the reheating temperature in a braneworld inflation for various cosmological parameters. The variation of reheating [Formula: see text]-folding number and reheating temperature were obtained and analyzed as function of a spectrum of perturbation for a polynomial potential [Formula: see text]. We have applied the slow-roll approximation in the high energy limit to constraint the parameter potentials by confronting our results to recent Planck 2018 observations. We have shown that in general the best values of the predicted reheating temperature is of the order [Formula: see text] GeV, with a brane tension [Formula: see text] GeV4. We have also shown that the polynomial potential in the case [Formula: see text] provides the best fit results with recent observational constraints.

scholarly journals Causality and universality in low-energy quantum scattering

2009 ◽  
Vol 681 (5) ◽  
pp. 500-503 ◽  
Author(s):  
H.-W. Hammer ◽  
Dean Lee
Keyword(s):  
Low Energy ◽  
Quantum Scattering ◽  
Energy Quantum

scholarly journals NONPERTURBATIVE EFFECTIVE ACTIONS OF (N=2)-SUPERSYMMETRIC GAUGE THEORIES

1996 ◽  
Vol 11 (11) ◽  
pp. 1929-1973 ◽  
Author(s):  
A. KLEMM ◽  
W. LERCHE ◽  
S. THEISEN
Keyword(s):  
Riemann Surface ◽  
Effective Action ◽  
Gauge Theories ◽  
Gauge Coupling ◽  
Low Energy ◽  
Yang Mills ◽  
Hyperelliptic Riemann Surface ◽  
Supersymmetric Gauge ◽  
Energy Quantum ◽  
Appell Functions

We elaborate on our previous work on (N=2)-supersymmetric Yang-Mills theory. In particular, we show how to explicitly determine the low energy quantum effective action for G=SU(3) from the underlying hyperelliptic Riemann surface, and calculate the leading instanton corrections. This is done by solving Picard-Fuchs equations and asymptotically evaluating period integrals. We find that the dynamics of the SU(3) theory is governed by an Appell system of type F4, and compute the exact quantum gauge coupling explicitly in terms of Appell functions.

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