scholarly journals Cosmological Perturbations via Quantum Corrections in M-Theory

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 425
Author(s):  
Kazuho Hiraga ◽  
Yoshifumi Hyakutake
Keyword(s):  
Early Universe ◽  
Effective Action ◽  
Quantum Effect ◽  
Equations Of Motion ◽  
Quantum Corrections ◽  
Cosmological Perturbations ◽  
Dimensional Spacetime ◽  
Analytic Expressions ◽  
Tensor Perturbations ◽  
M Theory

In the early universe, it is important to take into account the quantum effect of gravity to explain the feature of inflation. In this paper, we consider the M-theory effective action which consists of 11-dimensional supergravity and (Weyl)4 terms. The equations of motion are solved perturbatively, and the solution describes the inflation-like expansion in 4-dimensional spacetime. Equations of motion for tensor perturbations around this background are derived perturbatively. We also check that the equations of motion are obtained from the effective action up to the second order of the perturbations. Finally, we solve the equations of motion for the tensor perturbations perturbatively and obtain analytic expressions for them.

Review of inflationary cosmology via quantum corrections in M-theory

2019 ◽  
Vol 34 (33) ◽  
pp. 1930016
Author(s):  
Kazuho Hiraga ◽  
Yoshifumi Hyakutake
Keyword(s):  
Scalar Curvature ◽  
Early Universe ◽  
Quantum Effect ◽  
Quantum Corrections ◽  
Inflationary Cosmology ◽  
Superstring Theory ◽  
Inflationary Scenario ◽  
Starobinsky Model ◽  
M Theory

In this paper, we review inflationary cosmology in M-theory with quantum corrections. In old days the inflation was proposed as a resolution to the cosmological problems, and nowadays models of the inflation are severely restricted by the observations. Among them, the predictions of the Starobinsky model, which contains scalar curvature squared term, is consistent with the observations. The higher curvature terms will come from quantum effect of the gravity, and it is natural to ask its origin in superstring theory or M-theory. We investigate inflationary solution in the M-theory with higher curvature terms. We show that higher curvature terms induce an exponentially expanding solution in the early universe, and the inflation naturally ends when the corrections are suppressed. We also discuss that the ambiguity of the higher curvature terms do not affect the inflationary scenario in the M-theory.

scholarly journals Scalar cosmological perturbations in M-theory with higher-derivative corrections

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Kazuho Hiraga ◽  
Yoshifumi Hyakutake
Keyword(s):  
Power Spectrum ◽  
Equations Of Motion ◽  
Cosmological Perturbations ◽  
Curvature Perturbation ◽  
Linearized Equations ◽  
Higher Derivative ◽  
Expansion Of The Universe ◽  
M Theory ◽  
The Universe ◽  
Scalar Perturbations

Abstract We investigate the inflationary expansion of the universe induced by higher-curvature corrections in M-theory. The inflationary evolution of the geometry is discussed in K. Hiraga and Y. Hyakutake, Prog. Theor. Exp. Phys. 2018, 113B03 (2018), which we follow to analyze metric perturbations around the background. We especially focus on scalar perturbations and analyze linearized equations of motion for the scalar perturbations. By solving these equations explicitly, we evaluate the power spectrum of the curvature perturbation. The scalar spectrum index is estimated under some assumptions, and we show that it becomes close to 1.

Infrared finiteness of the two-loop correction to the Chern–Simons term in the Yang–Mills–Chern–Simons theory

1995 ◽  
Vol 73 (5-6) ◽  
pp. 344-348 ◽  
Author(s):  
Yeong-Chuan Kao ◽  
Hsiang-Nan Li
Keyword(s):  
Effective Action ◽  
Background Field ◽  
Landau Gauge ◽  
Quantum Corrections ◽  
Simons Theory ◽  
Loop Correction ◽  
Loop Contribution ◽  
Yang Mills ◽  
Chern Simons ◽  
Chern Simons Theory

We show that the two-loop contribution to the coefficient of the Chern–Simons term in the effective action of the Yang–Mills–Chern–Simons theory is infrared finite in the background field Landau gauge. We also discuss the difficulties in verifying the conjecture, due to topological considerations, that there are no more quantum corrections to the Chern–Simons term other than the well-known one-loop shift of the coefficient.

scholarly journals Effective Action from M-Theory on Twisted Connected Sum G 2-Manifolds

2017 ◽  
Vol 359 (2) ◽  
pp. 535-601 ◽  
Author(s):  
Thaisa C. da C. Guio ◽  
Hans Jockers ◽  
Albrecht Klemm ◽  
Hung-Yu Yeh
Keyword(s):  
Effective Action ◽  
Connected Sum ◽  
M Theory

scholarly journals FROM p-BRANES TO COSMOLOGY

1999 ◽  
Vol 14 (26) ◽  
pp. 4121-4142 ◽  
Author(s):  
H. LÜ ◽  
S. MUKHERJI ◽  
C. N. POPE
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Dimensional Reduction ◽  
Cosmological Models ◽  
Cosmological Solutions ◽  
M Theory ◽  
The Relationship

We study the relationship between static p-brane solitons and cosmological solutions of string theory or M theory. We discuss two different ways in which extremal p-branes can be generalized to nonextremal ones, and show how wide classes of recently discussed cosmological models can be mapped into nonextremal p-brane solutions of one of these two kinds. We also extend previous discussions of cosmological solutions to include some that make use of cosmological-type terms in the effective action that can arise from the generalized dimensional reduction of string theory or M theory.

THE VILKOVISKY EFFECTIVE ACTION IN THE EVEN-DIMENSIONAL QUANTUM GRAVITY

1989 ◽  
Vol 04 (07) ◽  
pp. 633-644 ◽  
Author(s):  
I. L. BUCHBINDER ◽  
E. N. KIRILLOVA ◽  
S. D. ODINTSOV
Keyword(s):  
Numerical Calculation ◽  
Effective Potential ◽  
Effective Action ◽  
Equations Of Motion ◽  
Flat Space ◽  
Einstein Gravity ◽  
Quantum Field ◽  
Dimensional Torus ◽  
Spontaneous Compactification ◽  
The One

The one-loop Vilkovisky effective potential which is not dependent on a gauge and a parametrization of quantum field, is investigated. We have considered Einstein gravity on a background manifold of (flat space) × (d−4- sphere) or × (d−4- dimensional torus ), d is even, and of R3 × (1- sphere ), where R3 is flat space. The numerical calculation for the cases R4 × Td−4 (d = 6,8,10) and R3 × S1 is done. The solution to the one-loop corrected equations of motion is found, although the spontaneous compactification is not stable in these cases.

scholarly journals On TCS G2 manifolds and 4D emergent strings

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Fengjun Xu
Keyword(s):  
Moduli Space ◽  
Quantum Corrections ◽  
Type Ii ◽  
Quantum Level ◽  
Weakly Coupled ◽  
G2 Manifolds ◽  
Fundamental Type ◽  
M Theory ◽  
Distance Limit ◽  
Refined Version

Abstract In this note, we study the Swampland Distance Conjecture in TCS G2 manifold compactifications of M-theory. In particular, we are interested in testing a refined version — the Emergent String Conjecture, in settings with 4d N = 1 supersymmetry. We find that a weakly coupled, tensionless fundamental heterotic string does emerge at the infinite distance limit characterized by shrinking the K3-fiber in a TCS G2 manifold. Such a fundamental tensionless string leads to the parametrically leading infinite tower of asymptotically massless states, which is in line with the Emergent String Conjecture. The tensionless string, however, receives quantum corrections. We check that these quantum corrections do modify the volume of the shrinking K3-fiber via string duality and hence make the string regain a non-vanishing tension at the quantum level, leading to a decompactification. Geometrically, the quantum corrections modify the metric of the classical moduli space and are expected to obstruct the infinite distance limit. We also comment on another possible type of infinite distance limit in TCS G2 compactifications, which might lead to a weakly coupled fundamental type II string theory.

scholarly journals Deliberations on 11D superspace for the M-theory effective action

2001 ◽  
Vol 508 (1-2) ◽  
pp. 155-167 ◽  
Author(s):  
S.James Gates ◽  
Hitoshi Nishino
Keyword(s):  
Effective Action ◽  
M Theory
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