BULK SCALAR-FIELD INFLUENCED FRW UNIVERSE MODEL

2012 ◽  
Vol 27 (01) ◽  
pp. 1250003 ◽  
Author(s):  
TAE HOON LEE ◽  
SUNNYEO LEE
Keyword(s):  
Sigma Model ◽  
Scalar Fields ◽  
Einstein Gravity ◽  
Warp Factor ◽  
Nonlinear Sigma Model ◽  
Universe Model ◽  
Frw Universe ◽  
Brane Model ◽  
Bulk Scalar Field ◽  
The One

We consider a nonlinear sigma-model-like theory of bulk scalar fields coupled to the five-dimensional Einstein gravity. In Robertson–Walker spacetimes, we find some power-law cosmological solutions for the scale factor when the expansion rate of an extra dimension is proportional to one of our (3+1)-dimensional universe. Among them, the solution with a decreasing warp factor could be related to the one-brane model of Randall and Sundrum.

scholarly journals CHAOTIC INFLATION ON THE RANDALL–SUNDRUM TWO-BRANE MODEL

2010 ◽  
Vol 25 (31) ◽  
pp. 2697-2713
Author(s):  
KOUROSH NOZARI ◽  
SIAMAK AKHSHABI
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Friedmann Equation ◽  
Warp Factor ◽  
Model Parameters ◽  
Stabilization Mechanism ◽  
Brane Model ◽  
Inflation Model ◽  
Bulk Scalar Field ◽  
Chaotic Inflation

We construct an inflation model on the Randall–Sundrum I (RSI) brane where a bulk scalar field stabilizes the inter-brane separation. We study impact of the bulk scalar field on the inflationary dynamics on the brane. We proceed in two different approaches: in the first approach, the stabilizing field potential is directly appeared in the Friedmann equation and the resulting scenario is effectively a two-field inflation. In the second approach, the stabilization mechanism is considered in the context of a warp factor so that there is just one field present that plays the roles of both inflaton and stabilizer. We study constraints imposed on the model parameters from recent observations.

scholarly journals INFLATONLESS INFLATION

2012 ◽  
Vol 27 (25) ◽  
pp. 1250151 ◽  
Author(s):  
CHIU MAN HO ◽  
THOMAS W. KEPHART
Keyword(s):  
Extra Dimensions ◽  
Sigma Model ◽  
Einstein Gravity ◽  
Nonlinear Sigma Model ◽  
Ordinary Space

We consider a (4+N)-dimensional Einstein gravity coupled to a nonlinear sigma model. This theory admits a solution in which the N extra dimensions contract exponentially while the ordinary space expand exponentially. Physically, the nonlinear sigma fields induce the dynamical compactification of the extra dimensions, which in turn drives inflation. No inflatons are required.

Non-Abelian BFFT embedding, Schrödinger quantization and the field–antifield anomaly of the O(N) nonlinear sigma model

2016 ◽  
Vol 31 (01) ◽  
pp. 1550225 ◽  
Author(s):  
E. M. C. de Abreu ◽  
J. Ananias Neto ◽  
A. C. R. Mendes ◽  
G. Oliveira-Neto
Keyword(s):  
Excited States ◽  
Sigma Model ◽  
Nonlinear Sigma Model ◽  
Quantum Level ◽  
Abelian Gauge ◽  
Abelian Gauge Theory ◽  
Class System ◽  
Gauge Symmetries ◽  
Nonlocal Field ◽  
The One

We have embedded the [Formula: see text] nonlinear sigma model in a non-Abelian gauge theory. After that as a first class-system, it was quantized using two different approaches: the functional Schrödinger method and the nonlocal field–antifield procedure. First, the quantization was performed with the functional Schrödinger method, for [Formula: see text], obtaining the wave functionals for the ground and excited states. Second, using the well-known BV formalism, we have computed the one-loop anomaly. This result shows that the classical gauge symmetries, which appear due to the conversion via BFFT method, are broken at the quantum level.

THE BOSONIC SIGMA MODEL ON A COMPACT SURFACE

1990 ◽  
Vol 05 (25) ◽  
pp. 2031-2037 ◽  
Author(s):  
M. LEBLANC ◽  
P. MADSEN ◽  
R. B. MANN ◽  
D. G. C. McKEON
Keyword(s):  
Sigma Model ◽  
Stereographic Projection ◽  
Two Dimensions ◽  
Compact Surface ◽  
Three Dimensions ◽  
Dimensional Euclidean Space ◽  
Nonlinear Sigma Model ◽  
Β Function ◽  
The One ◽  
Infrared Divergences

A stereographic projection is used to map the bosonic nonlinear sigma model with torsion from two-dimensional Euclidean space onto a sphere-S2 embedded in three dimensions. The one-loop β-function of the torsionless σ-model is determined using operator regularization to handle ultraviolet divergences. Only by excluding the lowest eigenstate of the rotation operator on the sphere can the usual β-function be recovered; inclusion of this eigenstate leads to severe infrared divergences. Both the ultraviolet and infrared divergences can be regulated by working in n, rather than two, dimensions, in which case the contribution of the lowest mode cancels exactly against the contribution of all other modes, resulting in a vanishing β-function.

scholarly journals Higgs inflation as nonlinear sigma model and scalaron as its σ-meson

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Yohei Ema ◽  
Kyohei Mukaida ◽  
Jorinde van de Vis
Keyword(s):  
Sigma Model ◽  
Planck Scale ◽  
Scalar Fields ◽  
Target Space ◽  
Linear Sigma Model ◽  
Nonlinear Sigma Model ◽  
Jordan Frame ◽  
Quadratic Gravity ◽  
Frame Transformation ◽  
Definition Of

Abstract We point out that a model with scalar fields with a large nonminimal coupling to the Ricci scalar, such as Higgs inflation, can be regarded as a nonlinear sigma model (NLSM). With the inclusion of not only the scalar fields but also the conformal mode of the metric, our definition of the target space of the NLSM is invariant under the frame transformation. We show that the σ-meson that linearizes this NLSM to be a linear sigma model (LSM) corresponds to the scalaron, the degree of freedom associated to the R2 term in the Jordan frame. We demonstrate that quantum corrections inevitably induce this σ-meson in the large-N limit, thus providing a frame independent picture for the emergence of the scalaron. The resultant LSM only involves renormalizable interactions and hence its perturbative unitarity holds up to the Planck scale unless it hits a Landau pole, which is in agreement with the renormalizability of quadratic gravity.

Old wine in a new bottle: Technidilaton as the 125 GeV Higgs

2017 ◽  
Vol 32 (36) ◽  
pp. 1747026
Author(s):  
Koichi Yamawaki
Keyword(s):  
Sigma Model ◽  
Local Symmetry ◽  
Effective Theory ◽  
Nonlinear Sigma Model ◽  
Scale Invariant ◽  
Gauge Bosons ◽  
Strongly Coupled ◽  
Technicolor Model ◽  
Vector Bosons ◽  
The One

The first Nagoya SCGT workshop back in 1988 (SCGT 88) was motivated by the walking technicolor and technidilaton. Now at SCGT15 I returned to the “old wine” in “a new bottle”, the recently discovered 125 Higgs boson as the technidilaton. We show that the Standard Model (SM) Higgs Lagrangian is identical to the nonlinear realization of both the scale and chiral symmetries (“scale-invariant nonlinear sigma model”), and is further gauge equivalent to the “scale-invariant Hidden Local Symmetry (HLS) model” having possible new vector bosons as the HLS gauge bosons with scale-invariant mass: SM Higgs is nothing but a (pseudo) dilaton. The effective theory of the walking technicolor has precisely the same type of the scale-invariant nonlinear sigma model, thus further having the scale-invariant HLS gauge bosons (technirho’s, etc.). The technidilaton mass [Formula: see text] comes from the trace anomaly, which yields [Formula: see text] via PCDC, in the underlying walking [Formula: see text] gauge theory with [Formula: see text] massless flavors, where [Formula: see text] is the the decay constant and [Formula: see text]. This implies [Formula: see text] for [Formula: see text] in the one-family walking technicolor model [Formula: see text], in good agreement with the current LHC Higgs data. In the anti-Veneziano limit, [Formula: see text], with [Formula: see text]fixed and [Formula: see text]fixed [Formula: see text], we have a result: [Formula: see text]. Then the technidilaton is a naturally light composite Higgs out of the strongly coupled conformal dynamics, with its couplings even weaker than the SM Higgs. Related holographic and lattice results are also discussed. In particular, such a light flavor-singlet scalar does exists in the lattice simulations in the walking regime.

scholarly journals NONLINEAR SIGMA MODEL ON CONIFOLDS

2002 ◽  
Vol 17 (09) ◽  
pp. 517-533 ◽  
Author(s):  
R. PARTHASARATHY ◽  
K. S. VISWANATHAN
Keyword(s):  
Sigma Model ◽  
Equations Of Motion ◽  
Target Space ◽  
Warp Factor ◽  
Nonlinear Sigma Model ◽  
Explicit Solutions ◽  
Type Ii ◽  
Ricci Flat ◽  
Complex Dimension ◽  
Gauge Connection

Explicit solutions to the conifold equations with complex dimension n = 3, 4 in terms of complex coordinates (fields) are employed to construct the Ricci-flat Kähler metrics on these manifolds. The Kähler two-forms are found to be closed. The complex realization of these conifold metrics are used in the construction of two-dimensional nonlinear sigma model with the conifolds as target spaces. The action for the sigma model is shown to be bounded from below. By a suitable choice of the "integration constants", arising in the solution of Ricci flatness requirement, the metric and the equations of motion are found to be non-singular. As the target space is Ricci-flat, the perturbative one-loop counterterms being absent, the model becomes topological. The inherent U(1) fiber over the base of the conifolds is shown to correspond to a gauge connection in the sigma model. The same procedure is employed to construct the metric for the resolved conifold, in terms of complex coordinates and the action for a nonlinear sigma model with resolved conifold as target space, is found to have a minimum value, which is topological. The metric is expressed in terms of the six real coordinates and compared with earlier works. The harmonic function, which is the warp factor in Type II-B string theory, is obtained and the ten-dimensional warped metric has the AdS5 × X5 geometry.

Spontaneous Compactification Induced by Gravitons and Scalar Field

1997 ◽  
Vol 12 (28) ◽  
pp. 5007-5018
Author(s):  
N. Granda ◽  
E. Loaiza
Keyword(s):  
Sigma Model ◽  
Nonlinear Sigma Model ◽  
Dimensional Sphere ◽  
Minkowski Space Time ◽  
Background Space ◽  
Dimensional Minkowski Space ◽  
The One ◽  
Hilbert Action ◽  
Kaluza Klein ◽  
Made In

We evaluate the one-loop effective potential for the Einstein–Hilbert action coupled to a nonlinear sigma model in a Kaluza–Klein background space M4 × SN (M4 is the four-dimensional Minkowski space–time and SN is the N-dimensional sphere) for odd N. The computation is made in the harmonic and in the light cone gauges. The radius of compactification for some N was found.

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