scholarly journals ON FREE FIELD REALIZATIONS OF STRINGS IN BTZ

2004 ◽  
Vol 19 (10) ◽  
pp. 1579-1588 ◽  
Author(s):  
SAMULI HEMMING
Keyword(s):  
Scalar Field ◽  
Current Algebra ◽  
Free Field ◽  
Scalar Fields ◽  
Spectral Flow ◽  
Free Scalar ◽  
Discrete Representations ◽  
Continuous Representations

We discuss realizations of the SL (2,R) current algebra in the hyperbolic basis using free scalar fields. It has been previously shown by Satoh how such a realization can be used to describe the principal continuous representations of SL (2,R). We extend this work by introducing another realization that corresponds to the principal discrete representations of SL (2,R). We show that in these realizations spectral flow can be interpreted as twisting of a free scalar field. Finally, we discuss how these realizations can be obtained from the BTZ Lagrangian.

FREE FIELD AND PARAFERMIONIC REALIZATIONS OF TWISTED $su(3)^{(2)}_k$ CURRENT ALGEBRA

2002 ◽  
Vol 16 (14n15) ◽  
pp. 2153-2159
Author(s):  
XIANG-MAO DING ◽  
MARK D. GOULD ◽  
YAO-ZHONG ZHANG
Keyword(s):  
Scalar Field ◽  
Current Algebra ◽  
Energy Momentum Tensor ◽  
Free Field ◽  
Scalar Fields ◽  
Momentum Tensor ◽  
Free Fields

Free field and twisted parafermionic representations of twisted [Formula: see text] current algebra are obtained. The corresponding twisted Sugawara energy-momentum tensor is given in terms of three (β,γ) pairs and two scalar fields and also in terms of twisted parafermionic currents and one scalar field. Two screening currents of the first kind are presented in terms of the free fields.

scholarly journals Weak cosmic censorship with self-interacting scalar and bound on charge to mass ratio

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Yan Song ◽  
Tong-Tong Hu ◽  
Yong-Qiang Wang
Keyword(s):  
Scalar Field ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Mass Ratio ◽  
Quartic Coupling ◽  
Scalar Theory ◽  
Free Scalar ◽  
The One ◽  
Nonzero Scalar ◽  
Large Charge

Abstract We study the model of four-dimensional Einstein-Maxwell-Λ theory minimally coupled to a massive charged self-interacting scalar field, parameterized by the quartic and hexic couplings, labelled by λ and β, respectively. In the absence of scalar field, there is a class of counterexamples to cosmic censorship. Moreover, we investigate the full nonlinear solution with nonzero scalar field included, and argue that these counterexamples can be removed by assuming charged self-interacting scalar field with sufficiently large charge not lower than a certain bound. In particular, this bound on charge required to preserve cosmic censorship is no longer precisely the weak gravity bound for the free scalar theory. For the quartic coupling, for λ < 0 the bound is below the one for the free scalar fields, whereas for λ > 0 it is above. Meanwhile, for the hexic coupling the bound is always above the one for the free scalar fields, irrespective of the sign of β.

scholarly journals Free Scalar Fields in Finite Volume Are Holographic

Universe ◽  
2019 ◽  
Vol 5 (12) ◽  
pp. 223
Author(s):  
Csaba Balázs
Keyword(s):  
Scalar Field ◽  
Surface Area ◽  
Finite Volume ◽  
Degrees Of Freedom ◽  
Scalar Fields ◽  
Flat Space ◽  
Linear Size ◽  
Energy Mode ◽  
Free Scalar ◽  
Quantized Field

This brief note presents a back-of-the-envelope calculation showing that the number of degrees of freedom of a free scalar field in expanding flat space equals the surface area of the Hubble volume in Planck units. The logic of the calculation is the following. The amount of energy in the Hubble volume scales with its linear size, consequently the volume can only contain a finite number of quantized field modes. Since the momentum of the lowest energy mode scales inversely with the linear size of the volume, the maximal number of such modes in the volume scales with its surface area. It is possible to show that when the number of field modes is saturated the modes are confined to the surface of the volume. Gravity only enters this calculation as a regulator, providing a finite volume that contains the field, the entire calculation is done in flat space. While this toy model is bound to be incomplete, it is potentially interesting because it reproduces the defining aspects of holography, and advocates a regularization of the quantum degrees of freedom based on Friedmann’s equation.

scholarly journals THE QUANTUM THEORY OF SCALAR FIELDS ON THE DE SITTER EXPANDING UNIVERSE

2008 ◽  
Vol 23 (16n17) ◽  
pp. 2563-2577 ◽  
Author(s):  
ION I. COTĂESCU ◽  
COSMIN CRUCEAN ◽  
ADRIAN POP
Keyword(s):  
Scalar Field ◽  
Gordon Equation ◽  
Scalar Fields ◽  
Wave Functions ◽  
De Sitter ◽  
Scalar Quantum ◽  
Long Time ◽  
Klein Gordon ◽  
Free Scalar ◽  
Special Time

New quantum modes of the free scalar field are derived in a special time-evolution picture that may be introduced in moving charts of de Sitter backgrounds. The wave functions of these new modes are solutions of the Klein–Gordon equation and energy eigenfunctions, defining the energy basis. This completes the scalar quantum mechanics where the momentum basis is well known for long time. In this enlarged framework the quantization of the scalar field can be done in canonical way obtaining the principal conserved one-particle operators and the Green functions.

scholarly journals Noncommutativity in Effective Loop Quantum Cosmology

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Abraham Espinoza-García ◽  
Efraín Torres-Lomas ◽  
Sinuhé Pérez-Payán ◽  
Luis Rey Díaz-Barrón
Keyword(s):  
Scalar Field ◽  
Quantum Cosmology ◽  
Free Field ◽  
Matter Field ◽  
Field Energy ◽  
Loop Quantum Cosmology ◽  
Free Scalar ◽  
Key Features ◽  
Field Energy Density ◽  
The One

We construct a noncommutative extension of the Loop Quantum Cosmology effective scheme for the flat FLRW model with a free scalar field via a theta deformation. Firstly, a deformation is implemented in the configuration sector, among the holonomy variable and the matter degree of freedom. We show that this type of noncommutativity retains, to some degree, key features of the Loop Quantum Cosmology paradigm for a free field. Secondly, a deformation is implemented in the momentum sector, among the momentum associated with the holonomy variable and the momentum associated with the matter field. We show that in this latter case the scalar field energy density is the same as the one in standard Loop Quantum Cosmology.

The classical scalar field

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Scalar Field ◽  
Symmetry Breaking ◽  
Free Field ◽  
Scalar Fields ◽  
Global Symmetry ◽  
Lagrange Equations ◽  
Complex Scalar ◽  
Klein Gordon ◽  
Complex Scalar Field ◽  
The Fourier Transform

This chapter explains some of the properties of scalar fields, which are paradigmatic in relativistic field theory. It also shows how a complex scalar field can confer an effective mass to a ‘gauge’ field. The chapter first provides the Klein–Gordon equation derived from the Euler–Lagrange equations outlined in the previous chapter. It then illustrates the Fourier transform of a free field, before embarking on further discussions on complex fields, charge, and symmetry breaking. Finally, this chapter considers that the fact that global symmetry breaking leads to the appearance of a massless, and therefore long-range, scalar field is problematic because such a field is not observed experimentally. It thus takes a look at the BEH mechanism (named after its inventors, Robert Brout, François Englert, and Peter Higgs), which can make it ‘disappear’.

scholarly journals Small free field inflation in higher curvature gravity

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
José D. Edelstein ◽  
Robert B. Mann ◽  
David Vázquez Rodríguez ◽  
Alejandro Vilar López
Keyword(s):  
Scalar Field ◽  
Free Field ◽  
Planck Scale ◽  
Accelerated Expansion ◽  
Large Field ◽  
Quadratic Potential ◽  
Open Questions ◽  
Expansion Of The Universe ◽  
Free Scalar ◽  
The Universe

Abstract Within General Relativity, a minimally coupled scalar field governed by a quadratic potential is able to produce an accelerated expansion of the universe provided its value and excursion are larger than the Planck scale. This is an archetypical example of the so called large field inflation models. We show that by including higher curvature corrections to the gravitational action in the form of the Geometric Inflation models, it is possible to obtain accelerated expansion with a free scalar field whose values are well below the Planck scale, thereby turning a traditional large field model into a small field one. We provide the conditions the theory has to satisfy in order for this mechanism to operate, and we present two explicit models illustrating it. Finally, we present some open questions raised by this scenario in which inflation takes place completely in a higher curvature dominated regime, such as those concerning the study of perturbations.

scholarly journals FERMIONIC AND SCALAR FIELDS AS SOURCES OF INTERACTING DARK MATTER–DARK ENERGY

2011 ◽  
Vol 20 (13) ◽  
pp. 2543-2558 ◽  
Author(s):  
SAMUEL LEPE ◽  
JAVIER LORCA ◽  
FRANCISCO PEÑA ◽  
YERKO VÁSQUEZ
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Analytical Solution ◽  
Scalar Fields ◽  
Nonminimal Coupling ◽  
Field Equations ◽  
Fermionic Field ◽  
Minimal Coupling ◽  
Constant Type

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.

SPECTRAL FLOW AND FREE FIELD REALIZATIONS OF BOSONIC STRINGS ON NAPPI–WITTEN GROUP MANIFOLD

2011 ◽  
Vol 26 (01) ◽  
pp. 149-160
Author(s):  
GANG CHEN
Keyword(s):  
Lie Algebra ◽  
Bosonic Strings ◽  
Free Field ◽  
Geometric Interpretation ◽  
Closed String ◽  
Space Time ◽  
Spectral Flow ◽  
Affine Lie Algebra ◽  
Group Manifold ◽  
Free Field Realization

In this paper we study some aspects of closed string theories in the Nappi–Witten space–time. The effects of spectral flow on the geodesics are studied in terms of an explicit parametrization of the group manifold. The worldsheets of the closed strings under the spectral flow of the geodesics can be classified into four classes, each with a geometric interpretation. We also obtain a free field realization of the Nappi–Witten affine Lie algebra in the most general conditions using a different but equivalent parametrization of the group manifold.

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