scholarly journals Conformal wave expansions for flat space amplitudes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Chang Liu ◽  
David A. Lowe
Keyword(s):  
Three Dimensional ◽  
Principal Series ◽  
Minkowski Spacetime ◽  
Scalar Fields ◽  
Flat Space ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Holographic Approach ◽  
Unitary Principal Series ◽  
Celestial Sphere

Abstract The extended BMS algebra contains a conformal subgroup that acts on the celestial sphere as SO(1, 3). It is of interest to perform mode expansions of free fields in Minkowski spacetime that realize this symmetry in a simple way. In the present work we perform such a mode expansion for massive scalar fields using the unitary principal series representations of SO(1, 3) with a view to developing a holographic approach to gravity in asymptotically flat spacetime. These mode expansions are also of use in studying holography in three-dimensional de Sitter spacetime.

scholarly journals Discrete O(1,4) Transformations And New Scalar Quantum Modes On The De Sitter Spacetime

2012 ◽  
Vol 56 (1) ◽  
pp. 38-42
Author(s):  
Ion I. Cotăescu
Keyword(s):  
Time Reversal ◽  
Isometry Group ◽  
Three Dimensional ◽  
Minkowski Spacetime ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Scalar Quantum ◽  
Abelian Subgroups

AbstractIt is shown that the isometry group of the de Sitter spacetime includes two different three-dimensional Abelian subgroups which transform between themselves through a discrete isometry corresponding to the time reversal in the five-dimensional Minkowski spacetime embedding the de Sitter one. The eigenfunctions of the generators of these Abelian subgroups form two different sets of quantum modes correlated by the mentioned isometry.

scholarly journals Wavefunctions in dS/CFT revisited: principal series and double-trace deformations

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Hiroshi Isono ◽  
Hoiki Madison Liu ◽  
Toshifumi Noumi
Keyword(s):  
Principal Series ◽  
Light Fields ◽  
Quadratic Term ◽  
De Sitter Spacetime ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Complementary Series ◽  
Point Function ◽  
Sitter Spacetime ◽  
Simple Scaling

Abstract We study wavefunctions of heavy scalars on de Sitter spacetime and their implications to dS/CFT correspondence. In contrast to light fields in the complementary series, heavy fields in the principal series oscillate outside the cosmological horizon. As a consequence, the quadratic term in the wavefunction does not follow a simple scaling and so it is hard to identify it with a conformal two-point function. In this paper, we demonstrate that it should be interpreted as a two-point function on a cyclic RG flow which is obtained by double-trace deformations of the dual CFT. This is analogous to the situation in nonrelativistic AdS/CFT with a bulk scalar whose mass squared is below the Breitenlohner-Freedman (BF) bound. We also provide a new dS/CFT dictionary relating de Sitter two-point functions and conformal two-point functions in the would-be dual CFT.

scholarly journals Every timelike geodesic in Anti-de Sitter spacetime is a circle of the same radius

2016 ◽  
Vol 25 (01) ◽  
pp. 1650007 ◽  
Author(s):  
Leszek M. Sokołowski ◽  
Zdzisław A. Golda
Keyword(s):  
Flat Space ◽  
De Sitter Space ◽  
Ambient Space ◽  
Alternative Proof ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Timelike Geodesic ◽  
Sitter Spacetime

In this paper, we refine and analytically prove an old proposition due to Calabi and Markus on the shape of timelike geodesics of anti-de Sitter space in the ambient flat space. We prove that each timelike geodesic forms in the ambient space a circle of the radius determined by [Formula: see text], lying on a Euclidean two-plane. Then, we outline an alternative proof for [Formula: see text]. We also make a comment on the shape of timelike geodesics in de Sitter space.

UPPER AND LOWER BOUNDS FOR THE VOLUME OF A COMPACT SPACELIKE HYPERSURFACE IN A GENERALIZED ROBERTSON–WALKER SPACETIME

2013 ◽  
Vol 11 (01) ◽  
pp. 1450006 ◽  
Author(s):  
JUAN ÁNGEL ALEDO ◽  
ALFONSO ROMERO ◽  
RAFAEL M. RUBIO
Keyword(s):  
Lower Bounds ◽  
Three Dimensional ◽  
Spacelike Hypersurface ◽  
Upper And Lower Bounds ◽  
Warping Function ◽  
First Eigenvalue ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Angle Function ◽  
Spacelike Hypersurfaces

We provide upper and lower bounds for the volume of a compact spacelike hypersurface in an (n + 1)-dimensional Generalized Robertson–Walker (GRW) spacetime in terms of the volume of the fiber, the hyperbolic angle function and the warping function. Under several geometrical and physical assumptions, we characterize the spacelike slices as the only spacelike hypersurfaces where these bounds are attained. As a consequence of these results, we get an upper bound for the first eigenvalue of a compact spacelike surface in a three-dimensional GRW spacetime whose fiber is a topological sphere, which includes the case of the three-dimensional De Sitter spacetime, and show that the bound is attained if and only if M is a spacelike slice.

scholarly journals Gravitational thermodynamics of causal diamonds in (A)dS

2019 ◽  
Vol 7 (6) ◽  
Author(s):  
Theodore Jacobson ◽  
Manus Visser
Keyword(s):  
Killing Vector ◽  
Minkowski Spacetime ◽  
Conformal Killing ◽  
De Sitter Spacetime ◽  
Conformal Killing Vector ◽  
De Sitter ◽  
Thermodynamic Relation ◽  
Killing Field ◽  
Sitter Spacetime ◽  
Gravitational Thermodynamics

The static patch of de Sitter spacetime and the Rindler wedge of Minkowski spacetime are causal diamonds admitting a true Killing field, and they behave as thermodynamic equilibrium states under gravitational perturbations. We explore the extension of this gravitational thermodynamics to all causal diamonds in maximally symmetric spacetimes. Although such diamonds generally admit only a conformal Killing vector, that seems in all respects to be sufficient. We establish a Smarr formula for such diamonds and a ``first law" for variations to nearby solutions. The latter relates the variations of the bounding area, spatial volume of the maximal slice, cosmological constant, and matter Hamiltonian. The total Hamiltonian is the generator of evolution along the conformal Killing vector that preserves the diamond. To interpret the first law as a thermodynamic relation, it appears necessary to attribute a negative temperature to the diamond, as has been previously suggested for the special case of the static patch of de Sitter spacetime. With quantum corrections included, for small diamonds we recover the ``entanglement equilibrium'' result that the generalized entropy is stationary at the maximally symmetric vacuum at fixed volume, and we reformulate this as the stationarity of free conformal energy with the volume not fixed.

scholarly journals Light in dielectric media and scalar fields in a de Sitter spacetime

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
I. A. Pedrosa ◽  
B. F. Ramos ◽  
K. Bakke
Keyword(s):  
Scalar Field ◽  
Coherent States ◽  
Scalar Fields ◽  
Dielectric Medium ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Expectation Values ◽  
Dielectric Media ◽  
Sitter Spacetime ◽  
Constant Rate

AbstractIn the present work we discuss the behavior of light in a linear dielectric medium with a time-varying electric permittivity that increases exponentially at a constant rate and of a scalar field in a de Sitter spacetime, in both the classical and quantum contexts. Notably, we find that the behavior of these two systems are identical and can be described by similar Hamiltonians. By using the Lewis–Riesenfeld invariant method together with Fock states we solve the time-dependent Schrödinger equation for this problem and use its solutions to construct coherent states for the scalar field. Finally, we employ both the Fock and coherent states to evaluate some important properties of the quantized scalar field, such as expectation values of the amplitude and momentum of each mode their variances and the respective uncertainty principle.

scholarly journals Superstrings in thermal anti-de Sitter space

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Sujay K. Ashok ◽  
Jan Troost
Keyword(s):  
Free Energy ◽  
Partition Function ◽  
Isometry Group ◽  
Three Dimensional ◽  
Open Interval ◽  
Energy Calculation ◽  
De Sitter ◽  
Half Open Interval ◽  
Sitter Spacetime ◽  
Discrete Representations

Abstract We revisit the calculation of the thermal free energy for string theory in three-dimensional anti-de Sitter spacetime with Neveu-Schwarz-Neveu-Schwarz flux. The path integral calculation is exploited to confirm the off-shell Hilbert space and we find that the Casimir of the discrete representations of the isometry group takes values in a half-open interval. We extend the free energy calculation to the case of superstrings, calculate the boundary toroidal twisted partition function in the Ramond-Ramond sector, and prove lower bounds on the boundary conformal dimension from the bulk perspective. We classify Ramond-Ramond ground states and construct their second quantized partition function. The partition function exhibits intriguing modular properties.

scholarly journals Unruh-DeWitt detector responses for complex scalar fields in de Sitter spacetime

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Md Sabir Ali ◽  
Sourav Bhattacharya ◽  
Kinjalk Lochan
Keyword(s):  
Scalar Field ◽  
Response Function ◽  
Scalar Fields ◽  
Detector Response ◽  
Massless Scalar Field ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Complex Scalar ◽  
Sitter Spacetime ◽  
Complex Scalar Field

Abstract We derive the response function for a comoving, pointlike Unruh-DeWitt particle detector coupled to a complex scalar field ϕ, in the (3 + 1)-dimensional cosmological de Sitter spacetime. The field-detector coupling is taken to be proportional to ϕ†ϕ. We address both conformally invariant and massless minimally coupled scalar field theories, respectively in the conformal and the Bunch-Davies vacuum. The response function integral for the massless minimal complex scalar, not surprisingly, shows divergences and accordingly we use suitable regularisation scheme to find out well behaved results. The regularised result also contains a de Sitter symmetry breaking logarithm, growing with the cosmological time. Possibility of extension of these results with the so called de Sitter α-vacua is discussed. While we find no apparent problem in computing the response function for a real scalar in these vacua, a complex scalar field is shown to contain some possible ambiguities in the detector response. The case of the minimal and nearly massless scalar field theory is also briefly discussed.

scholarly journals DE SITTER TRANSITIVITY, CONFORMAL TRANSFORMATIONS AND CONSERVATION LAWS

2014 ◽  
Vol 23 (04) ◽  
pp. 1450035 ◽  
Author(s):  
J. G. PEREIRA ◽  
A. C. SAMPSON ◽  
L. L. SAVI
Keyword(s):  
Variational Principles ◽  
Matrix Representation ◽  
Minkowski Spacetime ◽  
The Other ◽  
Conformal Transformations ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Matrix Representations ◽  
Sitter Group ◽  
Sitter Spacetime

Minkowski spacetime is transitive under ordinary translations, a transformation that do not have matrix representations. The de Sitter spacetime, on the other hand, is transitive under a combination of translations and proper conformal transformations, which do have a matrix representation. Such matrix, however, is not by itself a de Sitter generator: it gives rise to a conformal re-scaling of the metric, a transformation not belonging to the de Sitter group, and in general not associated with diffeomorphisms in spacetime. When dealing with variational principles and Noether's theorem in de Sitter spacetime, it is necessary to regularize the transformations in order to eliminate the conformal re-scaling of the metric.

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