String Quantum Gravity and Physics at the Planck Energy Scale

10.1142/1830 ◽  
1993 ◽  
Keyword(s):  
Quantum Gravity ◽  
Energy Scale ◽  
Planck Energy

scholarly journals PHASE TRANSITION IN QUANTUM GRAVITY?

1999 ◽  
Vol 14 (16) ◽  
pp. 1079-1082
Author(s):  
VIQAR HUSAIN ◽  
SEBASTIAN JAIMUNGAL
Keyword(s):  
Phase Transition ◽  
General Relativity ◽  
Quantum Gravity ◽  
Fundamental Problem ◽  
Critical Energy ◽  
Energy Scale ◽  
Classical Symmetry ◽  
Metric Functions ◽  
Theory Calculation ◽  
Rule Out

A fundamental problem with attempting to quantize general relativity is its perturbative non-renormalizability. However, this fact does not rule out the possibility that nonperturbative effects can be computed, at least in some approximation. We outline a quantum field theory calculation, based on general relativity as the classical theory, which implies a phase transition in quantum gravity. The order parameters are composite fields derived from space–time metric functions. These are massless below a critical energy scale and become massive above it. There is a corresponding breaking of classical symmetry.

scholarly journals THERMAL QUASI-EQUILIBRIUM STATES ACROSS LANDAU HORIZONS IN THE EFFECTIVE GRAVITY OF SUPERFLUIDS

2001 ◽  
Vol 10 (01) ◽  
pp. 57-88 ◽  
Author(s):  
UWE R. FISCHER ◽  
GRIGORI E. VOLOVIK
Keyword(s):  
Energy Spectrum ◽  
Quantum Effect ◽  
Planck Scale ◽  
Momentum Tensor ◽  
Energy Scale ◽  
Hawking Temperature ◽  
Equilibrium States ◽  
Local Thermal Equilibrium ◽  
Quasi Equilibrium ◽  
Planck Energy

We give an account of the physical behaviour of a quasiparticle horizon due to non-Lorentz invariant modifications of the effective spacetime experienced by the quasiparticles ("matter") for high momenta. By introducing a "relativistic" conserved energy–momentum tensor, we derive quasi-equilibrium states of the fluid across the "Landau" quasiparticle horizon at temperatures well above the quantum Hawking temperature. Nonlinear dispersion of the quasiparticle energy spectrum is instrumental for quasiparticle communication and exchange across the horizon. It is responsible for the establishment of the local thermal equilibrium across the horizon with the Tolman temperature being inhomogeneous behind the horizon. The inhomogeneity causes relaxation of the quasi-equilibrium states due to scattering of thermal quasiparticles, which finally leads to a shrinking black hole horizon. This process serves as the classical thermal counterpart of the quantum effect of Hawking radiation and will allow for an observation of the properties of the horizon at temperatures well above the Hawking temperature. We discuss the thermal entropy related to the horizon. We find that only the first nonlinear correction to the energy spectrum is important for the thermal properties of the horizon. They are fully determined by an energy of order E Planck (T/E Planck )1/3, which is well below the Planck energy scale E Planck , so that Planck scale physics is not involved in determining thermal quantities related to the horizon.

Extragalactic background light inhomogeneities and Lorentz-Invariance Violation in gamma-gamma absorption and Compton scattering

2019 ◽  
Vol 15 (S356) ◽  
pp. 364-364
Author(s):  
Hassan Abdalla
Keyword(s):  
Compton Scattering ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Energy Scale ◽  
Fundamental Physics ◽  
Extragalactic Background Light ◽  
Invariance Violation ◽  
Gamma Absorption ◽  
The Impact ◽  
Planck Energy

AbstractAt energies approaching the Planck energy scale 1019GeV, several quantum-gravity theories predict that familiar concepts such as Lorentz (LIV) symmetry can be broken. Such extreme energies are currently unreachable by experiments on Earth, but for photons traveling over cosmological distances the accumulated deviations from the Lorentz symmetry may be measurable using the Cherenkov Telescope Array (CTA). To study the spectral hardening feature observed in some VHE gamma-ray blazars, we calculate the reduction of the EBL gamma-gamma opacity due to the existence of underdense regions along the line of sight to VHE -gamma ray sources and we compared with the possibility of a LIV signature. Considering the LIV effect, we found that the cosmic opacity for VHE-gamma rays with energy more than 10 TeV can be strongly reduced. I will further discuss the impact of LIV on the Compton scattering process, and how future CTA observations may open an exciting window on studies of the fundamental physics.

scholarly journals On the Role of Einstein–Cartan Gravity in Fundamental Particle Physics

Universe ◽  
2020 ◽  
Vol 6 (8) ◽  
pp. 112
Author(s):  
Carl F. Diether III ◽  
Joy Christian
Keyword(s):  
Particle Physics ◽  
Mechanical Energy ◽  
Planck Scale ◽  
Energy Scale ◽  
Fundamental Particle ◽  
Strong Force ◽  
Open Questions ◽  
Low Mass ◽  
Planck Energy

Two of the major open questions in particle physics are: (1) Why do the elementary fermionic particles that are so far observed have such low mass-energy compared to the Planck energy scale? (2) What mechanical energy may be counterbalancing the divergent electrostatic and strong force energies of point-like charged fermions in the vicinity of the Planck scale? In this paper, using a hitherto unrecognised mechanism derived from the non-linear amelioration of the Dirac equation known as the Hehl–Datta equation within the Einstein–Cartan–Sciama–Kibble (ECSK) extension of general relativity, we present detailed numerical estimates suggesting that the mechanical energy arising from the gravitationally coupled self-interaction in the ECSK theory can address both of these questions in tandem.

scholarly journals Particle–Antiparticle Asymmetry in Relativistic Deformed Kinematics

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1266
Author(s):  
José Manuel Carmona ◽  
José Luis Cortés ◽  
José Javier Relancio
Keyword(s):  
Quantum Gravity ◽  
Particle System ◽  
High Energy ◽  
Energy Scale ◽  
Muon Decay ◽  
Total Momentum ◽  
Gravity Theory ◽  
Residual Effects ◽  
Cpt Symmetry ◽  
High Energy Scale

Relativistic deformed kinematics are usually considered a way to capture the residual effects of a fundamental quantum gravity theory. These kinematics present a non-commutative addition law for the momenta so that the total momentum of a multi-particle system depends on the specific ordering in which the momenta are composed. We explore in the present work how this property may be used to generate an asymmetry between particles and antiparticles through a particular ordering prescription, resulting in a violation of CPT symmetry. We study its consequences for muon decay, obtaining a difference in the lifetimes of the particle and the antiparticle as a function of the new high-energy scale, parameterizing such relativistic deformed kinematics.

scholarly journals Constraints on Lorentz Invariance Violation From Optical Polarimetry of Astrophysical Objects

2018 ◽  
Author(s):  
Fabian Kislat
Keyword(s):  
Standard Model ◽  
Quantum Gravity ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Effective Field ◽  
Energy Scale ◽  
Theory Of Relativity ◽  
Standard Model Extension ◽  
Polarization Measurements ◽  
The Standard Model

Theories of quantum gravity suggest that Lorentz invariance, the fundamental symmetry of the Theory of Relativity, may be broken at the Planck energy scale. While any deviation from conventional Physics must be minuscule in particular at attainable energies, this hypothesis motivates ever more sensitive tests of Lorentz symmetry. In the photon sector, astrophysical observations, in particular polarization measurements, are a very powerful tool because tiny deviations from Lorentz invariance will accumulate as photons propagate over cosmological distances. The Standard-Model Extension (SME) provides a theoretical framework in the form of an effective field theory that describes low-energy effects due to a more fundamental quantum gravity theory by adding additional terms to the Standard Model Lagrangian. These terms can be ordered by the mass dimension d of the corresponding operator and lead to a wavelength, polarization, and direction dependent phase velocity of light. In this paper, we analyze optical polarization measurements from 63 Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRBs) in order to search for Lorentz violating signals. We derive the first set limits on each of the 10 individual birefringent coefficients of the minimal SME with d = 4, with 95% confidence limits on the order of 10−34 on the dimensionless coefficients.

scholarly journals Discreteness of space from anisotropic spin–orbit interaction

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Ahmed Farag Ali ◽  
Barun Majumder
Keyword(s):  
Quantum Gravity ◽  
Energy Scale ◽  
Minimal Length ◽  
Orbit Interaction ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Modified Dispersion Relation ◽  
Spin Orbit Interaction ◽  
Quantum Gravity Effect ◽  
The Cost

AbstractVarious approaches to Quantum Gravity suggest an existence of a minimal measurable length. The cost to have such minimal length could be modified uncertainty principle, modified dispersion relation, non-commutative geometry or breaking of continuous Lorentz symmetry. In this paper, we propose that minimal length can be obtained naturally through spin–orbit interaction. We consider Dresselhaus anisotropic spin–orbit interaction as the perturbative Hamiltonian. When applied to a particle, it implies that the space, which seizes this particle, should be quantized in terms of units that depend on particle’s mass. This suggests that all measurable lengths in the space are quantized in units depending on existent mass and the Dresselhaus coupling constant. On one side, this indicates a breakdown of the space continuum picture near the scale of tabletop experiments, and on the other side, it proposes that spin–orbit interaction is a possible quantum gravity effect at low energy scale that leads naturally to space quantization.

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