The phase and critical point of quantum Einstein–Cartan gravity

Xue, She‐Sheng

doi:10.1016/j.physletb.2012.04.024

Cited by 18 publications

(12 citation statements)

References 46 publications

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“…Since the scaled cosmological constant can be viewed as a measure of the intrinsic curvature of the vacuum, the above argument then leads to an effective positive cosmological constant for this phase, corresponding to a manifold which behaves semiclassically as de Sitter (λ > 0) on very large scales [47]. For related interesting ideas see also [75].…”

Section: Renormalization Group Running Of Newton's Gmentioning

confidence: 99%

Vacuum Condensate Picture of Quantum Gravity

Hamber

2019

Symmetry

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In quantum gravity perturbation theory in Newton's constant G is known to be badly divergent, and as a result not very useful. Nevertheless, some of the most interesting phenomena in physics are often associated with non-analytic behavior in the coupling constant and the existence of nontrivial quantum condensates. It is therefore possible that pathologies encountered in the case of gravity are more likely the result of inadequate analytical treatment, and not necessarily a reflection of some intrinsic insurmountable problem. The nonperturbative treatment of quantum gravity via the Regge-Wheeler lattice path integral formulation reveals the existence of a new phase involving a nontrivial gravitational vacuum condensate, and a new set of scaling exponents characterizing both the running of G and the long-distance behavior of invariant correlation functions. The appearance of such a gravitational condensate is viewed as analogous to the (equally nonperturbative) gluon and chiral condensates known to describe the physical vacuum of QCD. The resulting quantum theory of gravity is highly constrained, and its physical predictions are found to depend only on one adjustable parameter, a genuinely nonperturbative scale ξ in many ways analogous to the scaling violation parameter ΛM S of QCD. Recent results point to significant deviations from classical gravity on distance scales approaching the effective infrared cutoff set by the observed cosmological constant. Such subtle quantum effects are expected to be initially small on current cosmological scales, but could become detectable in future high precision satellite experiments.

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Section: Renormalization Group Running Of Newton's Gmentioning

confidence: 99%

Vacuum Condensate Picture of Quantum Gravity

Hamber

2019

Symmetry

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Section: Gravitational Wilson Loop and Curvature Condensatementioning

confidence: 99%

Vacuum Condensate Picture of Quantum Gravity

Hamber¹

2018

Preprint

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In quantum gravity perturbation theory in Newton's constant $G$ is known to be badly divergent, and as a result not very useful. Nevertheless, some of the most interesting phenomena in physics are often associated with non-analytic behavior in the coupling constant and the existence of nontrivial quantum condensates. It is therefore possible that pathologies encountered in the case of gravity are more likely the result of inadequate analytical treatment, and not necessarily a reflection of some intrinsic insurmountable problem. The nonperturbative treatment of quantum gravity via the Regge-Wheeler lattice path integral formulation reveals the existence of a new phase involving a nontrivial gravitational vacuum condensate, and a new set of scaling exponents characterizing both the running of $G$ and the long-distance behavior of invariant correlation functions. The appearance of such a gravitational condensate is viewed as analogous to the (equally nonperturbative) gluon and chiral condensates known to describe the physical vacuum of QCD. The resulting quantum theory of gravity is highly constrained, and its physical predictions are found to depend only on one adjustable parameter, a genuinely nonperturbative scale $\xi$ in many ways analogous to the scaling violation parameter $\Lambda_{\bar MS} $ of QCD. Recent results point to significant deviations from classical gravity on distance scales approaching the effective infrared cutoff set by the observed cosmological constant. Such subtle quantum effects are expected to be initially small on current cosmological scales, but could become detectable in future high precision satellite experiments.

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“…1.2 a pl [36][37][38][39], where the Planck length a pl ∼ 10 −33 cm and scale Λ pl = π/a pl ∼ 10 19 GeV. However, the no-go theorem [40][41][42] tells us that there is no any consistent way to regularize the SM bilinear fermion Lagrangian to exactly preserve the SM chiral-gauge symmetries, which must be explicitly broken at the scale of fundamental space-time cutoffã.…”

Section: Regularization and Quantum Gravitymentioning

confidence: 99%

“…1 In the regularized and quantized EC theory [36][37][38][39] with a basic space-time cutoff, in addition to dimension-6 four-fermion operators, there are high-dimensional fermion operators (d > 6), e.g., ∂σJ µ ∂ σ Jµ, which are suppressed at least by O(ã 4 ).…”

Section: Einstein-cartan Theory With Sm Gauge Symmetries and Fermion mentioning

confidence: 99%

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An effective strong-coupling theory of composite particles in UV-domain

Xue

2017

J. High Energ. Phys.

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We briefly review the effective field theory of massive composite particles, their gauge couplings and characteristic energy scale in the UV-domain of UV-stable fixed point of strong four-fermion coupling, then mainly focus the discussions on the decay channels of composite particles into the final states of the SM gauge bosons, leptons and quarks. We calculate the rates of composite bosons decaying into two gauge bosons γγ, γZ 0 , W + W − , Z 0 Z 0 and give the ratios of decay rates of different channels depending on gauge couplings only. It is shown that a composite fermion decays into an elementary fermion and a composite boson, the latter being an intermediate state decays into two gauge bosons, leading to a peculiar kinematics of final states of a quark (or a lepton) and two gauge bosons. These provide experimental implications of such an effective theory of composite particles beyond the SM. We also present some speculative discussions on the channels of composite fermions decaying into W W , W Z and ZZ two boson-tagged jets with quark jets, or to four-quark jets. Moreover, at the same energy scale of composite particles produced in high-energy experiments, composite particles are also produced by high-energy sterile neutrino (dark matter) collisions, their decays lead to excesses of cosmic ray particles in space and signals of SM particles in underground laboratories.

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The phase and critical point of quantum Einstein–Cartan gravity

Cited by 18 publications

References 46 publications

Vacuum Condensate Picture of Quantum Gravity

Vacuum Condensate Picture of Quantum Gravity

Vacuum Condensate Picture of Quantum Gravity

An effective strong-coupling theory of composite particles in UV-domain

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