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Register a new userPrediction for the Cosmological Constant and Constraints on SUSY GUTS: Status Report for Resummed Quantum Gravity
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We give a status report on the theory of resummed quantum gravity. We recapitulate the use of our resummed quantum gravity approach to Einsteins general theory of relativity to estimate the value of the cosmological constant as $rho_Lambda=(0.0024{mathrm{eV}})^4$. The estimate is made in the context of the Planck scale cosmology formulation of Bonanno and Reuter. We discuss the constraints on susy GUT models that follow from the closeness of the estimate to experiment. Various consistency checks on the calculation are addressed and we use the Heisenberg uncertainty principle to remove a large part of the remaining uncertainty in our estimate of $rho_Lambda$.
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Working in the context of the Planck scale cosmology formulation of Bonanno and Reuter, we use our resummed quantum gravity approach to Einsteins general theory of relativity to estimate the value of the cosmological constant as $rho_Lambda =(0.0024 eV)^4$. We show that susy GUT models are constrained by the closeness of this estimate to experiment. We also address various consistency checks on the calculation. In particular, we use the Heisenberg uncertainty principle to remove a large part of the remaining uncertainty in our estimate of $rho_Lambda$
We use the amplitude-based resummation of Feynman`s formulation of Einstein`s theory to arrive at a UV finite approach to quantum gravity. We show that we recover the UV fixed point recently claimed by the exact field-space renormalization group approach. We use our approach in the context of the attendant Planck scale cosmology formulation of Bonanno and Reuter to estimate the value of the cosmological constant as rho_Lambda=(0.0024 eV)^4. We show that the closeness of this estimate to experiment constrains susy GUT models.
We argue that the cosmological constant is exponentially suppressed in a candidate ground state of loop quantum gravity as a nonperturbative effect of a holographic Fermi-liquid theory living on a two-dimensional spacetime. Ashtekar connection components, corresponding to degenerate gravitational configurations breaking large gauge invariance and CP symmetry, behave as composite fermions that condense as in Bardeen-Cooper-Schrieffer theory of superconductivity. Cooper pairs admit a description as wormholes on a de Sitter boundary.
In the investigation and resolution of the cosmological constant problem the inclusion of the dynamics of quantum gravity can be a crucial step. In this work we suggest that the quantum constraints in a canonical theory of gravity can provide a way of addressing the issue: we consider the case of two-dimensional quantum dilaton gravity non-minimally coupled to a U(1) gauge field, in the presence of an arbitrary number of massless scalar matter fields, intended also as an effective description of highly symmetrical higher-dimensional models. We are able to quantize the system non-perturbatively and obtain an expression for the cosmological constant Lambda in terms of the quantum physical states, in a generalization of the usual QFT approach. We discuss the role of the classical and quantum gravitational contributions to Lambda and present a partial spectrum of values for it.
We present cosmological constraints on the scalar-tensor theory of gravity by analyzing the angular power spectrum data of the cosmic microwave background obtained from the Planck 2015 results together with the baryon acoustic oscillations (BAO) data. We find that the inclusion of the BAO data improves the constraints on the time variation of the effective gravitational constant by more than $10%$, that is, the time variation of the effective gravitational constant between the recombination and the present epochs is constrained as $G_{rm rec}/G_0-1 <1.9times 10^{-3} (95.45% {rm C.L.})$ and $G_{rm rec}/G_0-1 <5.5times 10^{-3} (99.99 % {rm C.L.})$. We also discuss the dependence of the constraints on the choice of the prior.
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