Thermal RG flow of AS quantum gravity
We perform the thermal Renormalization Group (RG) study of the Asymptotically Safe (AS) quantum gravity in the Einstein-Hilbert truncation by relating the temperature parameter to the running RG scale as T≡kT=τk (in natural units) in order to determine its thermal evolution in terms of the dimension...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-05-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269325002011 |
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| Summary: | We perform the thermal Renormalization Group (RG) study of the Asymptotically Safe (AS) quantum gravity in the Einstein-Hilbert truncation by relating the temperature parameter to the running RG scale as T≡kT=τk (in natural units) in order to determine its thermal evolution in terms of the dimensionless temperature τ which is associated with the temperature of the expanding Universe. Thus, kT and k are understood as running cutoffs for thermal and quantum fluctuations, respectively. Quantum effects are taken into account by moving along the thermal RG trajectory with fixed value of τ producing the quantum effective action at a given dimensionless temperature. The τ-evolution of the dimensionless Newton coupling g(τ) and the dimensionless cosmological constant λ(τ) results in a vanishing g-coordinate of the Reuter (i.e., non-Gaussian UV) fixed point in the high temperature limit (τ→∞) which means that only the symmetric phase of AS gravity survives at τ=∞. Thus, in case of large temperatures the cosmological constant takes on a negative value in the limit k→0 which was also initially predicted by certain string theories, however, in our approach this is not in disagreement with observations, since during the thermal evolution of the Universe a phase transition occurs and the cosmological constant runs to the expected positive value at low temperatures. |
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| ISSN: | 0370-2693 |