Upper bound on the matter content of Quantum Distortion Gravity from the UV fixed point
Authors/Creators
Description
We derive an explicit polynomial characterization of the ultraviolet fixed point of Quantum Distortion Gravity (QDG) in the minimal truncation. Eliminating the dimensionless Newton coupling $\tilde G$ from the fixed-point equations $\beta_{\tilde G}=0$ and $\beta_\lambda=0$ via resultants yields a polynomial $P(\lambda; n_f)$ of degree $7$ in the cosmological coupling $\lambda$, with coefficients that depend explicitly on the number of Dirac fermions $n_f$. The physical fixed point corresponds to a specific real root of $P$. We show that this root exists only for $n_f \leq n_f^{\rm crit} = 4.896577961599$, where the critical value is determined by the vanishing of the denominator $1-\tilde G^* B(\lambda^*)$ of the gravitational anomalous dimension. For $n_f > n_f^{\rm crit}$, the only real root in the physical range has $\tilde G^* < 0$, corresponding to repulsive gravity, and is not a physical fixed point. The Standard Model matter content ($n_f = 3$) is safely below the bound, with a margin of about $1.9$ fermion generations. We discuss the physical interpretation, the mechanism of the transition, and the limitations of the minimal truncation.
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qdg4.pdf
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Additional details
Software
- Repository URL
- https://zenodo.org/uploads/23150654
- Programming language
- Python
- Development Status
- Active