Abstract
We use the framework of asymptotically safe quantum gravity to derive predictions for scalar leptoquark solutions to the brightarrow s and brightarrow c flavor anomalies. The presence of an interactive UV fixed point in the system of gauge and Yukawa couplings imposes a set of boundary conditions at the Planck scale, which allows one to determine low-energy values of the leptoquark Yukawa matrix elements. As a consequence, the allowed leptoquark mass range can be significantly narrowed down. We find that a consistent gravity-driven solution to the brightarrow s anomalies predicts a leptoquark with the mass of 4–7 ,mathrm {TeV}, entirely within the reach of a future hadron-hadron collider with sqrt{s}=100,mathrm {TeV}. Conversely, in the case of the brightarrow c anomalies the asymptotically safe gravity framework predicts a leptoquark mass at the edge of the current LHC bounds. Complementary signatures appear in flavor observables, namely the (semi)leptonic decays of B and D mesons and kaons.
Highlights
The important finding that quantum gravity and matter can feature interactive fixed points in the extreme trans-Planckian regime has opened the exciting possibility of deriving the values of the observable quantities of the Standard Model (SM) from first principles [34–37]
The renormalization group (RG) flow of the system, emerging from the UV fixed point, down to the electroweak symmetry breaking (EWSB) scale along the UV-safe trajectory, has led to specific predictions for the top Yukawa coupling [34] and the quartic coupling of the Higgs potential [36]. This framework was used to predict the Lagrangian couplings of a few New Physics (NP) models extending the SM by an extra U(1) gauge symmetry and a scalar field with portal couplings [38–42]
In the corresponding channel with final-state tau leptons – appropriate to test the value given in Eq (37), Y2R3 = 0.85 – the LHC sensitivity drops, and is expected to exclude a Yukawa coupling larger by approximately 60% than in the muon case [101]
Summary
The important finding that quantum gravity and matter can feature interactive fixed points in the extreme trans-Planckian regime has opened the exciting possibility of deriving the values of the observable quantities of the SM (gauge, Yukawa and scalar couplings) from first principles [34–37]. If we require consistency with the neutral-current, b → s flavor anomalies, the information derived from the trans-Planckian fixed-point analysis leads to very specific predictions for the mass of the LQ, which should lie approximately in the 5–10 TeVrange. This places it outside of the foreseeable reach of the LHC, but well within the early reach of a 100 TeV hadron machine according to the most conservative estimates. Some technical details of the LQ models and of the RG flow analyses are given in Appendix A and Appendix B
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