2025/10/20 by Arianna Tinari, Tinari, Arianna
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2510.18138
openalex publication_date 2025/10/20 · openalex created_date 2025/10/24 · openalex updated_date 2026/07/28
Flavor-changing neutral current decays such as b → s ℓ ℓ are highly suppressed in the Standard Model (SM) and therefore provide sensitive tests for new physics. Persistent tensions between SM predictions and experimental results in branching ratios and angular observables can be explained by a shift of the Wilson coefficient C9 of the effective operator O9 by ∼ 20 % relative to the SM value. This shift could arise from a non-standard short-distance contribution or from an inaccurate description of long-distance dynamics, particularly charm rescattering contributions. We therefore investigate charm rescattering contributions in B0 → K0 ℓℓ using a model of fundamental hadronic degrees of freedom inspired by heavy-hadron chiral perturbation theory and improved by appropriate form factors as well as experimental data. Our analysis shows that such effects, with a high degree of fine-tuning, could shift C9 by ∼ 20%, at the cost of introducing a more pronounced q2 dependence, whereas experimental data are consistent with a q2-independent shift of C9 with the current experimental uncertainties. In the most natural scenario, we find these effects to be of the order of ∼ 5%. Connections with other flavor anomalies further illustrate the strong discovery potential of b → s ℓ ℓ modes.