Renormalization-group evolution of new physics contributions to (semi)leptonic meson decays (1706.00410v2)

Abstract: We study the renormalization group evolution (RGE) of new physics contributions to (semi)leptonic charged-current meson decays, focusing on operators involving a chirality flip at the quark level. We calculate their evolution under electroweak and electromagnetic interactions, including also the three-loop QCD running and provide numerical formulas that allow us to connect the values of the corresponding Wilson coefficients from scales at the TeV to the low-energy scales. The large mixing of the tensor operator into the (pseudo)scalar ones has important phenomenological implications, such as the RGE of new physics bounds obtained from light quark decays or in $b\to c\ell\nu$ transitions. For instance, we study scenarios involving tensor effective operators, which have been proposed in the literature to address the $B$-decay anomalies, most notably those concerning the $R_{D^{(*)}}$ ratios. We conclude that the loop effects are important and should be taken into account in the analysis of these processes, especially if the operators are generated at an energy scale of $\sim 1$ TeV or higher.

• The paper analyzes the renormalization group evolution of new physics contributions to (semi)leptonic meson decays, including EW, EM, and three-loop QCD effects on chirality-flip operators.
• It derives numerical formulas connecting high-energy Wilson coefficients to low-energy scales and highlights large mixing of tensor into (pseudo)scalar operators.
• The study emphasizes including renormalization group evolution effects in future meson decay analyses, especially for high-energy scales or B meson anomalies like R_D^{(*)}.

Renormalization-Group Evolution of New Physics Contributions to (Semi)leptonic Meson Decays

The paper, authored by Gonzalez-Alonso et al., explores the intricate details of renormalization group evolution (RGE) as it pertains to new physics contributions impacting (semi)leptonic meson decays. This investigation is particularly centered around operators that involve a chirality-flip at the quark level. Through meticulous calculations, the work examines the evolution of these operators under the influence of electroweak (EW) and electromagnetic interactions, inclusive of three-loop QCD running effects.

Core Contributions

Key contributions of the paper include the derivation of numerical formulas that establish a connection between Wilson coefficients at TeV-scale high energies and those at low-energy scales significant for phenomenology. This is crucial for analyzing light quark decays and transitions such as $b\to c\ell\nu$. The paper concludes that loop effects must be accounted for, especially if operators are generated at scales around 1 TeV or higher due to their discernible impact on phenomenological models.

Numerical Results

The paper highlights several numerical results illustrating the large mixing of tensor operators into (pseudo)scalar operators. This mixing has substantial implications for new physics analyses derived from light quark decays or anomalies observed in $B$ meson decays such as the $R_{D^{(*)}}$ ratios. The authors emphasize the need for accounting RGE effects in theoretical models predicting these anomalies, offering a novel look at how standard computational approaches might require adjustments in light of these findings.

Implications and Future Directions

From a practical standpoint, the implications of this paper suggest that future analyses concerning (semi)leptonic meson decays should routinely incorporate RGE effects, particularly when dealing with high-energy scales exceeding 1 TeV. This nuanced understanding will benefit both the precision verification of framework models like the SMEFT or in pinning down discrepancies within experimental data.

Theoretically, adhering to the RGE-induced transformations of chirality-flipping operators invites further research into pinpointing exact contributions from heavy quark transitions. The intricacy of these calculations, substantiated by powerful multi-loop analyses in QCD and EW domains, signifies the growing complexity of field theories as they evolve with experimental advancements.

Conclusion

The paper by Gonzalez-Alonso and colleagues is emblematic of the rigor required in current particle physics research to bridge observed anomalies with theoretical predictions. Their work stands as a pivotal reference for individuals advancing the interplay between renormalization group theory and particle physics, especially in the context of meson decay phenomena and beyond. In anticipating future developments in artificial intelligence, such analyses may inform how machine learning models are utilized to parse complex quantum mechanical interactions effectively.