Flavour Anomalies: A comparative analysis using a machine learning algorithm

Abstract

We present an analysis on flavour anomalies in semileptonic rare $B$-meson decays using an effective field theory approach and assuming that new physics affects only one generation in the interaction basis and non-universal mixing effects are generated by the rotation to the mass basis. A global fit to experimental data is performed, focusing on LFU ratios $R_{D^{(\ast )}}$ and $R_{J/\psi }$ and branching ratios that exhibit tensions with Standard Model predictions on $B\to K^{(\ast )}\nu \bar{\nu }$ decays. In our analysis, we use a Machine Learning Montecarlo algorithm, a framework that emulates the highly non-Gaussian structure of the likelihood landscape with minimal training cost. This method enables the generation of high-resolution confidence regions and detailed correlation analyses. By comparing three different scenarios, we show that the one that introduces only mixing between the second and third quark generations and no mixing in the lepton sector, as well as independent coefficients for the singlet and triplet four fermion effective operators, provides the best fit to the experimental data. A comparison with previous results is performed. We highlight the key strengths of the Machine Learning framework in our analysis.

21 pages, 12 figures, 2 tables, title changes, references updated. Published version

References in corpus (38)

• Dimension-Six Terms in the Standard Model Lagrangian
• Test of lepton universality with $B^0\to K^{\ast 0}{\ell }^{+}{\ell }^{-}$ decays
• Measurement of the ratio of branching fractions $\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\mu }^{-}{\overline{\nu }}_{\mu })$
• Observation of the rare $B_s^0\to {\mu }^{+}{\mu }^{-}$ decay from the combined analysis of CMS and LHCb data
• Search for lepton-universality violation in $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays
• Low-Energy Effective Field Theory below the Electroweak Scale: Operators and Matching
• Effective field theory approach to $b\to s\ell {\ell }^{(\prime )}$, $B\to K^{(\ast )}\nu \bar{\nu }$ and $B\to D^{(\ast )}\tau \nu$ with third generation couplings
• Patterns of New Physics in $b\to s{\ell }^{+}{\ell }^{-}$ transitions in the light of recent data
• Testing leptoquark models in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Measurement of the ratio of the $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ and $B^0\to D^{\ast -}{\mu }^{+}{\nu }_{\mu }$ branching fractions using three-prong $\tau$-lepton decays
• B-decay discrepancies after Moriond 2019
• Measurement of the $B_s^0\to {\mu }^{+}{\mu }^{-}$ branching fraction and effective lifetime and search for $B^0\to {\mu }^{+}{\mu }^{-}$ decays
• New physics in the weak interaction of $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark
• Matching of gauge invariant dimension 6 operators for $b\to s$ and $b\to c$ transitions
• Extraction of $|V_{cb}|$ from $B\to D^{(\ast )}\ell {\nu }_{\ell }$ and the Standard Model predictions of $R(D^{(\ast )})$
• New Physics in $b\to s{\mu }^{+}{\mu }^{-}$ after the Measurement of $R_{K^{\ast }}$
• A Global Likelihood for Precision Constraints and Flavour Anomalies
• B physics Beyond the Standard Model at One Loop: Complete Renormalization Group Evolution below the Electroweak Scale
• The $B$ Anomalies and New Physics in $b\to s{e}^{+}{e}^{-}$
• Gauge-invariant implications of the LHCb measurements on Lepton-Flavour Non-Universality
• On the Importance of Electroweak Corrections for B Anomalies
• With or without U(2)? Probing non-standard flavor and helicity structures in semileptonic B decays
• Search for the decays $B_s^0\to {\tau }^{+}{\tau }^{-}$ and $B^0\to {\tau }^{+}{\tau }^{-}$
• Anomalies in Bottom from new physics in Top
• Measurement of the phase difference between short- and long-distance amplitudes in the $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ decay
• The impact of flavour data on global fits of the MFV SMEFT
• Low-energy Effects of Lepton Flavour Universality Violation
• Interplay of dineutrino modes with semileptonic rare $\mathbf{B}$-decays
• Vector Leptoquarks Beyond Tree Level III: Vector-like Fermions and Flavor-Changing Transitions
• $B$ meson anomalies and large $B^{+}\to K^{+}\nu \bar{\nu }$ in non-universal $U(1{)}^{\prime }$ models
• More Synergies from Beauty, Top, $Z$ and Drell-Yan Measurements in SMEFT
• Disentangling Lepton Flavour Universal and Lepton Flavour Universality Violating Effects in $b\to s{\ell }^{+}{\ell }^{-}$ Transitions
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Evidence for the decay $B_s^0\to \overline{K}{}^{\ast 0}{\mu }^{+}{\mu }^{-}$
• Anatomy of a six-parameter fit to the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies
• Scrutinizing New Physics in Semi-leptonic $B_c\to J/\psi \tau \nu$ Decay
• Using Machine Learning techniques in phenomenological studies in flavour physics

Cited by in corpus (1)

• Lecture notes on Machine Learning applications for global fits