arXiv subjects

Riccardo Bartocci

Publications and source records attributed to Riccardo Bartocci.

6 recordsLinked to original sources

arXiv2026

Three-particle di-light-cone distribution amplitudes of the $B$-meson in heavy-quark effective theory

We present a systematic study of the three-particle di-light-cone distribution amplitudes (DLCDAs) of the $B$-meson. They are defined through $B$-meson--to--vacuum matrix elements of trilocal HQET operators, in which the light antiquark and the gluon field-strength tensor are located on two back-to-back light rays. In this sense, the DLCDAs generalise the conventional $B$-meson light-cone distribution amplitudes to configurations where soft fields couple to collinear degrees of freedom in two distinct directions. As such, they parametrise the non-perturbative dynamics associated with non-factorisable soft-gluon contributions in rare and non-leptonic exclusive $B$-meson decays. We derive the complete Lorentz decomposition of the matrix elements of generic trilocal operators, identify eight independent DLCDAs, and organise them in a basis of definite twist. Using local operator identities and equations-of-motion constraints, we obtain tree-level relations for their normalisation integrals and first moments in terms of a minimal set of hadronic parameters. These relations allow us to construct simple momentum-space models for all independent DLCDAs. For the leading-twist distribution, we further incorporate the perturbative radiative tail at order $α_s$ and discuss its impact on the resulting parametrisation.

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arXiv2025

NLO analysis of the subleading-power $Q_1-Q_{7γ}$ interference in $\bar{B}\to X_sγ$ at large photon energies

We report on progress towards including next-to-leading order (NLO) radiative corrections to the subleading-power factorization formula for the $Q_1^{q}-Q_{7γ}$ interference contribution in $\bar{B}\to X_sγ$ at large photon energies, $m_b - 2E_γ= \mathcal{O}(Λ_{\rm QCD})$. The novel ingredients for a NLO analysis are the one-loop anomalous dimension of the subleading shape function $g_{17}(ω,ω_1;μ)$, which was recently computed by us, and the two-loop corrections to the jet function with an internal charm loop. Here we summarize the renormalization of $g_{17}(ω,ω_1;μ)$, and further discuss that our insights allow for a simplified renormalization of a specific generalization of a three-particle $B$-meson light-cone distribution amplitude, but with non-aligned light-like separations of the fields.

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arXiv2025

Renormalisation group evolution of the shape function $g_{17}$ in $\bar{B}\to X_s γ$ and $\bar{B} \to X_s \ell^+\ell^-$ at subleading power

We derive and solve the renormalisation-group (RG) equation of the shape function $g_{17}(ω,ω_1;μ)$, which appears at subleading power in the factorization of the inclusive decays $\bar{B} \to X_s γ$ and $\bar B \to X_s \ell^+\ell^-$. Our results provide the first ingredient for a next-to-leading order analysis of the respective resolved-photon ${Q}^{c}_{1} - {Q}_{7γ}$ interference contribution, whose current uncertainties are among the largest ones in both inclusive penguin modes. As a by-product of our study, we find that the analytic properties of the soft anomalous dimension as well as the jet functions in a factorization theorem allow for a simplified renormalisation of operators in Heavy-Quark Effective Theory that are composed of fields smeared along distinct light-cone directions. Their hadronic matrix elements become relevant in various inclusive and exclusive $B$-decays beyond leading power in the heavy-quark and large-energy expansion. Using these insights, we derive and solve a simpler ``reduced'' RG equation of an amplitude-level soft function that describes the long-distance QCD dynamics for penguin contributions to exclusive $\bar{B}_{d,s} \to γγ$ decays, and which has recently been discussed in the literature.

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arXiv2024

Renormalisation group evolution effects on global SMEFT analyses

Global analyses in the Standard Model Effective Field Theory (SMEFT) framework serve as a tool to probe potential directions of new physics. To break degeneracies between the Wilson coefficients of the SMEFT, it is essential to combine observables from various experiments. Since different observables entering global fits may be measured at different energy scales, it becomes increasingly important to account for this fact through the renormalisation group evolution (RGE) of the Wilson coefficients. In this work, we investigate the effects of the RGE on a global SMEFT fit under the assumption of a $U(3)^5$ symmetry within the minimal flavour violation framework. We comment on the role of next-to-leading order SMEFT predictions for breaking potential degeneracies between Wilson coefficients arising as a result of RGE effects.

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arXiv2024

Global analysis of the $U(3)^5$ symmetric SMEFT

The $U(3)^5$ symmetry within the SMEFT framework restricts the inclusion of only fully flavor-conserving operators at dimension six. This proceeding presents a global analysis of the SMEFT under this assumption. We provide global constraints on all 41 Wilson coefficients, utilizing leading-order and next-to-leading-order SMEFT predictions for various experiments including parity-violating experiments, Electroweak Precision Observables (EWPO), Higgs physics, top quark interactions, flavor observables, dijet production, and lepton scatterings. We address issues concerning the constraints of specific four-quark operators, investigate correlations between observables at different energy scales, and assess the impact of next-to-leading-order contributions on the global fit.

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arXiv2023

A global analysis of the SMEFT under the minimal MFV assumption

We present comprehensive global fits of the SMEFT under the $\textit{minimal}$ minimal flavour violation (MFV) hypothesis, i.e. assuming that only the flavour-symmetric and CP-invariant operators are relevant at the high scale. The considered operator set is determined by theory rather than the used datasets. We establish global limits on these Wilson coefficients using leading order and next-to-leading order SMEFT predictions for electroweak precision observables, Higgs, top, flavour and dijets data as well as measurements from parity violation experiments and lepton scattering. Our investigations reveal an intriguing crosstalk among different observables, underscoring the importance of combining diverse observables from various energy scales in global SMEFT analyses.

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