arXiv subjects

Gael Finauri

Publications and source records attributed to Gael Finauri.

9 recordsLinked to original sources

arXiv2026

Inclusive $\bar B_s\mapsto X_{\bar sc} \ell \bar ν$ decays from lattice QCD: computational strategy and a first physical result

We present a strategy to compute the inclusive decay rate for the process $\bar B_s \mapsto X_{\bar sc} \ell \barν$ from first principles in lattice QCD. The physical decay rate is obtained from the interpolation of non-perturbative lattice data, obtained at lighter than physical heavy meson masses ($M_{\bar B_s}^\mathrm{max}=4.3$GeV), with the Operator Product Expansion predictions, which become exact in the limit of infinitely heavy quarks. We also present a new method for the computation of the required lattice four-point correlators, which represents a considerable improvement over the state-of-the-art on the subject. We show the effectiveness of the strategy by performing the calculation on a subset of the available $n_f=2+1+1$ physical-point Extended Twisted Mass Collaboration (ETMC) gauge ensembles. Our current determination of the inclusive decay rate has a 7% total error, that is dominated by uncertainties due to the relatively limited configuration ensembles considered herein, and can be significantly reduced in the near future.

hep-lat↗

arXiv2026

New Physics in inclusive $\bar{B} \to X_c \ell \barν$ decays

We present the first global phenomenological fit of inclusive $\bar B\to X_c\ell\barν$ observables to all available experimental data allowing for generic dimension-six New Physics interactions in the Weak Effective Theory. The fit includes both New Physics Wilson coefficients and non-perturbative QCD parameters. New Physics contributions are calculated including power corrections up to $\mathcal O(Λ_{\rm QCD}^3/m_b^3)$ and perturbative QCD corrections up to $\mathcal O(α_s)$. We find no significant preference for New Physics and obtain bounds on the size of the relevant Wilson Coefficients competitive with those coming from exclusive modes.

hep-ph↗

arXiv2026

One-Loop QCD Corrections to $\bar{B}\to X_c \ell \barν_\ell$ in and Beyond the Standard Model

We compute one-loop QCD corrections to the triple differential width of the inclusive decay $\bar{B} \to X_c \ell \barν_\ell$ including contributions from all relevant dimension-six operators in the Weak Effective Theory (WET), at leading power in heavy quark expansion. Furthermore we derive for the first time up to order $\mathcal{O}(α_s)$ analytic expressions for the first three moments of the distribution in the lepton energy, hadronic invariant mass and dilepton invariant mass, in the presence of beyond the Standard Model contributions from the WET.

hep-ph↗

arXiv2025

New Physics in inclusive semileptonic $B$ decays

We study inclusive semileptonic $\bar{B}\to X_c \ell \barν$ decays ($\ell = e,μ$) in the presence of generic physics Beyond the Standard Model (BSM) that is heavy compared to the $b$-quark mass. Its effect is encoded in the Wilson coefficients of dimension-six operators of the Weak Effective Theory (WET). We compute the resulting BSM contributions to the experimentally measured kinematic moments and the total decay rate through order $\mathcal{O}(Λ_{\rm QCD}^3/m_b^3)$ in the Heavy Quark Expansion, as well as the $\mathcal{O}(α_s)$ corrections for the right-handed vector current. We then perform fits to the full set of available inclusive measurements in several single-mediator scenarios and in the full WET basis. We find qualitatively new bounds in several of these scenarios, complementary to and competitive with constraints from exclusive decays.

hep-ph↗

arXiv2025

Kinematic Moments of $\bar{B}\to X_c \ell \barν_\ell$ to Order $\mathcal{O}(Λ_{\rm QCD}^5/m_b^5)$

We investigate the heavy-quark expansion (HQE) for inclusive semileptonic $\bar{B}$ decays, at tree level, by computing the fully differential decay rate up to order $\mathcal{O}(Λ_{\rm QCD}^5/m_b^5)$. We provide analytic results for the first three moments in the lepton energy, hadronic invariant mass and leptonic invariant mass ($q^2$) with a lower cut on the lepton energy in the $\bar{B}$ rest frame, as well as for the first three $q^2$ moments with a lower cut on $q^2$. By means of the lowest-lying state saturation ansatz we study the numerical behaviour of the HQE providing insights into the theoretical error budget associated with power corrections. Available CLEO data on the second central $q^2$ moment with a lower cut on the lepton energy present puzzling discrepancies with the theoretical expectations. This observation makes new measurements of these observables desirable, which could improve the precision of global fit analyses for the inclusive determination of $|V_{cb}|$.

hep-ph↗

arXiv2024

Indirect constraints on third generation baryon number violation

The non-observation of baryon number violation suggests that the scale of baryon-number violating interactions at zero temperature is comparable to the GUT scale. However, the pertinent measurements involve hadrons made of the first-generation quarks, such as protons and neutrons. One may therefore entertain the idea that new flavour physics breaks baryon number at a much lower scale, but only in the coupling to a third generation quark, leading to observable baryon-number violating $b$-hadron decay rates. In this paper we show that indirect constraints on the new physics scale $Λ_{\rm BNV}$ from the existing bounds on the proton lifetime do not allow for this possibility. For this purpose we consider the three dominant proton decay channels $p \to \ell^+ ν_\ell \barν$, $p \to π^+ \barν$ and $p \to π^0 \ell^+$ mediated by a virtual bottom quark.

hep-ph↗

arXiv2024

The $q^2$ moments in inclusive semileptonic $B$ decays

We compute the first moments of the $q^2$ distribution in inclusive semileptonic $B$ decays as functions of the lower cut on $q^2$, confirming a number of results given in the literature and adding the $O(α_s^2β_0)$ BLM contributions. We then include the $q^2$-moments recently measured by Belle and Belle II in a global fit to the moments. The new data are compatible with the other measurements and slightly decrease the uncertainty on the nonperturbative parameters and on $|V_{cb}|$. Our updated value is $|V_{cb}|=(41.97\pm 0.48)\times 10^{-3}$.

hep-ph↗

arXiv2023

QCD Light-Cone Distribution Amplitudes of Heavy Mesons from boosted HQET

Light-cone distribution amplitudes (LCDAs) frequently arise in factorization theorems involving light and heavy mesons. The QCD LCDA for heavy mesons includes short-distance physics at energy scales of the heavy-quark mass. In this paper we achieve the separation of this perturbative scale from the purely hadronic effects by matching the QCD LCDA to the convolution of a perturbative function with the universal, quark-mass independent LCDA defined in heavy-quark effective theory. This factorization allows to resum potentially large logarithms between $Λ_{\rm QCD}$ and $m_Q$ as well as between $m_Q$ and the scale $Q$ of the hard process in the production of boosted heavy mesons at colliders. As an application we derive new theoretical predictions for the branching ratio of the decay $W^\pm \to B^\pm γ$. Furthermore, we provide phenomenological models for the QCD LCDAs of both the $\bar{B}$ and $D$ mesons expressed as expansions in Gegenbauer polynomials.

hep-ph↗

arXiv2021

QED factorization of two-body non-leptonic and semi-leptonic $B$ to charm decays

The QCD$\times$QED factorization is studied for two-body non-leptonic and semi-leptonic $B$ decays with heavy-light final states. These non-leptonic decays, like $\bar{B}^0_{(s)}\to D^+_{(s)} π^-$ and $\bar{B}_d^0 \to D^+ K^-$, are among the theoretically cleanest non-leptonic decays as penguin loops do not contribute and colour-suppressed tree amplitudes are suppressed in the heavy-quark limit or even completely absent. Advancing the theoretical calculations of such decays requires therefore also a careful analysis of QED effects. Including QED effects does not alter the general structure of factorization which is analogous for both semi-leptonic and non-leptonic decays. For the latter, we express our result as a correction of the tree amplitude coefficient $a_1$. At the amplitude level, we find QED effects at the sub-percent level, which is of the same order as the QCD uncertainty. We discuss the phenomenological implications of adding QED effects in light of discrepancies observed between theory and experimental data, for ratios of non-leptonic over semi-leptonic decay rates. At the level of the rate, ultrasoft photon effects can produce a correction up to a few percent, requiring a careful treatment of such effects in the experimental analyses.

hep-ph↗