Exclusive determinations of $\vert V_{cb} \vert$ and $R(D^{*})$ through unitarity

Martinelli, G.; Simula, Silvano; Vittorio, Ludovico

doi:10.48550/arxiv.2109.15248

Cited by 11 publications

(26 citation statements)

References 10 publications

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“…As for the B → D ( * ) case [22,23], in this work we limit ourselves to the case q 2 0 = 0 and we postpone the discussion of the phenomenological implications of the choice q 2 0 = 0 to a forthcoming work. Following Refs.…”

Section: A the Unitarity Bounds On The Ffsmentioning

confidence: 99%

“…Finally, as discussed in Refs. [16,22,23], we use the mean values, the uncertainties and (when available) the correlations of the LQCD computations of the FFs and the susceptibilities to construct a multivariate Gaussian distribution for generating a sample of bootstrap events to each of which the DM method is applied.…”

Section: A the Unitarity Bounds On The Ffsmentioning

confidence: 99%

“…It turns out that the unitarity bounds for both f π 0 and f π + as well as the KC f π 0 (0) = f π + (0) ≡ f π (0) are satisfied by 98 ÷ 100% of the events and, therefore, neither the skeptical nor the iterative procedures described in Refs. [16,22,23] need to be applied. In Figs.…”

Section: A Direct Computation Of the Two-fold Differential Decay Widt...mentioning

confidence: 99%

“…The FFs, instead, are taken from the results of the RBC/UKQCD [18] and FNAL/MILC [19] Collaborations for the B → π ν decays, and from RBC/UKQCD [18], HPQCD [20] and FNAL/MILC [21] Collaborations for the B s → K ν decays. As already done for the analysis of the exclusive B → D ( * ) decays [22,23], we stress that only LQCD computations of the FFs for small values of the recoil will be used to determine the shape of the FFs in the whole kinematical range without making any assumption on their momentum dependence. Moreover, the experimental data are not used to constrain the shape of the FFs, but only to obtain the final exclusive determination of |V ub |.…”

Section: Introductionmentioning

confidence: 99%

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Exclusive semileptonic $B \to π\ell ν_\ell$ and $B_s \to K \ell ν_\ell$ decays through unitarity and lattice QCD

Martinelli,

Simula,

Vittorio

2022

Preprint

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The Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V ub | is obtained from exclusive semileptonic B → π ν and B s → K ν decays adopting the unitarity-based dispersion matrix approach for the determination of the hadronic form factors (FFs) in the whole kinematical range. We use lattice computations of the relevant susceptibilities and of the FFs in the large-q 2 regime in order to derive their behavior in the low-q 2 region without assuming any specific momentum dependence and without constraining their shape using experimental data. Then, we address the extraction of |V ub | from the experimental data, obtaining |V ub | = (3.62±0.47)•10 −3 from B → π and |V ub | = (3.81±1.03)•10 −3 from B s → K. These results are compatible with the most recent inclusive value |V ub | incl = 4.13 (26) • 10 −3at the 1σ level. We also present purely theoretical estimates of the ratio of the τ /µ differential decay rates R τ /µ π(K) , the normalized forward-backward asymmetry Ā ,π(K) F B and the normalized lepton polarization asymmetry Ā ,π(K) polar .

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Section: A the Unitarity Bounds On The Ffsmentioning

confidence: 99%

Section: A the Unitarity Bounds On The Ffsmentioning

confidence: 99%

Section: A Direct Computation Of the Two-fold Differential Decay Widt...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exclusive semileptonic $B \to π\ell ν_\ell$ and $B_s \to K \ell ν_\ell$ decays through unitarity and lattice QCD

Martinelli,

Simula,

Vittorio

2022

Preprint

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“…The DM method has been already successfully applied in [7][8][9] and other applications are underway.…”

Section: Discussionmentioning

confidence: 99%

Non-Perturbative Bounds for Semileptonic Decays in Lattice QCD

Carlo¹,

Martinelli²,

Naviglio³

et al. 2021

Preprint

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We present a new method aiming at a non-perturbative, model-independent determination of the momentum dependence of the form factors entering semileptonic decays using unitarity and analyticity constraints. We extend the original proposal and, using suitable two-point functions computed non-perturbatively, we determine the form factors at low-momentum transfer 𝑞 2 from those computed explicitly on the lattice at large 𝑞 2 , without making any assumption about their 𝑞 2 dependence. As a training ground we apply the new method to the analysis of the lattice data of the semileptonic 𝐷 → 𝐾ℓ𝜈 ℓ decays obtained both at finite values of the lattice spacing and at the physical pion point in the continuum limit. We show that, starting from a limited set of data at large 𝑞 2 , it is possible to determine quite precisely the form factors in a model independent way in the full kinematical range, obtaining a remarkable agreement with the direct calculation of the form factors. This finding opens the possibility to obtain non-perturbatively the form factors entering the semileptonic B decays in the full kinematical range.

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QCD and Supercomputers

Martinelli

2023

Springer Proceedings in Physics

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The title of this talk should rather have been Lattice QCD and Supercomputers. I will introduce Lattice QCD as the fundamental tool to predict (postdict) the hadron spectrum and most of the matrix elements relevant for hadronic physics in the non-perturbative regime. Lattice calculations are used to study the dynamics of QCD at large temperature or chemical potential, the anomalous magnetic moment of the muon, $$g-$$ g - 2, the nucleon structure functions, the meson scattering amplitudes at low and intermediate energies and, last but not least, the weak matrix elements relevant in flavour physics and CP violation. In this presentation only some example particularly illustrative of the present sophistication and accuracy of lattice QCD calculations will be discussed in some detail.

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Exclusive determinations of $\vert V_{cb} \vert$ and $R(D^{*})$ through unitarity

Cited by 11 publications

References 10 publications

Exclusive semileptonic $B \to π\ell ν_\ell$ and $B_s \to K \ell ν_\ell$ decays through unitarity and lattice QCD

Exclusive semileptonic $B \to π\ell ν_\ell$ and $B_s \to K \ell ν_\ell$ decays through unitarity and lattice QCD

Non-Perturbative Bounds for Semileptonic Decays in Lattice QCD

QCD and Supercomputers

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