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Abstract We apply the SACOT-m T general-mass variable flavour number scheme (GM-VFNS) to the inclusive B-meson production in hadronic collisions at next-to-leading order in perturbative Quantum Chromodynamics. In the GM-VFNS approach one matches the fixed-order heavy-quark production cross sections, accurate at low transverse momentum (p T), with the zero-mass cross sections, accurate at high p T. The physics idea of the SACOT-m T scheme is to do this by accounting for the finite momentum transfer required to create a heavy quark-antiquark pair throughout the calculation. We compare our results with the latest LHC data from proton-proton and proton-lead collisions finding a very good agreement within the estimated theoretical uncertainties. We discuss also scheme-related differences and their impact on the scale uncertainties.

Abstract Motivated by the first LHCb searches for the rare B ¯ s , d 0$$ {\\overline{B}}_{s,d}^0 $$→ J/ψμ + μ − decays, we perform a detailed study of these processes within the QCD factorization formalism. Since the transverse size of the J/ψ meson is small in the heavy quark mass limit, this formalism is generally expected to hold for these decays. We include both the leading- and next-to-leading-order QCD corrections to the hard-scattering kernels, which are convoluted with the light-cone distribution amplitudes (LCDAs) of the initial- and final-state hadrons. It is numerically found that, depending on the model parameters for the leading-twist B-meson LCDA, the maximum branching ratios of B ¯ s 0$$ {\\overline{B}}_s^0 $$→ J/ψμ + μ − and B ¯ d 0$$ {\\overline{B}}_d^0 $$→ J/ψμ + μ −, integrated over the dimuon invariant mass squared q 2 from 1 GeV2 to ( m B s , d$$ {m}_{B_{s,d}} $$− m J/ψ )2, can reach up to 2.21 × 10−9 and 7.69 × 10−11 at the leading order in α s , respectively. After incorporating the non-factorizable one-loop vertex corrections, these branching ratios are further reduced by about one order of magnitude, with B B ¯ s 0 → J / ψ μ + μ − q 2 ≥ 1 GeV 2$$ \\mathcal{B}{\\left.\\left({\\overline{B}}_s^0\\to J/\\psi {\\mu}^{+}{\\mu}^{-}\\right)\\right|}_{q^2\\ge 1{\\textrm{GeV}}^2} $$= 2.88 × 10−10 and B B ¯ d 0 → J / ψ μ + μ − q 2 ≥ 1 GeV 2$$ \\mathcal{B}{\\left.\\left({\\overline{B}}_d^0\\to J/\\psi {\\mu}^{+}{\\mu}^{-}\\right)\\right|}_{q^2\\ge 1{\\textrm{GeV}}^2} $$= 1.07 × 10−11. In addition, we have presented the dimuon invariant mass distributions of the individual and total helicity amplitudes squared, as well as the differential and integrated longitudinal polarization fractions of the J/ψ meson, which could be probed by the future LHCb and Belle II experiments with more accumulated data.

Abstract We study the impact of third-order QCD corrections for several kinematic moments of the inclusive semileptonic B decays, to first order in the 1/m b expansion. We consider the first four moments of the charged-lepton energy E R spectrum, the total leptonic invariant mass q 2 and the hadronic invariant mass M X 2 M_(X)² . No experimental cuts are applied. Our analytic results are obtained via an asymptotic expansion around the limit m b m c . After converting the scheme for the bottom mass to the kinetic scheme we compare the size of higher QCD corrections to the contributions from 1/ m b 2 m_(b)² and 1/ m b 3 m_(b)³ power corrections and to the relative uncertainties.

Abstract We present updated and comprehensive Standard Model predictions for the inclusive rare decay B → X s ν ν ¯ B→ X_(s)ν ν̅ . Using a state-of-the-art determination of the short-distance coefficient, including NLO QCD and electroweak effects, and implementing a consistent treatment of heavy-quark masses and power corrections within the kinetic scheme, we compute the total decay rate and the neutrino invariant mass spectrum. We incorporate all known perturbative contributions in the heavy quark limit up to O α s 3 𝓞\\left{(}{α}{_(s)}³\\right) , evaluate non-perturbative corrections through the Heavy Quark Expansion up to 1 / m b 3 1/m_(b)³ , and include estimates of four-quark operator matrix elements from HQET sum rules. We obtain the Standard Model branching ratios Br( B 0 → X s ν ν ¯ B⁰→ X_(s)ν ν̅ ) = (3.35 ± 0.10) × 10−5 and Br( B + → X s ν ν ¯ B⁺→ X_(s)ν ν̅ ) = (3.62 ± 0.11) × 10−5, representing a significant improvement in both central value and precision compared to previous determinations. We also provide predictions for partial rates with kinematic cuts relevant to Belle II. Our results are timely in view of recent measurements of B → Kν ν ¯ B→ Kν ν̅ and the first upper limits on inclusive B → X s ν ν ¯ B→ X_(s)ν ν̅ , and they offer a robust baseline for future searches for physics beyond the Standard Model in b → sν ν ¯ b→ sν ν̅ transitions.

Abstract Many contributions to the decay rate of the inclusive radiativeB̅→ X _(s)γ transition have been calculated to NNLO in QCD during the past decades. However, there are still a few unknown contributions from multi-parton final states which are formally NLO. In the present work, we compute those four-bodyb→ sqq̅ ̅γ contributions at NLO in QCD which need to be supplemented by the five-bodyb→ sqq̅ ̅gγ bremsstrahlung. This calculation formally completes the purely perturbative contributions toB̅→ X _(s)γ at NLO. Our results are obtained by applying modern techniques of integral reduction and evaluation of master integrals. In particular, the analytic integration over the four and five-particle phase space in the presence of a cut on the photon energy turns out to be technically involved. We give our results completely analytically in terms of multiple polylogarithms, including the dependence on the collinear logarithms which arise from the mass-regularisation of collinear divergences. The numerical impact of multi-parton corrections on theB̅→ X _(s)γ decay rate turns out to be small, owing to a partial cancellation between LO and NLO contributions.

A bstract We provide improved Standard Model theory predictions for the exclusive rare semimuonic processes B → K (*) μ + μ − and B s → ϕμ + μ − . Our results are based on a novel parametrization of the non-local form factors, which manifestly respects a recently developed dispersive bound. We critically compare our predictions to those obtained in the framework of QCD factorization. Our predictions provide, for the first time, parametric estimates of the systematic uncertainties due to non-local contributions. Comparing our predictions within the Standard Model to available experimental data, we find a large tension for B → Kμ + μ − . A simple model-independent analysis of potential effects beyond the Standard Model yields results compatible with other approaches, albeit with larger uncertainties for the B → K * μ + μ − and B s → ϕμ + μ − decays. Our approach yields systematically improvable predictions, and we look forward to its application in further analyses beyond the Standard Model.

Abstract Based on explicitly gauge invariant interpolating operators we compute complete next-leading order QED-corrections for leptonic decays. These are sizeable since the helicity-suppression in V-A interactions allows for structure-dependent collinear logs. We have explicitly checked that these logs are absent for helicity-unsuppressed Yukawa-type transitions. Based on B → γ form factors we present the rates for B − → μ − τ − ν ¯ γ$$ {B}^{-}\\to \\left({\\mu}^{-},{\\tau}^{-}\\right)\\overline{\\nu}\\left(\\gamma \\right) $$in differential and integrated form as a function of the photon energy cut-off E γ cut$$ {E}_{\\gamma}^{\\textrm{cut}} $$. The effect of the virtual structure-dependent corrections are approximately +5% and +3% for the μ- and τ-channel respectively. The structure dependence of the real radiation exceeds that of the virtual one for E γ cut μ$$ {\\left.{E}_{\\gamma}^{\\textrm{cut}}\\right|}_{\\mu } $$> 0.18(3) GeV and is subdominant for the tau channel even when fully inclusive.

Abstract We investigate the decays B c −$$ {B}_c^{-} $$→ D ¯ ∗ 0 ℓ − ν ¯ ℓ$$ {\\overline{D}}^{\\left(\\ast \\right)0}{\\ell}^{-}{\\overline{\\nu}}_{\\ell } $$and B c −$$ {B}_c^{-} $$→ D (∗)− ℓ + ℓ − within the Standard Model (SM), employing perturbative QCD (pQCD) form factors that are sensitive to the wave functions of B c and D (∗) mesons. Using lattice QCD inputs for B → D (∗) and B c → D transitions, we extract the shape parameters of the meson wave functions and estimate the q 2-dependence of B c → D ∗ form factors via heavy quark spin symmetry. We present predictions for branching fractions, lepton flavor violating observables, and perform a detailed angular analysis of the cascade decay B c −$$ {B}_c^{-} $$→ D ∗−(→ D 0 π −)ℓ + ℓ −, providing SM expectations for several angular observables.

Abstract We perform a detailed model-independent phenomenological analysis of B ¯ → D ¯ D B̅→ D̅D decays. Employing an SU(3) F analysis including symmetry-breaking contributions together with a conservative power counting for various suppression effects, we obtain updated Standard Model predictions for all branching fractions and CP asymmetries from a fit to the available experimental data, testable at Belle II and the LHC experiments. These results include all relevant suppressed contributions, thereby providing upper limits on subleading Standard Model (SM) effects like “penguin pollution”, enabling searches for physics beyond the SM. Importantly, allowing in the same fit for the production fractions of charged and neutral B mesons to be different, we find f d /f u = 0.86 ± 0.05, which is 2.5σ away from unity, which, if confirmed, would have important phenomenological consequences.

Abstract Recent publications by three lattice QCD collaborations have provided an unprecedented wealth of theoretical predictions for the B ¯ q → D q ∗$$ {\\overline{B}}_q\\to {D}_q^{\\left(\\ast \\right)} $$form factors, for spectator flavours q = u/d and q = s. We analyse these predictions within the framework of the heavy-quark expansion (HQE) to order α s , 1/m b , and 1 / m c 2$$ 1/{m}_c^2 $$. For the first time, our analysis imposes unitarity bounds for all of the B ¯ q ∗ → D q ∗$$ {\\overline{B}}_q^{\\left(\\ast \\right)}\\to {D}_q^{\\left(\\ast \\right)} $$form factors; this includes newly identified tensor form factors arising in B ¯ q ∗ → D q ∗$$ {\\overline{B}}_q^{\\ast}\\to {D}_q^{\\left(\\ast \\right)} $$. This enables us to treat all form factors in the same fashion. At the level of our present analysis, the inclusion of the tensor bounds is not yet constraining the HQE parameter space. We find the lattice QCD results to be well compatible with each other in a joint HQE fit as well as with QCD sum rule estimates that were used in previous HQE analyses. This is in contrast to the strong variability of the posterior predictions, in particular of the form factors ratios R 0 and R 2. Using the posterior distributions of our HQE analysis, we provide predictions for angular observables and LFU ratios in the B ¯ q → D q ∗ ℓ − ν ¯$$ {\\overline{B}}_q\\to {D}_q^{\\left(\\ast \\right)}{\\ell}^{-}\\overline{\\nu} $$decays.