Semileptonic Form Research Articles

HQET form factors for Bs → Klv decays beyond leading order

We compute semi-leptonic Bs decay form factors using Heavy Quark Effective Theory on the lattice. To obtain good control of the 1 /mb expansion, one has to take into account not only the leading static order but also the terms arising at O (1/mb): kinetic, spin and current insertions. We show results for these terms calculated through the ratio method, using our prior results for the static order. After combining them with non-perturbative HQET parameters they can be continuum-extrapolated to give the QCD form factor correct up to O (1/[see formula in PDF]) corrections and without O (αs(mb)n) corrections.

Matching of heavy-light flavour currents between HQET at order 1/m and QCD: I. Strategy and tree-level study

We present a strategy how to match the full set of components of the heavy-light axial and vector currents in Heavy Quark Effective Theory (HQET), up to and including 1/m h -corrections, to QCD. While the ultimate goal is to apply these matching conditions non-perturbatively, in this study we first have implemented them at tree-level, in order to find good choices of the matching observables with small $ \mathcal{O}\left( {{1 \left/ {{m_{\mathrm{h}}^2}} \right.}} \right) $ contributions. They can later be employed in the non-perturbative matching procedure which is a crucial part of precision HQET computations of semileptonic decay form factors in lattice QCD.

PION AND KAON STRUCTURES FROM THE INSTANTON VACUUM

In this presentation, we briefly review recent investigations on pion and kaon structures from the instanton vacuum. Starting from the low-energy QCD partition function, we have computed the Gasser-Leutwyler low-energy constants, electromagnetic form factors of the pion and kaon, and semileptonic decay form factors of the kaon. The results are in good agreement with the experimental and empirical data.

B and D mesons on the lattice

I review the status of lattice calculations of D and B mesons decay constants and semileptonic decay form factors, as well as B 0 – B ¯ 0 mixing parameters. I will mainly discuss those calculations that fully incorporate vacuum polarization effects by considering three flavours of sea quarks.

Recent Semileptonic Decay Results from FOCUS

I review recent semileptonic decay results from the FOCUS collaboration. E831/FOCUS is a fixed target photoproduction experiment that ran at Fermilab during the 1996-1997 fixed target run. With a high statistics sample of reconstructed charm (over 1 million decays in the channels D + → K − π + π + , D 0 → K − π + and D 0 → K − π + π − π + ) the FOCUS collaboration has measured semileptonic branching ratios, form factors, and interference phenomena.

Bounds on Heavy-to-Heavy Weak Decay Form Factors

We provide upper and lower bounds on the semileptonic weak decay form factors for B → D(*) and Λb → Λc decays by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to second order in ΛQCD/mQ and first order in αs. The [Formula: see text] corrections to the bounds at zero recoil are also presented.

ωb semileptonic decay form factors for mc≠∞

Abstract At leading order in 1 m , the fourteen form factors of the decays ω b →ω c e v and ω b →ω ∗ c e v can be described by two nonperturbative functions whose normalization at threshold is known. We extend these results to O( 1 m c ), and find that five additional functions and one dimensional constant enter into the form factor relations. At threshold all O( 1 m c ) corrections /fvanish, and the normalization is preserved.