2012/05/01 by Zuohong Li, Zuo-Hong Li, Nan Zhu +2
Physics and Astronomy · #Bar (unit) #Cabibbo–Kobayashi–Maskawa matrix #Geometry #High-Energy Particle Collisions Research #Light cone #Momentum transfer #Particle physics #Particle physics theoretical and experimental studies #Physics #Pi #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Quark #Scattering #Twist #Zero (linguistics) #hep-ph
paper · pdf · doi:10.1007/jhep05(2012)160
published as JHEP 05(2012)160 · 23 pages, 4 figures, 3 tables, published in JHEP
openalex publication_date 2012/05/01 · arxiv created 2012/06/01 · arxiv updated 2012/06/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a QCD study on B, D→π semileptonic transitions at zero momentum transfer and an estimate of magnitudes of the associated CKM matrix elements. Light cone sum rules (LCSRs) with chiral correlator are applied to calculate the form factors fB→ π+(0) and fD→ π+(0). We show that there is no twist-3 and-5 component involved in the light-cone expansions such that the resulting sum rules have a good convergence and offer an understanding of these form factors at twist-5 level. A detailed O(αs) computation is carried out in leading twist-2 approximation and the MS masses are employed for the underlying heavy quarks. With the updated inputs and experimental data, we have fB→ π+(0)=0.28+0.05-0.02 and |Vub|=(3.4+0.2-0.6±0.1±0.1)×10-3; fD→ π+(0)=0.62±0.03 and |Vcd|=0.244±0.005±0.003±0.008. As a by-product, a numerical estimate for the decay constant fD is yielded as fD=190+12-11MeV.