2018/03/31 by De-Liang Yao, D. -L. Yao, P. Fernandez-Soler +3 · 11 citations
Physics and Astronomy · #Cabibbo–Kobayashi–Maskawa matrix #Form factor (electronics) #Helicity #Homogeneous space #Meson #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Quantum and Classical Electrodynamics #Quantum chromodynamics #Quark #Scalar (mathematics) #Scalar meson #hep-ph
paper · pdf · open access · doi:10.1140/epjc/s10052-018-5790-4
published in The European Physical Journal C 78(4) (Springer Science+Business Media) · includes further discussions and references; matches the accepted version
openalex created_date 2018/03/29 · openalex publication_date 2018/04/01 · arxiv created 2018/04/09 · arxiv updated 2018/05/09 · openalex updated_date 2026/08/05
By solving the Muskhelishvili–Omnès integral equations, the scalar form factors of the semileptonic heavy meson decays D→ π ℓ ν _ℓ , D→ K ℓ ν _ℓ , B→ π ℓ ν _ℓ and Bs→ K ℓ ν _ℓ are simultaneously studied. As input, we employ unitarized heavy meson–Goldstone boson chiral coupled-channel amplitudes for the energy regions not far from thresholds, while, at high energies, adequate asymptotic conditions are imposed. The scalar form factors are expressed in terms of Omnès matrices multiplied by vector polynomials, which contain some undetermined dispersive subtraction constants. We make use of heavy quark and chiral symmetries to constrain these constants, which are fitted to lattice QCD results both in the charm and the bottom sectors, and in this latter sector to the light-cone sum rule predictions close to q2=0 as well. We find a good simultaneous description of the scalar form factors for the four semileptonic decay reactions. From this combined fit, and taking advantage that scalar and vector form factors are equal at q2=0 , we obtain |Vcd|=0.244± 0.022 , |Vcs|=0.945± 0.041 and |Vub|=(4.3± 0.7)× 10-3 for the involved Cabibbo–Kobayashi–Maskawa (CKM) matrix elements. In addition, we predict the following vector form factors at q2=0 : |f+D→ η (0)|=0.01± 0.05 , |f+Ds→ K(0)|=0.50 ± 0.08 , |f+Ds→ η (0)|=0.73± 0.03 and |f+^B→ η (0)|=0.82 ± 0.08 , which might serve as alternatives to determine the CKM elements when experimental measurements of the corresponding differential decay rates become available. Finally, we predict the different form factors above the q2- regions accessible in the semileptonic decays, up to moderate energies amenable to be described using the unitarized coupled-channel chiral approach.