2018/09/30 by E. Waheed, P. Urquijo, I. Adachi +204 · 115 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1103/physrevd.100.052007
published in Physical review. D/Physical review. D. 100(5) (American Physical Society)
arxiv created 2019/04/19 · openalex created_date 2019/04/25 · openalex publication_date 2019/09/11 · arxiv updated 2019/09/25 · openalex updated_date 2026/08/05
We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| from B0\ensuremath→D^*\ensuremath-\ensuremathℓ+\ensuremathν_\ensuremathℓ decays, reconstructed with the full Belle data set of 711 fb^\ensuremath-1 integrated luminosity. Two form factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)\ensuremathηEW|Vcb| and the decay form factors, where F(1) is the normalization factor and \ensuremathηEW is a small electroweak correction. In the CLN parametrization we find F(1)\ensuremathηEW|Vcb|=(35.06\ifmmode±\else\textpm\fi0.15\ifmmode±\else\textpm\fi0.56)\ifmmode×\else\texttimes\fi10^\ensuremath-3, \ensuremathρ2=1.106\ifmmode±\else\textpm\fi0.031\ifmmode±\else\textpm\fi0.007, R1(1)=1.229\ifmmode±\else\textpm\fi0.028\ifmmode±\else\textpm\fi0.009, R2(1)=0.852\ifmmode±\else\textpm\fi0.021\ifmmode±\else\textpm\fi0.006. For the BGL parametrization we obtain F(1)\ensuremathηEW|Vcb|=(34.93\ifmmode±\else\textpm\fi0.23\ifmmode±\else\textpm\fi0.59)\ifmmode×\else\texttimes\fi10^\ensuremath-3, which is consistent with the world average when correcting for F(1)\ensuremathηEW. The branching fraction of B0\ensuremath→D^*\ensuremath-\ensuremathℓ+\ensuremathν_\ensuremathℓ is measured to be B(B0\ensuremath→D^*\ensuremath-\ensuremathℓ+\ensuremathν_\ensuremathℓ)=(4.90\ifmmode±\else\textpm\fi0.02\ifmmode±\else\textpm\fi0.16)%. We also present a new test of lepton flavor universality violation in semileptonic B decays, \fracB(B0\ensuremath→D^*\ensuremath-e+\ensuremathν)B(B0\ensuremath→D^*\ensuremath-\ensuremathμ+\ensuremathν)=1.01\ifmmode±\else\textpm\fi0.01\ifmmode±\else\textpm\fi0.03. The errors quoted correspond to the statistical and systematic uncertainties, respectively. This is the most precise measurement of F(1)\ensuremathηEW|Vcb| and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement.