C2a: Hadronic Matrix Elements and Exclusive Semileptonic Decays

Principal Investigators
Prof. Thorsten Feldmann University of Siegen
Prof. Thomas Mannel University of Siegen


In this project we will improve the theoretical predictions for various exclusive semileptonic b-decay processes, including new classes of decay modes where precision calculations have not been available so far. Starting point for the evaluation of exclusive b-hadron decays are the light-cone distribution amplitudes (LCDAs) that parametrize the essential hadronic infor- mation in the light-cone sum rule (LCSR) and QCD factorization (QCDF) approaches. With these methods the (generalized) form factors that describe the semileptonic transition into single hadrons or multi-hadron final states can be investigated. The results of this project are essential for precise determinations of the fundamental parameters |Vub| and |Vcb| appearing in the Cabbibo-Kobayashi-Maskawa matrix, and for tests of the Standard Model against New Physics in charged-current (CC) transitions.


  1. Factorization and Light-Cone Distribution Amplitudes
    • 2- and 3-particle LCDAs of the B-meson
    • Implications for B → γlν, B− → μ−ν ̄μ+μ− decays
    • Theoretical properties of quasi-distribution amplitudes
  2. Theoretical Development of QCD Sum Rules and Related Methods
    • Interplay of sum rules and unitarity bounds
    • 1/mQ power corrections to B → D(∗) form factors ◦ Form factors for semileptonic Bc transitions
  3. New Channels and Multi-Hadron Final States
    • B → ππlν and Bs → Kπlν decays
    • Semileptonic decays of heavy baryons
    • Heavy-to-heavy and heavy-to-light decays of Bc
  4. Inclusive Rate from the Sum over Exclusive Channels
    • Realistic description of B → D + nπ contributions ◦ Excited states contributing to b → ulν
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