====== C2a: Hadronic Matrix Elements and Exclusive Semileptonic Decays======

^Principal Investigators ^^
|[[http://www.physik.uni-siegen.de/tp1/research/researchgroups/feldmann.html?lang=de | Prof. Thorsten  Feldmann  ]] |University of Siegen | 
|[[http://www.physik.uni-siegen.de/tp1/research/researchgroups/mannel.html?lang=de | Prof. Thomas  Mannel]] | University of Siegen  |



==== Subject ====
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.


==== Topics ==== 

  - 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
  -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
  -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
  - Inclusive Rate from the Sum over Exclusive Channels
    *Realistic description of B → D + nπ contributions ◦ Excited states contributing to b → ulν