https://doi.org/10.1140/epjc/s10052-016-4576-9
Regular Article - Theoretical Physics
Zooming in on 
decays at low recoil
1
Theoretische Physik 1, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068, Siegen, Germany
2
Institut für Physik, Technische Universität Dortmund, 44221, Dortmund, Germany
* e-mail: ivan.nisandzic@tu-dortmund.de
Received:
12
June
2016
Accepted:
15
December
2016
Published online:
9
January
2017
We analyse decays in the region of low hadronic recoil, where an operator product expansion (OPE) in 
applies. Using a local model for charm contributions based on 
against the OPE provides a data-driven method to access the limitations to the OPE’s accuracy related to binnings in the dilepton mass. Model-independent fits to 
low recoil angular observables exhibit presently only small sensitivity to different charm models. They give similar results to the fits based on the OPE and are in agreement with the standard model, but leave also room for new physics. Measurements with resolution small enough to probe charm resonances would be desirable.
© The Author(s), 2017
