https://doi.org/10.1140/epjc/s10052-018-5918-6
Letter
Long-distance effects in 
from analyticity
1
Physik Department, TU München, James-Franck-Straße 1, 85748, Garching, Germany
2
Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748, Garching, Germany
3
Physik-Institut, Universität Zürich, Winterthurer Strasse 190, 8057, Zürich, Switzerland
4
H.Niewodniczanski, Institute of Nuclear Physics Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342, Krakow, Poland
5
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
* e-mail: mchrzasz@cern.ch
Received:
3
March
2018
Accepted:
19
May
2018
Published online:
5
June
2018
We discuss a novel approach to systematically determine the dominant long-distance contribution to decays in the kinematic region where the dilepton invariant mass is below the open charm threshold. This approach provides the most consistent and reliable determination to date and can be used to compute Standard Model predictions for all observables of interest, including the kinematic region where the dilepton invariant mass lies between the 
and the 
resonances. We illustrate the power of our results by performing a New Physics fit to the Wilson coefficient 
. This approach is systematically improvable from theoretical and experimental sides, and applies to other decay modes of the type 
, 
and 
.
© The Author(s), 2018
