https://doi.org/10.1140/epjc/s10052-015-3676-2
Regular Article - Theoretical Physics
Constraints on tensor and scalar couplings from 
and 
1
C2PAP, Excellence Cluster Universe, Ludwig-Maximilians-Universität München, Garching, Germany
2
Institute for Advanced Study, Technische Universität München, Garching, Germany
3
Excellence Cluster Universe, Technische Universität München, Garching, Germany
4
Max Planck Institute for Physics, Munich, Germany
* e-mail: bobeth@ph.tum.de
** e-mail: christoph.bobeth@ph.tum.de
Received:
10
August
2015
Accepted:
9
September
2015
Published online:
28
September
2015
The angular distribution of B → Kℓ̅ℓ (
) depends on two parameters, the lepton forward–backward asymmetry, 
, and the flat term, 
. Both are strongly suppressed in the standard model and constitute sensitive probes of tensor and scalar contributions. We use the latest experimental results for 
in combination with the branching ratio of to derive the strongest model-independent bounds on tensor and scalar effective couplings to date. The measurement of 
provides a complementary constraint to that of the branching ratio of and allows us – for the first time – to constrain all complex-valued (pseudo-)scalar couplings and their chirality-flipped counterparts in one fit. Based on Bayesian fits of various scenarios, we find that our bounds even become tighter when vector couplings are allowed to deviate from the standard model and that specific combinations of angular observables in 
are still allowed to be up to two orders of magnitude larger than in the standard model, which would place them in the region of LHCb’s sensitivity.
© The Author(s), 2015
