https://doi.org/10.1140/epja/i2011-11120-6
Regular Article - Theoretical Physics
Bound state nature of the exotic Zb states
1
Institute for Advanced Simulation and Jülich Center for Hadron Physics, Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
2
Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115, Bonn, Germany
* e-mail: fkguo@hiskp.uni-bonn.de
Received:
6
July
2011
Revised:
16
September
2011
Accepted:
19
September
2011
Published online:
17
October
2011
The assumption that the newly observed charged bottomonia states Z
b(10610) and Z
b(10650) are of molecular nature is confronted with the measured invariant-mass distributions for the transitions of the ϒ(5S) to the final states h
b
π
+
π
− and h
b(2P)π
+
π
−. It is shown that the assumption that the Z
b(10610) and Z
b(10650) are B
+ c.c. and B
*
bound states, respectively, with very small binding energies is consistent with the data. The calculation is based on a power counting for bottom meson loops, which is explicitly given up to two-loop in the framework of a nonrelativistic effective-field theory. We also show that if the Zb states are of molecular nature, then the data should not be analyzed by using a Breit-Wigner parametrization.
© SIF, Springer-Verlag Berlin Heidelberg, 2011
