https://doi.org/10.1140/epjc/s10052-019-6929-7
Regular Article - Theoretical Physics
decays into 
and 
and 
and heavy quark spin symmetry
1
Instituto de Física Corpuscular (Centro Mixto CSIC-UV), Institutos de Investigación de Paterna, Aptdo. 22085, 46071, Valencia, Spain
2
Institute of Theoretical Physics, CAS, Zhong Guan Cun East Street 55, Beijing, 100190, China
* e-mail: shsakai@itp.ac.cn
Received:
28
March
2019
Accepted:
3
May
2019
Published online:
17
May
2019
We study the implications for 
and 
and decays that can be deduced from heavy quark spin symmetry (HQSS). Identifying the odd parity 
and 
resonances as HQSS partners, with total angular momentum–parity 
for the light degrees of freedom, we find that the ratios 
and 
agree, within errors, with the experimental values given in the Review of Particle Physics. We discuss how future, and more precise, measurements of the above branching fractions could be used to shed light into the inner HQSS structure of the narrow odd-parity resonance. Namely, we show that such studies would constrain the existence of a sizable 
component in its wave-function, and/or of a two-pole pattern, in analogy to the case of the similar 
resonance in the strange sector, as suggested by most of the approaches that describe the as a hadron molecule. We also investigate the lepton flavor universality ratios 
, and discuss how 
may be affected by a new source of potentially large systematic errors if there are two poles.
© The Author(s), 2019
