Speaker
Dr
Bo Wang
(Hebei University)
Description
We generalize the framework of chiral effective field theory to
study the interactions of the isovector $D^\ast\bar{D}^{(\ast)}$ and
$B^\ast\bar{B}^{(\ast)}$ systems up to the next-to-leading order, in
which the long-, mid-, and short-range force contributions as well
as the $S$-$D$ wave mixing are incorporated. Based on the
Lippmann-Schwinger equation, we fit the invariant mass distributions
of the elastic channels measured by the BESIII and Belle
Collaborations. Our results indicate that the four charged
charmoniumlike and bottomoniumlike states $Z_c(3900)$, $Z_c(4020)$
and $Z_b(10610)$, $Z_b(10650)$ can be well identified as the
$D\bar{D}^{\ast},D^\ast\bar{D}^{\ast}$ and
$B\bar{B}^{\ast},B^\ast\bar{B}^{\ast}$ molecular resonances. The
bound state explanations are vetoed in our framework. Our study
favors the $Z_c$ and $Z_b$ states are the twin partners under the
heavy quark symmetry.
The newly observed $P_c(4312)$, $P_c(4440)$ and
$P_c(4457)$ at the LHCb experiment are very close to the
$\Sigma_c\bar{D}$ and $\Sigma_c\bar{D}^\ast$ thresholds. In this
work, we perform a systematic study and give a complete picture on
the interactions between the $\Sigma_c^{(\ast)}$ and
$\bar{D}^{(\ast)}$ systems in the framework of heavy hadron chiral
effective field theory, where the short-range contact interaction,
long-range one-pion-exchange contribution, and intermediate-range
two-pion-exchange loop diagrams are all considered.
Primary author
Dr
Bo Wang
(Hebei University)
