# 8th Workshop of the APS Topical Group on Hadronic Physics

10-12 April 2019
Denver, CO
US/Mountain timezone
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# Contribution contributed talk

Denver, CO - Director's Row E

# Production of $X(3872)$ accompanied by a pion in $B$ meson decay

• Liping HE

## Content

If the $X(3872)$ is a weakly bound charm-meson molecule, it can be produced by the creation of $D^{0} \bar{D}^0$ or $D^{0} \bar{D}^{0}$ at short distances followed by the formation of the bound state from the charm-meson pairs. It can also be produced by the creation of $D^{} \bar{D}^$ at short distances followed by the rescattering of the charm mesons into $X \pi$. An effective field theory for charm mesons and pions called XEFT predicts that the rate for producing $X$ accompanied by a pion should be roughly comparable to that for producing an isolated $X$. We use results of a previous isospin analysis of $B$ meson decays into $K D^{()} \bar D^{()}$ to estimate the short-distance amplitudes for creating $D^ \bar D^$. We use XEFT to calculate the amplitudes for rescattering of $D^{} \bar{D}^$ into $X \pi$ with small relative momentum. The resulting predictions for decays of $B$ mesons into $K X\pi$ are consistent with measurements made by the Belle collaboration.
If $K^* X$ events are removed, the remaining $K X\pi$ events are predicted to come primarily from the region of the Dalitz plot where the relative momentum of $X \pi$ is order $m_\pi$ or smaller.