中国物理学会高能物理分会第十一届全国会员代表大会暨学术年会

The double-charm tetraquark meson $T_{cc}^+​(3875)$ can be produced in high-energy proton-proton collisions by the creation of the charm mesons $D^{*+} D^0$ at short distances followed by their binding into $T_{cc}^+​$. The $T_{cc}^+​$ can also be produced by the creation of $D^{*+} D^{*+}$ at short distances followed by their rescattering into $T_{cc}^+ ​π^+$. A charm-meson triangle singularity produces a narrow peak in the $T_{cc}^+ ​π^+$ invariant mass distribution 6.1 MeV above the threshold with a width of about 1 MeV. Well beyond the peak, the differential cross section decreases with the invariant kinetic energy E of $T_{cc}^+ ​π^+$ as $E^{-1/2}$. The fraction of T_{cc}^+​ that are accompanied by $π^+$ with $E< m_π​$ is estimated to be roughly 3%. The fraction of $T_{cc}^+$ events with $T_{cc}^+​ π^+$ in the narrow peak from the triangle singularity could be comparable.