Triangle singularity in the production of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mi>c</mml:mi><mml:mi>c</mml:mi></mml:mrow><mml:mo>+</mml:mo></mml:msubsup><mml:mo stretchy="false">(</mml:mo><mml:mn>3875</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> and a soft pion

Abstract

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 ${T}_{cc}^{+}{\ensuremath{\pi}}^{+}$. A charm-meson triangle singularity produces a narrow peak in the ${T}_{cc}^{+}{\ensuremath{\pi}}^{+}$ 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 ${T}_{cc}^{+}{\ensuremath{\pi}}^{+}$ as ${E}^{\ensuremath{-}1/2}$. The fraction of ${T}_{cc}^{+}$ that are accompanied by ${\ensuremath{\pi}}^{+}$ with $E&lt;{m}_{\ensuremath{\pi}}$ is estimated to be roughly 3%. The fraction of ${T}_{cc}^{+}$ events with ${T}_{cc}^{+}{\ensuremath{\pi}}^{+}$ in the narrow peak from the triangle singularity could be comparable.

Topics & Concepts