Triangle Singularity in the Production of T+cc(3875) and a Soft Pion at Hadron Colliders

Abstract

If the double-charm tetraquark meson T+cc(3875) is a loosely bound molecule, it can be produced in high-energy proton-proton collisions by the creation of the charm mesons D∗+D0 at short distances followed by their binding into T+cc. It can also be produced by the creation of D∗+D∗+ at short distances followed by their rescattering into T+ccπ+ through a charm-meson triangle loop. A charm-meson triangle singularity produces a narrow peak in the T+ccπ+ invariant mass distribution 6.1 MeV above the threshold with a width of about 1 MeV. The fraction of T+cc that are accompanied by π+ with E < mπ is estimated to be roughly 3%. The fraction of T+cc events with T+ccπ+ in the narrow peak from the triangle singularity could be comparable.