Discovery of the Doubly Charmed Ξ_{cc} Baryon Implies a Stable bbu[over ¯]d[over ¯] Tetraquark.

Recently, the LHCb Collaboration discovered the first doubly charmed baryon Ξ_{cc}^{++}=ccu at 3621.40±0.78  MeV, very close to our theoretical prediction.

Erratum: Quark-level analogue of nuclear fusion with doubly heavy baryons.

This corrects the article DOI: 10.1038/nature21697.

Quark-level analogue of nuclear fusion with doubly heavy baryons.

The essence of nuclear fusion is that energy can be released by the rearrangement of nucleons between the initial- and final-state nuclei. The recent discovery of the first doubly charmed baryon , which contains two charm quarks (c) and one up quark (u) and has a mass of about 3,621 megaelectronvolts (MeV) (the mass of the proton is 938 MeV) also revealed a large binding energy of about 130 MeV between the two charm quarks. Here we report that this strong binding enables a quark-rearrangement, exothermic reaction in which two heavy baryons (Λ) undergo fusion to produce the doubly charmed baryon and a neutron n (), resulting in an energy release of 12 MeV.

New Exotic Meson and Baryon Resonances from Doubly Heavy Hadronic Molecules.

We predict several new exotic doubly heavy hadronic resonances, inferring from the observed exotic bottomoniumlike and charmoniumlike narrow states X(3872), Z_{b}(10610), Z_{b}(10650), Z_{c}(3900), and Z_{c}(4020/4025). We interpret the binding mechanism as mostly molecularlike isospin-exchange attraction between two heavy-light mesons in a relative S-wave state. We then generalize it to other systems containing two heavy hadrons which can couple through isospin exchange.