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 (Λc) undergo fusion to produce the doubly charmed baryon and a neutron n (), resulting in an energy release of 12 MeV. This reaction is a quark-level analogue of the deuterium-tritium nuclear fusion reaction (DT → 4He n). The much larger binding energy (approximately 280 MeV) between two bottom quarks (b) causes the analogous reaction with bottom quarks () to have a much larger energy release of about 138 MeV. We suggest some experimental setups in which the highly exothermic nature of the fusion of two heavy-quark baryons might manifest itself. At present, however, the very short lifetimes of the heavy bottom and charm quarks preclude any practical applications of such reactions.

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. We use the same methods to predict a doubly bottom tetraquark T(bbu[over ¯]d[over ¯]) with J^{P}=1^{+} at 10 389±12 MeV, 215 MeV below the B^{-}B[over ¯]^{*0} threshold and 170 MeV below the threshold for decay to B^{-}B[over ¯]^{0}γ. The T(bbu[over ¯]d[over ¯]) is therefore stable under strong and electromagnetic interactions and can only decay weakly, the first exotic hadron with such a property. On the other hand, the mass of T(ccu[over ¯]d[over ¯]) with J^{P}=1^{+} is predicted to be 3882±12 MeV, 7 MeV above the D^{0}D^{*+} threshold and 148 MeV above the D^{0}D^{+}γ threshold. T(bcu[over ¯]d[over ¯]) with J^{P}=0^{+} is predicted at 7134±13 MeV, 11 MeV below the B[over ¯]^{0}D^{0} threshold. Our precision is not sufficient to determine whether bcu[over ¯]d[over ¯] is actually above or below the threshold. It could manifest itself as a narrow resonance just at threshold.

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. The new predicted states include resonances in meson-meson, meson-baryon, baryon-baryon, and baryon-antibaryon channels. These include those giving rise to final states involving a heavy quark Q=c,b and antiquark Q[over ¯]^{'}=c[over ¯],b[over ¯], namely, DD[over ¯]^{*}, D^{*}D[over ¯]^{*}, D^{*}B^{*}, B[over ¯]B^{*}, B[over ¯]^{*}B^{*}, Σ_{c}D[over ¯]^{*}, Σ_{c}B^{*}, Σ_{b}D[over ¯]^{*}, Σ_{b}B^{*}, Σ_{c}Σ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{b}, Σ_{b}Σ[over ¯]_{b}, Σ_{b}Λ[over ¯]_{b}, and Σ_{b}Λ[over ¯]_{c}, as well as corresponding S-wave states giving rise to QQ^{'} or Q[over ¯]Q[over ¯]^{'}.