Heavy-Quark Spin Symmetry Partners of the X(3872) Molecule

Abstract

Heavy quark spin symmetry (HQSS) partners of the X(3872) J PC = 1 ++ molecule are discussed in a coupled-channel approach with non-perturbative pions. In the strict heavy-quark limit the 1 ++ molecular state has three degenerate partner states with the 1 +− , 0 ++ and 2 ++ quantum numbers. In the presence of pions this result is shown to be correct only if all allowed coupled-channel transitions between the DD, DD * and D * D * channels governed by the one-pion exchange potential are included.In particular, it is demonstrated that neglecting some of the coupled-channel transitions leads to a severe violation of HQSS as well as to regulator-dependent results for the partner states. The effect of HQSS violations by the D * -D mass difference on the properties of the 2 ++ partner state of the X(3872) is also discussed.

Study of charmonium and charmonium-like contributions in B+ → J/ψηK+ decays

“…Other hypotheses include, but are not limited to, a tetraquark state [52][53][54], a ccg hybrid meson [55], a vector glueball [56], a hadro-charmonium state [57], a cusp [36] or a χ c1 (2P) charmonium state [58,59]. For some models, the existence of χ c1 (3872) partner states is predicted [52][53][54][60][61][62][63][64]. Among these are charged partner X ± states and a C-odd partner, referred to hereafter as X C state.…”