The Compact X and Z and their Invisible Molecular Partners

Abstract

We propose a model explaining the strong isospin violations observed in X(3872) decays. The X is assumed to be a compact isosinglet tetraquark and its charged partners to form an isotriplet, together with an additional neutral state mixing with the isosinglet. The isotriplet results from the loose binding of open charm mesons and, in isolation, has strongly suppressed production rates. However, its neutral component can still mix with the isosinglet and induce the large isospin violations observed. The compact-isosinglet/molecular-isotriplet pattern appears reversed when the Z(3900) resonances are considered. The Z particles observed correspond to a compact isotriplet and there is no evidence of a neutral isosinglet Z. We show that no isospin violation in the Z decays is expected.

24 pages, 12 figures, JHEP version

References in corpus (15)

• Diquark-Antidiquarks with Hidden or Open Charm and the Nature of X(3872)
• Isospin breaking of the narrow charmonium state of Belle at 3872 MeV as a deuson
• Low-energy Universality and the New Charmonium Resonance at 3870 MeV
• Rho-omega mixing, vector meson dominance and the pion form-factor
• Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?
• Production of the X(3872) at the Tevatron and the LHC
• Decays of the X(3872) into J/psi and Light Hadrons
• The observation of light nuclei at ALICE and the X(3872) conundrum
• The nature of $X(3872)$ from high-multiplicity $pp$ collisions
• A Mechanism for Hadron Molecule Production in p pbar(p) Collisions
• Predicting isovector charmonium-like states from X(3872) properties
• The role of the pion in the lineshape of the $X(3872)$
• The nature of ${\chi }_{c1}\left(3872\right)$ and $T_{cc}^{+}\left(3875\right)$
• Tetraquarks in the Born-Oppenheimer approximation
• A short review on the compositeness of the $X(3872)$