Possibility of Exotic States in the Upsilon system

Abstract

Recent data from Belle show unusually large partial widths Upsilon(5S) --> Upsilon(1S) pi^+pi^- and Υ(5S) --> Υ(2S) pi^+ pi^-. The Z(4430) narrow resonance also reported by Belle in psi' pi^+ spectrum has the properties expected of a (cbar c u dbar) charged isovector tetraquark T^{+-}_cc The analogous state T^{+-} in the bottom sector might mediate anomalously large cascade decays in the Upsilon system, Upsilon(mS) --> T^{+-}_bb pi^{-+} --> Upsilon(nS) pi^+ π^-, with a tetraquark-pion intermediate state. We suggest looking for the (bbar b u dbar) tetraquark in these decays as peaks in the invariant mass of Upsilon(1S) pi or Upsilon(2S) pi systems. The (bbar b u sbar) tetraquark can appear in the observed decays Upsilon(5S) --> Upsilon(1S) K^+ K^- as a peak in the invariant mass of Upsilon(1S) K system. We review the model showing that these tetraquarks are below the two heavy meson threshold, but respectively above the Upsilon pi pi and Upsilon K Kbar thresholds.

LaTex, 5 pages

References in corpus (2)

• Observation of a resonance-like structure in the pi^+- psi' mass distribution in exclusive B-->K pi^+- psi' decays
• Observation of anomalous Upsilon(1S)pi+pi- and Upsilon(2S)pi+pi- production near the Upsilon(5S) resonance

Cited by in corpus (15)

• Non-Standard Heavy Mesons and Baryons, an Experimental Review
• Exotics: Heavy Pentaquarks and Tetraquarks
• New Exotic Meson and Baryon Resonances from Doubly-Heavy Hadronic Molecules
• Observation of an enhancement in $e^{+}{e}^{-}\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$, ${\rm Y}(2S){\pi }^{+}{\pi }^{-}$, and ${\rm Y}(3S){\pi }^{+}{\pi }^{-}$ production around $\sqrt{s}=10.89$ GeV at Belle
• Observation of an enhancement in e+e- to Upsilon(1S)pi+pi-, Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- production near sqrt{s}=10.89 GeV at Belle
• $X(3872)$, $X_b$, and the ${\chi }_{b1}(3P)$ state
• Heavy quark spectroscopy and prediction of bottom baryon masses
• No Radial Excitations in Low Energy QCD. II. The Shrinking Radius of Hadrons
• Possible bound state of the double heavy meson-baryon system
• The doubly heavies: (Qbar Q qbar q), (Q Q qbar qbar) tetraquarks and (Q Q q) baryons
• Tetraquarks, their Masses and Decays in QED_2
• Doubly Heavy Tetraquarks and Baryons
• Heavy Baryons and Exotics Spectrum
• Hadron Spectroscopy Results from Belle
• Concluding Talk: A Theorist Overview on Particle Physics