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Dynamics of hadro-quarkonium system is formulated, based on the channel coupling of a light hadron ( h) and heavy quarkonium $$\left( {Q\bar Q} \right)$$ to heavy-light mesons ( $$Q_{\bar q}$$ , $$\bar Q_q$$ ). Equations for hadro-quarkonium amplitudes and resonance positions are written explicitly, and numerically calculated for the special case of πϒ( nS) ( n = 1, 2, 3). It is also shown that the recently observed by Belle two peaks Zb(10610) and Zb(10650) are in agreement with the proposed theory. It is demonstrated that theory predicts peaks at the BB*, B* B* thresholds in all available πϒ( nS) channels. [ABSTRACT FROM AUTHOR]

Hyperfine splittings (HFS) are calculated within the Field Correlator Method, taking into account relativistic corrections. The HFS in bottomonium and the B ( q = n, s) mesons are shown to be in full agreement with experiment if a universal coupling α = 0.310 is taken in perturbative spinspin potential. It gives M( B*) − M( B) = 45.7(3) MeV, M( B ) − M( B) = 46.7(3) MeV ( n = 4), while in bottomonium Δ( b % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXgatC % vAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDharyavP1wz % ZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbb % L8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpe % pae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaam % aaeaqbaaGcbaGafmOyaiMbaebaaaa!3C30! $$ \bar b $$) = M(Υ(9460)) − M( η(1 S)) = 63.4 MeV for n = 4 and 71.1 MeV for n = 5 are obtained; just the latter agrees with recent BaBar data. For unobserved excited states we predict M(Υ(2 S))− M( η(2 S)) = 36(2)MeV, M(Υ(3 S))− M( η(3 S)) = 28(2)MeV, and also M( B) = 6334(4) MeV, M( B(2 S)) = 6868(4) MeV, M( B (2 S)) = 6905(4) MeV. The mass splittings between D(2 S) − D(2 S), D(2 S) − D(2 S) are predicted to be ∼75 MeV, which are significantly smaller than in several other studies but agree with the mass splitting between recently observed D(2533) and D*(2610). [ABSTRACT FROM AUTHOR]

The dielectron widths of Y( nS)( n = 1, ..., 7) and vector decay constants are calculated using the relativistic string Hamiltonian with a universal interaction. For Y( nS) ( n = 1, 2, 3) the dielectron widths and their ratios are obtained in full agreement with the latest CLEO data. For Y(10580) and Y(11020) a good agreement with experiment is reached only if the 4 S-3 D mixing (with a mixing angle θ = 27°± 4°) and 6 S-5 D mixing (with θ = 40°±5°) are taken into account. The possibility to observe higher “mixed D-wave” resonances, $$ \tilde \Upsilon $$( n3 D1) with n = 3, 4, 5 is discussed. In particular, $$ \tilde \Upsilon $$(≈11120), originating from the pure 53 D1 state, can acquire a rather large dielectron width, ∼130 eV, so that this resonance may become manifest in the e+ e− experiments. On the contrary, the widths of pure D-wave states are very small, Γ ee( n3 D1)≤ 2 eV. [ABSTRACT FROM AUTHOR]

A new measurement of the rare, doubly radiative decay η → π0γγ was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Γ(η → π0γγ), on the two-photon invariant-mass squared, m²(γγ), as well as a new, more precise value for the decay width, Γ(η → π0γγ) = (0.33 ± 0.03tot) eV, are based on analysis of 1.2 × 10³η → π0γγ decays from a total of 6 × 107η mesons produced in the γp → ηp reaction. The present results for dΓ(η → π0γγ)/dm²(γγ) are in good agreement with previous measurements and recent theoretical calculations for this dependence. [ABSTRACT FROM AUTHOR]