Further study of double charmonium production in e+ e- annihilation at Belle

We report a new analysis of double charmonium production in e+ e- annihilation using a data sample collected by the Belle experiment. We confirm our previous observation of the processes e+ e- -> J/psi eta_c (chi_c0, eta_c(2S)) and perform an angular analysis for these processes. Processes of the type e+ e- -> psi(2S) (c cbar)_resonant are observed for the first time. We also observe a new charmonium state - X(3940), produced in the process e+ e- -> J/psi X(3940).Comment: Contributed to 32nd International Conference on High-Energy Physics (ICHEP 04), Beijing, China, 16-22 Aug 200

Charged charmonium-like Z+(4430) from rescattering in conventional B decays

In a previous paper we suggested an explanation for the peak designated as $Z(4430)^+$ in the $\psi^\prime\pi^+$ mass spectrum, observed by Belle in ${\bar{\!B}} \to {\psi^\prime} \pi^+ K$ decays, as an effect of $\bar{\!D}{}^{\,*0}D^{\,+} \to \psi^\prime\pi^+$ rescattering in the decays ${\bar{\!B}} \to {D_{s}^{\,\prime -}} {D}$, where the $D_{s}^{\,\prime -}$ is an as-yet unobserved radial excitation of the pseudoscalar ground state $D_{s}^{\,-}$-meson. In this paper, we demonstrate that this hypothesis provides an explanation of the double $Z^+$-like peaking structures, which were studied by LHCb with much higher statistics. While according to our hypothesis, the origin of the peaking structures is purely kinematical, reflecting the presence of a conventional resonance in the hidden intermediate state, the amplitude of the $Z(4430)^+$ peak carries a Breit-Wigner-like complex phase, arising from the intermediate $D_{s}^{\,\prime -}$ resonance. Thus, our hypothesis is entirely consistent with the recent LHCb measurement of the resonant-like amplitude behaviour of the $Z(4430)^+$. We perform a toy fit to the LHCb data, which illustrates that our approach is also consistent with all the observed structure in the LHCb $M({{\psi^\prime}\pi^+})$ spectrum. We suggest a critical test of our hypothesis that can be performed experimentally.Comment: 6 pages, 5 figure

Effect of nuclear interactions of neutral kaons on CP asymmetry measurements

We examine the effect of the difference in nuclear interactions of ${K}^0$ and $\bar{K}^0$ mesons on the measurement of CP asymmetry for experiments at $e^+e^-$ colliders - charm and $B$-meson factories. We find that this effect on CP asymmetry can be as large as 0.3%, and therefore sufficiently significant in interpreting measurements of CP asymmetry when neutral kaons are present in the final state.Comment: accepted to PR

Study of Scintillator Strip with Wavelength Shifting Fiber and Silicon Photomultiplier

The performance of the $200\times2.5\times1$ cm$^3$ plastic scintillator strip with wavelength shifting fiber read-out by two novel photodetectors called Silicon PhotoMultipliers (SiPMs) is discussed. The advantages of SiPM relative to the traditional multichannel photomultiplier are shown. Light yield and light attenuation measurements are presented. This technique can be used in muon or calorimeter systems.Comment: 9 pages, 5 figure

Charged charmonium-like states as rescattering effects in B -> D_sJ D^(*) decays

Using purely phenomenological approach we show that the peaking structures observed in the psi(2S) pi+ and chi_c1 pi+ mass spectra in B -> psi(2S)(chi_c1) pi+ K decays can be result of (D \bar{D}^(*))+ -> (ccbar)_res pi+ rescattering in the decays B -> D_sJ (-> \bar{D}(*) K) D(*). In particular, the position of the peak in the chain B -> D_s(2S) D+ -> K- \bar{D}*0 D+ -> K- psi(2S) pi+ coincides well with the measured Z(4430) mass, assuming the mass of D_s(2S) (the first radial excitation of D_s) to be 2610 MeV/c2. The widths of the Z(4430) peak is also well reproduced in this approach independent on the width of D_s(2S). Although the decay B -> D_s(2S) D+ has not been observed so far and even D_s(2S)-meson is not discovered yet, this decay is expected to be large, and the mass of D_s(2S) is predicted in the range (2600-2650)MeV/c2. The broad bump in chi_c1 pi+ spectrum can be attributed to the B -> D_s*(2S) D+ -> K- \bar{D}0 D+ decay observed with a large branching fraction followed by rescattering \bar{D}0 D^+ -> chi_c1 pi+.Comment: 4 pages, 3 figure

How Resonances can synchronise with Thresholds

The mechanism by which a threshold may capture a resonance is examined. It involves a threshold cusp interfering constructively with either or both (i) a resonance produced via confinement, (ii) attractive t- and u-channel exchanges. The fo(980), X(3872) and Z(4430) are studied in detail. The fo(980) provides a valuable model of the locking mechanism. The X(3872) is too narrow to be fitted by a cusp, and requires either a resonance or virtual state. The Z(4430) can be fitted as a resonance but also can be fitted successfully by a cusp with no nearby resonant pole.Comment: 19 pages, 6 figures. Replaces 0709.125