1,418 research outputs found
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
in the mass spectrum, observed by Belle in
decays, as an effect of
rescattering in the decays
, where the is
an as-yet unobserved radial excitation of the pseudoscalar ground state
-meson. In this paper, we demonstrate that this hypothesis
provides an explanation of the double -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 peak carries a Breit-Wigner-like complex phase,
arising from the intermediate resonance. Thus, our
hypothesis is entirely consistent with the recent LHCb measurement of the
resonant-like amplitude behaviour of the . 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 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
and mesons on the measurement of CP asymmetry for experiments at
colliders - charm and -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 cm 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
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