Chiral symmetry breaking and meson decays in a relativistic quark model

Applying two different Lorentz-covariant quark models, one of them being essentially nonrelativistic, chiral symmetry breaking parameters of strong interaction will be calculated. Also attention will be paid to meson decays. The model retaining relativistic spinor structure for quark-antiquark wave functions turns out to be more appropriate than the nonrelativistic one.     

Double charmonium production in exclusive bottomonium decays

Exclusive bottomonium decays leading to the production of charmonium pairs are considered. The respective decay widths are calculatedwithin the approach of line-cone expansion for the amplitude and nonrelativistic QCD. It is shown that the production of L _z ≠ 0 P-wave charmonium states is possible even in the leading-twist approximation. This means a violation of selection rules that require the suppression of such decays. The reason for this violation is discussed in detail.     

Flavor symmetry in two body decays of bottom mesons

Dominant decays of bottom mesons into two pseudoscalars are studied in the framework of the six-quark model of the weak interactions of Kobayashi and Maskawa. Some simpleSU (3) relations between the amplitudes are obtained without using any dynamical assumptions.     

The OZI rule violating radiative decays of the heavy pseudoscalars

In lowest order of QCD, the rates for radiative transitions violating the OZI rule of heavy pseudoscalars are found to be extremely small. The η_c→ γ + ?, ω, ? width is predicted two orders of magnitude below present experimental bounds on X(2.8) → γ+π⁺π^?. As a by product, we get for the 4_γ parapositronium decay width Γ=m_eα⁷ · 1.352 X 10^?2.     

Momentum-dependent effects in the decays of charmonium and upsilon

Decay widths of quarkonia are determined in a calculation in which the momentum distribution resulting from the localization of the quarks is taken into account. The e⁺e⁻ decay modes of charmonium and upsilon are considered with the momentum-dependent corrections to the well-known van Royen-Weisskopf formula for leptonic widths. The momentum-dependent effects are found to be significant, and amount to approximately a 20% correction. The γη(1440) decay mode is also examined to investigate a decay involving a propagating quark in the bound state. Here the momentum-dependent corrections to the static approximation are very large and suppress the decay widths by well over a factor of 3. Therefore one must exercise caution in using a static approximation.     

Isgur-Wise function in B_c decays to charmonium with the Bethe-Salpeter method

The heavy quark effective theory vastly reduces the weak-decay form factors of hadrons containing one heavy quark. Many works attempt to directly apply this theory to hadrons with multiple heavy quarks. In this paper,we examine this confusing application by the instantaneous Bethe-Salpeter method from a phenomenological perspective, and give the numerical results for Bc decays to charmonium where the final states include 1S, 1P, 2S, and 2P. Our results indicate that the form factors parameterized by a single Isgur-Wise function deviate substantially from the full ones, especially when excited states are involved. The relativistic corrections(1/mQcorrections) require the introduction of more non-perturbative universal functions, similar to the Isgur-Wise function, which are the overlapping integrals of the wave functions with the relative momentum between the quark and antiquark.     

The effects of configuration mixing on excited charmonium decays

Configuration mixing betwenn ψ, ψ′ and ψ″ is considered in two models. In one model the confining potential consists of a scalar and a vector part; in the other model the vector confining potential interacts with a colour anomalous magnetic moment. It is shown that strong configuration mixing affects theEl transition rate and electronic decay widths of the vector mesons considerably.     

Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium

We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/psi, psi(2S) and chi(c1), and the light meson is either K or K(*). We use a sample of about 124x10(6) BB pairs collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.     

Some topics on charmonium decays at BESⅢ experiment

The construction of BESⅢ detector has been finished and the data taking is under plan. Some physics topics on charmonium decays at BESⅢ experiment are discussed in this paper. The measurement of properties of ηc and η'c at BESⅢ is discussed and the expected precision of the measurement is estimated based on BOSS. Also the XcJ decay and the measurement of hyperon decay parameters are mentioned.