Narrow Results

Based on the mass relation derived under the assumption that for the almost ideally mixing meson nonets, the corrections deduced by the flavor-dependent quarkonia transition can be ignored, the mass of the isodoublet of the 2 ¹S₀ nonet is predicted to be 1391.8±67.7 MeV. The quarkonia content of isoscalar states of the 2 ¹S₀ nonet, i.e. η(1295) and η(1475), is given, and some predictions on the decays of the two isoscalar state are presented. These predictions can be tested in Beijing Electron Positron Collider Bejing Spectrometers (BEPC/BES) with 58 million J/ψ events in the near future.

The production asymmetry of both π and ρ mesons in the reaction p↑p→hX is calculated in a two-component model in which hadrons are produced by a nonperturbative recombination process and by fragmentation of quarks in the final state. Thomas precession in the recombination mechanism seems to be responsible of the single spin asymmetry. We obtain a good description of experimental data. Predictions of single spin asymmetries for ρ production at RHIC energies are presented.

Employing three different and complementary approaches, chiral equal-splitting laws, Regge phenomenology and meson–meson mixing, we show that the mass of the isodoublet of the 2 ³S₁ meson nonet is in the range in 1530–1580 MeV.

We discuss possible realizations of the hypothesis that all the fundamental interactions of the elementary particles should be of gauge type, including the Yukawa and Higgs ones. In the minimal SUSY extension of the standard model, where the quartic Higgs couplings are "gauged" through the D-terms, it is also possible to generate radiatively the Yukawa matrices for the light generations, thus expressing them as functions of gauge couplings. The program can also be applied to the SUSY LR model, where the possibility to induce radiatively the mixing angles, can help to make viable the parity solution to the strong CP problem. The superpotential of the model still includes some non-gauge couplings, namely, the Yukawa constants for the third generation and the trilinear terms λχ_LΦχ_R and , involving the Higgs bi-doublet (Φ) and two pairs of doublets (χ_L, χ_R and their conjugates). Additional progress to relate these parameters to gauge couplings, can be made by embedding the LR model within a SUSY model SU(4)_W×U(1)_B-L in five dimensions, where the Higgs bi-doublet is identified as the extra component of the 5D gauge field.

In the framework of meson–meson mixing, in the presence of the a₄(2040), and f₄(2050) being the 1 ³F₄ states, we suggest that the f′₄, the ninth member of the 1 ³F₄ meson nonet, has a mass of about 2084 MeV, and some predictions on the f₄ and f′₄ decaying into two photons and pseudoscalar mesons are presented. Also, the mass of the lowest lying 4⁺⁺ glueball is predicted to be about 3.15 GeV by using the meson-glueball mass relation derived from the glueball dominance picture, which is in agreement with 3.42 GeV, the average value of the recent predicted results was given by lattice QCD, potential model, semi-relativistic potential model and quasi-particle model.

In this short review, the calculation of the next-to-next-to-leading order QCD corrections to the inclusive radiative decay is described. We summarize the salient features of the calculational framework adopted, discuss the results obtained in the last few years, and indicate the technical tools that made the NNLO calculations possible. We conclude by comparing the current NNLO theoretical estimate for the branching ratio with the experimental measurement and by briefly discussing the size and origin of the residual theoretical uncertainty.

The effect of quark mass on the Regge trajectory is analyzed. Modifications in the equations of Regge trajectories are shown for mesonic as well as baryonic systems. For mesonic systems, the Regge trajectories get modified, but still remain linear. Contrary to the mesonic case, the Regge trajectories for baryonic systems indicate nonlinearity. It is shown that in low mass and angular momentum region two hadrons with different quark compositions can have same mass and angular momentum.

Meson photoproduction was studied at the CEBAF Large Acceptance Spectrometer (CLAS) utilizing a 5.5 GeV/c photon beam incident on a hydrogen target. Here we report on the partial wave analyzes (PWA) performed on the exclusive final states π⁺π⁺π^-n and K⁺K^-π⁺n. In addition, CLAS has data on the final state π⁺π⁰π^-p which will be reported in the near future. The analysis of the π⁺π⁺π^- system shows clearly the a₂(1320), as well as evidence for the a₁(1260) and the π₂(1670). The π₁(1600), previously observed in π^-p interactions, is seen very weakly here. In the K⁺K^-π⁺n channel there is is evidence for the Θ⁺(1540) S=+1 baryon pentaquark. The PWA of this system gives an excellent description of the background which rules out mesonic reflection as a source of the signal.

We study the radiative ρ, ω and ϕ decay into π⁰π⁰γ and π⁰ηγ taking into account mechanisms in which there are two sequential vector-vector-pseudoscalar or axial-vector–vector–pseudoscalar steps followed by the coupling of a vector meson to the photon, considering the final state interaction of the two mesons. Other mechanisms in which two kaons are produced through the same sequential mechanisms or from vector meson decay into two kaons which undergo final state interaction leading to the final pair of pions or π⁰η, are also considered. The results of the parameter free theory, together with the theoretical uncertainties, are compared with the latest experimental results at Frascati and Novosibirsk.

Preliminary results on the beam asymmetry Σ for η and π⁰ photoproduction on the proton and the neutron in the deuteron in a quasi free kinematics regime have been obtained. Very preliminary results will be presented on the status of art of the GRAAL search for the two members of the exotic penta-quarks anti-decuplet, the P11 and the Θ⁺.

Relative branching fractions of decays (where h, h′ = K or π) and the direct CP asymmetry in the mode are measured with 179 ± 11 pb^-1 of data collected at using the CDF II detector at the Fermilab Tevatron collider. The first branching-fraction measurement of a meson to two pseudoscalars, , and a search for the baryon mode are also presented, in addition to branching-fraction limits on the rare channels , , and .

In this conference presentation I discuss CLEO-c opportunities in Dalitz plot analyzes with the data samples available now and projected by the end of CESR-c run. Using 281 pb^-1 of e⁺e^- collisions at mass of ψ(3770) we present results of the Dalitz plot analysis of D⁺ → π^-π⁺π⁺. Using the CLEO-c and CLEO III samples of 5 pb^-1, accrued at mass of ψ(2S), we study three body decays of χ_cJ produced in the radiative decay ψ(2S) → γχ_cJ, where J=0,1,2. A clear signal from at least one of χ_cJ is found in eight final states: π⁺π^-η, π⁺π^-η′, K⁺K^-π⁰, , ηK⁺K^-, , , and . For these modes we measured or set an upper limit on the branching fraction. A Dalitz plot analysis is performed on three modes χ_c1 → π⁺π^-η, K⁺K^-π⁰, and .

Latest experimental results, obtained from the ψ(2S) data, collected with the CLEO detector are reviewed.

The neglected 35 MeV/c² particle mass quantization hypothesis has recently been reassessed for all known meson states. The rule is found to be statistically relevant, once the states are grouped by quark composition and J^PC, with slightly different mass units for each group. In certain groups the mass unit is spin-dependent. Also the mass units are linearly quantized, with highly structured correlation patterns. The baryon masses are organized along similar lines. These results support an indication that hadrons might be shell-structured.

This is a summary of the MESON2008 workshop in Kraków. The original powerpoint summary with all the figures can be found on the conference webpage and in the proceedings of the original talks in this volume. These Proceedings of the summary will therefore not contain the original figures which can be looked up at the two locations mentioned.

Electroproduction of a ρ⁰ vector meson in the process γ* + N → V + N^′ is measured with a 27.6 GeV longitudinally polarized electron/positron beam in the HERMES experiment. Kinematical dependences of real and imaginary parts of the ratio of the helicity amplitudes are extracted from the data.

A relativistic power-law potential model of independent quarks is used to study the leptonic decays of neutral vector mesons. Here, the transition probability amplitude for leptonic decay of meson is determined from the momentum distribution function which is found from the assumption of a strong correlation existing between the momenta of quark and antiquark inside the meson. The model parameters are first determined from the application of the model to study the ground state spectra of ρ, ω, ϕ, ψ and ϒ mesons together with the radiative decay widths of mesons. The same model with no adjustable parameters is then used to evaluate the leptonic decay widths and the electromagnetic decay constants for the vector mesons ρ, ω, ϕ, ψ and ϒ. The calculated results are in remarkable agreement with the corresponding experimental values.

An independent quark model with a relativistic power-law potential is used to study the weak leptonic decays of light and heavy pseudoscalar mesons. The partial decay width and the decay constant for the weak leptonic decay are derived from the quark–antiquark momentum distribution amplitude which is obtained from the bound quark eigenfunction with the assumption of a strong correlation existing between quark–antiquark momenta inside the decaying meson in its rest frame. The model parameters are first determined from the application of the model to study the ground state hyperfine splitting of ρ, K, D, D_s, B, B_s and B_c mesons. The same model with no adjustable parameters is then used to evaluate the decay constants f_M and the decay widths of pseudoscalar mesons. The model predictions agree quite well with the available experimental data as well as with those of several other models. The decay constant for pion and kaon are obtained as f_π = 132 MeV and f_k = 161 MeV which closely agree with experimental values. But in case of heavier mesons for which experimental data are not yet available, the present model gives its predictions as f_BC > f_BS > f_B, f_DS > f_D, f_D > f_B and f_π > f_B which are in conformity with most of other model predictions. The model predictions of the corresponding decay widths and the branching ratios for the and decay modes are in close agreement with the available experimental data.

We have investigated the Regge trajectories of exotic hadrons by considering different possible pentaquark configurations with finite quark mass in the flux tube model. Significant deviation is observed in the linear behavior of the Regge trajectories for pentaquark systems in view of the universal value of the Regge slope parameter for hadrons. The modified Regge trajectories are also compared with the available experimental and lattice data. It is observed that the nonlinear Regge trajectories of such pentaquark systems can be well described by the relativistic corrections in view of the current quark masses and the high rotational speed of the quarks at the end of flux tube structure.

In this paper, we first derive two QCD sum rules QCDSR I and QCDSR II which are, respectively, used to extract observable quantities of the ground states and the first radially excited states of the D-wave vector $\rho$ and $\varphi$ mesons. In our calculations, we consider the contributions of vacuum condensates up to dimension-7 in the operator product expansion. The predicted masses for $1^3{D}_1$$\rho$ meson and $2^3{D}_1$$\varphi$ meson are consistent well with the experimental data of $\rho$($1700$) and $\varphi$($2170$), respectively. Besides, our analysis indicates that it is reliable to assign the recent reported $Y$($2040$) state as the $2^3{D}_1$$\rho$ meson. Finally, we obtain the decay constants of these states with QCDSR I and QCDSR II. These predictions are helpful not only to reveal the structure of the newly observed $Y$($2040$) state, but also to establish $\varphi$ meson and $\rho$ meson families.