Systematics of q anti-q states in the (n,M^2) and (J,M^2) planes

In the mass region up to M < 2400 MeV we systematise mesons on the plots (n,M^2) and (J,M^2), thus setting their classification in terms of n^{2S+1}L_J q anti-q states. The trajectories on the (n,M^2)-plots are drawn for the following (IJ^{PC})-states: a_0(10^{++}), a_1(11^{++}), a_2(12^{++}), a_3(13^{++}), a_4(14^{++}), pi(10^{-+}), pi_2(12^{-+}), eta(00^{-+}), eta_2(02^{-+})$, rho(11^{--}), f_0(00^{++}), f_2(02^{++}). All trajectories are linear, with nearly the same slopes. At the (J,M^2)-plot we set out meson states for leading and daughter trajectories: for pi, rho, a_1, a_2 and P'.Comment: 6 pages, LaTeX, 16 EPS figures, epsfig.st

Reactions gamma gamma -> pi pi and gamma gamma -> K \bar K: the (IJ^{PC}=00^{++})-wave spectra at E_{gamma gamma}^{(c.m.)} = 300- 1900 MeV

We calculate the $00^{++}$-wave two-meson spectra for the reactions $\gamma\gamma\to\pi^0\pi^0$, $\gamma\gamma\to\pi^+\pi^-$, $\gamma\gamma\to K^0\bar K^0$ and $\gamma\gamma\to K^+ K^-$ on the basis of: (i) the results of the $K$-matrix analysis of the $00^{++}$ amplitudes for the reactions $\pi\pi \to \pi\pi$, $K\bar K$, $\eta\eta$, $\eta\eta'$, $\pi\pi\pi\pi$, and (ii) recently developed method for calculation of the decay amplitudes $f_0(1^3P_0q\bar q)\to \gamma\gamma$, $f_0(2^3P_0q\bar q)\to \gamma\gamma$. The reconstructed $\pi\pi$ and $K\bar K$ spectra can be used as a guide for the extraction of partial widths of scalar/isoscalar resonances $f_0(980)\to \gamma\gamma$, $f_0(1300)\to \gamma\gamma$, $f_0(1500)\to \gamma\gamma$, $f_0(1750)\to \gamma\gamma$. As follows from our calculations, the resonances $f_0(980)$ and $f_0(1500)$ in the $\pi^+\pi^-$ and $\pi^0\pi^0$ spectra reveal themselves as dips.Comment: 13 pages, LaTeX, elsart + 7 EPS figures, epsfig.st

Resonance f0(1500)f_0(1500): Is it a scalar glueball ?

The ratios of partial widths for the decay of a glueball into two pseudoscalar mesons are calculated under the assumption that the production of light quark pairs ($u\bar u,d\bar d,s\bar s$) in soft gluon-\-induced reactions goes on within universal symmetry breaking. Parameter of the violation of flavour symmetry is fixed by the central hadron production data in high energy hadron collisions and/or by the ratios of radiative decay amplitudes $J/\Psi \to \gamma\eta/\gamma\eta'$ and $J/\Psi \to \gamma \phi \phi/\gamma \omega \omega$. The ratios of coupling constants $glueball\to\pi\pi,K\bar K, \eta\eta,\eta\eta'$ which are calculated with this parameter coincide reasonably with those of $f_0(1500)$, supporting an idea about glueball nature of $f_0(1500)$.Comment: LaTex, 8 pages, 2 .eps figures in one uuencoded file, uses epsfi

Partial widths a_0(980)\to\gamma\gamma, f_0(980)\to\gamma\gamma and q\bar q-classification of the lightest scalar mesons

We calculate partial widths for the decays a_0(980)\to\gamma\gamma and f_0(980)\to\gamma\gamma under the assumption that a_0(980) and f_0(980) are members of the basic 1^3P_0 q\bar q nonet. The results are in a reasonable agreement with data thus giving an argument for a q\bar q origin of these mesons. We also calculate the \gamma\gamma partial widths for the other scalar mesons, members of the 2^3P_0 q\bar q nonet.Comment: 9 pages, LaTeX, 5 EPS figures, epsfig.st

Nonet Classification of Scalar/Isoscalar Resonances in the Mass Region below 1900 MeV: Observation of the Lightest Scalar Glueball

We summarize the results of the investigation of the $IJ^{PC}=00^{++}$ wave which is devoted to the search for the lightest scalar glueball. In the framework of the K-matrix formalism, the $q\bar q$-nonet classification of the scalar/isoscalar states is performed in the mass region below 1900 MeV basing on the following data: GAMS data for $\pi^-p\to\pi^0\pi^0n$, $\eta\eta n$, $\eta\eta'n$; CERN-M\"unich data for $\pi^-p\to\pi^+\pi^-n$; Crystal Barrel data for $p\bar p\to\pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$, $\pi^0\eta\eta$; BNL data for $\pi\pi\to K\overline K$. It is shown the existence of an extra state for $q\bar q$ classification: this state is a good candidate for the lightest scalar glueball. Analysis of the glueball/$q\bar q$ mixing shows that the glueball state has mainly dispersed over three real resonances: $f_0(1300)$, $f_0(1500)$ and $f_0(1530^{+90}_{-250})$. The broad resonance with complex mass $m=1530^{+90}_{-250}-i(560\pm 140)$ MeV is descendant of the pure glueball. The restored mass of the pure glueball is equal to 1695 MeV. This value agrees well with the results of lattice gluodynamics.Comment: LaTex, 5 pages and 7 figures. Talk given by V.V.Anisovich at LEAP96, Dinkelsbuhl, German

K-Matrix Analysis of the (IJPC=00++{IJ}^{PC}=00^{++}) Amplitude in the Mass Region up to 1550 MeV

K-matrix analysis of the $00^{++}$ wave is performed in the channels $\pi\pi,~K\bar K,~\eta\eta$ and $4\pi$ in the mass region up to 1550 MeV. The fit is based on the following data: $p\bar p ~(at~rest)\to \pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta,~\pi^0\eta\eta$ [1,2], $\pi N\to \pi\pi N$ [3,4], $\pi N\to K\bar K N$ [5] and the inelastic cross section of the $\pi\pi$ interaction [6]. Simultaneous analysis of these data confirms the existence of the scalar resonances: $f_0(980),~f_0(1300)$ and $f_0(1500)$, the poles of the amplitude being at the following complex masses (in MeV): $(1008\pm 10)- i(43\pm 5)$, $(1290\pm 25)-i(120\pm 15)$, and $(1497\pm 6)-i(61\pm 5)$. The fourth pole has sunk deeply into the complex plane: $(1430 \pm 150) - i(600\pm 100)$. Positions of the K-matrix poles (which are referred to the masses of bare states) are at $750\pm 120$ MeV, $1240\pm 30$ MeV, $1280\pm 30$ MeV and $1615\pm 40$ MeV. Coupling constants of the K-matrix poles to the $\pi\pi$, $\eta\eta$ and $K\bar K$ channels are found that allow us to analyze the quark and gluonic content of bare states. It is shown that $f_0^{bare}(1240)$ and $f_0^{bare}(1615)$ (which are strongly related to $f_0(1500)$) can be considered as good candidates for scalar glueball.Comment: 19 pages, LATEX, 6 figures in one uu-fil

The light sigma meson

In the framework of the dispersion relation N/D-approach, we restore the low-energy pi-pi (IJ^{PC}=00^{++})-wave amplitude sewing it with the previously obtained K-matrix solution for the region 450-1900 MeV. The restored N/D-amplitude has a pole on the second sheet of the complex-s plane near the pi-pi threshold, that is the light sigma meson.Comment: 5 pages, LaTeX, 3 EPS figures, epsfig.st

Nucleon participants or quark participants?

We show that centrality dependence of charged particle pseudorapidity density at midrapidity in Au+Au collisions at RHIC is well described as proportional to We show that centrality dependence of charged particle pseudorapidity density at midrapidity in Au+Au collisions at RHIC is well described as proportional to the number of participating constituent quarks. In this approach there is no need for an additional contribution from hard processes usually considered in the models based on the number of the nucleon participants.Comment: 3 pages, 4 figures, latex, version accepted for publication in Phys.Rev.

0++0^{++}-Glueball/qqˉq \bar q-State Mixing in the Mass Region near 1500 MeV

Basing on the results of the K-matrix fit of $(IJ^{PC}=00^{++})$ wave, we analyze the analytic structure of the amplitude and $q \bar q$/glueball content of resonances in the mass region 1200-1900 MeV, where an extra state for $q \bar q$-systematics exists being a good candidate for the lightest scalar glueball. Our analysis shows that the pure glueball state dispersed over three resonances: $f_0(1300)$, $f_0(1500)$ and $f_0(1530^{+90}_{-250})$, while the glueball admixture in $f_0(1750)$ is small. The broad resonance $f_0(1530^{+90}_{-250})$ is the descendant of the lightest pure glueball. The mass of pure glueball is $1630\pm {70\atop 30}$ MeV, in agreement with Lattice calculation results.Comment: LaTex, 12 pages, 2 figure

Partial wave analysiss of pbar-p -> piminus-piplus, pizero-pizero, eta-eta and eta-etaprime

A partial wave analysis is presented of Crystal Barrel data on pbar-p -> pizero-pizero, eta-eta and eta-etaprime from 600 to 1940 MeV/c, combined with earlier data on d\sigma /d\Omega and P for pbar-p->piminus-piplus. The following s-channel I=0 resonances are identified: (i) J^{PC} = 5^{--} with mass and width (M,\Gamma) at (2295+-30,235^{+65}_{-40}) MeV, (ii) J^{PC} = 4^{++} at (2020+-12, 170+-15) MeV and (2300+-25, 270+-50) MeV, (iii) 3D3 JPC = 3^{--} at (1960+-15, 150+-25) MeV and (2210+-4$, 360+-55) MeV, and a 3G3 state at (2300 ^{+50}_{-80}, 340+-150) MeV, (iv) JPC = 2^{++} at (1910+-30, 260+-40) MeV, (2020+-30, 275+-35) MeV, (2230+-30, 245+-45) MeV, and (2300+-35, 290+-50) MeV, (v) JPC = 1^{--} at (2005+-40, 275+-75) MeV, and (2165+-40, 160 ^{+140}_{-70}) MeV, and (vi) JPC = 0^{++} at (2005+-30, 305+-50) MeV, (2105+-15, 200+-25) MeV, and (2320+-30, 175+-45) MeV. In addition, there is a less well defined 6^{++} resonance at 2485+-40 MeV, with Gamma = 410+-90 MeV. For every JP, almost all these resonances lie on well defined linear trajectories of mass squared v. excitation number. The slope is 1.10+-0.03 Gev^2 per excitation. The f_0(2105) has strong coupling to eta-\eta, but much weaker coupling to pizero-pizero. Its flavour mixing angle between q-qbar and s-sbar is (59-71.6)deg, i.e. dominant decays to s-sbar. Such decays and its strong production in pbar-p interactions strongly suggest exotic character.Comment: Makes available the combined fit to Crystal Barrel data on pbar-p -> 2-body final states. 29 pages, 11 figures. Typo corrected in version