arXiv subjects

A. V. Anisovich

Publications and source records attributed to A. V. Anisovich.

104 records · Page 6Linked to original sources

arXiv2001

Radiative decays of basic scalar, vector and tensor mesons and the determination of the P-wave q\bar q multiplet

We perform simultaneous calculations of the radiative decays of scalar mesons f_0(980)-> γγ, a_0(980)-> γγ, vector meson ϕ(1020)-> γf_0(980), γa_0(980), γπ^0, γη, γη' and tensor mesons a_2(1320)-> γγ, f_2(1270)-> γγ, f_2(1525)-> γγassuming all these states to be dominantly the q\bar q ones. A good description of the considered radiative decays is reached by using almost the same radial wave functions for scalar and tensor mesons that supports the idea for the f_0(980), a_0(980) and a_2(1320), f_2(1270), f_2(1525) to belong to the same P -wave q\bar q multiplet.

hep-ph↗

arXiv2001

Quark/gluon content of eta(1295) and eta(1440)

The quark/gluon content of eta(1295) and eta(1440) mesons is discussed, mesons being considered as members of the first radial excitation 2^1S_0 qqbar nonet. Recent results on eta(1295) and eta(1440) two-photon widths from L3 together with the information on radiative J/Psi decay allow one to evaluate the eta(1295)/eta(1440) mixing angle and the admixture of the glueball component. We found that eta(1440) is dominantly non-strange qqbar state, with a possible admixture of the glueball component (20 pm 20)%.

hep-ph↗

arXiv2001

Quark structure of f0(980) from the radiative decays phi(1020)->gamma f0(980), gamma eta, gamma eta', gamma pi0 and f0(980)->gamma gamma

Partial widths of the radiative decays $ϕ(1020)\toγf_0(980)$, $γη$, $γη'$, $γπ^0$ and $f_0(980)\toγγ$ are calculated assuming all mesons under consideration to be $q\bar q$ states: $ϕ(1020)$ is dominantly an $s\bar s$ state ($n\bar n$ component $\lesssim 1%$), $η$, $η'$ and $π^0$ are standard $q\bar q$ states, $η= n\bar n\cosθ- s\bar s\sinθ$ and $η'=n\bar n\sinθ+ s\bar s\cosθ$ with $θ\simeq 37^\circ$, and $f_0(980)$ is the $q\bar q$ meson with the flavour wave function $n\bar n\cosϕ+ s\bar s \sinϕ$. Calculated partial widths for the decays $ϕ\toγη$, $γη'$, $γπ^0$ are in a reasonable agreement with experiment. The measured value of the branching ratio $BR(ϕ\toγf_0(980))$ requires $25^\circ\le |ϕ|\le 90^\circ$; for the decay $f_0(980)\toγγ$ the agreement with data is reached at either $77^\circ\leϕ\le 93^\circ$ or $(-54^\circ)\leϕ\le (-38^\circ)$. Simultaneous analysis of the decays $ϕ(1020)\toγf_0(980)$ and $f_0(980)\toγγ$ provides arguments in favour of the solution with negative mixing angle $ϕ=-48^\circ\pm 6^\circ$.

hep-ph↗

arXiv2000

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'.

hep-ph↗

arXiv1999

Low- and intermediate-energy nucleon-nucleon interactions and the analysis of deuteron photodisintegration within the dispersion relation technique

The nucleon-nucleon interaction in the region of the nucleon kinetic energy up to 1000 MeV is analysed together with the reaction $γd \to pn$ in the photon energy range $E_γ=0-400$ MeV. Nine nucleon-nucleon $s$-channel partial amplitudes are reconstructed in the dispersion relation $N/D$ method: $^1S_0$, $^3S_1-^3D_1$, $^3P_0$, $^1P_1$, $^3P_1$, $^3P_2$, $^1D_2$, $^3D_2$ and $^3F_3$. Correspondingly, the dispersive representation of partial amplitudes $NΔ\to pn$, $NN^* \to pn$ and $NNπ\to pn$ is given. Basing on that, we have performed parameter-free calculation of the amplitude $γd \to pn$, taking into account: $(i)$ pole diagram, $(ii)$ nucleon-nucleon final-state rescattering $γd \to pn \to pn$, and $(iii)$ inelastic final-state rescatterings $γd \to NΔ(1232) \to pn$, $γd \to NN^*(1400) \to pn$ and $γd \to NNπ\to pn$. The $γd \to pn$ partial amplitudes for nine above-mentioned channels are found. It is shown that the process $γd \to pn \to pn$ is significant for the waves $^1S_0$, $^3P_0$, $^3P_1$, at $E_γ =50 -100$ MeV, while $γd \to NΔ\to pn$ for the waves $^3P_2$, $^1D_2$,$^3F_3$ dominates at $E_γ > 300$ MeV. Meson exchange current contributions into the deuteron disintegration are estimated: they are significant at $E_γ=100-400$ MeV.

nucl-th↗

arXiv1999

Partial widths for the decays eta(1295) -> gamma gamma and eta(1440) -> gamma gamma

We discuss gamma gamma partial widths of pseudoscalar/isoscalar mesons eta(M) in the mass region M = 1000-1500 MeV. The transition amplitudes eta(1295) -> gamma gamma and eta(1440) -> gamma gamma are studied within an assumption that the decaying mesons are the members of the first radial excitation nonet 2^1S_0 q\bar q. The calculations show that partial widths being of the order of 0.1 keV are dominantly due to the n\bar n meson component while the contribution of the s\bar s component is small.

hep-ph↗

arXiv1999

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 $γγ\toπ^0π^0$, $γγ\toπ^+π^-$, $γγ\to K^0\bar K^0$ and $γγ\to K^+ K^-$ on the basis of: (i) the results of the $K$-matrix analysis of the $00^{++}$ amplitudes for the reactions $ππ\to ππ$, $K\bar K$, $ηη$, $ηη'$, $ππππ$, and (ii) recently developed method for calculation of the decay amplitudes $f_0(1^3P_0q\bar q)\to γγ$, $f_0(2^3P_0q\bar q)\to γγ$. The reconstructed $ππ$ and $K\bar K$ spectra can be used as a guide for the extraction of partial widths of scalar/isoscalar resonances $f_0(980)\to γγ$, $f_0(1300)\to γγ$, $f_0(1500)\to γγ$, $f_0(1750)\to γγ$. As follows from our calculations, the resonances $f_0(980)$ and $f_0(1500)$ in the $π^+π^-$ and $π^0π^0$ spectra reveal themselves as dips.

hep-ph↗

arXiv1999

Partial widths a_0(980)\toγγ, f_0(980)\toγγand q\bar q-classification of the lightest scalar mesons

We calculate partial widths for the decays a_0(980)\toγγand f_0(980)\toγγunder 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 γγpartial widths for the other scalar mesons, members of the 2^3P_0 q\bar q nonet.

hep-ph↗

arXiv1997

K-matrix analysis of the K-pi S-wave in the mass region 900-2100 Mev and nonet classification of scalar qqbar-states

A K-matrix re-analysis of the K-pi S-wave is performed in the mass region 900-2100 MeV, and solutions which describe the data well are found. The solution with two resonances in the (IJ^P=1/2 0^+)-wave has poles at (1415 pm 25)- i(165 pm 25) MeV and (1820 pm 40) -i(125 pm 50) MeV, close to the previous result of D. Aston et al., Nucl.Phys., B296 (1988) 493. The corresponding bare states, which are the subjects of a qqbar classification, are: K_0^{bare}(1220^{+50}_{-60}) and K_0^{bare}(1885^{+50}_{-80}). Within the restored bare states, a construction of the 1^3P_0 qqbar and 2^3P_0 qqbar nonets is completed. The three resonance solutions are analysed as well, the corresponding bare states are found, and the qqbar-nonet classification is suggested. In all variants of our qqbar-classification, the resonances a_0(980) and f_0(980) (or their bare counterparts) are non-exotic, and an extra scalar/isoscalar state exists in the mass region 1300-1700 MeV, being a good candidate for the lightest scalar glueball.

hep-ph↗

arXiv1997

Scalar glueball: analysis of the (IJ^{PC}=00^{++})-wave

Basing on the previously performed K-matrix analysis of experimental data, we investigate, in the framework of the propagator matrix (D-matrix) technique, the 1100-1900 MeV mass region, where overlapping resonances $f_0(1300)$, $f_0(1500)$, $f_0(1530^{+90}_{-250})$, and $f_0(1780)$ are located. Necessary elements of the D-matrix technique are developed. The D-matrix analysis confirms previous K-matrix results: in the region 900-1900 MeV five scalar/isoscalar states are located. Four of them are members of the two $q\bar q$-nonets, while one state is an extra for the $q\bar q$ systematics, being a good candidate for the lightest scalar glueball. The D-matrix analysis shows that this extra state, a candidate for the lightest scalar glueball, is dispersed, due to a mixing with $q\bar q$- states, over three resonances: $f_0(1300)$, $f_0(1500)$, and $f_0(1530^{+90}_{-250})$. The broad resonance $f_0(1530^+{90}_{-250})$ is a descendant of the lightest glueball carrying about 50% of the gluonium component, the rest of the gluonium is shared between $f_0(1300)$ and $f_0(1500)$.

hep-ph↗

arXiv1996

$0^{++}$-Glueball/$q \bar q$-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.

hep-ph↗

arXiv1996

Three-body dispersion-relation N/D equations for the coupled decay channels ppbar (J^{PC}=0^{-+}) --> pi^0 pi^0 pi^0, eta pi^0 pi^0, eta eta pi^0, K Kbar pi^0

During several years the data on different channels ppbar (J^{PC}=0^{-+}) --> 3 mesons presented by Crystal Barrel Collaboration were successfully analyzed by extracting the leading amplitude singularities - pole singularities - with the aim to obtain information about two-meson resonances. But these analyses do not take into account three-body final state interactions (FSI) in an explicitly correct way. This paper is devoted to the consideration of this problem.

hep-ph↗

arXiv1996

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 $π^-p\toπ^0π^0n$, $ηηn$, $ηη'n$; CERN-Münich data for $π^-p\toπ^+π^-n$; Crystal Barrel data for $p\bar p\toπ^0π^0π^0$, $π^0π^0η$, $π^0ηη$; BNL data for $ππ\to K\overline K$. 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.

hep-ph↗

arXiv1996

Dispersive analysis of the decay eta -> 3 pi

We demonstrate that the decay eta -> 3 pi represents a sensitive probe for the breaking of chiral symmetry by the quark masses. The transition amplitude is proportional to the mass ratio (m_d^2-m_u^2)/(m_s^2-m^2). The factor of proportionality is calculated by means of dispersion relations, using chiral perturbation theory to determine the subtraction constants. The theoretical uncertainties in the result are shown to be remarkably small, so that eta-decay may be used to accurately measure this ratio of quark masses.

hep-ph↗