Searcharxiv⌕ Search

arXiv subjects

Yu. S. Surovtsev

Publications and source records attributed to Yu. S. Surovtsev.

At least 19 recordsLinked to original sources
arXiv2016

Effect of the $ηη$ channel and interference phenomena in the two-pion transitions of charmonia and bottomonia

The basic shape of di-pion mass spectra in the two-pion transitions of both charmonia and bottomonia states is explained by an unified mechanism based on contributions of the $ππ$, $K\overline{K}$ and $ηη$ coupled channels including their interference. The role of the individual $f_0$ resonances in shaping the di-pion mass distributions in the charmonia and bottomonia decays is considered.

hep-ph↗
arXiv2015

Effect of coupled channels of the multi-channel pion-pion scattering in two-pion transitions of the $Υ$ mesons

The effect of isoscalar S-wave processes $ππ\toππ,K\overline{K},ηη$ is considered in the analysis of data (from the ARGUS, CLEO, CUSB, Crystal Ball, Belle, BABAR collaborations) on the bottomonia decays --- $Υ(mS)\toΥ(nS)ππ$ ($m>n, m=2,3,4,5, n=1,2,3$). It is shown that the dipion mass spectra of these decays are explained by the unified mechanism related to the contribution of the multichannel $ππ$ scattering in the final states of these reactions. Since in the analysis the multichannel $ππ$-scattering amplitudes did not change in comparison with the ones in our combined analysis of data on the multichannel $ππ$ scattering and on the charmonia decays --- $J/ψ\toϕ(ππ, K\overline{K})$ and $ψ(2S)\to J/ψ(ππ)$ (from the Crystal Ball, DM2, Mark II, Mark III, and BES II) --- the results confirm all our earlier conclusions on the scalar mesons.

hep-ph↗
arXiv2014

The effect of multi-channel pion-pion scattering in decays of the $Υ$-family mesons

The effect of isoscalar S-wave multi-channel pion-pion scattering ($ππ\toππ,K\bar{K},ηη$) is considered in the analysis of data on decays of the $Υ$-meson family -- $Υ(2S)\toΥ(1S)ππ$, $Υ(3S)\toΥ(1S)ππ$ and $Υ(3S)\toΥ(2S)ππ$. The analysis, which aims at studying the scalar mesons, is performed jointly considering the multi-channel pion-pion scattering, which is described in our model-independent approach based on analyticity and unitarity and using an uniformizing variable method, and the charmonium decay processes $J/ψ\toϕ(ππ, K\bar{K})$, $ψ(2S)\to J/ψ(ππ)$. Results of the analysis confirm all our earlier conclusions on the scalar mesons. It is also shown that in the final states of the $Υ$-meson family decays (except for the $ππ$ scattering) the contribution of the coupled processes, e.g., $K\bar{K}\toππ$, is important even if these processes are energetically forbidden. This is in accordance with our previous conclusions on the wide resonances: If a wide resonance cannot decay into a channel which opens above its mass but the resonance is strongly connected with this channel (e.g. the $f_0(500)$ and the $K\bar}$ channel), one should consider this resonance as a multi-channel state with allowing for the indicated channel taking into account the Riemann-surface sheets related to the threshold branch-point of this channel and performing the combined analysis of the considered and coupled channels.

hep-ph↗
arXiv2014

Parameters of scalar resonances from the combined analysis of data on processes $ππ\toππ,K\bar{K},ηη$ and $J/ψ$ decays

A combined analysis of data on isoscalar S-wave processes $ππ\toππ,K\overline{K},ηη$ and on decays $J/ψ\toϕππ,ϕK\overline{K}$ from the DM2, Mark III and BESIII collaborations is performed to study $f_0$ mesons. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. In the analysis limited only to the multi-channel $ππ$-scattering data, two possible sets of parameters of the $f_0(500)$ were found: in both cases the mass was about 700 MeV but the total width was either about 600 or 930 MeV. The extension of the analysis using only the DM2 and Mark III data on the $J/ψ$ decays does not allow to choose between these sets. However, the data from BESIII on the di-pion mass distribution in the decay $J/ψ\toϕπ^+π^-$ clearly prefers the wider $f_0(500)$ state. Spectroscopic implications from results of the analysis are also discussed.

hep-ph↗
arXiv2012

Can parameters of f_0-mesons be determined correctly analyzing only pion-pion scattering?

The coupled processes -- the pion-pion scattering and pi pi --> K antiK in the I^GJ^{PC}=0^+0^{++} channel -- are analyzed (both separately and combined) in a model-independent approach based on analyticity and unitarity and using a uniformization procedure. It is shown: 1) a structure of the Riemann surface of the S-matrix for considered coupled processes must be allowed for calculating both amplitudes and resonance parameters, such as the mass and width; 2) the combined analysis of coupled processes is needed as the analysis of only pi-pi channel does not give correct values of resonance parameters even if the Riemann surface structure is included.

hep-ph↗
arXiv2011

The $f_2$- and $ρ_3$-mesons in multi-channel pion-pion scattering

In a multi-channel $S$-matrix approach, data on $ππ\toππ,K\bar{K},ηη$ in the $I^GJ^{PC}=0^+2^{++}$ sector and $ππ$ scattering in the $1^+3^{--}$ sector are analyzed to study the $f_2$- and $ρ_3$-mesons, respectively. Spectroscopic implications and possible classification of the $f_2$-states in terms of the SU(3) multiplets are also discussed.

hep-ph↗
arXiv2008

Rho-Like Mesons from Analysis of the Pion-Pion Scattering

Considering analyticity, unitarity and an influence of coupled channels, experimental data on the isovector P-wave of pion-pion scattering was analyzed to study rho-like mesons below 1900 MeV. The analysis indicates evidently that in the energy range 1200--1800 MeV, there are three rho-like mesons: rho(1250), rho(1450) and rho(1600), unlike the PDG tables. The obtained P-wave pion-pion scattering length (a_1^1=33.9+- 2.02 [10^{-3}m_{pi^+}^{-3}]) most matches to the one calculated in the local Nambu--Jona-Lasinio model.

hep-ph↗
arXiv2005

Electroproduction, photoproduction, and inverse electroproduction of pions in the first resonance region

Methods are set forth for determining the hadron electromagnetic structure in the sub-$N\bar{N}$-threshold timelike region of the virtual-photon ``mass'' and for investigating the nucleon weak structure in the spacelike region from experimental data on the process $πN\to e^+e^- N$ at low energies. These methods are formulated using the unified description of photoproduction, electroproduction, and inverse electroproduction of pions in the first resonance region in the framework of the dispersion-relation model and on the basis of the model-independent properties of inverse electroproduction. Applications of these methods are also shown.

nucl-th↗
arXiv2003

On the nature of $f_0$ mesons below 1.9 GeV and lower scalar nonets

The combined 3-channel analysis of experimental data on the coupled processes $ππ\toππ,K\bar{K},ηη$ is carried out in the channel with the vacuum quantum numbers. An approach, using only first principles (analyticity and unitarity) and the uniformizing variable, is applied. Definite indications of the QCD nature of the $f_0$ resonances below 1.9 GeV are obtained, among them a surprising indication for $f_0(980)$ to be the $ηη$ bound state. An assignment of the scalar mesons below 1.9 GeV to lower nonets is proposed.

hep-ph↗
arXiv2003

Mesons of the $f_0$-family in the processes $ππ\toππ,K\bar{K},ηη$ up to 1.9 GeV

In combined 2- and 3-channel analyses of experimental data on the coupled processes $ππ\toππ,K\bar{K},ηη$ in the channel with $I^GJ^{PC}=0^+0^{++}$, various scenarios of these reactions(with different numbers of resonances) are considered. In a model-independent approach, confirmation of the $σ$-meson below 1 GeV and definite indications of the QCD nature of other $f_0$ resonances are obtained. The conclusion on the linear realization of chiral symmetry is drawn.

hep-ph↗
arXiv2002

Mesons of the $f_0$ family in processes $ππ\toππ,K\bar{K}$ up to 2 GeV and chiral symmetry

In a combined analysis of the experimental data on the coupled processes $ππ\toππ,K\bar{K}$ in the channel with $I^GJ^{PC}=0^+0^{++}$, the various scenarios of these reactions (with different numbers of resonances) are considered. In a model-independent approach, based only on analyticity and unitarity, a resonance is represented by of a pole cluster (poles on the Riemann surface) of the definite type that is defined by the state nature. The best scenario contains the resonances $f_0(665)$ (with properties of the $σ$-meson), ${f_0}(980)$ (with a dominant $s{\bar s}$ component), $f_0(1500)$ (with a dominant flavour-singlet, {\it e.g.}, glueball component) and the ${f_0}(1710)$ (with a considerable $s{\bar s}$ component). If the ${f_0}(1370)$ exists, it has a dominant $s{\bar s}$ component. The coupling constants of observed states with the considered channels and the $ππ$ and $K\bar{K}$ scattering lengths are obtained. The conclusion on the linear realization of chiral symmetry is drawn.

hep-ph↗
arXiv2002

The $f_0$ Mesons in Processes $ππ\toππ, K\bar{K}$ and Chiral Symmetry

In a combined analysis of the experimental data on the coupled processes $ππ\toππ,K\bar{K}$ in the channel with $I^GJ^{PC}=0^+0^{++}$, the following results are obtained in a model-independent way: 1) The $f_0(665)$ state with properties of the $σ$-meson is proved to exist; 2) it is shown that the ${f_0}(980)$ and especially ${f_0}(1370)$ (if exists) have a dominant $s{\bar s}$ component; 3) indications of the glueball nature of the $f_0(1500)$ and of a considerable $s{\bar s}$ component in the ${f_0}(1710)$ are obtained; 4) conclusion on the linear realization of chiral symmetry is drawn.

hep-ph↗
arXiv2001

Model-independent approach as a tool of studying chiral symmetry

A simultaneous analysis (in the model-independent approach) of the $ππ$ scattering (from the threshold to 1.9 GeV) and of the $ππ\to K\overline{K}$ process (from the threshold to $\sim$ 1.46 GeV) is carried out in channel with $I^GJ^{PC}=0^+0^{++}$. The existence of the $f_0(665)$ state with properies of the $σ$-meson is proved. An indication for the glueball nature of the $f_0(1500)$ is obtained. A minimum scenario of the simultaneous description of the processes $ππ\toππ,K\overline{K}$ does without the ${f_0}(1370)$ resonance. A version including this state is also considered. In this case the ${f_0}(1370)$ resonance has the dominant $s{\bar s}$ component (the ratio of its coupling constant with the $ππ$ channel to the one with the $K\overline{K}$ channel is 0.12). The coupling constants of the observed states with the $ππ$ and $K\overline{K}$ systems and the $ππ$ and $K\overline{K}$ scattering lengths are obtained. A parameterless description of the $ππ$ background is given by allowance for the left-hand branch-point in the uniformizing variable. On the basis of this and of the fact that all the adjusted parameters for the $ππ$ scattering are only the positions of poles describing resonances, it is concluded that our model-independent approach is a valuable tool for studying the realization schemes of chiral symmetry. The existence of the $f_0(665)$ state and the obtained $ππ$-scattering length ($a_0^0\approx 0.27 m_{π^+}^{-1}$) seem to suggest the linear realization of chiral symmetry.

hep-ph↗
arXiv2001

Existence and Properties of the $f_0(665)$ State and Chiral Symmetry

On the basis of a simultaneous description of the isoscalar s-wave of $ππ$ scattering (from the threshold up to 1.9 GeV) and of $ππ\to K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV) in the model-independent approach, it is shown that there exists the $f_0(665)$ state with properies of the $σ$-meson, the glueball nature of $f_0(1500)$ is indicated, and the $f_0(1370)$ is assigned mainly to $s{\bar s}$ state. The coupling constants of the observed states with $ππ$ and $K\bar{K}$ systems and scattering lengths $a_0^0(ππ)$ and $a_0^0(K\bar{K})$ are calculated. The existence of the $f_0(665)$ state and the obtained $ππ$-scattering length ($a_0^0\approx 0.27 m_{π^+}^{-1}$) seem to suggest the linear realization of chiral symmetry.

hep-ph↗