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M. A. Matveev

Publications and source records attributed to M. A. Matveev.

32 records · Page 2Linked to original sources
arXiv2010

Searching for the quark--diquark systematics of baryons composed by light quarks $q=u,d$

Supposing quark--diquark structure of baryons, we look for systematics of baryons composed of light quarks ($q=u,d$). We systematize baryons using the notion of two diquarks: (i) axial--vector state, $D^{1}_{1}$, with the spin $S_D=1$ and isospin $I_D=1$ and (ii) scalar one, $D^{0}_{0}$, with the spin $S_D=0$ and isospin $I_D=0$. We consider several schemes for the composed baryons: (1) with different diquark masses, $M_{D^0_0} \ne M_{D^1_1}$, (2) with $M_{D^0_0} = M_{D^1_1}$ and overlapping $qD^0_0$ and $qD^1_1$ states (resonances), (3) with/without SU(6) constraints for low-lying states (with quark--diquark orbital momenta L=0). In the high-mass region the model predicts several baryon resonances at $M\sim 2.0-2.9$ GeV. Moreover, the model gives us the double pole structure (i.e. two poles with the same Re$M$ but different Im$M$) in many amplitudes at masses $M\ga 2.0$ GeV. We see also that for description of low-lying baryons (with L=0), the SU(6) constraint is needed.

hep-ph↗
arXiv2009

Two-pion decays of mesons and confinement singularities

We consider the two-pion decay of the $ρ$-meson, the $^3S_1q\bar q$-state of the constituent quarks -- the decay being determined by the transition $q\bar q\to ππ$ contains information about confinement interactions. One can specify in this decay two types of transitions: ({\bf i}) the bremsstrahlung radiation of a pion $q\to q+π$ (or $\bar q\to\bar q+π$) with the subsequent fusion $q\bar q\to π$, and ({\bf ii}) the direct transition $q\bar q\to ππ$. We demonstrate how in the amplitudes of the corresponding transitions the quark singularities have to disappear, {\it i.e.} what is the way the quark confinement at relatively short distances can be realized. We calculate and estimate the contributions of processes with bremsstrahlung radiation of the pion and of the direct transition $q\bar q\to ππ$. The estimates demonstrate that the processes involving the direct transition $q\bar q\to ππ$ are necessary, but they cannot be determined unambiguously by the decay $ρ(775)\to ππ$. We conclude that for the determination of the $q\bar q\to ππ$ transition more complete data on the resonance decays into the $ππ$ channels are required than those available at the moment.

hep-ph↗
arXiv2009

The rho -> gamma pi and omega -> gamma pi decays in quark-model approach and estimation of coupling for pion emission by quark

In the framework of the relativistic and gauge invariant spectral integral technique, we calculate radiative decays rho(770)-> gamma pi(140) and omega(780)-> gamma pi(140) supposing all mesons (pi, rho and omega) to be quark-antiquark states. The q anti-q wave functions found for mesons and photon lead to a reasonably good description of data ($Γ^{(exp)}_{ρ^{\pm} \toγπ^{\pm}}=68\pm 30$ keV, $Γ^{(exp)}_{ρ^{0}\toγπ^0}=77\pm 28$ keV, $Γ^{(exp)}_{ω\toγπ^0}=776\pm 45$ keV) that makes it possible to estimate the coupling for the bremsstrahlung emission of pion by quarks $g_π\equiv g_π(u\to d π)$. We have found two values for the pion bremsstrahlung coupling: $|g_π|=16.7 \pm 0.3 ^{+0.1}_{-2.3}$ (Solution I) and $|g_π|=3.0 \pm 0.3 ^{+0.1}_{-2.1}$ (Solution II). Within SU(6)-symmetry for nucleons, Solution I gives us for pi NN coupling the value $16.4 \le g_{πNN}^2/(4π) \le 23.2$ that is in qualitative agreement with the pi N scattering data, $g_{πNN}^2/(4π)\simeq 14$. For excited states, we have estimated the partial widths in Solution I as follows: $Γ(ρ_{2S}^\pm\to γπ)\simeq 10 - 130$ keV, $Γ(ρ_{2S}^0\to γπ)\simeq 10 -130$ keV, $Γ(ω_{2S}\to γπ)\simeq 60 - 1080$ keV. The large uncertainties emphasise the necessity to carry out measurements of the meson radiative processes in the region of large masses.

hep-ph↗
arXiv2005

Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge I.} Bottomonia

In the framework of the spectral integral equation, we consider the $b\bar b$ states and their radiative transitions. We reconstruct the $b\bar b$ interaction on the basis of data for the levels of the bottomonium states with $J^{PC}=0^{-+}$, $1^{--}$, $0^{++}$, $1^{++}$, $2^{++}$ as well as the data for the radiative transitions $Υ(3S) \toγχ_{bJ}(2P) $ and $Υ(2S) \toγχ_{bJ}(1P) $ with $J=0,1,2$. We calculate bottomonium levels with the radial quantum numbers $n\le 6$, their wave functions and corresponding radiative transitions. The ratios $Br[χ_{bJ}(2P)\toγΥ(2S)]/Br[χ_{bJ}(2P)\toγΥ(1S)]$ for $J=0,1,2$ are found in the agreement with data. We determine the $b\bar b$ component of the photon wave function using the data for the $e^+e^-$ annihilation, $e^+e^- \toΥ(9460)$, $Υ(10023)$, $Υ(10036)$, $Υ(10580)$, $ Υ(10865)$, $Υ(11019)$, and predict partial widths of the two-photon decays $η_{b0}\to\ggam$, $χ_{b0}\to\ggam$, $χ_{b2}\to\ggam$ for the radial excitation states below $B\bar B$ threshold ($n\le 3$).

hep-ph↗
arXiv2005

Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge II.} Charmonia

In the precedent paper of the authors (hep-ph/0510410), the $b\bar b$ states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative decays of the considered bottomonia. In the present paper, such a study is carried out for the charmonium $(c\bar c)$ states. We reconstruct the interaction in the $c\bar c$-sector on the basis of data for the charmonium levels with $J^{PC}=0^{-+}$, $1^{--}$, $0^{++}$, $1^{++}$, $2^{++}$, $1^{+-}$ and radiative transitions $ψ(2S)\toγχ_{c0}(1P)$, $γχ_{c1}(1P)$, $γχ_{c2}(1P)$, $γη_{c}(1S)$ and $χ_{c0}(1P)$, $χ_{c1}(1P)$, $χ_{c2}(1P)\toγJ/ψ$. The $c\bar c$ levels and their wave functions are calculated for the radial excitations with $n\le 6$. Also, we determine the $c\bar c$ component of the photon wave function using the $e^+e^-$ annihilation data: $e^+e^- \to J/ψ(3097)$, $ψ(3686)$, $ψ(3770)$, $ψ(4040)$, $ ψ(4160)$, $ψ(4415)$ and perform the calculations of the partial widths of the two-photon decays for the $n=1$ states: $η_{c0}(1S)$, $χ_{c0}(1P)$, $χ_{c2}(1P)\toγγ$, and $n=2$ states: $η_{c0}(2S)\toγγ$, $χ_{c0}(2P)$, $χ_{c2}(2P)\to γγ$. We discuss the status of the recently observed $c\bar c$ states X(3872) and Y(3941): according to our results, the X(3872) can be either $χ_{c1}(2P)$ or $η_{c2}(1D)$, while Y(3941) is $χ_{c2}(2P)$.

hep-ph↗
arXiv2005

Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge III.} Light mesons

We continue the investigation of mesons in terms of the spectral integral equation initiated before [hep-ph/0510410, hep-ph/0511005] for the $b\bar b$ and $c\bar c$ systems: in this paper we consider the light-quark ($u, d,s$) mesons with masses $M\le 3$ GeV. The calculations have been performed for the mesons lying on linear trajectories in the $(n,M^2)$-planes, where $n$ is the radial quantum number. Our consideration relates to the $q\bar q$ states with one component in the flavor space, with the quark and antiquark masses equal to each other, such as $π(0^{-+})$, $ρ(1^{--})$, $ω(1^{--})$, $ϕ(1^{--})$, $a_0(0^{++})$, $a_1(1^{++})$, $a_2(2^{++})$, $b_1(1^{+-})$, $f_2(2^{++})$, $π_2(2^{-+})$, $ρ_3(3^{--})$, $ω_3(3^{--})$, $ϕ_3(3^{--})$, $π_4(4^{-+})$ at $n\le 6$. We obtained the wave functions and mass values of mesons lying on these trajectories. The corresponding trajectories are linear, in agreement with data. We have calculated the two-photon decays $π\to γγ$, $a_0(980)\to γγ$, $a_2(1320)\to γγ$, $f_2(1285)\to γγ$, $f_2(1525)\to γγ$ and radiative transitions $ρ\toγπ$, $ω\toγπ$, that agree qualitatively with the experiment. On this basis, we extract the singular part of the interaction amplitude, which corresponds to the so-called "confinement interaction". The description of the data requires the presence of the strong $t$-channel singularities for both scalar and vector exchanges.

hep-ph↗
arXiv2005

Radiative decays of quarkonium states, momentum operator expansion and nilpotent operators

We present the method of calculation of radiative decays of composite quark-antiquark systems with different J^{PC}: (Q\bar Q)_{in} -> gamma (Q\bar Q)_{out}. The method is relativistic invariant, it is based on the double dispersion relation integrals over the masses of composite mesons, it can be used for the high spin particles and provides us with the gauge invariant transition amplitudes. We apply this method to the case when the photon is emitted by a constituent in the intermediate state (additive quark model). We perform the momentum operator expansion of the spin amplitudes for the decay processes. The problem of nilpotent spin operators is discussed.

hep-ph↗
arXiv2005

Sector of the $2^{++}$ mesons: observation of the tensor glueball

Data of the Crystal Barrel and L3 collaborations clarified essentially the situation in the $2^{++}$ sector in the mass region up to 2400 MeV, demonstrating the linearity of $(n,M^2)$ trajectories, where $n$ is the radial quantum number of a quark-antiquark state with mass $M$. We discuss these data and show that there exists a superfluous state for the $(n,M^2)$ trajectories: a broad resonance $f_2(2000)$. We pay special attention to the reactions $p\bar p\toππ,ηη,ηη'$ in the mass region 1990--2400 MeV where, together with $f_2(2000)$, four relatively narrow resonances are seen: $f_2(1920)$, $f_2(2020)$, $f_2(2240)$, $f_2(2300)$. We analyse the branching ratios of all these resonances and show that only the decay couplings of the broad state $f_2(2000)\toπ^0π^0,ηη, ηη'$ satisfy relations inherent in the glueball decay.

hep-ph↗
arXiv2005

Determination of the quarkonium--gluonium content of the isoscalar tensor resonances $f_2(1920)$, $f_2(2020)$, $f_2(2240)$, $f_2(2300)$ and of the broad state $f_2(2000)$ based on decay couplings to $π^0π^0,ηη,ηη'$

In the reactions $p\bar p\toπ^0π^0,ηη,ηη'$ there are four relatively narrow resonances $f_2(1920)$, $f_2(2020)$, $f_2(2240)$, $f_2(2300)$, and a broad one $f_2(2000)$ in the mass region 1990--2400 MeV. In the framework of quark combinatorics we carry out an analysis of the decay constants for all five resonances. It is shown that the relations for the decay constants corresponding to the broad resonance $f_2(2000)\toπ^0π^0,ηη, ηη'$ are the same as those corresponding to a glueball. An additional argument in favour of the glueball--nature of $f_2(2000)$ is the fact that $f_2(1920)$, $f_2(2020)$, $f_2(2240)$, $f_2(2300)$ fit well the $q\bar q$ trajectories in the $(n,M^2)$-plane (where $n$ is the radial quantum number), while the broad $f_2(2000)$ resonance turns out to be an unnecessary extra state for these trajectories.

hep-ph↗
arXiv2003

Description of composite systems in the spectral integration technique: the gauge invariance and analyticity constraints for the radiative decay amplitudes

The constraints followed from gauge invariance and analyticity are considered for the amplitudes of radiative transitions of composite systems when composite systems are treated in terms of spectral integrals. We discuss gauge-invariant amplitudes for the transitions S -> gamma S and V -> gamma S with scalar S and vector V mesons being two-particle composite systems of scalar (or pseudoscalar) constituents, and we demonstrate the mechanism of cancellation of false kinematical singularities. Furthermore, we explain how to generalize the performed consideration for quark-antiquark systems, in particular, for the reaction phi(1020) -> gamma f0(980). Here we also consider in more detail the quark-model non-relativistic approach for this reaction.

hep-ph↗
arXiv2002

Two-photon partial widths of tensor mesons

We calculate partial widths of the gamma-gamma decay of the tensor q\bar q states a_2(1320), f_2(1270), f_2(1525), their radial excitations a_2(1660), f_2(1640), f_2(1800) as well as ^3F_2 q\bar q states. Calculations are performed in the framework of the same approach which was used before for the study of radiative decays f_0(980) -> gamma-gamma, a_0(980) -> gamma-gamma and phi(1020) -> gamma-f_0(980): the assumption made is that of q\bar q structure of f_0(980) and a_0(980) [A.V. Anisovich et al., Phys. Lett. B 456, 80 (1999); Eur. Phys. J. A 12, 103 (2001)]. The description of the decay partial widths for a_2(1320), f_2(1270), f_2(1525) and f_0(980), a_0(980) is reached with the approximately equal radial wave functions, thus giving a strong argument in favour of the fact that these scalar and tensor mesons are to be classified as members of the same P-wave q\bar q multiplet.

hep-ph↗