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The work is devoted to the transverse polarization () of -hyperons and corresponding antihyperons produced in meson–proton and meson–nuclear interactions in inclusive reactions. The currently available experimental data are compared with calculations based on the chromomagnetic polarization of quark (CPQ) model. The main features of the CPQ model are the prediction of hyperon polarization oscillations depending on the Feynman variable in the case of a sufficiently strong chomomagnetic field and resonant dependence of the polarization on the c.m. energy () for some reactions. Calculations based on the CPQ model were performed for still unexplored kinematic regions and various targets and can be tested in the SPASCHARM experiment at the NRC "Kurchatov Institute"—IHEP. [ABSTRACT FROM AUTHOR]

Relativistic corrections to the pair production of mesons and baryons consisting of heavy quarks and in the Higgs boson decay are calculated. Relativistic amplitudes and decay rates are constructed within perturbative Standart Model and relativistic quark model. The numerical values of the relativistic effects turn out to be significant and must be taken into account in order to achieve good calculation accuracy. [ABSTRACT FROM AUTHOR]

At present, production, properties, and decays of heavy baryons are vigorously studied both experimentally and theoretically. The flavor symmetry allows an existence of a large number of hidden charm pentaquark states which differ by their light quark content. Here, ratios of weak decay widths of bottom baryons into a pentaquark and light meson are presented. The most interesting for experimental observation decays of bottom baryons are specified. [ABSTRACT FROM AUTHOR]

A new relativistic semiclassical expression is derived for leptonic decay widths of vector mesons as a composite system of two quarks having equal masses and interacting via a funnel-like potential. This new expression is compared with its nonrelativistic spinless and relativistic spin and spinless analogs. The effect of the spins of equal-mass quarks forming vector mesons on the behavior of the leptonic decay widths of these mesons is analyzed. This analysis is performed within the relativistic quasipotential approach based on the covariant Hamiltonian formulation of quantum field theory by means of a transition from the momentum representation in Lobachevsky space to the three-dimensional relativistic configuration representation for the case of a composite system of two relativistic spin equal-mass particles. [ABSTRACT FROM AUTHOR]

Exact solutions of relativistic quasipotential equations in the configuration representation are found for the -state wave function for a composite system of two arbitrary-mass relativistic spinor quarks interacting via a Coulomb-like chromodynamic potential. Composite systems whose spinor structure corresponds to the pseudoscalar, pseudovector, and vector cases are considered. Quantization conditions for the energy levels of the meson -wave state are determined in the pseudoscalar, pseudovector, and vector cases. Expressions for the relativistic threshold resummation factor corresponding to a Coulomb-like chromodynamic potential are obtained for these spinor meson structures, and the properties of this factor are studied. New regularities in the behavior of the threshold factor are revealed. The present analysis is performed within the relativistic quasipotential approach based on the covariant Hamiltonian formulation of quantum field theory by means of the transition from the momentum representation in Lobachevsky space to the three-dimensional relativistic configuration representation for the case of a composite system of two arbitrary-mass relativistic spinor particles. [ABSTRACT FROM AUTHOR]

The meson spectrum of QCD is studied in the framework of nonperturbative QCD as a function of varying quark masses m. It is shown that the total spectrum consists of two branches: 1) the standard one, which may be called the flux-tube spectrum, depending approximately linearly on m, and 2) the chiral symmetry breaking (CSB) spectrum for pseudoscalar (PS) flavor nonsinglet mesons with mass dependence √ m. The formalism for PS mesons is derived from the QCD Lagrangian with m corrections, and a unified form of the PS propagator was derived. It is shown that the CSB branch of PS mesons joins to the flux-tube branch at around m = 200 MeV. All these results are in close correspondence with recent numerical data on large lattices. [ABSTRACT FROM AUTHOR]

Bound states in a simple quark model that are due to correlation effects are analyzed. The confining properties of this model in meson (quark-antiquark and diquark) channels manifest themselves at any quark momenta, and an extra potential field may only enhance the confining effect. [ABSTRACT FROM AUTHOR]

Cross sections for Jψ-meson pair production in proton-proton interaction at the c.m. collision energy of $$\sqrt s = 7$$ TeV were theoretically predicted under conditions of various kinematical cuts. The possible contribution to this process from the decays of 4 c tetraquarks, new hypothetic particles consisting of two valence c quarks and two valence $$\bar c$$ antiquarks, was studied. It is shown that at least one such state (tensor 4 c tetraquark) can in principle be observed experimentally under conditions of the LNCb experiment. [ABSTRACT FROM AUTHOR]

Radiative decays π( π) → γ + γ, π → ρ( ω) + γ, ρ( ω′) → π + γ, ρ( ω′) → π + γ, and some processes of π production at lepton colliders are considered in the framework of the nonlocal SU(2) × SU(2) Nambu-Jona-Lasinio model. Mixing of the radially excited and the ground meson states is taken into account. Numerical results for the decay and production processes are presented. [ABSTRACT FROM AUTHOR]

We consider as an example the two-pion decay of the ρ meson, the 3 S1 q $$ \bar q $$ state of the constituent quarks—the decay being determined by the transition q $$ \bar q $$ → ππ contains information about confinement interactions. One can specify in this decay two types of transitions: (i) the bremsstrahlung radiation of a pion q → q + π (or $$ \bar q $$ → $$ \bar q $$ + π) with a subsequent fusion q $$ \bar q $$ → π, and (ii) the direct transition q $$ \bar q $$ → ππ. We demonstrate how in the amplitudes of the corresponding transitions the quark singularities have to disappear, 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 $$ \bar q $$ → ππ. The estimates demonstrate that the processes involving the direct transition q $$ \bar q $$ → ππ are necessary, but they cannot be determined unambiguously by the decay ρ(775) → ππ. We conclude that for the determination of the q $$ \bar q $$ → ππ transition more complete data on the resonance decays into the ππ channels are needed than those available at the moment. [ABSTRACT FROM AUTHOR]

The two-photon decay widths of scalar mesons σ(600), f0(980), and a0(980) are calculated in the framework of the local Nambu-Jona-Lasinio model. The contributions of the quark loops (Hartree-Fock approximation) and the meson loops (next 1/ N c approximation, where N c is the number of colors) are taken into account. These contributions, as we show, are the values of the same order of magnitude. For the f0 decay the K-loop contribution turns out to play the dominant role. The results are in satisfactory agreement with modern experimental data. [ABSTRACT FROM AUTHOR]

Some very unusual features of the hadron structure functions, obtained in generalized QCD sum rules, like the surprisingly strong difference between longitudinally and transversally polarized ρ-meson structure functions and the strong suppression of the gluon sea in the longitudinally polarized ρ meson, are discussed. [ABSTRACT FROM AUTHOR]

On the basis of the assumption of quark-hadron duality, it is shown that the color-singlet contribution to the cross sections for the processes e + g → e + J/ψ + g and gg → J/ψg increases upon taking into account the relative motion of quarks in the J/ψ meson. [ABSTRACT FROM AUTHOR]

It is shown that, as in the case of light mesons, heavy-quarkonium states lie, to a high precision, on Regge trajectories in the ( n, M 2) and ( M 2, J) planes with a universal slope. Specifically, $$c\bar c$$ states are described to a high precision by linear trajectories. For $$b\bar b$$ states, there is no such linearity but, as in the other cases, there is a universal quantum-number dependence of the trajectory. [ABSTRACT FROM AUTHOR]

We continue the investigation of mesons in terms of the spectral integral equation initiated before for the $$b\bar b$$ and $$c\bar c$$ systems; we consider the light-quark ( u, d, s) mesons with masses M ≤ 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 ≤ 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, a 0(980), a 2(1320), f 2(1285), f 2(1525) and radiative transitions ρ, ω → γπ, which 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. [ABSTRACT FROM AUTHOR]

Results of recent studies that indicate that allowance for the relative motion of quarks in mesons leads to an increase in the cross sections for the process e + e − → J/ ψη c are confirmed. It is shown that the same effect also leads to an increase in the width of scalar and tensor mesons with respect to their decay to two vector mesons, so that the decays χ b0,2 → 2 J/ ψ can be used to observe these mesons at the Tevatron collider and LHC. [ABSTRACT FROM AUTHOR]

The inclusive production of heavy quarks and quarkonia in photon-photon collisions at the LEP2 collider is considered within the semihard ( k T-factorization) QCD approach. The dependence of the total and differential cross sections for the production of heavy ( c and b) quarks and D* and J/ψ mesons on the choice of unintegrated gluon distribution is studied. The transition of a $$c\bar c$$ charmed pair to observed J/ψ mesons is described on the basis of the color-singlet model. The results of the calculations are compared with currently available experimental data obtained by the L3, OPAL, ALEPH, and DELPHI Collaborations. It is shown that the polarization properties of J/ψ mesons at the LEP2 collider are sensitive to the behavior of unintegrated gluon distributions. This means that experimental investigations of the polarization properties of quarkonia in photon-photon collisions may provide a direct test of the dynamics of gluon distributions in the photon. [ABSTRACT FROM AUTHOR]

The features of the associated production of ϕ mesons and neutral kaons are studied on the basis of data obtained at the EXCHARM spectrometer (Serpukhov accelerator) in neutron—carbon interactions at neutron-beam energies in the range 20–70 GeV. The cross section for the inclusive associated production of ϕ and K 0/ -K 0 is obtained. The fraction of processes allowed by the Okubo-Zweig-Iizuka rule is estimated in the reactions of ϕ-meson inclusive production. [ABSTRACT FROM AUTHOR]

The rare radiative leptonic decays B0d,s → ℓ+ℓ–γ are studied. The contributions to the respective amplitude from the emission of photons from the quark loop, bremsstrahlung from leptons, and weak-annihilation effects are taken into account in relevant calculations. Results are presented for the partial widths and distributions of leptons in the final state. It is shown that the previously disregarded contributions of vector resonances associated with virtual-photon emission from the light valence quark of the B meson have a significant effect on the mass spectra of dileptons.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The Bethe–Salpeter equations for quark–antiquark composite systems with different quark masses, such as qs (with q = u,d ), qQ, and sQ (with Q = c,b), are written in terms of spectral integrals. For mesons characterized by the mass M, spin J, and radial quantum number n, the equations are written for the (n, M2) trajectories with fixed J. The mixing between states with different quark spin S and angular momentum L is also discussed.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The transverse-momentum spectra of direct J/psi; arid psi;' mesonis in pp interactions at the Tevatron collider energy of √ 8 = 1.8 TeV are calculated on the basis of nonrelativistic QCD, the fragmentation model, the kT-factorization approach, arid the standard parton model. The contribution of gluon fragmentation is shown to exceed the contribution of c-quark fragmentation both within the parton model arid within the kT-factorization approach. Experimental data of the CDF Collaboration agree with the assumption that gluon fragmentation plays a dominant role in the QQ [³3 S1, 8] octet state, with the nonperturbative matrix element taking approximately equal values in the parton model arid in the kT- factorization approach. [ABSTRACT FROM AUTHOR]

This article presents information related to forthcoming books on nuclear physics published in the December 2004 issue of "Physics of Atomic Nuclei." Few of the listed books are: "Exclusive Production of Charmed-Meson Pairs," A. V. Berezhnoy and A. K. Likhoded; "Pion Electromagnetic Form Factor in QCD Sum Rules," by V. V. Braguta and A. I. Onishchenko; "Subthreshold Photofission of Even Nuclei," by S. G. Kadmensky and L. V. Rodionova; "Application of the Salpeter Equation to Describing Quark Antiquark Interaction," by I. V. Mokrov.

We show on gauge invariance grounds that a new threshold phenomenon has been discovered in the radiative decays φ → γa0 → γπ0η and φ → γf0 → γπ0π0. This enables us to conclude that production of the light scalar mesons a0(980) and f0(980) in these decays is caused by the four-quark transitions, resulting in strong restrictions on the large-Nc expansions of the decay amplitudes. The analysis shows that these constraints give new evidence in favor of the four-quark nature of a0(980) and f0(980) mesons.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We calculate the processes Ds+ → π+ss and Ds+ → π+resonance, respectively, in the spectator and W-annihilation mechanisms. The data on the reaction Ds+ → π+ρ0, which is due to the W-annihilation mechanism only, point to a negligibly small contribution of the W annihilation to the production of scalar–isoscalar resonances Ds+ → π+f0. As to spectator mechanism, we evaluate the 13P0ss component in the resonances f0(980), f0(1300), and f0(1500) and broad state f0(1200–1600) on the basis of data on the decay ratios (Ds+ → π+f0)/(Ds+ → π+φ). The data point to a large ss component in the f0(980): 40 ≲ ss ≲ 70%. Nearly 30% of the 13P0ss component flows to the mass region 1300–1500 MeV, being shared by f0(1300), f0(1500), and broad state f0(1200–1600): the interference of these states results in a peak near 1400 MeV with the width around 200 MeV. Our calculations show that the yield of the radial-excitation state 23P0ss is relatively suppressed, Γ(Ds+ → π+(23P0ss))/Γ(Ds+ → π+(13P0ss)) <= 0.05.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Masses and interactions of light mesons are described in the framework of the model with the chiral invariant SU (2)×SU (2) four-quark interaction. The nonlocal kernel of the interaction is chosen in the form that ensures the absence of ultraviolet divergences in the Feynman diagrams and poles in the quark propagator. Within this model, we demonstrate that, in the chiral limit, the pion mass equals zero and the Goldberger–Treiman relation is fulfilled. The sigma-meson mass and the widths of strong decays σ →ππ , ρ →ππ are estimated.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The light hadron spectrum as computed in nonperturbative QCD is reviewed and compared to lattice data and experiment. The mixing of mesons, hybrids, and glueballs is calculated in the field correlator method. The strong decay mechanisms are found in the method and compared to the known phenomenological models. The role of sea quarks (unquenched approximation) is studied analytically, using radially excited mesons as an example, and compared to experiment. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The low-temperature relations for the trace of the energy–momentum tensor in QCD with two and three quarks are obtained. It is shown that the temperature derivatives of the anomalous and normal (quark massive term) contributions to the trace of the energy–momentum tensor in QCD are equal to each other in the low-temperature region. Leading corrections connected with ππ interaction and thermal excitations of K and η mesons are calculated.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The process γ[sup *]γ → σ is investigated in the framework of the SU(2) × SU(2) chiral NJL model. The form factor of the process is derived for arbitrary virtuality of γ[sup *] in the Euclidean kinematic domain. The asymptotic behavior of this form factor resembles the asymptotic behavior of the γ[sup *]γ → π form factor.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The momentum distribution of kaons in the proton and the coupling-constant ratio f[sub KΛN]/f[sub KΣN] are determined on the basis of the [sup 3]P[sub 0] quark model of meson–baryon coupling. The longitudinal cross section for kaon electroproduction is calculated. The results of the present study are compatible with available experimental data, but more detailed data on the longitudinal cross section would make it possible to refine the absolute values of the coupling constants f[sub KΛN] and f[sub KΣN].© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The paper represents a review of our present knowledge on the phenomenology of weak decays of quarks and their role in the determination of the parameters of the Standard Model. Specifically, we focus on CP violation in B decays and the determination of the Cabibbo–Kobayashi–Maskawa matrix element V[sub cb] from exclusive and inclusive semileptonic B decays. We also briefly discuss phenomenological applications concerning the electron energy spectra in inclusive semileptonic B and B[sub c] decays.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The deep-inelastic production of J/ψ mesons in electron–proton interactions at the HERA collider is considered within the semihard (k[sub T]-factorization) QCD approach and within the color-singlet model. The dependence of the Q[sup 2], p[sub T][sup 2], z, y[sup *], and W distributions of J/ψ mesons on various sets of unintegrated gluon distributions and the dependence of the spin parameter α on p[sub T][sup 2] and Q[sup 2] are investigated. The results of the calculations are compared with the latest experimental data obtained by the H1 and ZEUS Collaborations at the HERA collider. It is shown that experimental investigations of the polarization properties of J/ψ mesons over the kinematical region Q[sup 2] < 1 GeV[sup 2] may provide an additional test of the statement that the dynamics of gluon distributions is governed by the Balitsky–Fadin–Kuraev–Lipatov equations.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Weak radiative decay &lgr; → ne[SUP+]e[SUP-] depends in general on four independent electromagnetic transition form factors. These form factors can be fixed in an extended model of dominance of vector mesons, where the asymptotic behavior of form factors is in agreement with quark counting rules. The dependence of the branching ratio of the &lgr; → ne[SUP+]e[SUP-] decay on the relative weight of four electromagnetic form factors is investigated. [ABSTRACT FROM AUTHOR]

On the basis of the decay couplings f[SUB0] ππ, K&Kmacron;, ηη, ηeta;' found earlier in the study of analytical (IJ[SUPPC]= 00[SUP++]) amplitude in the mass range 450-1900 MeV, we analyze the quark-gluonium content of the resonances f[SUB0](980), f[SUB0](1300), f[SUB0](1500), and f[SUB0] (1750) and the broad state f[SUB0](1420) [SUB-70,SUP+150]. The K-matrix technique used in the analysis makes it possible to evaluate the quark-gluonium content both for the states with switched-off decay channels (bare states, (f[SUB0,SUPbare]) and for the real resonances. We observe a significant change in the quark-gluonium composition in the evolution from bare states to real resonances, which is due to the mixing of states in the transitions f[SUB0] (m[SUB1]) → real mesons &rarr f[SUB0] (m[SUB2]) responsible for the)decay processes as well. For f[SUB0](980), the analysis confirmed the dominance of q&qmcrn; component, thus proving the n&nmcr;/s&smacr; composition found in the study of the radiative decays. For the mesons f[SUB0] (1300), f[SUB0](1500), and f[SUB0](1750), the hadronic decays do not allow one to determine uniquely the n&nmcr; s&smacr;, and gluonium components, providing relative percentage only. The analysis shows that the broad state f[SUB0] (1420[SUB-70,SUP+150]) can mix with the flavor singlet q&qmac; component only, which is consistent with gluonium origin of the broad resonance. [ABSTRACT FROM AUTHOR]

The N[sub c] dependence of PPPγ vertices, where P is a pseudoscalar meson and N[sub c] is the number of colors, is analyzed with allowance for the N[sub c] dependence of the quark charges. It is shown that the reactions Kγ → Kπ and π[sup ±]γ → π[sup ±]η and the decay η → π[sup +]π[sup –]γ are the best processes for determining N[sub c]. The cross section σ(π[sup –]γ → π[sup –]η) as measured by using the VES facility at IHEP agrees with the value of N[sub c] = 3.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

In a nonlocal U(3) x U(3) chiral quark model with the local 't Hooft interaction, the first radial excitations of scalar mesons are described. Simple Lorentz-covariant form factors, having a polynomial form in the momentum space, are used for the description of radially excited states. Due to the chiral symmetry, the form factors for scalar states coincide with those for pseudoscalars. As a result, using the experimental values for the masses of pseudoscalar mesons, we predict the mass spectrum of the ground and radially excited scalar-meson states. The scalar glueball is introduced into the effective meson Lagrangian by means of the dilaton model. It is shown that 19 scalar states with masses from 0.4 to 1.7 GeV can be interpreted as two scalar nonets and a glueball. Strong decay widths of scalar mesons are calculated. The state f[sub 0](1500) is shown to be the most probable candidate for the scalar glueball. [ABSTRACT FROM AUTHOR]

The asymmetry between the spectra of leading and nonleading charmed mesons that was measured in Σ[sup -]A interactions at p[sub L] = 340 GeV/c in the WA89 experiment is described within the Model of Quark-Gluon Strings (QGS model also known as QGSM) under the assumption that there is a fraction of charmed sea quark-antiquark pairs (intrinsic charm) in an interacting hyperon. It is shown that the asymmetries between D[sup -]- and D[sup +]-meson spectra and between D[sup -, sub s]- and D[sup +, sub s] -meson spectra can be approximated by QGSM curves obtained with the same string-fragmentation parameter, a[sup 1] = 10, and the same intrinsic-charm fraction, δ[sub c, &cmarc;] = 0.01, as those that were used in describing D[sup -, sub s]/D[sup +, sub s]-meson asymmetry of π[sup -]A experiments in previous studies. The asymmetry between the spectra of Λ[sub c] and &Λmacr;[sub c] that was measured in Σ[sup -]A collisions at p[sub L] = 600 GeV/c in the E781 experiment is also described within this scheme. The QGSM results are compared with the results of the calculations in the next-to-leading approximation of perturbative QCD that were performed by other authors. [ABSTRACT FROM AUTHOR]

In this paper, we investigate an SU(3) extension of the chiral quark-meson model. The spectra of baryons with strangeness, charm, and bottom are considered within a "rigid oscillator" version of this model. The similarity between the quark sector of the Lagrangian in the model and the Wess-Zumino term in the Skyrme model is noted. The binding energies of baryonic systems with baryon numbers B = 2 and 3 possessing strangeness or heavy flavor are also estimated. The results are in good qualitative agreement with those obtained previously in the chiral soliton (Skyrme) model. [ABSTRACT FROM AUTHOR]