A. V. Nefediev

Institute for Theoretical and Experimental Physics, Moskva, Moscow, Russia

Are you A. V. Nefediev?

Claim your profile

Publications (81)116.54 Total impact

  • Source
    A. Denig, Feng-Kun Guo, C. Hanhart, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: Direct production of the charmonium-like state $X(3872)$ in $e^+e^-$ collisions is considered in the framework of the vector meson dominance model. An order-of-magnitude estimate for the width $\Gamma(X\to e^+e^-)$ is found to be $\gtrsim$0.03 eV. The same approach applied to the $\chi_{c1}$ charmonium decay predicts the corresponding width of the order 0.1 eV in agreement with earlier estimates. Experimental perspectives for the direct production of the $1^{++}$ charmonia in $e^+e^-$ collisions are briefly discussed.
    05/2014;
  • A. Denig, Feng-Kun Guo, C. Hanhart, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: Direct production of the charmonium-like state $X(3872)$ in $e^+e^-$ collisions is considered in the framework of the vector meson dominance model. An order-of-magnitude estimate for the width $\Gamma(X\to e^+e^-)$ is found to be $\gtrsim$0.03 eV. The same approach applied to the $\chi_{c1}$ charmonium decay predicts the corresponding width of the order 0.1 eV in agreement with earlier estimates. Experimental perspectives for the direct production of the $1^{++}$ charmonia in $e^+e^-$ collisions are briefly discussed.
    04/2014;
  • Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: The 1 D 2 charmonium assignment for the X(3872) is considered, which is compatible with the 2-+ quantum numbers, as favoured by the BABAR Collaboration analysis presented recently for the π + π - π 0 J/ψ decay mode. It is demonstrated that established properties of the X(3872) are in a drastic conflict with the 1 D 2 c assignment. Furthermore, it is argued that a combined analysis of the data for different decay channels of the X, with the help of theoretical formulae which meet a number of constraints imposed by phenomenology, results in a suitable description of the experimental data for the X compatible with its quantum numbers 1++.
    Physics of Atomic Nuclei 11/2013; 76(12). · 0.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We explore the quark-mass dependence of the pole position of the X(3872) state within the molecular picture. The calculations are performed within the framework of a nonrelativistic Faddeev-type three-body equation for the $D\bar{D}\pi$ system in the $J^{PC}=1^{++}$ channel. The $\pi D$ interaction is parametrised via a $D^*$ pole, and a three-body force is included to render the equations well defined. Its strength is adjusted such that the X(3872) appears as a $D\bar{D}^*$ bound state 0.5 MeV below the neutral threshold. We find that the trajectory of the X(3872) depends strongly on the assumed quark-mass dependence of the short-range interactions which can be determined in future lattice QCD calculations. At the same time we are able to provide nontrivial information on the chiral extrapolation in the $X$ channel.
    Physics Letters B 06/2013; 726(1). · 4.57 Impact Factor
  • Source
    Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: We re-examine one-pion exchange as a possible binding mechanism in the X(3872) charmonium-like state and argue it to be not sufficiently binding for this purpose. We conclude therefore that other short-range dynamics are responsible for the X formation.
    JETP Letters 12/2012; 97(2). · 1.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We point out the physics opportunities of future high-luminosity B-factories at the Upsilon(5S) resonance and above. In this paper we discuss numerous interesting investigations, which can be performed in the e+e- centre-of-mass energy region from the Upsilon(5S) and up to 11.5 GeV, where an efficient data taking operation should be possible with the planned B-factories. These studies include abundant Bs production and decay properties; independent confirmation and if found, exhaustive exploration of Belle's claimed charged bottomonia; clarification of puzzles of interquarkonium dipion transitions; extraction of the light quark mass ratio from hadronic Upsilon(5S) decays; analysis of quarkonium and exotic internal structure from open flavour decays, leading to severe SU(3) symmetry violations; clarification of whether a hybrid state has similar mass to the Upsilon(5S) bottomonium, making it a double state; searches for molecular/tetraquark states that should be more stable with heavy quarks; completion of the table of positive-parity B_J mesons and study of their basic properties; production of Lambda_b\bar{Lambda}_b heavy baryon pairs, that, following weak decay, open vistas on the charmed baryon spectrum and new channels to study CP violation; confirmation or refutation of the deviation from pQCD of the pion transition form factor, by extending the Q^2 reach of current analysis; and possibly reaching the threshold for the production of triply-charmed baryons. If, in addition, the future colliders can be later upgraded to 12.5 GeV, then the possibility of copious production of B_c\bar{B}_c pairs opens, entailing new studies of CP violation and improved, independent tests of the CKM picture (through determination of V_{bc}), and of effective theories for heavy quarks.
    European Physical Journal A 10/2012; 49(1). · 2.04 Impact Factor
  • Source
    A. V.nefediev, Yu. A.simonov, M. A.trusov
    [Show abstract] [Hide abstract]
    ABSTRACT: The theory of confinement and deconfinement is discussed as based on the properties of the QCD vacuum. The latter are described by field correlators of color-electric and color-magnetic fields in the vacuum, which can be calculated analytically and on the lattice. As a result one obtains a self-consistent theory of the confined region in the (μ, T) plane with realistic hadron properties. At the boundary of the confining region, the color-electric confining correlator vanishes, and the remaining correlators describe strong nonperturbative dynamics in the deconfined region with (weakly) bound states. Resulting equation of state for μ = 0, p(T), are in good agreement with lattice data. Phase transition occurs due to evaporation of a part of the color-electric gluon condensate, and the resulting critical temperatures Tc(μ) for different nf are in good correspondence with available data.
    International Journal of Modern Physics E 01/2012; 18(03). · 0.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We re-analyse the two- and three-pion mass distributions in the decays X(3872)->rho J/psi and X(3872)->omega J/psi and argue that the present data favour the 1++ assignment for the quantum numbers of the X.
    Physical review D: Particles and fields 11/2011; 85(1).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the role played by the three-body DD̅ π dynamics on the near-threshold resonance X(3872) charmonium state, which is assumed to be formed by nonperturbative DD̅ * dynamics. It is demonstrated that, as compared to the naive static-pions approximation, the imaginary parts that originate from the inclusion of dynamical pions reduce substantially the width from the DD̅ π intermediate state. In particular, for a resonance peaked at 0.5 MeV below the D0D̅ *0 threshold, this contribution to the width is reduced by about a factor of 2, and the effect of the pion dynamics on the width grows as long as the resonance is shifted towards the D0D̅ 0π0 threshold. Although the physical width of the X is dominated by inelastic channels, our finding should still be of importance for the X line shapes in the DD̅ π channel below DD̅ * threshold. For example, in the scattering length approximation, the imaginary part of the scattering length includes effects of all the pion dynamics and does not only stem from the D* width. Meanwhile, we find that another important quantity for the X phenomenology, the residue at the X pole, is weakly sensitive to dynamical pions. In particular, we find that the binding energy dependence of this quantity from the full calculation is close to that found from a model with pointlike DD̅ * interactions only, consistent with earlier claims. Coupled-channel effects (inclusion of the charged DD̅ * channel) turn out to have a moderate impact on the results.
    Physical review D: Particles and fields 10/2011; 84(7).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the role played by the three-body $D\bar{D}\pi$ dynamics on the near-threshold resonance X(3872) charmonium state, which is assumed to be formed by nonperturbative $D\bar D^*$ dynamics. It is demonstrated that, as compared to the naive static-pions approximation, the imaginary parts that originate from the inclusion of dynamical pions reduce substantially the width from the $D\bar{D}\pi$ intermediate state. In particular, for a resonance peaked at 0.5 MeV below the $D^0\bar D^{*0}$ threshold, this contribution to the width is reduced by about a factor of 2, and the effect of the pion dynamics on the width grows as long as the resonance is shifted towards the $D^0\bar{D^0}\pi^0$ threshold. Although the physical width of the $X$ is dominated by inelastic channels, our finding should still be of importance for the $X$ line shapes in the $D\bar{D}\pi$ channel below $D{\bar D}^*$ threshold. For example, in the scattering length approximation, the imaginary part of the scattering length includes effects of all the pion dynamics and does not only stem from the $D^*$ width. Meanwhile, we find that another important quantity for the $X$ phenomenology, the residue at the $X$ pole, is weakly sensitive to dynamical pions. In particular, we find that the binding energy dependence of this quantity from the full calculation is close to that found from a model with pointlike $D\bar D^*$ interactions only, consistent with earlier claims. Coupled-channel effects (inclusion of the charged $D\bar{D}^*$ channel) turn out to have a moderate impact on the results.
    08/2011;
  • J. E. F. T. Ribeiro, D. Antonov, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: A possibility is suggested for the formation in the Universe of domains occupied by coherent‐like states of strongly correlated quark‐antiquark pairs. Only domains of the radius larger than 5 fm had a chance to survive over the entire history of the Universe, while the requirement of stability against the gravitational collapse restricts the maximum domain’s radius to 14 km. Within the Generalised Nambu–Jona‐Lasinio model, an exponential suppression with the domain’s volume is found for the overlap between the macroscopic ground‐state wavefunction of the quark‐antiquark pairs and the QCD vacuum. This finding supports, at the microscopic level, the above arguments in favour of the stability of the domains.
    AIP Conference Proceedings. 05/2011; 1343(1):571-573.
  • Source
    C. Hanhart, Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the interplay of quark and meson degrees of freedom in a physical state representing a near-threshold resonance for the case of multiple continuum channels. The aim is to demonstrate the full complexity of possible near-threshold phenomena. It turns out that those are especially rich, if both quark and meson dynamics generate simultaneously weakly coupled near-threshold poles in the S-matrix. We study the properties of this scenario in detail, such as t-matrix and production amplitude zeros, as well as various effects of the continuum channels interplay.
    European Physical Journal A 01/2011; 47(8):1-10. · 2.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Formation of stable domains filled with strongly correlated coherent quark matter is discussed in general terms and is exemplified further in the framework of the Generalised Nambu-Jona-Lasinio model. It is argued that such domains, if exist in the Universe, appear dark to an external observer.
    JETP Letters 11/2010; 92(11). · 1.52 Impact Factor
  • Source
    D. Antonov, J. E. F. T. Ribeiro, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: We suggest the possibility of creation in the early Universe of stable domains of radius a few kilometers wide, formed by coherently excited states of $\pi$-mesons. Such domains appear dark to an external observer, since the decay rate of the said coherent pionic states into photons is vanishingly small. The related thermal insulation of the domains from the outer world could have allowed them to survive till present days. The estimated maximum radius and the period of rotation of such objects turn out to be compatible with those of certain pulsars. Comment: 30 pages, 4 figures
    08/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate that in calculation, where unitarity constraints are properly imposed, the deeply bound hadronic molecules recently proposed by Close and Downum do not exist.
    Physical Review Letters 07/2010; 105(1):019101. · 7.73 Impact Factor
  • Source
    C. Hanhart, Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: We discuss on very general grounds possible lineshapes of composite particles with one unstable constituent. Expressions are derived in a coupled-channel formalism for constituents interacting in an S-wave with no assumption made on the width of one of them. We show how easy-to-use formulae, already existing in the literature, emerge for narrow constituents and identify the parameter that controls the regime of their applicability. Comment: RevTeX4, 27 pages, short discussions added, typos corrected, references updated, to appear in Phys.Rev.D
    Physical review D: Particles and fields 02/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: A procedure for investigation of the contents of hadronic states is discussed in detail as based on the original Weinberg approach. The case of the charmonium-like state X(3872) is considered as a paradigmatic example of application of the developed approach.
    Physics of Atomic Nuclei 01/2010; 73(9):1592-1611. · 0.54 Impact Factor
  • Source
    Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: The D21 charmonium assignment for the X(3872) meson is considered, as prompted by a recent result from the BABAR Collaboration, favoring 2-+ quantum numbers for X. It is shown that established properties of X(3872) are in a drastic conflict with the D21 cc¯ assignment.
    Physical review D: Particles and fields 01/2010; 82.
  • Source
    Yu. S. Kalashnikova, A. V. Nefediev
    [Show abstract] [Hide abstract]
    ABSTRACT: Properties of the charmonium-like state X(3872) are investigated and its nature is discussed as based on the existing experimental data. In particular, we analyse the new data from Belle and BaBar Collaborations and argue that, while the BaBar data prefer the dynamically generated virtual state in the D\bar{D}* system, the new Belle data clearly indicate a sizable c\bar{c} 2^3P_1 component in the X wave function. Comment: RevTeX4, 25 pages
    Physical review D: Particles and fields 07/2009;
  • Source
    A. V. Nefediev, J. E. F. T. Ribeiro
    [Show abstract] [Hide abstract]
    ABSTRACT: Generalised Nambu-Jona-Lasinio model for QCD is considered at finite temperatures in the framework of a real-time formalism. The proposed approach allows one to study various properties of the model at T>0, such as chiral symmetry breaking and restoration, properties of the bound-state spectrum, and so on. Comment: LaTeX2e, 6 pages, uses jetpl.cls (included), version to appear in JETP Lett
    JETP Letters 06/2009; · 1.52 Impact Factor

Publication Stats

826 Citations
116.54 Total Impact Points

Institutions

  • 1995–2013
    • Institute for Theoretical and Experimental Physics
      Moskva, Moscow, Russia
  • 2008
    • Karl-Franzens-Universität Graz
      • Institute of Physics
      Graz, Styria, Austria
  • 2006
    • Forschungszentrum Jülich
      • Institut für Kernphysik (IKP)
      Düren, North Rhine-Westphalia, Germany
  • 2001–2003
    • Instituto Técnico y Cultural
      Santa Clara de Portugal, Michoacán, Mexico
    • Instituto Superior de Contabilidade e Administração de Lisboa
      Lisboa, Lisbon, Portugal