A. V. Nefediev

Reconciling the X(3872) with the near-threshold enhancement in the D{sup 0}D*{sup 0} final state

We investigate the enhancement in the DD̄π final state with the mass M = 3875.2 ± 0.7 −1.6 ± 0.8 MeV found recently by the Belle Collaboration in the B → KDD̄π decay and test the possibility that this is yet another manifestation of the well–established resonance X(3872). We perform a combined Flattè analysis of the data for the DD̄π mode, and for the ππJ/ψ mode of the X(3872). Only if the X(3872) is a virtual state in the DD̄ channel, the data on the new enhancement comply with those on the X(3872). In our fits, the mass distribution in the DD̄ mode exhibits a peak at 2 ÷ 3 MeV above the DD̄ threshold, with a distinctive non-Breit–Wigner shape.

Insight into scalar mesons from their radiative decays

We estimate the rates for radiative transitions of the lightest scalar mesons f{sub 0}(980) and a{sub 0}(980) to the vector mesons {rho} and {omega}. We argue that measurements of the radiative decays of those scalar mesons can provide important new information on their structure.

The radiative decays Φ → γa0/f0 in the molecular model for the scalar mesons

Abstract.We investigate the radiative decays of the φ-meson to the scalar mesons a0(980) and f0(980). We demonstrate that, contrary to earlier claims, these decays should be of the same order of magnitude for a molecular state and for a compact state and, therefore, the available experimental information is consistent with both a molecular as well as a compact structure of the scalars. Thus, the radiative decays of the φ-meson into scalars establish a sizable K¯ component of the scalar mesons, but do not allow to discriminate between molecules and compact states.

Interplay of quark and meson degrees of freedom in a near-threshold resonance: Multi-channel case

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. PACS. 12.38.Lg – 11.55.Bq – 12.39.Mk

Nature of X(3872) from data

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 DD̄∗ system, the new Belle data clearly indicate a sizable cc̄ 2P1 component in the X wave function.

Interplay of quark and meson degrees of freedom in a near-threshold resonance

We investigate the interplay of quark and meson degrees of freedom in a physical state representing a near-threshold resonance for the case of a single continuum channel. We demonstrate that such a near-threshold resonance may possess quite peculiar properties if both quark and meson dynamics generate weakly coupled near-threshold poles in the S -matrix. In particular, the scattering t -matrix may possess zeros in this case. We also discuss possible implications for production reactions as well as studies within lattice QCD.

Interplay of quark and meson degrees of freedom in near-threshold states: A practical parametrization for line shapes

We propose a practical parametrization for the line shapes of near-threshold states compatible with all requirements of unitarity and analyticity. The coupled-channel system underlying the proposed parametrization includes bare poles and an arbitrary number of elastic and inelastic channels treated fully nonperturbatively. The resulting formulas are general enough to be used for a simultaneous analysis of the data in all available production and decay channels of the (system of) state(s) under consideration for a quite wide class of reactions. As an example, we fit the experimental data currently available for several decay channels for the charged Z(b)((r)) states in the spectrum of bottomonia and find a good overall description of the data. We find the present data to be consistent with the Z(b)(10610) as a virtual state and with the Z(b)(10650) as a resonance, both residing very close to the B (B) over bar* and B*(B) over bar* threshold, respectively.

Three-body Ddquer pion dynamics for the X(3872)

We investigate the role played by the three-body

Heavy-light mesons spectrum from the nonperturbative QCD in the einbein field formalism

Dbar{D}pi

Practical Parametrization for Line Shapes of Near-Threshold States.

dynamics on the near-threshold resonance X(3872) charmonium state, which is assumed to be formed by nonperturbative