Microscopic derivation of the pion coupling to heavy-light mesons

The Goldberger--Treiman relation for heavy--light systems is derived in the context of a quark model. As a paradigmatic example, the case of ${\bar D}\to {\bar D}' \pi$ is studied in detail. The fundamental role played by the pion two-component wave function, in the context of the Salpeter equation, is emphasized.Comment: 6 pages, 2 figures, version to appear in Phys. Rev.

On two- and three-body descriptions of hybrid mesons

Hybrid mesons are exotic mesons in which the color field is not in its ground state. Their understanding deserves interest from a theoretical point of view, because it is intimately related to nonperturbative aspects of QCD. In this work, we analyze and compare two different descriptions of hybrid mesons, namely a two-body $q\bar q$ system with an excited string, or a three-body $q\bar q g$ system. In particular, we show that the constituent gluon approach is equivalent to an effective excited string in the heavy hybrid sector. Instead of a numerical resolution, we use the auxiliary field technique. It allows to find simplified analytical mass spectra and wave functions, and still leads to reliable qualitative predictions. We also investigate the light hybrid sector, and found a mass for the lightest hybrid meson which is in satisfactory agreement with lattice QCD and other effective models.Comment: 2 figure

Parity doublers in chiral potential quark models

The effect of spontaneous breaking of chiral symmetry over the spectrum of highly excited hadrons is addressed in the framework of a microscopic chiral potential quark model (Generalised Nambu-Jona-Lasinio model) with a vectorial instantaneous quark kernel of a generic form. A heavy-light quark-antiquark bound system is considered, as an example, and the Lorentz nature of the effective light-quark potential is identified to be a pure Lorentz-scalar, for low-lying states in the spectrum, and to become a pure spatial Lorentz vector, for highly excited states. Consequently, the splitting between the partners in chiral doublets is demonstrated to decrease fast in the upper part of the spectrum so that neighboring states of an opposite parity become almost degenerate. A detailed microscopic picture of such a "chiral symmetry restoration" in the spectrum of highly excited hadrons is drawn and the corresponding scale of restoration is estimated.Comment: LaTeX2e, 4 pages, uses aipproc class, Talk given by A.Nefediev at the conference "Quark Confinement and the Hadron Spectrum VII", 2-7 September 2006, Acores, Portugal, to appear in Proceeding

Confinement and parity doubling in heavy-light mesons

In this paper, we study the chiral symmetry restoration in the hadronic spectrum in the framework of generalised Nambu-Jona-Lasinio quark models with instantaneous confining quark kernels. We investigate a heavy-light quarkonium and derive its bound-state equation in the form of a Schroedingerlike equation and, after the exact inverse Foldy-Wouthuysen transformation, in the form of a Diraclike quation. We discuss the Lorentz nature of confinement for such a system and demonstrate explicitly the effective chiral symmetry restoration for highly excited states in the mesonic spectrum. We give an estimate for the scale of this restoration.Comment: RevTeX4, 21 pages, 6 Postscript figures, uses epsfig.sty, to appear in Phys.Rev.

Chiral symmetry restoration in excited hadrons, quantum fluctuations, and quasiclassics

In this paper, we discuss the transition to the semiclassical regime in excited hadrons, and consequently, the restoration of chiral symmetry for these states. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of the instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. It has been shown recently that the effective single-quark potential is of the Lorentz-scalar nature, for the low-lying hadrons, while, for the high-lying states, it becomes a pure Lorentz vector and hence the model exhibits the restoration of chiral symmetry. We demonstrate explicitly the quantum nature of chiral symmetry breaking, the absence of chiral symmetry breaking in the classical limit as well as the transition to the semiclassical regime for excited states, where the effect of chiral symmetry breaking becomes only a small correction to the classical contributions.Comment: RevTeX4, 20 pages, 4 Postscript figures, uses epsfig.sty, typos correcte

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

We investigate the enhancement in the D^0\bar{D}^0\pi^0 final state with the mass M=3875.2\pm 0.7^{+0.3}_{-1.6}\pm 0.8 MeV found recently by the Belle Collaboration in the B\to K D^0\bar{D}^0\pi^0 decay and test the possibility that this is yet another manifestation of the well-established resonance X(3872). We perform a combined Flatte analysis of the data for the D^0\bar{D}^0\pi^0 mode, and for the \pi^+\pi^- J/\psi mode of the X(3872). Only if the X(3872) is a virtual state in the D^0\bar{D}^{*0} channel, the data on the new enhancement comply with those on the X(3872). In our fits, the mass distribution in the D^0\bar{D}^{*0} mode exhibits a peak at 2-3 MeV above the D^0\bar{D}^{*0} threshold, with a distinctive non-Breit-Wigner shape.Comment: RevTeX4, 17 pages, some references updated and corrected, version published in Phys. Rev.

Spatial asymmetry of optically excited spin waves in anisotropic ferromagnetic film

We analytically discuss and micromagnetically prove the ways to tune the spatial asymmetry of the initial phase, amplitude, and wavevectors of magnetostatic waves driven by ultrafast laser excitation. We consider that the optical pulse heats a thin ferromagnetic metallic film and abruptly decreases the saturation magnetization and the parameter of uniaxial anisotropy. The two corresponding terms of laser-induced torque have different azimuthal symmetries, with the 4-fold symmetry of the demagnetization-related term, and the isotropic distribution of the anisotropy-related term. As a result, the initial phase and amplitude of excited magnetostatic waves have a non-trivial azimuthal distribution tunable with the angle between the external magnetic field and anisotropy axis, and the laser spot diameter. Moreover, the variation of these parameters tunes the distribution of wavevectors, resulting in additional asymmetry between the spectral components of the waves propagating in different directions.Comment: 8 pages, 5 figure

Features of Written Existence of Charm Tradition in Ulyanovsk Volga Region

The features of the written existence of charm tradition are considered. The texts from the so-called “cherished notebooks,” which are understood as a kind of manuscript collections created by Russian peasants in the territory of the Ulyanovsk Volga region, mainly by women, in the second half of the 20th - early 21st centuries, are analyzed. It is shown that these notebooks include primarily texts intended for home worship: prayers, Psalms, spiritual verses, etc. It is noted that in some of them there are also traditional charms and prayers that functioned as charms. The material for this research was “cherished notebooks” collected in the period from 1995 to 2008 during folklore expeditions of the Department of Literature of Ulyanovsk State Pedagogical University named after I. N. Ulyanov and stored in the archive of scientific and educational center “Traditional culture and folklore of the Ulyanovsk Volga region.” This article presents the results of the analysis of data on the owners of “cherished notebooks”: the division by sex and age. The geography of this tradition is reported. The content and structure of notebooks are characterized. Attention is paid to the typology of charms recorded in the “cherished notebooks.