Analyses of decay constants and light-cone distribution amplitudes for s-wave heavy meson

In this paper, a study of light-cone distribution amplitudes (LCDAs) for $s$-wave heavy meson are presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, $\phi_M(u)$, and their relevant decay constants of heavy pseudoscalar and vector mesons, $f_M$, have simple relations. These relations can be further simplified when the heavy quark limit is taken into consideration. After fixing the parameters that appear in both Gaussian and power-law wave functions, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six $\xi$-moments of $\phi_M(u)$ are plotted and estimated. A conclusion is drawn from these results: Even though the values of the decay constants of the distinct mesons are almost equal, the curves of their LCDAs may have quite large differences, and vice versa. Additionally, in the heavy quark limit, the leading twist LCDAs, $\Phi_{Qq}(\omega)$ and $\Phi_{Qq}(\omega)$, are compared with the $B$-meson LCDAs, $\psi_+(\omega)$, suggested by the other theoretical groups.Comment: 25 pages, 3 figures, 4 tables, some typos are corrected, version to be published in Phys. Rev.

Observations on the radiative corrections to pion beta-decay

We find that, in the local V-A theory, the radiative corrections to pion beta-decay involving the weak vector current, when evaluated in the current algebra (CA) formulation in which quarks are the fundamental underlying fields, show a small difference with the more elementary calculations based directly on the pion fields. We show that this difference arises from a specific short-distance effect that depends on the algebra satisfied by the weak and electromagnetic currents. On the other hand, we present a simple theoretical argument that concludes that this difference does not occur when the CA formulation is compared with the chiral perturbation theory (chiPT) approach. Comparisons with previous studies, and with a more recent calculation based on chiPT, are included. We also briefly review the important differences between the results in the local V-A theory and the Standard Model.Comment: 5 pages, 1 figure. V2: two paragraphs have been added in Section III. Final version on PR

SU(3) symmetry breaking in decay constants and electromagnetic properties of pseudoscalar heavy mesons

In this paper, the decay constants and mean square radii of pseudoscalar heavy mesons are studied in the SU(3) symmetry breaking. Within the light-front framework, the ratios $f_{D_s}/f_D$ and $f_{B_s}/f_B$ are individually estimated using the hyperfine splittings in the $D_{(s)}^*-D_{(s)}$ and $B_{(s)}^*-B_{(s)}$ states and the light quark masses, $m_{s,q}$ ($q=u,d$), to extract the wave function parameter $\beta$. The values $f_{D_s}/f_D= 1.29\pm0.07$ and $f_{B_s}/f_B= 1.32\pm 0.08$ are obtained, which are not only chiefly determined by the ratio of light quark masses $m_s/m_q$, but also insensitive to the heavy quark masses $m_{c,b}$ and the decay constants $f_{D,B}$. The dependence of $f_{B_c}/f_B$ on $\Delta M_{B_cB^*_c}$ with the varied charm quark masses is also shown. In addition, the mean square radii are estimated as well. The values $\sqrt{} =0.740^{-0.041}_{+0.050}$ and $\sqrt{} =0.711^{-0.049}_{+0.058}$ are obtained, and the sensitivities of $$ on the heavy and light quark masses are similar to those of the decay constants.Comment: 21 pages, 5 figures, 4 tables, some typos are corrected, version to be published in Phys. Rev.

Twist-2 Light-Cone Pion Wave Function

We present an analysis of the existing constraints for the twist-2 light-cone pion wave function. We find that existing information on the pion wave function does not exclude the possibility that the pion wave function attains its asymptotic form. New bounds on the parameters of the pion wave function are presented.Comment: 7 pages, LaTeX, 1 PS-figure, one reference added, minor changes in the tex

Diffractive Higgs Production from Intrinsic Heavy Flavors in the Proton

We propose a novel mechanism for exclusive diffractive Higgs production $pp \to p H p$ in which the Higgs boson carries a significant fraction of the projectile proton momentum. This mechanism will provide a clear experimental signal for Higgs production due to the small background in this kinematic region. The key assumption underlying our analysis is the presence of intrinsic heavy flavor components of the proton bound state, whose existence at high light-cone momentum fraction $x$ has growing experimental and theoretical support. We also discuss the implications of this picture for exclusive diffractive quarkonium and other channels.Comment: 30 pages, 5 figure

Resonant spin-dependent electron coupling in a III-V/II-VI heterovalent double quantum well

We report on design, fabrication, and magnetooptical studies of a III-V/II-VI hybrid structure containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW). The structure design allows one to tune the QW levels into the resonance, thus facilitating penetration of the electron wave function from the diluted magnetic semiconductor ZnCdMnSe QW into the nonmagnetic GaAs QW and vice versa. Magneto-photoluminescence studies demonstrate level anticrossing and strong intermixing resulting in a drastic renormalization of the electron effective g factor, in perfect agreement with the energy level calculations.Comment: 4 pages, 5 Postscript figures, uses revtex

Form factors of the exotic baryons with isospin I=5/2

The electromagnetic form factors of the exotic baryons are calculated in the framework of the relativistic quark model at small and intermediate momentum transfer. The charge radii of the E+++ baryons are determined.Comment: 12pages, 2 figure

Pion Interactions in Chiral Field Theories

We study in various chiral models the pion charge radius, $\pi_{e3}$ form factor ratio, $\pi^\circ \to \gamma \gamma$ amplitude, charge pion polarizabilities, $\gamma\gamma \to \pi^\circ \pi^\circ$ amplitude at low energies and the $\pi\pi$ s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.Comment: 12 pages, 9 eps figure

Pion Generalized Dipole Polarizabilities by Virtual Compton Scattering πe→πeγ\pi e \to \pi e\gamma

We present a calculation of the cross section and the event generator of the reaction $\pi e\to \pi e \gamma$. This reaction is sensitive to the pion generalized dipole polarizabilities, namely, the longitudinal electric $\alpha_L(q^2)$, the transverse electric $\alpha_T(q^2)$, and the magnetic $\beta(q^2)$ which, in the real-photon limit, reduce to the ordinary electric and magnetic polarizabilities $\bar{\alpha}$ and $\bar{\beta}$, respectively. The calculation of the cross section is done in the framework of chiral perturbation theory at ${\cal O}(p^4)$. A pion VCS event generator has been written which is ready for implementation in GEANT simulation codes or for independent use.Comment: 33 pages, Revtex, 15 figure

Relativistic Correction to the First Moment of the Spin-Dependent Structure Function of the Deuteron Γ1D(Q2)\Gamma_1^D(Q^2) in the Light-Cone Formalism

The deuteron is considered as a superposition of two-nucleon Fock states with the invariant mass depending on the relative momentum in a proton-neutron pair. The condition of the transversality of the polarization vectors should be imposed at the Fock component level and these vectors depend on the invariant mass of the Fock component. Such "running" longitudinal polarization vector was not used in early estimates of relativistic effects. The technique for the calculation of the average helicity of the proton in the deuteron has been considered in the light-cone variables. A receipt has been proposed for the consistent calculation of relativistic nuclear corrections to the average helicity of the proton in the deuteron and to the first moment of the spin-dependent structure function of the deuteron.Comment: 34 pages, 6 figures, an extended version of the paper published in Journal of Experimental and Theoretical Physics, 201