arXiv subjects
Publications and source records attributed to S. Veseli.
We present a simple and straightforward method for relating the form factors in HQET, as defined by the covariant trace formalism, to the overlaps of the rest frame wave functions of the light degrees of freedom. We also point out several inconsistencies present in recent calculations of the radiative rare $B$ decays, and also show how these can be fixed even within the framework of the non-relativistic quark model.
Quark-antiquark bound states are examined in the long-range strong-coupling limit with the minimal area law of lattice gauge theory assumed as input. Matrix element relations are established which in the effective theory obtain dynamical equations equivalent to a formulation of the flux-tube model.
We present a systematic algebraic and numerical investigation of the instantaneous Bethe-Salpeter equation. Emphasis is placed on confining interaction kernels of the Lorentz scalar, time component vector, and full vector types. We explore stability of the solutions and Regge behavior for each of these interactions, and conclude that only time component vector confinement leads to normal Regge structure and stable solutions.
We use a $1S$ lattice QCD heavy-light wavefunction to generate a single parameter, model independent description of the Isgur-Wise function. Using recent data we find the zero-recoil slope to be $ξ'(1)= -1.16\pm 0.17$, while the second derivative turns out to be $ξ''(1)= 2.64\pm 0.74$.
We consider possible dynamical models for a light fermion confined by a potential field. With the Dirac equation only Lorentz scalar confinement yields normalizable wavefunctions, while with the ``no pair'' variant of the Dirac equation only Lorentz vector confinement has normal Regge behaviour. A systematic investigation of Regge properties and phenomenological properties is carried out, including calculations of the Isgur-Wise function. We point out that the Isgur-Wise function provides a sensitive test of confinement models. In particular, the slope of the IW function at zero recoil point is found to be $ξ'(1)\simeq -0.90$ for the Dirac equation with scalar confinement, and $ξ'(1)\simeq -1.20$ for the no pair equation with vector confinement. Using heavy-light data alone we argue against scalar confinement.
The Relativistic Flux Tube model is used to calculate of the Isgur-Wise functions describing the exclusive semileptonic decays of $\bar{B}$ and $\bar{B}_{s}$ mesons. The light quark mass dependence is investigated and the predicted universal function agrees well with the results of lattice simulations, and with the experimental data. Recent experimental measurements of the $\bar{B}\ra D^{*}l\barν_{l}$ decay distribution yield the CKM element $V_{bc}=0.035\pm 0.001$. The IW function slope and second derivative at the zero recoil point are predicted to be $ξ'(1) = -0.93\pm 0.04$ and $ξ''(1)= 1.7\pm 0.1$ for a range of light quark massses. The importance of including higher derivatives in analyses of experiment is emphasized.