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The mass spectrum of the L=1 orbitally excited heavy baryons with light quarks in the spin-flavor symmetric representation is studied by the $1/N_c$ expansion method in the framework of the heavy quark effective theory. The mixing effect from the baryons in the mixed representation is considered. The general pattern of the spectrum is predicted which will be verified by the experiments in the near future. The $1/m_Q$ and SU(3) corrections are also considered. Mass relations for the baryons $\Lambda_{c1}^{(*)}$, $\Sigma_{c1}^{(*)}$, $\Xi_{c1}^{(')(*)}$, and $\Omega_{c1}^{(*)}$ are derived., Comment: 13 pages, revTex, no figure, to appear in PRD, Liu's above address corrected

We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate $\Gamma (\bar B \to X_s\gamma$) and the rate of a free b-quark decay. The main features of our approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the $\bar B$-meson. Using various b-quark light-front (LF) distribution functions, both phenomenological one and the ones derived from current constituent quark models, and neglecting perturbative corrections we compute the photon energy spectra and the moments of the shape function. It is shown that the parton-like approach is fully consistent with the Heavy Quark Effective Theory (HQET) provided the b-quark constituent mass is redefined in the way similar to that used in HQET to define the pole mass of the b quark. In this way the correction to first order in $1/m_b$ can be eliminated from the total width in agreement with the general statement of HQET. We have also found that the photon energy spectra calculated in the LF approach agree well with the ones obtained in the ACM model, provided the same distribution function is used as input in both cases. In spite of the simplicity of the model our results show a fair good agreement both with the HQET predictions and available experimental data., Comment: 14 pages, LaTeX, 3 ps figures

The decay of $��_b\to��_c^{(*)}��l{\bar��}$ processes are calculated in the framework of heavy baryon chiral perturbation theory with help of the $1/N_c$ expansion. The decay rate distributions over $v\cdot v^{\prime}$ where $v$ and $v^{\prime}$ are the 4-vector velocities of $��_b$ and $��_c^{(*)}$ respectively, and over the pion and lepton energies are given. The decay branching ratios amount to about $1.21(0.971)%$ for $��_b\to��_c��l{\bar��}$ and $0.798(0.640)%$ for $��_b\to��_c^*��l{\bar��}$ by using the baryonic Isgur-Wise function predicted by QCD sum rule (large $N_c$ QCD)., 17 pages, 8 figures, to appear in PRD

We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate $��(\bar B \to X_s��$) and the rate of a free b-quark decay. The main features of our approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the $\bar B$-meson. Using various b-quark light-front (LF) distribution functions, both phenomenological one and the ones derived from current constituent quark models, and neglecting perturbative corrections we compute the photon energy spectra and the moments of the shape function. It is shown that the parton-like approach is fully consistent with the Heavy Quark Effective Theory (HQET) provided the b-quark constituent mass is redefined in the way similar to that used in HQET to define the pole mass of the b quark. In this way the correction to first order in $1/m_b$ can be eliminated from the total width in agreement with the general statement of HQET. We have also found that the photon energy spectra calculated in the LF approach agree well with the ones obtained in the ACM model, provided the same distribution function is used as input in both cases. In spite of the simplicity of the model our results show a fair good agreement both with the HQET predictions and available experimental data., 14 pages, LaTeX, 3 ps figures

L=1 excited heavy baryon masses are analyzed by heavy quark and large N_c expansions. In heavy quark limit, mass is parameterized by \Lambda-bar and it is expanded further by spin-flavor breaking operators to the zeroth order of 1/N_c. Expanding coefficients will be fixed by more data on the excited baryons in the near future., Comment: 13 pages, revtex, one figure, submitted to Phys. Rev. D

The Lambda_b to Lambda_c semileptonic decay is analyzed in the framework of heavy quark effective theory to the order of 1/m_c and 1/m_b. The QCD sum rule and large N_c predictions to the decay form factors are applied. It argues that the subleading baryonic Isgur-Wise function in the large N_c limit vanishes. The decay rates, distributions and asymmetry parameters are calculated numerically. Some of the nonleptonic decay modes are discussed in the end., 20 pages, latex, 4 figures, to appear in Phys. Rev. D (1998)

It is pointed out that the radiative decays of a $\phi$ meson, $\phirho$ and $\phiom$, receive dominant contributions from the pseudoscalar ($P = \eta, \eta^{'}$) exchanges. Using the vector meson dominance model, we find that $B (\phirho) \approx 1.3 \times 10^{-4}$ and $B (\phiom) \approx 1.5 \times 10^{-5}$, which are mainly from the $\eta^{'}$ pole. Thus, these decays are well within the reach of the $\phi$ factory. Our estimates are a few orders of magnitude larger than the chiral loop contributions in the heavy vector meson chiral lagrangian, which is about ( a few ) $\times 10^{-9}$., Comment: 10 pages, 2 Encapsuled-Postscript figures, uses epsfig.sty

It is pointed out that the radiative decays of a $��$ meson, $\phirho$ and $\phiom$, receive dominant contributions from the pseudoscalar ($P = ��, ��^{'}$) exchanges. Using the vector meson dominance model, we find that $B (\phirho) \approx 1.3 \times 10^{-4}$ and $B (\phiom) \approx 1.5 \times 10^{-5}$, which are mainly from the $��^{'}$ pole. Thus, these decays are well within the reach of the $��$ factory. Our estimates are a few orders of magnitude larger than the chiral loop contributions in the heavy vector meson chiral lagrangian, which is about ( a few ) $\times 10^{-9}$., 10 pages, 2 Encapsuled-Postscript figures, uses epsfig.sty

The spin and flavor symmetries of the heavy quark effective theory are employed to discuss the exclusive cross sections for pair production of heavy mesons in photon-photon collision. The ratios of the exclusive cross sections for heavy mesons are obtained explicitly and the validity of results is discussed., Comment: 10pages (LaTex) (two figures, available on request), SNUTP 92-57

The spin and flavor symmetries of the heavy quark effective theory are employed to discuss the exclusive cross sections for pair production of heavy mesons in photon-photon collision. The ratios of the exclusive cross sections for heavy mesons are obtained explicitly and the validity of results is discussed., 10pages (LaTex) (two figures, available on request), SNUTP 92-57