Baryon Masses in the 1/N Expansion

The masses of baryons and heavy quark baryons are studied analytically in an expansion in 1/N, SU(3) flavor symmetry breaking and heavy-quark symmetry breaking. The measured baryon masses are in striking agreement with the 1/N hierarchy.Comment: Lattice 2000 (Spectrum

Charm and Bottom Baryon Masses in the 1/N Expansion

The masses of heavy quark baryons are studied in an expansion in 1/N_c, SU(3) flavor symmetry breaking, and heavy-quark symmetry breaking. Very accurate model-independent mass relations are obtained for charm and bottom baryons.Comment: Proceedings of ICHEP2002, Amsterda

Hyperfine Mass Splittings of Baryons Containing a Heavy Quark in Large N QCD

The hyperfine mass splittings of baryons containing a heavy quark are derived at leading order in large $N$ QCD. Hyperfine splittings either preserve or violate heavy quark spin symmetry. Previous work proves that the splittings which preserve heavy quark spin symmetry are proportional to ${\bf J}^2$ at order $1/N$, where $J$ is the angular momentum of the light degrees of freedom of the baryon. This work proves that the splittings which violate heavy quark spin symmetry are proportional to ${\bf J} \cdot {\bf S_Q}$ at order $1/(N m_Q)$ in the $1/N$ and $1/m_Q$ expansions.Comment: (8 pages, no figures, uses harvmac), UCSD/PTH 93-2

Baryon-Pion Couplings from Large-N QCD

We derive a set of consistency conditions for the pion-baryon coupling constants in the large-N limit of QCD. The consistency conditions have a unique solution which are precisely the values for the pion-baryon coupling constants in the Skyrme model. We also prove that non-relativistic $SU(2N_f)$ spin-flavor symmetry (where $N_f$ is the number of light flavors) is a symmetry of the baryon-pion couplings in the large-N limit of QCD. The symmetry breaking corrections to the pion-baryon couplings vanish to first order in $1/N$. Consistency conditions for other couplings, such as the magnetic moments are also derived.Comment: (12 pages, 2 figs, uses harvmac and uufiles), UCSD/PTH 93-1

Large-N Baryons, Chiral Loops, and the Emergence of the Constituent Quark

Meson loop corrections to baryon axial currents are computed in the 1/N expansion. It is already known that the one-loop corrections are suppressed by a factor 1/N; here it is shown that the two-loop corrections are suppressed by (1/N)^2. To leading order, these corrections are exactly what would be calculated in the constituent quark model. Some applications are discussed

Light Quark Spin-Flavor Symmetry for Baryons Containing a Heavy Quark in Large N QCD

The couplings and interactions of baryons containing a heavy quark are related by light quark spin-flavor symmetry in the large $N$ limit. The single pion coupling constant which determines all heavy quark baryon-pion couplings is equal to the pion coupling constant for light quark baryons. Light quark symmetry relations amongst the baryon couplings are violated at order $1/N^2$. Heavy quark spin-flavor symmetry is used in conjunction with large $N$ light quark spin-flavor symmetry to determine the couplings of the degenerate doublets of heavy quark baryons.Comment: (14 pages, 2 figs, uses harvmac and uufiles), UCSD/PTH 93-1

Recent Results in Chiral Perturbation Theory for Mesons Containing a Single Heavy Quark

Chiral symmetry and heavy quark symmetry constrain the interactions of mesons containing a single heavy quark with low-momentum pions. Chiral corrections to the Isgur-Wise function for $\bar B_s \rightarrow D_s^{(*)}$ versus $\bar B \rightarrow D^{(*)}$ semileptonic decay, the ratio of heavy meson decay constants $f_{D_s}/ f_D$ or $f_{B_s}/ f_B$, the amplitudes for $B_s - \bar B_s$ versus $B^0 - \bar B{\,}^0$ mixing, and the heavy meson mass splittings are calculated in chiral perturbation theory. (Invited talk Rencontres de Moriond 1993)Comment: UCSD/PTH 93-10, 6 pages, 2 figure