Spectrum and Static Properties of Heavy Baryons

Using several realistic interquark potentials, the ground-state energies of all the baryons containing one, two or three heavy quarks of type c or b are studied within a non-relativistic quark model. The three-body problem is rigorously solved using the Faddeev formalism. Various static properties, such as mass radii, charge radii, magnetic moments, and wave functions at the origin are calculated as well. The complete spectrum for all these baryons is computed using a harmonic-oscillator basis with states up to 8 quanta. Emphasis is put on the levels lying below the thresholds corresponding to quark-pair creation. Received December 2, 1994; revised January 30, 1995; accepted for publication February 24, 1995     

Heavy Quark Spin Symmetry and Heavy Baryons: Electroweak Decays

Heavy quark spin symmetry is discussed in the context of single and doubly heavy baryons. A special attention is paid to the constraints/simplifications that this symmetry imposes on the non-relativistic constituent quark model wave functions and on the b ?? c semileptonic decays of these hadrons.     

双重味重子的理想混合角

本工作研究了双重味重子的理想混合角。理想混合角是将$^{2S+1}(l_\lambda)_J$态转换为具有确定重夸克对称性的态时所对应的旋转角度。在标准的$\rho-\lambda$图像下,求得了$L_\rho=0$情形时重夸克对称性的态$\left(J, j_\ell\right)$和$\left(J, s_{\rm q}+j_\rho\right)= $$ \left(J, \{^4l_\lambda/^2l_\lambda\}\right)$态之间的理想混合角,其中${\boldsymbol{j}}_\ell={\boldsymbol{l}}_\lambda+{\boldsymbol{s}}_{\rm q}$, ${\boldsymbol{s}}_\rho={\boldsymbol{s}}_{\rm Q1}+{\boldsymbol{s}}_{\rm Q2}$和${\boldsymbol{j}}_\rho={\boldsymbol{s}}_\rho+{\boldsymbol{L}}_\rho$。本工作指出当研究双重味重子的衰变性质时,需要采用$(1S1p)1/2^-$和$(1S1p)3/2^-$等理想混合态。     

Weak Transition Form Factors Among Heavy to Light and Heavy to Heavy Baryons

The matrix elements among heavy to light and heavy to heavy baryons are evaluated by using the method developed by the author in previous paper. It is found from this method that the form factors can be written down in a simple constructing rule by introducing a set of useful spin tensors. The method also allows us to obtain absolutely normalized form factors at the maximum momentum transfer for Q → Q' or q induced weak transitions among baryon states such as 1/2⁺ → 1/2⁺, 3/2⁺, 1/2^-, 3/2^- etc.     

Exotic Baryons from a Heavy Meson and a Nucleon

We study hadronic molecules formed by a heavy meson and a nucleon respecting heavy quark symmetry. It is shown that the tensor force plays a dominant role to yield a strong attraction in this system.     

Wave Functions of Doubly Heavy Baryons on the Light Cone

Physics of Atomic Nuclei - Heavy mesons and doubly heavy baryons with the dynamic properties governed by the light quark motion relative to the fixed center of forces are studied within the Heavy...     

The Spin Symmetry of Heavy Baryons in the Framework of the Bethe-Salpeter Equation

We study the baryons containing a heavy quark in the framework of Bethe-Salpeter (BS) equation. The most general forms of the BS wavefunctions are given. In the heavy-quark limit we simplify the BS equations and we show clearly that the spin symmetry exists in heavy baryon states.     

带有两个重夸克的重子谱计算中几个困难问题的研究

由两个重夸克和一个轻夸克组成的重子可以看作是一个两体系统.它的两个重夸克组成一个玻色型的双夸克团.利用B–S方程导出了它的轻夸克和重的双夸克之间的等效相互作用势.在利用这种势计算重子质量的过程中,发现有几个困难问题需要深入探讨.它们是:(1)算符排序,(2)由非相对论展开带来的误差,(3)自旋–自旋耦合,(4)在标量双夸克组成的重子态和矢量双夸克组成的重子态之间的混合.本文详细地讨论并适当地处理了这些问题.     

Inclusive semileptonic decays of polarized Λb Baryons into polarized τ-leptons

We employ OPE techniques within HQET to calculate the inclusive semileptonic decays of polarized Λ_b baryons. Lepton mass effects are included which enables us to also discuss rates into polarized τ-leptons. We present explicit results for the longitudinal polarization of the τ in the Λ_b rest frame as well as in the (τ^?, v_τ) c.m. frame. In both the Λ_b rest frame and in the (τ^?, v_τ) c.m. frame we make use of novel calculational techniques which considerably simplify the calculations. The transverse polarization components of the τ are calculated in the (τ^?, v_τ) c.m. frame. We delineate how to measure the full set of 14 polarized and unpolarized structure functions of the decay process by angular correlation measurements. A set of observables are identified that allow one to isolate the contributions of the twoO(1/m _t ²) nonperturbative matrix elementsK _b and ε_b.     

Strong Coupling Constants of the Doubly Heavy Spin-1/2 Baryons with Light Pseudoscalar Mesons

The strong coupling constants of hadronic multiplets are fundamental parameters which carry information about the strong interactions among participating particles.These parameters can help us construct the hadron-hadron strong potential and gain information about the structure of the involved hadrons.Motivated by the recent observation of the doubly charmed cc state by LHCb,we determine the strong coupling constants among the doubly heavy spin-1/2 baryons, Ξ_QQ′/(′),Ω_QQ′/(′) and light pseudoscalar mesons,π,κ,η and η′within the framework of the light cone QCD sum rules.The obtained results may help experimental groups in analysis of the related data at hadron colliders.     

Baryons and dual unitarization

Processes involving baryons are discussed in the scheme of dual unitarization. In particular, the topological expansion is generalized to any hadronic S-matrix elements involving baryons and/or mesons. Our expansion is based on a model for the baryon propagator, which is a set of three planar Feynman diagrams joined at a junction line. The resulting expansion is a double expansion in 1/N (N= the number of quark flavours) and in the number of baryon loops. Based on this, several new observations are made in phenomenological problems, and a unifying point of view is stressed. The scheme is evidently crossing invariant, and unitarity constraints are imposed order by order in 1/N and in the baryon loop number.     

Mass Difference of Baryons

Russian Physics Journal -     

Baryons and nuclei as skyrmions

The topological soliton model, including its various extensions, is reviewed. The model is very compact and involves only small number of Lagrangian parameters which in principle are calculable from QCD. It provides a nice tool for describing the structure of baryons.Lectures held at the Indian-Summer School on Electromagnetic and Weak Interactions of Particles with Nuclei, Sázava, Czechoslovakia, 6–11 September 1992