Search results for "baryon"
showing 10 items of 759 documents
Spectra of the lightest baryons containing two heavy quarks in a potential model
2000
The spectra of baryons which include two heavy quarks can be treated as a two-body system, where the two heavy quarks constitute a bosonic diquark. We derive the effective potential between the light quark and the heavy diquark in terms of the Bethe-Salpeter equation. To obtain the spectra, several serious problems need to be solved: (1) the operator ordering, (2) the errors caused by the nonrelativistic expansion, (3) spin-spin coupling, and (4) the mixing between the scalar-diquark-baryon and vector-diquark-baryon. In this work we take reasonable approaches to deal with them.
Quark-mass dependence of baryon resonances
2004
We study the quark-mass dependence of J^P = \frac12^- s-wave and J^P = \frac32^- d-wave baryon resonances. Parameter-free results are obtained in terms of the leading order chiral Lagrangian. In the 'heavy' SU(3) limit with m_\pi =m_K \simeq 500 MeV the s-wave resonances turn into bound states forming two octets plus a singlet representations of the SU(3) group. Similarly the d-wave resonances turn into bound states forming an octet and a decuplet in this limit. A contrasted result is obtained in the 'light' SU(3) limit with m_\pi =m_K \simeq 140 MeV for which no resonances exist.
Meson-Baryon s-wave Resonances with Strangeness -3
2006
Starting from a consistent SU(6) extension of the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian (Phys. Rev. D74 (2006) 034025), we study the s-wave meson-baryon resonances in the strangeness S=-3 and negative parity sector. Those resonances are generated by solving the Bethe-Salpeter equation with the WT interaction used as kernel. The considered mesons are those of the 35-SU(6)-plet, which includes the pseudoscalar (PS) octet of pions and the vector (V) nonet of the rho meson. For baryons we consider the 56-SU(6)-plet, made of the 1/2+ octet of the nucleon and the 3/2+ decuplet of the Delta. Quantum numbers I(J^P)=0(3/2^-) are suggested for the experimental resonances Omega*(2250)-…
Compositeness of the strange, charm and beauty odd parity $\Lambda$ states
2015
14 pages.- 2 figures.- 5 tables
Strong pionic decays of baryons from a spectroscopic quark model
1996
From a refined non-relativistic quark model that fits the baryonic low-energy spectrum the study of strong pion decay processes within an elementary emission model scheme points out the need of incorporating size-contributing components into the baryon wave functions. In particular the effect of a (qqq ) component is investigated in the framework of a quark pair creation model.
A study of beauty baryons with extended local hidden gauge approach
2016
Abstract In present work we investigate the interaction of B ‾ N , B ‾ Δ , B ‾ ⁎ N and B ‾ ⁎ Δ states, together with their coupled channels. Taking into account the heavy quark spin symmetry for pion exchange and the results of the Weinberg Tomozawa term in the extended local hidden gauge approach, we search for states dynamically generated from the interaction, and find two states with small width, which we associate to the Λ b ( 5912 ) and Λ b ( 5920 ) states. In addition to these two Λ b states, we find three more states with I = 0 and eight more states in I = 1 , some of which are degenerate in different spin J .
Search for flavor changing neutral currents via quark–gluon couplings in single top quark production using 2.3 fb−1 of pp¯ collisions
2010
We present a search for flavor changing neutral currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb(-1) of integrated luminosity collected with the DO detector at the Fermilab Tevatron Collider. We select events containing a single top quark candidates with an additional jet, and obtain separation between signal and background using Bayesian neural networks. We find consistency between background expectation and observed data, and set limits on flavor changing neutral current gluon couplings of the top quark to up quarks (tgu) and charm quarks (tgc). The cross section limits at the 95% C.L. are sigma(tgu) gu) gc) < 3.9 x 10(-3).
On heavy baryon decay form factors
1991
We consider in detail the consequences of the heavy quark mass limit in the weak decay of 1/2+ heavy baryons to 1/2+ and 3/2+ heavy baryon final states. We also analyze heavy baryon to light baryon transitions as well ase+e−-annihilation into heavy baryon-antibaryonpairs. We discuss possible approximations to the most general approach and some of their implications for future experiments.
Towards a Unified Description of the Baryon Spectrum and the Baryon-Baryon Interaction within a Potential Model Scheme
1995
We study the low energy part of the nucleon and ∆ spectra by solving the Schrodinger equation for the three-quark system in the hyperspherical harmonic approach. The quark-quark hamiltonian considered includes, besides the usual one-gluon exchange, pion and sigma exchanges generated by the chiral symmetry breaking This quark-quark potential reproduces, in a Resonating Group Method calculation, the nucleon-nucleon scattering phase shifts and the deuteron properties. The baryonic spectrum obtained is quite reasonable and the resulting wave function is consistent with the ansatz used in the two baryon system.
Understanding the Low Energy Hadron Spectrum in a Chiral Quark Cluster Model
1999
The low energy N and Δ spectra are studied by means of a chiral quark cluster model. We solve the Schrodinger equation in the hyperspherical harmonic approach. The interacting potential includes Goldstone boson exchanges besides the usual one-gluon exchange. The predicted baryonic spectrum is quite reasonable. However, if consistency with the two-baryon sector is required, the observed inversion of the positive and negative parity excitations of the nucleon cannot be obtained. Alternative solutions are discussed.