نتایج جستجو برای: quark

تعداد نتایج: 30103  

2004
C. Albertus J. E. Amaro E. Hernández

We evaluate masses of bottom and charmed baryons using several non-relativistic quark potentials which parameters have been adjusted to the meson spectra. Heavy Quark Symmetry leads to important simplifications of the three body problem, which turns out to be easily solved by a simple variational ansatz. The wave functions obtained can be readily used to compute further observables as mass dens...

1998
Di Qing Xiang-Song Chen Fan Wang

Hadron structure studies might be traced back to Fermi-Yang [1] and Sakata models [2]. Gell-Mann [3] and Zweig [4] proposed the quark model of hadrons. Lepton-nucleon deep inelastic scattering (DIS) [5] verified the quark structure of hadrons. However the quark revealed in DIS is found to be different from the quark as a carrier of SU(3) symmetry in Gell-Mann-Zweig model. The former is almost a...

1997
Ivan Schmidt

Two new sum rules for the quark tensor charges of the nucleon are proposed, based on a relation connecting the quark transversity distributions to the quark helicity distributions and the quark model spin distributions, and on the sum rules for the quark helicity distributions. The two sum rules are useful for an estimate of the values of the quark tensor charges δU and δD from the measured qua...

2000
Fl. Stancu

We study the nucleon-nucleon interaction within a chiral constituent quark model which reproduces succesfully the baryon spectra. We calculate the 3 S 1 and 1 S 0 phase shifts by using the resonating group method. They clearly indicate the presence of a strong repulsive interaction at short distance, due to the spin-flavor symmetry of the quark-quark interaction and of the quark interchange bet...

1997
Xiangdong Ji

I introduce a gauge invariant decomposition of the nucleon spin into quark helicity, quark orbital, and gluon contributions. The total quark (and hence the quark orbital) contribution is shown to be measurable through virtual Compton scattering in a special kinematic region where single quark scattering dominates. This deeply-virtual Compton scattering (DVCS) has much potential to unravel the q...

2005
B S Zou

A brief review on some recent progresses in our understanding of multi-quark components in baryons is presented. The multi-quark components in baryons seem to be mainly in colored quark cluster configurations rather than in " meson cloud " configurations or in the form of a sea of quark-antiquark pairs. The colored quark cluster multi-quark picture gives a natural explanation of empirical indic...

2000
H. G. Dosch M. Eidemüller M. Jamin E. Meggiolaro

Taking the gauge invariant quark correlator as an example, in this work we perform a direct comparison of lattice QCD simulations with the QCD sum rule approach. The quark correlator is first investigated in the framework of QCD sum rules and the correlation length of the quark field is calculated. Comparing the phenomenological part of the sum rule with previous measurements of the quark corre...

Journal: :Astronomy & Astrophysics 2002

Journal: :Nature 1979

1995
A. Valcarce

By solving the Schrödinger equation for the three-quark system in the hyperspherical harmonic approach, we have studied the low energy part of the nucleon and ∆ spectra using a quark-quark interaction which reproduces the nucleon-nucleon phenomenology. The quark-quark hamiltonian considered includes, besides the usual one-gluon exchange, pion and sigma exchanges generated by the chiral symmetry...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید