Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userRetardation Terms in The One-Gluon Exchange Potential
241
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
It is pointed out that the retardation terms given in the original Fermi-Breit potential vanish in the center of mass frame. The retarded one-gluon exchange potential is rederived in this paper from the three-dimensional one-gluon exchange kernel which appears in the exact three-dimensional relativistic equation for quark-antiquark bound states. The retardation part of the potential given in the approximation of order $p^2/m^2$ is shown to be different from those derived in the previous literature. This part is off-shell and does no longer vanish in the center of mass frame.
rate research
Read More
We consider the interquark potential in the one-gluon-exchange (OGE) approximation, using a fully nonperturbative gluon propagator from large-volume lattice simulations. The resulting VLGP potential is non-confining, showing that the OGE approximation is not sufficient to describe the infrared sector of QCD. Nevertheless, it represents an improvement over the perturbative (Coulomb-like) potential, since it allows the description of a few low-lying bound states of charmonium and bottomonium. In order to achieve a better description of these spectra, we add to VLGP a linearly growing term. The obtained results are comparable to the corresponding ones in the Cornell-potential case. As a byproduct of our study, we estimate the interquark distance for the considered charmonium and bottomonium states.
The leading nonperturbative QCD corrections to the one gluon exchange quark-quark, quark-antiquark and $q bar{q}$ pair-excitation potentials are derived by using a covariant form of nonlocal two-quark and two-gluon vacuum expectation values. Our numerical calculation indicates that the correction of quark and gluon condensates to the quark-antiquark potential improves the heavy quarkonium spectra to some degree.
We study thermodynamic properties and speed of sound in a free en- ergy evolution of quark-gluon plasma (QGP) with one loop correction factor in the mean-field potential. The values of the thermodynamic prop- erties like pressure, entropy and specific heat are calculated for a range of temperatures. The results agree with the recent lattice results. The speed of sound is found to be C2 s = 0.3 independent of parameters used in the loop correction which matches almost with lattice calculations.
A review is given of the present situation in YN scattering. Special attention is given to the handling of SU(3) in the various meson exchanges. The importance of the almost always ignored contribution of the Pomeron is reiterated.
The lower excitation spectrum of the nucleon and $Delta$ is calculated in a relativistic chiral quark model. Corrections to the baryon mass spectrum from the second order self-energy and exchange diagrams induced by pion and gluon fields are estimated in the field -theoretical framework. Convergent results for the self-energy terms are obtained when including the intermediate quark and antiquark states with a total momentum up to $j=25/2$. Relativistic one-meson and color-magnetic one-gluon exchange forces are shown to generate spin 0, 1, 2, etc. operators, which couple the lower and the upper components of the two interacting valence quarks and yield reasonable matrix elements for the lower excitation spectrum of the Nucleon and Delta. The only contribution to the ground state nucleon and $Delta$ comes from the spin 1 operators, which correspond to the exchanged pion or gluon in the l=1 orbit, thus indicating, that the both pion exchange and color-magnetic gluon exchange forces can contribute to the spin of baryons. Is is shown also that the contribution of the color-electric component of the gluon fields to the baryon spectrum is enormously large (more than 500 MeV with a value $alpha_s=0.65$) and one needs to restrict to very small values of the strong coupling constant or to exclude completely the gluon-loop corrections to the baryon spectrum. With this restriction, the calculated spectrum reproduces the main properties of the data, however needs further contribution from the two-pion exchange and instanton induced exchange (for the nucleon sector) forces in consistence with the realistic NN-interaction models.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
