arXiv subjects
Publications and source records attributed to L. Semlala.
We present new results concerning the masses and the decay widths of the most interesting hybrid meson states taking as inputs the gluon mass mg and the non-perturbative QCD running coupling constant ?alpha_s(0) comming from both LQCD and SDE recent estimations.
The hybrid meson is one of the most interesting new hadron specie beyond the naive quark model. It acquire a great attention both from the theoretical and experimental efforts. Many good candidates have been claimed to be observed, but there is no absolute confirmation about existence of hybrid mesons. In the present work we propose new calculations of the masses and decay widths of the hybrid mesons in the context of constituent gluon model.
The new recently experiments at the B-factories yield a renewed interest in the charm and charmonium spectroscopy. New intriguing states have been observed, which appear to be non-conventional mesons, such as X(3862) and Y(4260) and request more theoretical investigations. We will explore the possibility for the Y(4260) to be a c-cbar-g hybrid meson. Using the quark-gluon constituent model, we exclude its existence as QE-hybrid meson, and as mixing of c-cbar-g hybrid with conventional c-cbar meson. We find the only interpretation as GE-hybrid, decaying in D_(1)-Dbar channels. Then more experimental studies are needed to confirm the existence of this resonance and to give its properties.
We estimate the ground state masses of the heavy hybrid mesons using a phenomenological QCD-type potential. 0^{- -},1^{- -},0^{- +},1^{- +} and 0^{+ -} J^{PC} states are considered.
In this paper, we study the nucleon energy spectrum in the ground-state (with orbital momentum L=0) and the first excited state (L=1). The aim of this study is to find the mass and mixing angles of excited nucleons using a potential model describing QCD. This potential is of the "Coulombian + linear" type and we take into account some relativistic effects, namely we use essentially a relativistic kinematic necessary for studying light flavors. By this model, we found the proton and $Δ(1232)$ masses respectively equal to ($968MeV$, $1168MeV$), and the masses of the excited states are between $1564MeV$ and $1607MeV$.
We expose arguments concerning the π_{1}(1400) observed decaying into ηπand claimed to be an exotic meson. We conclude that this object cannot be a qqbar-g hybrid meson.
The existence of hadrons containing gluons as constituent particles (like hybrid mesons) will involve the necessity to admit an hadronic spectroscopy beyond the naive quark model. In the QGC model, the lowest J^{PC}= 1^{-+} hybrid mesons may be built in two different modes: the GE-mode corresponding to an angular momentum between the gluon and qqbar system, while the QE-mode corresponding to an angular momentum between q and qbar. In this paper, we give an analysis of the possible 1^{-+} hybrid mesons in the 1.32-2.04 GeV mass range, and predictions on their decay. We discuss on the inconsistency between some theoretical results and experimental data.We find that the 1^{-+}(1400 MeV), dominated by the QE-mode will decay in the favourite rho-pi channel, while the GE-1^{-+}(1600 MeV), and the 1^{-+}(2.0 GeV), pure GE-hybrids, will decay preferably into b1-pi channel (never observed); we indicate problems concerning the observation of decay channels which are forbidden by theoretical present models.The total decay widths of the 1^{-+}(2.0 GeV) and the GE-1^{-+}(1600 MeV) being very large, this leads to a problem of their observability as resonances. We may conclude that at this time, there is no absolute confirmation of their existence, but some asked questions remain not solved.