On Some Properties of (Θ+) Excited States

Abstract

The mass splitting and the decay width of pentaquark ( + ) at the higher angular momentum states have been investigated in the framework of flux tube model considering the diquark-diquark-antiquark configuration for + along with statistical model. A quasi particle model for diquark has been considered. The Regge trajectory of + has also been investigated with interesting some observations. Keywords Exotic particle · Quasiparticle · Decay width · Regge trajectory · Mass spectrum Diakonov et al. theoretically proposed the low mass (1530 MeV) and total decay width ( < 15 MeV) of + baryon in the framework of chiral soliton model [1] denoting the exotic baryon as a pentaquark state. The LEPS collaboration [2] reported the first experimental evidence of a sharp baryon resonance peak at 1540 ± 10 MeV with a width smaller than 25 MeV whereas, SAPHIR [3] detector detected the resonance peak at 1540 ± 4 ± 2 MeV with < 25 MeV at 90 percent c.l. ZEUS collaboration [4] reported the experimental existence of pentaquark ( + ) suggesting the mass to be 1521.5 ± 1.5 MeV and decay width 6.1 ± 1.6 MeV whereas CLAS collaboration [5,6] suggested the value to be 1555 ± 10 MeV and decay width ≤ 26 MeV. Since LEPS collaboration reported the existence of + resonance several groups confirm the state whereas a number of experiments gives null result. The next generation of experiments have been taken by JLAB, CLAS for further search.The theoretical states of + has been studied by Doi [7] in the direct QCD calculation. The low lying states of this exotic baryon have been investigated in the context of pseudoscalar vector skryme model by . Diakonov [9] has made a mean field approach to study the pentaquark excitation using SU(3) flavor symmetries. Iwasaki

Dynamical Calculation of Θ+ Mass and Decay width in the Quark Model

“…[20] the value have obtained as 1668 MeV in the context of constituent quark model. In the recent work [8] the ground state energy have obtained as 1610 MeV whereas the experimental data tell us that M + (0) = 1540 ± 10 MeV [16]. Therefore our result is most agree with the experimental data.…”

“…In the Ref. [8] m * = 506 MeV is obtained for the diquark [ud]. Here we fixed our parameters by baryon properties and NN scattering as m u = m d = 313 MeV, α s = 1.54, K = 241.5 MeV/fm 2 for the light quark system [14] and r = 5.38 GeV −1 as the radius parameter of the diquark [15], and find that m * = 447 MeV for the diquark [ud].…”

“…[7] the mass estimate of the d * dibaryon is improved by a dynamical calculation in the quark delocalization, color screening model. We follow in the similar way for the + which is studied originally in the recent work [8] as a diquark-diquark-antiquark configuration. In this paper we assume that + is a combination of diquark and triquark [9], so in order to obtain mass and decay width we use methods of the Refs.…”

“…In this paper we assume that + is a combination of diquark and triquark [9], so in order to obtain mass and decay width we use methods of the Refs. [7] and [8]. In Sect.…”

The mass spectra and decay properties of dimesonic states, using the Hellmann potential

“…The multiquark states were predicted and studied previously in MIT Bag model and in nonrelativistic potential models [8,9,10]. The molecular like structure have been studied and proposed in various models like potential models [32,33,34,35,36,37,38,39,40], chiral SU(3) quark model approach [41], gauge invariant model [42], Bethe-Salpeter equation approach [43], QCD sum rules [44], an effective field theory approach [45] and nonperturbative chiral approach [46]. We are using the potential model to predict the masses, digamma decay and decay width of dimesonic systems in variational scheme.…”