Exotic Pentaquarks, Crypto-Heptaquarks and Linear Three-Hadronic Molecules

Abstract

In this talk, multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range interaction is computed and it is shown to be repulsive, a narrow pentaquark cannot be in the groundstate. As a possible excitation, an additional quark-antiquark pair is then considered, and this is suggested to produce linear molecular system, with a narrow decay width. This excitation may be energetically favourable to the p-wave excitation suggested by the other pentaquark models. Here, the quarks assemble in three hadronic clusters, and the central hadron provides stability. The possible crypto-heptaquark hadrons with exotic pentaquark flavours are studied.Exotic multiquarks are expected since the early works of Jaffe 1 , and the masses and decays in the SU(3) exotic anti-decuplet were first predicted within the chiral soliton model 2 .The pentaquarks have been revived recently by several searches of the Θ + (discovered at LEPS 3 , and by searches of the Ξ −− (1860) 21,22,23 and of the D * − p(3100) 24 , observed respectively at NA49 21 and at H1 24 . Pentaquark structures have also been studied on the lattice 25,26,27,28,29,30,31,32 . Moreover multiquarks are favoured by the presence of several different flavours 33,34,35 . The observation of the D * − p(3100) at H1, the observation of double-charmed baryons at SELEX 36 , and the future search of double-charmed baryons at COMPASS 37 suggest that new pentaquarks with heavy quarks may be discovered.In this talk it is shown that the pentaquarks cannot be in the groundstate. The lowest excitation consists in including a light quark-antiquark pair in the system. This results in a heptaquark and in a linear molecular system. The possible crypto-heptaquark hadrons with exotic pentaquark

Exploring the Masses of Exotic Heavy Pentaquarks

“…New impetus has been put forward to the study of the properties and dynamics of the multiquark states by Jaffe et al [2]. The works of Lipkin [3], Gignoux et al [4], Monemzadeh et al [5], Diakonov [6] in the context of the exotic doublets (cuuds) (cudds), Bicudo [7]for possible crypto heptaquark hadrons with exotic flavors, Kopeliovich et al [8] for cryptoexotic pentaquarks with hidden beauty are noteworthy.…”