The spectrum of theP-wave baryons and hadronic loops

Charmlets

“…Further investigations along this line using other models, like potential models or lattice calculations, are certainly needed to clarify this question. In this context, it is interesting to note that meson exchange contributions are important for binding multiquark systems as pointed out by several authors [2][3][4]6].…”

“…Certain exotic states with charm quarks have been discussed intensively in the literature. Multiquark states have been studied in potential models using meson exchange [2][3][4]. The tetraquark with two heavy quarks of mass m Q and two light (u,d,s) quarks is bound in the limit of m Q → ∞, but the situation for the charm quark with m c ≈ 1.5 GeV is less clear (see e.g.…”

Isf0(1500) a scalar glueball?

“…That the f nn 0 width will be very broad is a rather general conclusion of all standard quark models (see also ref. [53]); unitarisation effects do not alter this conclusion [32].…”

“…There is rather general agreement that the ground state nn state is manifested here. The debate is one of detail on the relationship of the f 0 (1370) to the broad f 0 (1300), in particular as to whether these are two independent states or manifestations of a single state, and to what extent unitarity corrections are important [32]. This issue is peripheral to our main analysis which will rely only on the generally accepted association of the ground state nn as the seed for the phenomenology in the f 0 (1300 − 1370) region and that this is distinct from the f 0 (1500) state observed by the Crystal Barrel collaboration decaying to π 0 π 0 [8,9], ηη [10,22] and ηη ′ [11].…”

Electromagnetic decays of excited hyperons (II)

“…[7,11] The chiral bag model, like the Cloudy Bag Model, has a specific coupling to the open hadronic channels through the meson cloud. An improved treatment of this meson cloud (i.e., a proper inclusion of dispersive effects of the hadronic widths) might explain the observed L · S splitting of the lowest J P = 1 2 − and 3 2 − Λ * -states, [20,21,22,23] an effect we shall estimate within our model in this work. If the Λ(1405) is a molecular (or quasi-boundKN/πΣ) state, then a further and so far un-observed low-lying three-quark Λ * ( 1 2 − ) state should exist.…”