A large number of experimental discoveries especially in the heavy quarkonium sector that did not at all fit to the expectations of the until then very successful quark model led to a renaissance of hadron spectroscopy Among various explanations of the internal structure of these excitations, hadronic molecules, being analogues of light nuclei, play a unique role since for those predictions can be made with controlled uncertainty We review experimental evidences of various candidates of hadronic molecules, and methods of identifying such structures Nonrelativistic effective field theories are the suitable framework for studying hadronic molecules, and are discussed in both the continuum and finite volumes Also pertinent lattice QCD results are presented Further, we discuss the production mechanisms and decays of hadronic molecules, and comment on the reliability of certain assertions often made in the literature

Hadronic molecules

Chiral dynamics in the presence of bound states: kaon–nucleon interactions revisited

http://cds.cern.ch/record/338287/files/9711022.pdf

Non-perturbative chiral approach to s-wave kn interactions

Chiral dynamics and the low-energy kaon - nucleon interaction

We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e{sup +}e{sup -} collider DA{phi}NE. Almost monochromatic K{sup -}'s produced through the decay of {phi}(1020) mesons are used to observe K{sup -} absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K{sup -}pp through its two-body decay into a {lambda} hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115{sub -5}{sup +6}(stat){sub -4}{sup +3}(syst) MeV and 67{sub -11}{sup +14}(stat){sub -3}{sup +2}(syst) MeV, respectively.

/pdf/evidence-for-a-kaon-bound-state-k-pp-produced-in-k-oit573mpms.pdf

G. Vanhomwegen

Papers

Charged Σ hyperon production by K− meson interactions at rest