Exotic hadrons with hidden charm and strangeness

Introduction. In the last few years we are witnessing the discovery of a number of new narrow hadronicresonances with charm which do not match standard quark-antiquark interpretation, thereby named exotichadrons. This has called for alternative interpretations of their inner structure. One of the possible explanationsis that these particles are loosely bound molecules of open charm mesons [1]. Another possibility is that newaggregation patterns of quarks in matter are possible. We follow the suggestion by Jaffe and Wilczek of havingdi-quarks as building blocks [2]. Light diquarks have been object of several lattice studies. Recently we havestudied the hypothesis of treating the diquark as a fundamental field in large N Chromodynamics in twodimensions [3] finding some qualitative features of the spectra which are common to real ones. The idea thatthe colored diquark can be handled as a constituent building block is at the core of the approach taken in thispaper.Motivated by our former study on the interpretation of the Y(4260) resonance [4], we analyze the possibilityof a spectroscopy of particles with hidden strangeness and charm embodied in diquark-antidiquark structuresof the kind [cs][¯cs¯], where