Seminarium Kosmologia i Fizyka Cząstek

There is a strong experimental evidence from B and charm factories for theexistence of exotic hadronic quarkonia, narrow resonances which cannotbe made from a quark and an antiquark. Their masses and decay modesshow that they contain a heavy quark-antiquark pair, but their quantumnumbers are such that they must also contain a light quark-antiquark pair.I discuss their interpretation as "hadronic molecules" and provide fairlyprecise predictions for masses and quantum numbers of the additionalexotic states which are naturally expected in the molecular picture buthave yet to be observed.I also discuss another type of hadrons containing two heavy quarks -doubly heavy baryons. The large number of $B_c$ mesons observed by LHCbsuggests a sizable cross section for producing doubly-heavy baryonsin the same experiment. Estimates are provided for the masses of thedoubly-heavy ccq, bbq and bcq baryons, using a method which accuratelypredicts the masses of ground-state baryons with a single heavy quark.The production mechanisms, decay modes, lifetimes, and prospects fordetection of doubly heavy baryons are also discussed.