Pentaquarks at LHCb
ABSTRACT :
It has been over 50 years since the quark model was postulated, and in that time it has been enormously successful in classifying the known hadrons. These hadrons have historically fallen neatly into the categories of three-quark baryons or quark-antiquark mesons. Yet even since quarks were first proposed it has been suggested that they could arrange themselves into other conifgurations, such as two quarks and two antiquarks (tetraquarks), or four quarks and an antiquark (pentaquarks). To this day there is no clear reason why such ``exotic'' combinations of quarks such as these should not exist, and indeed in recent years a number of strong tetraquark candidates have been found. Additionally, in the last few years LHCb has established two strong pentaquark candidates, which will be discussed here. An amplitude analysis is presented which was performed in order to demonstrate that the well-established, conventional hadrons could not explain the data, and then extended in order to characterise these unconventional contributions. Additionally, a model-independent confirmation of the existence of something in the data beyond the conventional resonances will be presented. Finally, an overview of LHCb's more recent spectroscopy efforts will be presented, with an emphasis on pentaquark-related studies.