Assertion: ion's number | /r/HasProperty | discovered at the beginning of the 1960s
Facets:
value: along with theories
type: OTHER
Source sentences:
text: At the beginning of the 1960s a number of these particles had been discovered or proposed, along with theories suggesting how they relate to each other, some of which had already been reformulated as field theories in which the objects of study are not particles and forces, but quantum fields and their symmetries.:150