If your "sum" field is a calculation field that uses the Sum function to calculate a value and is not a summary field, you can search for records with a value of 1 or larger using: >1 as your search criteria. For your container field, I think you'd need a calculation field with an expression such as:
Length ( ContainerField )
And you'd search that field for a 0. Or you could define it as:
IsEmpty ( ContainerField ) and you'd search that field for a 1.
Normally, you can search for records where a certain field is empty by using a lone = operator, but as far as I know, that won't work with container field.
For examples of scripted finds, see: Scripted Find Examples