I found this term/operator in some papers that can generate masses, e.g Riva-Biggio-Pomarol(2012), Fox-Nelson-Weiner
∫d4θX†XM2Q†Q
Could anyone explain about this term?
Is there any references that explain this term?
This post imported from StackExchange Physics at 2014-12-30 13:58 (UTC), posted by SE-user Panuluh