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--- models:speculative_models:seesaw_models [2019/07/02 13:25]
jakobadmin created
+++ models:speculative_models:seesaw_models [2019/07/02 13:30]
jakobadmin [Concrete]
@@ Line 9: / Line 9: @@
 <tabbox Concrete>
-Seesaw scenarios can be understood systematically by looking at the Weinberg operator. The Weinberg operator $\frac{1}{\Lambda}$ LL \phi \phi$ is a (non-renormalizable) dimension-5 operator that yields nonzero masses for the neutrinos. Since it is an dimension-5 operator, it is suppressed by some large mass scale $\Lambda$. The origin of the Weinberg operator can be understood in terms of concrete seesaw scenarios (UV-completions).
+Seesaw scenarios can be understood systematically by looking at the Weinberg operator. The Weinberg operator $\frac{1}{\Lambda} LL \phi \phi$ is a (non-renormalizable) dimension-5 operator that yields nonzero masses for the neutrinos. Since it is an dimension-5 operator, it is suppressed by some large mass scale $\Lambda$. The origin of the Weinberg operator can be understood in terms of concrete seesaw scenarios (UV-completions).
-There are three seesaw scenarios that yield the Weinberg operator in the low-energy limit when we integrate out all heavy fields and thus use an effective field theory approach.
+There are three seesaw scenarios that yield the Weinberg operator in the low-energy limit when we integrate out all heavy fields and thus use an [[advanced_tools:effective_field_theory|effective field theory]] approach. In particular, we can distinguish different scenarios depending on how we understand the contractions of our $SU(2)_L$ multiplets:
+{{ :models:speculative_models:weinberg1.png?nolink |}}
+{{ :models:speculative_models:weinberg2.png?nolink |}}
+In terms of Feynman diagrams, the three scenarios can be understood as follows:
+{{ :models:speculative_models:weinberg3.png?nolink |}}
+Here, $N_R$ denotes a heavy right-handed ($SU(2)_L$ singlet) neutrino, $\Delta^0$ the neutral component of an
+$SU(2)_L$ scalar triplet and $\Sigma_R^0$, the neutral component of a fermionic $SU(2)_L$ triplet.
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