Updated: I was reading a paper discussing a Higgs triplet under SU(2)(adsbygoogle = window.adsbygoogle || []).push({}); _{L}. In addition to the usual Higgs doublet. Both are written as:

[tex] D = \begin{pmatrix} x \\ y \end{pmatrix} [/tex]

[tex] T = \begin{pmatrix} X \\ Y \\ z \end{pmatrix} [/tex]

Now, at some point, the author says the lagrangian contains a term like,

[tex]D D T^{\dagger} [/tex]

[tex] \sim c \begin{pmatrix} x \\ y \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix} \begin{pmatrix} X & Y & z \end{pmatrix} [/tex]

In the paper, c is a factor that doesn't carry any group index.

I have a naive question:

How can: (2 ×1) (2 ×1) (1×3) be an allowed term? Also, this reminded me of something I heard and didn't understand, which is that two doublets can produce a triplet. But I don't see how.

Please note that I encounter group theory very little in my studies, hence I find myself constantly confused about some of its techniques.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Two doublets and a triplet

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**