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1

I don't know what you mean with "rigorously" determine the Feynman diagrams that contribute to a process. In general from a theoretical point of view you can have two approaches 1)The hamiltonian approach in interaction picture, thorugh Dyson expansion 2)The path integral formalism. LSZ formula relates the transition amplitude to a green function. ...

3

A phase transition, as I've always used the term, does not say anything about whether you will or won't find a holographic CFT. In the Landau-Ginzburg paradigm, it is familiar that if you make the coupling constant too small, it will run to zero in the IR and lead to a free theory. If you instead raise the coupling to a zero of the beta function first, the ...

2

Squarks can be written in terms of their left and right components - gauge eigenstates, if you will. Similar to the distinction between flavour and mass eigenstates for neutrinos, these gauge eigenstates are different from the mass eigenstates for the stop and sbottom - in other words, the mass matrix is not diagonal (whereas for the other squarks the off-...

2

Drawing the diagrams this way reflects the fact that the Higgs interacts with fermions via $\phi \bar{f} f$ but interacts with scalars via $\phi^2 S S^*$. This is plausible because in $d = 4$, four scalars have the same engineering dimension as one scalar and two fermions. Moreover, the mass term for a fermion is $m^2 S S^*$ for a scalar whereas it is \$m f \...

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