# Tag Info

## New answers tagged gauge-theory

1

The answer to the question in the title is no. Everything comes to the idea of the swampland in the string theory context. Not every effective QFT can be UV-completed into a string theory, in particular that appears to be the case for $\mathcal{N}=2$ theories in four dimensions. One of the swampland conjectures explicitly locate $\mathcal{N}=2,d=4$ ...

3

Short answer: Read Weinberg, Vol I, Section 2.5. Longer answer, hopefully covering more of what Weinberg takes for granted: In relativistic physics, the Hilbert space is a representation of the Poincare group; rotations, translations, and boosts act on the state vectors linearly, turning one state into another. Representation theory is useful here ...

3

In the case of linearised GR, one of the main reasons for choosing our gauge fixing condition is just sheer convenience. If we're doing a metric perturbation of $g_{\mu \nu} = \eta_{\mu \nu} + h _{\mu \nu}$, then our corresponding action that we get from perturbing our Ricci scalar is the Fierz-Pauli action which is second order in $h$ (since the first ...

0


Top 50 recent answers are included