# Questions tagged [gauge-theory]

A gauge theory has internal degrees of freedom that do not affect the foretold physical outcomes of the theory. The theory has a Lie group of *continuous symmetries* of these internal degrees of freedom, *i.e.* the predicted physics under any transformation in this group on the degrees of freedom. Examples include the $U(1)$-symmetric quantum electrodynamics and other Yang-Mills theories wherein non-Abelian groups replace the $U(1)$ gauge group of QED.

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### Form of the optical theorem in non-Abelian theory

I am studying chapter 16.3 from Peskin & Schroeder and I am trying to follow through the argument where we include contributions from ghosts to satisfy the Ward identity in non-Abelian gauge ...
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### Nonlinear symmetry realization: what is it for and caveats

I have several doubts regarding the nonlinear realization of a spontaneously broken symmetry and hope they are approppriate to be grouped, and I appreciate any insights. Consider the group breaking ...
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### Showing that the integration measure is preserved under gauge transformation in the non-Abelian case

I am trying to show that the integration measure we use in the Fadeev-Popov method of quantisation of non-Abelian gauge theory is invariant under a gauge transformation. I am using Peskin & ...
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### From where can I study $SU(2)\times U(1)$ Symmetry Breaking [duplicate]

I have done till $U(1)$ Symmetry Breaking for my master's thesis and need to do $SU(2)\times U(1)$ Symmetry Breaking. My supervisor suggested the book 'Gauge theory of elementary particle physics' for ...
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### Abelian Gauge Theory

Hello everyone I have a question on this exercise from my Supersymmetry class in 4d ${\cal N}=1$. Given a $\text{U}(1)^3$ gauge theory with 9 chirals $A_i , B_j , C_k$ with $i,j,k$ running from 1 to 3 ...
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### Advantages of using the potentials $A$ and $\phi$ instead of the fields $E$ and $B$ [duplicate]

I'm taking a quantum mechanics course and we briefly reviewed some facts of ED, namely the Maxwell equations and their equivalent version by expressing the electric field $E$ and magnetic field $B$ ...
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### Can we say tension is the ability to generate interference by this paper?

https://arxiv.org/abs/1206.2021 Abstract : We propose a method for measuring the string tension in gauge theories, by considering an interference effect of mesons, which is governed by a space-time ...
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### Area and perimeter

Apparently (?), a line operator over a very large loop with length $L$ can obey either perimeter law or area law, $-\log\langle U\rangle\sim L^a$ with $a=1,2$, respectively. We call these options &...
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### Translating an $\mathcal{N}=2$ quiver into an $\mathcal{N}=1$ one

I am quite new to quivers and I was wondering what does the $\mathcal{N}=2$ quiver (in 4d SUSY) look like in $\mathcal{N}=1$ language? I know that the $\mathcal{N}=2$ vplet gives an $\mathcal{N}=1$ ...
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### Do internal symmetries always leave the Lagrangian strictly invariant?

In order for the action to be invariant under a transformation, the Lagrangian can change by a total derivative. However, for internal symmetries (where the fields transform but not the coordinates), ...
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### What is / why the fiber bundle connection one-form from a physics point of view?

Take the Yang-Mills gauge theory for example. Gauge field $A$ is the pullback of the connection one-form to the base manifold. Other concepts of gauge theory also find their definition in fiber ...
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### Quantized periods in electromagnetic duality path integral

In John McGreevy's notes (page 64 of https://mcgreevy.physics.ucsd.edu/w21/2021W-239-lectures.pdf), he describes a path integral derivation of electromagnetic duality for $p$-form gauge fields. The ...
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### Existence of the Coulomb gauge

In reading about the Coulomb gauge, my mind seems to have painted itself into a corner. For, lets assume that Maxwells equations for the physics of the problem are solved by the magnetic vector ...
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### Stückelberg mechanism and the axion

In the so-called Stückelberg mechanism we have the BF term $$\sim \int m\; B_2\wedge F ~,$$ where the field $B_2$ is a 2-form and $F$ is the field strength arising from a $U(1)$. The Stückelberg ...
Let $\pi:P\rightarrow M$ denote a principal $G$-bundle, where $M$ is thought of as some spacetime and $G$ is an appropriate group (such as $\mathrm{U}(1)$ or $\mathrm{SU}(2)$). I want to understand ...