====== Wigner's Little Groups ======

<tabbox Why is it interesting?> 

<tabbox Layman> 

<note tip>
Explanations in this section should contain no formulas, but instead colloquial things like you would hear them during a coffee break or at a cocktail party.
</note>
  
<tabbox Student> 
<blockquote>The little group is a subgroup of the Poincare
group which leaves the four-momentum of a
given particle invariant. The little groups for
massive and massless particles are locally
isomorphic to the three-dimensional rotation
group and the two-dimensional euclidean group
respectively. <cite>GAUGE TRANSFORMATIONS AS LORENTZ-BOOSTED ROTATIONS by D. HAN et. al.</cite></blockquote>

  * A good explanation can be found at page 8 in https://indico.cern.ch/event/544849/contributions/2214530/attachments/1301154/1942518/yskim.pdf
  * Another great introduction is section 2 here https://arxiv.org/pdf/1709.04891.pdf
  * A good discussion can also be found in Groups, Physics, and Geometry by Gilmore
 
<tabbox Researcher> 

<note tip>
The motto in this section is: //the higher the level of abstraction, the better//.
</note>

--> Common Question 1#

 
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<tabbox Examples> 

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<tabbox History> 
https://arxiv.org/pdf/hep-th/9512151.pdf
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