Linear Algebra Homework: Matrix \Gamma^{\mu}p_{\mu} Rank

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SUMMARY

The discussion centers on the matrix \(\Gamma^{\mu}p_{\mu}\) in the context of string theory and its rank limitations due to the equations of motion. Specifically, it is established that the matrix can have at most half maximal rank when the equation \(\Gamma^{\mu} p_{\mu} \dot{\theta}=0\) is imposed, where \(\dot{\theta}\) is a 32-component anti-commuting spinor in 10 dimensions. The participant attempts to illustrate this with a simplified 3x3 matrix representation, concluding that the rank is affected by the linear independence of the resulting equations, suggesting a maximum rank of 1.

PREREQUISITES
  • Understanding of linear algebra concepts, particularly matrix rank and Jordan normal form.
  • Familiarity with the equations of motion in theoretical physics, specifically in string theory.
  • Knowledge of anti-commuting spinors and their role in supersymmetry.
  • Basic proficiency in manipulating matrices and solving linear equations.
NEXT STEPS
  • Study the properties of Jordan normal form in linear algebra.
  • Explore the implications of equations of motion in string theory.
  • Learn about the role of spinors in supersymmetry and their mathematical representation.
  • Investigate matrix rank and its significance in physical theories, particularly in high-dimensional spaces.
USEFUL FOR

The discussion is beneficial for theoretical physicists, mathematicians specializing in linear algebra, and students studying string theory, particularly those interested in the mathematical foundations of supersymmetry and matrix analysis.

Grieverheart
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Homework Statement


Ok, it seems I need to refresh my linear algebra a bit. In the string theory exams, we had a part about space-time supersymmetry of the superparticle. On of the questions was this:

Argue that the matrix [itex]\Gamma^{\mu}p_{\mu}[/itex] can have at most half maximal rank upon imposing the equations of motion.

(Recall that any matrix can be brought to Jordan normal form, meaning that it is diagonal with at most 1s in places right above the diagonal entries.

Homework Equations


Equations of Motion (the relevant ones):
[itex]\Gamma^{\mu} p_{\mu} \dot{\theta}=0[/itex], where [itex]\dot{\theta}(\tau)[/itex] is an anti-commuting spinor in space-time and has 32 components (we're working in 10 dimensions.


The Attempt at a Solution



I write [itex]\Gamma^{\mu}p_{\mu} \dot{\theta}=0[/itex] as (I use 3x3 for simplicity)

[itex]\begin{pmatrix}<br /> a & 1 & 0\\ <br /> 0 & b & 1\\ <br /> 0 & 0 & c<br /> \end{pmatrix}<br /> \begin{pmatrix}<br /> \dot{\theta_0}\\ <br /> \dot{\theta_1}\\ <br /> \dot{\theta_2}<br /> \end{pmatrix}=0[/itex]

From this I get 3 equations, but I'm not really sure how they affect the rank.
 
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I think it has something to do with the fact that the equations are linearly independent and so the rank of \Gamma^{\mu}p_{\mu} can be at most 3-2=1, but I'm not sure how to express this mathematically. Any help would be appreciated.
 

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