Antisymmetrizing a Factorized Polynomial Vanishes?

In summary, there is a discussion about an argument in a paper where it is claimed that a term with multiple factors of (z_i-z_j) would require antisymmetrization of twice as many variables, which is not possible. However, the speaker suggests that even for an expression like (z_1-z_2)(z_3-z_4), it can be antisymmetrized using the definition of the antisymmetrizer. The question then arises as to why the paper claims that the antisymmetrizer vanishes.
  • #1
thatboi
133
18
Hi all,
I am having trouble understanding the argument below equation (3.5) in https://arxiv.org/pdf/cond-mat/9605145.pdf where they claim that "Upon antisymmetrization, however, a term with ##k## factors of ##(z_{i}-z_{j})## would have to antisymmetrize ##2k## variables with a polynomial that is linear in each", which is impossible.

However, I thought that even for something like ##(z_{1}-z_{2})(z_{3}-z_{4})##, I can antisymmetrize this expression by just using the definition of the antisymmetrizer, i.e I sum over all permutations of the indices ##(1,2,3,4)## and include ##\pm## signs as appropriate depending on how many times an index has been shifted. So why does the paper claim that the antisymmetrizer vanishes?
Thanks.
 

FAQ: Antisymmetrizing a Factorized Polynomial Vanishes?

What does it mean for a factorized polynomial to be antisymmetrized?

Antisymmetrizing a factorized polynomial involves creating a new polynomial by summing over all permutations of the variables with alternating signs, depending on the permutation's parity (even or odd). This process ensures that the resulting polynomial changes sign whenever any two variables are swapped.

Why does antisymmetrizing a factorized polynomial often result in it vanishing?

Antisymmetrizing a factorized polynomial often results in it vanishing because the polynomial may not have the necessary symmetry properties. If the original polynomial is symmetric or does not have the proper antisymmetric components, the alternating signs in the antisymmetrization process can cancel out all the terms, leading to a zero polynomial.

Can you give an example of a factorized polynomial that vanishes when antisymmetrized?

Consider the factorized polynomial \( P(x_1, x_2) = (x_1 + 1)(x_2 + 1) \). When we antisymmetrize it, we get \( A(x_1, x_2) = (x_1 + 1)(x_2 + 1) - (x_2 + 1)(x_1 + 1) \). Since \( (x_1 + 1)(x_2 + 1) = (x_2 + 1)(x_1 + 1) \), the antisymmetrized polynomial is \( A(x_1, x_2) = 0 \).

What are some conditions under which a factorized polynomial does not vanish when antisymmetrized?

A factorized polynomial will not vanish when antisymmetrized if it inherently contains antisymmetric components. For example, polynomials that are products of differences like \( (x_1 - x_2) \) will not vanish because swapping \( x_1 \) and \( x_2 \) introduces a sign change that does not cancel out the terms completely.

How is antisymmetrization used in mathematical and physical applications?

Antisymmetrization is widely used in quantum mechanics, particularly in the context of wavefunctions for fermions, which must be antisymmetric under particle exchange due to the Pauli exclusion principle. It also appears in algebraic geometry and representation theory, where antisymmetric polynomials play a role in the study of determinants, exterior algebra, and more.

Back
Top