SU(2) Spinor: Is Product of Two Scalar-Type Entity?

  • Context: Graduate 
  • Thread starter Thread starter div curl F= 0
  • Start date Start date
  • Tags Tags
    Spinor Su(2)
Click For Summary
SUMMARY

The product of two SU(2) spinors, represented as \Phi_1^{\dagger} \Phi_1, is indeed a scalar-type entity. This scalar nature allows for the commutation of the product with other spinors, such as \Phi_2, under the condition that they are treated as bosonic quantities. The preservation of the hermitian inner product in SU(2) confirms that these products behave as scalars, while the commutation properties depend on whether the quantities are fermionic or bosonic. Care must be taken when dealing with operators as opposed to classical fields.

PREREQUISITES
  • Understanding of SU(2) group theory
  • Familiarity with spinor algebra
  • Knowledge of bosonic and fermionic properties
  • Basic concepts of hermitian inner products
NEXT STEPS
  • Study SU(2) group representations in quantum mechanics
  • Explore the properties of spinors in quantum field theory
  • Learn about the implications of bosonic versus fermionic statistics
  • Investigate the role of operators in quantum field theory
USEFUL FOR

The discussion is beneficial for theoretical physicists, quantum field theorists, and students studying advanced quantum mechanics, particularly those focusing on spinor fields and SU(2) symmetry.

div curl F= 0
Messages
18
Reaction score
0
I'm having a memory blank on this particular area of field theory. Is the product of two spinors a scalar or scalar type entity and if so, can I treat it like a scalar? (i.e. move it around without worrying about order etc)

i.e.

is [tex]\Phi_1^{\dagger} \Phi_1[/tex] a scalar?

and if so does:

[tex]\Phi_2 \left(\Phi_1^{\dagger} \Phi_1\right) = \left(\Phi_1^{\dagger} \Phi_1\right) \Phi_2[/tex]

where both phi's are SU(2) complex spinors.

Thanks
 
Last edited:
Physics news on Phys.org
Yes, if you think back to the definition of SU(2), it is precisely the group under which quantities like [itex]\psi^\dagger \psi[/itex] are scalars (namely, it preserves a hermitian inner product). Also, whether you can commute those quantities is not related to whether they are scalars, but does depend on if they are fermionic or bosonic (though, in this case, anything squared is bosonic, so commutes with everything). Also, if they are operators rather than classical fields you need to be careful.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 60 ·
3
Replies
60
Views
15K