Consider constructing the Ward identity associated with Lorentz invariance. It is possible to find a 3rd rank tensor Bρμν antisymmetric in the first two indices, then the stress-energy tensor can be made symmetric. Once done, the conserved current coming from the classical analysis is of the form
jμνρ=TμνBxρ−TμρBxν
This ensures the symmetry of the conserved current which can be seen most easily be invoking the conservation law ∂μjμνρ=0
Let X denote a set of n fields. The Ward identity associated with Lorentz invariance is then
∂μ⟨(Tμxρ−Tμρxν)X⟩=∑iδ(x−xi)[xνi∂ρi−xρi∂νi⟨X⟩−iSνρi⟨X⟩].
This is then equal to
⟨(Tρν−Tνρ)X⟩=−i∑iδ(x−xi)Sνρi⟨X⟩,
which states that the stress tensor is symmetric within correlation functions, except at the position of the other fields of the correlator.
My question is: how is this last equation and statement derived?
I think the Ward identity associated with translation invariance is used after perhaps splitting (1) up like so:
n∑ixνin∑iδ(x−xi)∂ρi⟨X⟩−n∑ixρin∑iδ(x−xi)∂νi⟨X⟩−in∑iδ(x−xi)Sνρi⟨X⟩
for example. The result I am getting is that ⟨((∂μTμν)xρ−(∂μTμρ)xν+Tρν−Tνρ)X⟩=∑ixνi∂μ⟨TμρX⟩+∑ixρi∂μ⟨TμνX⟩−i∑iδ(x−xi)Sνρi⟨X⟩
No comments:
Post a Comment