An energy-momentum tensor in a local quantum field theory is a tensor-valued operator-valued
distribution whose conserved currents generate translations. For a symmetric
conserved tensor 
and virial field 
,
a conserved dilation current has the form
 |
with trace identity 
. In dimension
4, a local scalar 
with 
gives the traceless improvement
 |
The improvement must belong to the same physical field algebra and preserve the relevant charges.
