  The effect of different definitions of the momentum flux on the properties of
the coherent structures of the logarithmic region of wall-bounded turbulence is
investigated by comparing the structures of intense tangential Reynolds stress
with those of the alternative flux proposed in [J. Jimenez, J. Fluid Mech. 809,
585 (2016)]. Despite the fairly different statistical properties of the two
flux definitions, it is found that their intense structures show many
similarities, such as the dominance of 'wall-attached' objects, and geometric
self-similarity. The new structures are wider, but not taller, than the
classical ones, and include both high- and low-momentum regions within the same
object. It is concluded that they represent the same phenomenon as the
classical groups of a sweep, an ejection, and a roller, suggesting that these
groups should be considered the fundamental coherent structures of the momentum
flux. The present results show that the properties of these composite momentum
structures are robust with respect to the definition of the fluxes.
