By considering a flavour expansion about the SU (3)-flavour symmetric point, we investigate how flavour-blindness constrains octet baryon matrix elements after SU (3) is broken by the mass difference between quarks. Similarly to hadron masses we find the expansions to be constrained along a mass trajectory where the singlet quark mass is held constant, which provides invaluable insight into the mechanism of flavour symmetry breaking and proves beneficial for extrapolations to the physical point. Expansions are given up to third order in the expansion parameters. Considering higher orders would give no further constraints on the expansion parameters. The relation of the expansion coefficients to the quark-line-connected and quark-line disconnected terms in the 3-point correlation functions is also given. As we consider Wilson clover-like fermions, the addition of improvement coefficients is also discussed and shown to be included in the formalism developed here. As an example of the method we investigate this numerically via a lattice calculation of the flavour-conserving matrix elements of the vector first class form factors. Determination ofẐ

We present results from the QCDSF/UKQCD collaboration for the transverse spin densities of octet baryons obtained from simulations using N f = 2 + 1 flavours of O(a)-improved Wilson fermions. These densities are revealed through an analysis of the electromagnetic and tensor form factors of the octet baryons at two different lattice spacings with pion masses as low as 220 MeV. We find SU(3) flavour-breaking effects of the form factors and use these to extrapolate to the physical mass. Constructing combinations of Fourier transformed form factors reveal non-trivial spin densities in the transverse plane, with similar deformations across the baryon octet.

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