[b1_ana] Follow up [Fwd: Inclusive paper by Arenhoevel]

[O. A. Rondon]

Hi,

Per Fig. 1 of Arenhoevel's inclusive paper, the target orientation is
defined relative to the q vector.

Here are some additional comments:

- on a vector target asymmetry contribution.

For field along q, the d^1_{-1,0}(theta_d) function in eq. (25)
vanishes, no A^V_d.

For field not aligned along q, even if the form factor F^{1,-1}_{LT}
does not vanish above pion threshold, A^V_d would still be zero if the
data were symmetric about the q vector azimuthal axis.

However, because the field stays always in the horizontal lab plane, and
the scattered electrons are deflected in one direction (usually down),
the mean <phi_d> is not zero, so there would be some vector A^V_d,
proportional to sin(<phi_d>).

So, unless P_z = 0, or if it can be canceled between two subsets of
data, there would be an A^V_d, except for field along q.

- for the tensor asymmetry, since the contributions of FL20 and FT20 are
independent of the field direction, they would always contribute to a
single measurement, but measurements at different phi_d and theta_d
could be used to separate FLT(2,-1) and FTT(2,-2). However, the relevant
angle for doing this is phi_d, not theta_d, i.e. unrelated to section 6
of H-J-M, as I had thought.

But it is illuminating to see that FLT(2,-1) around the Delta is ~10 to
~50 times smaller than FT (compare Fig. (16) to Fig. (14)). Since  FT ~
F1, again we would be looking at a very small quantity.

Cheers,

Oscar





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