[G14_run] [EXTERNAL] paper by Hall A on double polarization asymmetries on 3He

[Alessandra Filippi]

Hi all,
I wanted to bring to your attention a recent paper by Hall A on double 
polarization asymmetries in electroproduction on 3He, that could be maybe 
useful to get some more inspiration about our studies with g14 data:

M. Mihovilovic et el, Phys. Lett. B 788 (2019), 117

https://urldefense.proofpoint.com/v2/url?u=https-3A__www.sciencedirect.com_science_article_pii_S0370269318308384-3Fvia-253Dihub&d=DwIBAg&c=CJqEzB1piLOyyvZjb8YUQw&r=5LSWsFN5KweowPCsdwCuTw&m=Y98DXCiCesylhdVFNmm7rEpSatN-s6jGCcw4PbTmE5M&s=9OZklxfNnV4D41x-QzmTidVRZ549oOyS1YHIiBmLKxE&e= 

I believed it was more recent... actually we are in 2020 and not 2019, I 
just realized! :-D
Anyway, the paper is interesting for us not really for the results (the 
spin-target asymmetry is plotted as a function of the missing momentum in 
the reaction, that is an inclusive electroproduction), but for the method 
they used to extract the relevant information. 
Indeed, I think the first equation in the paper is very similar to what we 
are using, changing properly the notation. Our Lambda_z is what they call 
S, the spin of the target, A0 is our P, A is our Pdot etc. I am trying to 
understand how they can express A as a simple ratio of cross sections 
as shown in the second equation, even assuming their A_e (our Idot) can be 
neglected... there is some factor that I miss.

Moreover, I'd like to understand whether there is any unitary-related 
requirement for each for the scalar products in the formula [1 + ...] to
be in the (-1,1) range (or maybe the full sum inside the brackets must 
be normalized, say, to the integral over all the different phi bins?).
I haven't found any hint on this in the old papers I went through, but of
course, if this is the case, what we observe must be properly rescaled.
Any idea is welcome!
cheers
     Alessandra