I understand why Pete and Genya are getting different results for the
vector asymmetry in ed elastic scattering. Below is a note that Genya
forwarded to Pete. By only using N1+N2 in the denominator, Genya's
asymmetry includes the tensor polarization in the denominator. N1+N2
is proportional to the cross section multiplied by (1 + P_T*A_T). The
tensor analyzing power is strongly negative, thereby reducing the
denominator and making the apparent asymmetry larger.
On the other hand, I have Pete dividing the same numerator N1-N2 by
the sum of all 6 polarization states, which is just proportional to
the cross section and independent of tensor polarization. Since 4
polarization states are used in the numerator and 6 in the denominator,
the resulting asymmetry is multiplied by 6/4. The reason for extracting
the vector asymmetry this way is obvious. It is independent of the
tensor asymmetry.
---------------------------- Original Message ----------------------------
Subject: Re: no timing cuts? (fwd)
From: "Peter Karpius" <karpiusp@einstein.unh.edu>
Date: Wed, April 28, 2004 1:57 pm
To: jrc@einstein.unh.edu
--------------------------------------------------------------------------
John-
Here is what I got from Genya- perhaps we are doing the same thing
he just separates tensor with cuts (this is what you said right? Tensor
beam-target asym is zero for elastic?)
Pete
>
> I calculate asymmentry as (N1 - N2)/(N1+N2),
> where N1 = N++ + N--; N2= N+- + N-+, where signs correspond to
> target polarization and beam helicity.
-- John R. Calarco Dept. of Physics Univ. of New Hampshire Durham, NH 03824 email: calarco@unh.edu phone: 603-862-2088 fax: 603-862-2998-- John R. Calarco Dept. of Physics Univ. of New Hampshire Durham, NH 03824 email: calarco@unh.edu phone: 603-862-2088 fax: 603-862-2998
-- John R. Calarco Dept. of Physics Univ. of New Hampshire Durham, NH 03824 email: calarco@unh.edu phone: 603-862-2088 fax: 603-862-2998
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