[G14_run] 4vecs for testing

[daoh at andrew.cmu.edu]

Dear all,

As you might recall from the last meeting, Peng, Tsuneo and I were tasked
to compute the cos(pim) in the overall center of mass frame for a 100
events supplied by Haiyun. The initial goal was to let these events go
through momentum correction and energy correction to check for
inconsistency. However, I realized that with only 4-vector momentum
information for the proton, pim, and the photon, one can not do energy
correction (need to know the interaction vertex), nor momentum correction
(need to know the sector, the run number, etc...). As a result, I had not
applied any correction and computed the cos(pim) directly. I assumed the
neutron is at rest, then I boosted the pim into the photon and at-rest
neutron rest frame. I then computed the cos(pim) with respect to the beam
line.

I attached a file with the computed values of cos(pim) with this email if
Peng and Tsuneo want to compare.
Sincerely,
Dao Ho



> As discussed, I attached a 100-event text file. Each event has three
> particles: photon beam, scattered proton and scattered pi- in order.
> Each particle occupies one line with energy, momentum in x direction,
> momentum in y, and momentum in z. All these variables are in Lab frame.
> There are totally 300 lines.
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