[Eic-core-phys] [EXTERNAL] CORE: Estimated Systematic Errors for DPAP

[Hyde, Charles E.]

The DPAP has asked us to estimate "total" errors
for several exclusive processes.
I attach the results of my suggested procedure for estimating
the systematic error in reconstructing a t-distribution, based
on an assumed uncertainty in the EMCal resolution.
This example is for ep DVCS, so EMCal dominates.

I used the event sample from the ePIC generator, as provided by Carlos Munoz Camacho.
The plots are as follows:
Left:
All histograms are normalized to the number of counts expected in the "DPAP" bin,
with an integrated luminosity of 10 inverse-fb
Magenta = EPIC "truth" distribution.
Black = Experimental yield from DELPHES
Red = Experimental yield with EMCal resolution =1.10*nominal CORE value
Green = Experimental yield with EMCal resolution =0.9*nominal CORE value
Error bars are MC errors, not true exp statistical errors

Middle:
Ratio of left panel Red/Black = Red histogram (with linear fit)
Ratio of left panel Green/Black = Green histogram (with linear fit)
Blue curve is sqrt(p0^2 + p1^2*x), where p0, p1 are the parameters of the fit to red hist.

Right:
Magenta = same  left panel, except now error bars are statistical sqrt(N_Experiment)
Black = same as left panel, with exp. statistical errors
Blue: error bars now include the "systematic" of middle panel, added in quadrature with statistical errors.
The Blue "total" error bars are almost indistinguishable from the pure statistical (magenta) error bars.
Please note I did NOT perform a true reconstruction, I just estimate how well I think we will do in a true reconstruction.  I think a 10% uncertainty on the our knowledge of the EMCal resolution is reasonable, but I don't have an absolute reason for this rather than, say, 15%, etc.

I would only include the right panel in our response to DPAP, with a little text.

Sincerely,

Dr. Charles E. Hyde
Eminent Scholar and University Professor of Physics
Old Dominion University
4600 Elkhorn Ave
Norfolk VA 23529
PS-II 2100D
1 (757) 683 5853

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