Summary of DVCS Analysis
------------------------

Sources: ZAF presentation by Andrii 14/08/2013.
File dvcs17.pdf from Andrii.


1) The electron in DVCS
   --------------------

a) DVCS MC truth/detector 

 Energy 25.07 +- 0.06 GeV  MC  Truth  see presentation P24 (14/08/2013 ZAF)
 Energy 25.48 +- 0.07 GeV  MC  Det using Siecorr3  see dvcs17  P6

Agree to 1.6 %.

b) DVCS  data using siecorr3

 Energy 25.12 +- 0.07  data  see dvcs17  P6

Agrees with MC det level to 1.4 %.


Conclude: DVCS MC and data agree to within ~2 % for
          the electron.  




2) The photon in DVCS.
   ------------------

With the electron understood to within  2% 
the photon transverse energy (EtG) as measured by ZUFOs can be 
compared with the transverse energy (EtE) of the electron.
Note that the transverse energy will not balance exactly
due to initial state QED radiation from the electron
and the momentum carried by the recoil proton.

The DVCS MC (plot 3  P26 of presentation) 
shows that the transverse energy  is expected
to balance within 2 +-0.7 % ( ratio  EtG/EtE = 1.024 +-0.07).

Plots 1 and 2 (P 26 of presentation) show that the ratio ETG(ZUFO)/EtE(siecorr) for data and MC
are  1.109 and 1.107, respectively.

Conclude: for data and MC,  the ZUFO-measured gamma transverse energy
should  be corrected by a factor 1.10;  this factor was also found
from studies of PHP MC events.
The uncertainty of this correction, originating from 
the electron uncertainty and the DVCS model,  is ~2%.