[12gevmoller_sim] [JeffersonLab/remoll] 51aa31: Demonstration of correct MG5 operations on e- e- >...

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  Branch: refs/heads/develop
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  Commit: 51aa3178d5956c49fb9b6c2520edebd0b3b8cdf3
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  Author: Wouter Deconinck <wdconinc at gmail.com>
  Date:   2019-01-20 (Sun, 20 Jan 2019)

  Changed paths:
    M generators/MG5/README.md
    A generators/MG5/e-e-/.gitignore
    A generators/MG5/e-e-/proc_card_mg5_ee_ee_NLO.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_ee_QED.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_ee_and_eemumu.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_eea__a_ee.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_eea__a_mumu.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_eeee.dat
    A generators/MG5/e-e-/proc_card_mg5_ee_eemumu.dat
    A generators/MG5/e-e-/template/madanalysis5_hadron_card.dat
    A generators/MG5/e-e-/template/madanalysis5_parton_card.dat
    A generators/MG5/e-e-/template/run_card.dat
    R generators/MG5/ee/.gitignore
    R generators/MG5/ee/proc_card_mg5_ee_ee.dat
    R generators/MG5/ee/proc_card_mg5_ee_ee_NLO.dat
    R generators/MG5/ee/proc_card_mg5_ee_ee_and_eemumu.dat
    R generators/MG5/ee/proc_card_mg5_ee_eea__a_ee.dat
    R generators/MG5/ee/proc_card_mg5_ee_eea__a_mumu.dat
    R generators/MG5/ee/proc_card_mg5_ee_eeee.dat
    R generators/MG5/ee/proc_card_mg5_ee_eemumu.dat
    R generators/MG5/ee/template/madanalysis5_hadron_card.dat
    R generators/MG5/ee/template/madanalysis5_parton_card.dat
    R generators/MG5/ee/template/run_card.dat
    M macros/hepmc/ee_ee.mac
    A scripts/lhef2hepmc.sh

  Log Message:
  -----------
  Demonstration of correct MG5 operations on e- e- > e- e-

With the commands
```
mg5_aMC proc_card_mg5_ee_ee_QED.dat
cd ee_ee_QED
bin/generate_events run_01 -f
```
at 11 GeV x 0.000511 GeV and without pT cuts we get a divergence,
and MG5 takes forever to complete. With pT cuts at small values
(small theta_cm to large pi - theta_cm range) the calculation takes
a long time, completes with high uncertainty. The default is now
the 30 deg to 150 deg range for pT over 0.0374 GeV. For 0.04 GeV,
the total cross section is about 1.53E+08 ± 1.10E+05 pb.

E.g. after generating a bunch of runs we do indeed get the following:
```
ptl12min [GeV]	sigma [pb]	theta_min [deg]
0.001	2.77E+11	0.76
0.002	6.97E+10	1.53
0.003	3.09E+10	2.29
0.004	1.74E+10	3.06
0.005	1.10E+10	3.82
0.01	2.75E+09	7.66
0.02	6.77E+08	15.47
0.03	2.89E+08	23.59
0.04	1.53E+08	32.24
0.05	8.77E+07	41.83
0.06	5.00E+07	53.16
0.07	2.26E+07	69.01
0.071	1.97E+07	71.26
0.072	1.67E+07	73.81
0.073	1.33E+07	76.83
0.074	9.09E+06	80.76
0.0747	4.76E+06	85.11
```

Due to the u and t processes, the integral over cos(theta) does not
compute as nicely as in the s-channel case (i.e. not something to do
on paper).

The maximum pT is 0.0748 GeV (hence pT at 30 deg is half that).


  Commit: 4fb7de14f9c2216808fe884c9aa00475e6cba75f
      https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FJeffersonLab%2Fremoll%2Fcommit%2F4fb7de14f9c2216808fe884c9aa00475e6cba75f&data=02%7C01%7C12gevmoller_sim%40jlab.org%7Cdb82ac101fb74d013c1f08d67ef86caa%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C1%7C636836002773092297&sdata=secpdtDDWssD9tRxTikgUGygqKEPcj23EmgQyyBy0ZM%3D&reserved=0
  Author: Wouter Deconinck <wdconinc at gmail.com>
  Date:   2019-01-20 (Sun, 20 Jan 2019)

  Changed paths:
    A generators/MG5/e+e-/.gitignore

  Log Message:
  -----------
  Ignore files in e+ e- > mu+ mu- directory


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