Unable to produce proton - photon (lpp = 3) process and sometime very different CS from older version of MG5

Asked by SUBHASISH BEHERA on 2021-05-15

Dear MG5 Team,

I am using version- 3.1.0 to produce the following:

define p = p b b~
define j = p
generate p a > b b~ j /h t~ t QED<=99

lpp2 = 3

I encounter error as follow:
============================
generate_events run_01
Traceback (most recent call last):
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/extended_cmd.py", line 1544, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/extended_cmd.py", line 1493, in onecmd_orig
    return func(arg, **opt)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/madevent_interface.py", line 2474, in do_generate_events
    self.run_generate_events(switch_mode, args)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/common_run_interface.py", line 7114, in new_fct
    original_fct(obj, *args, **opts)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/madevent_interface.py", line 2513, in run_generate_events
    self.exec_cmd('survey %s %s' % (self.run_name,' '.join(args)),
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/extended_cmd.py", line 1573, in exec_cmd
    stop = Cmd.onecmd_orig(current_interface, line, **opt)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/extended_cmd.py", line 1493, in onecmd_orig
    return func(arg, **opt)
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/interface/madevent_interface.py", line 3368, in do_survey
    jobs, P_zero_result = ajobcreator.get_helicity()
  File "/Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/madgraph/madevent/gen_ximprove.py", line 169, in get_helicity
    raise Exception(pjoin(self.me_dir,'error'))
Exception: /Users/SUBH/RESEARCH/EVENT_GENERATORS/MADGRAPH5/MG5_aMC_v3_1_0/PAjjj_2_ellis_pa2bbj/error
                              Run Options

============================

(1) Can you suggest where I am doing wrong?

(2) In addition, I was trying to produce the same event with version - 2.6.7, where it was working perfectly well. So, if 3.1.0 don't work, can I use the result from 2.6.7 without any problem?

(3) Another issue I was having while doing the showering of such events with standalone Pythia8, where it was seen that the "remnant electron (since the photon originate from electron)" was missing. Can you suggest if the issue with MG5 or not for version - 2.6.7 or 2.9.3?

(4) Till now I don't get any idea about the "dsqrt2_pdf = ?" value for E_e = 60 GeV? I sometime try with "10" but not sure why and how much should be the value. Can you also give some idea here?

(5) Another process:
define p = p b b~
define j = p
generate p a > b b~ j /h t~ t QED<=99

where I was getting CS values very very different in two different versions (with same setup):
MG_1_5_15 = 172500.0
MG_2_6_7 = 908.756825663

Can you provide the link from where I could get "MG_1_5_15" ? I just wanted the link for cross verification.

Thanks,
Subhasish

Question information

Language:
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Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said :
#1

The issue is on the automatic determination of mur for the proton beam.
(since for the photon we are using a fix scale for that).

So if you pass to a fix scale computation for the proton or to another dynamical_scale_choice you will not have that issue.

> (3) Another issue I was having while doing the showering of such events with standalone Pythia8, where it was seen that the "remnant electron (since the photon originate from electron)" was missing. Can you suggest if the issue with MG5 or not for version - 2.6.7 or 2.9.3?

please ask pythia8 author on this. if they want us to write the process in a different way we can do it obviously but I will need details on what they want as an input.

> (4) Till now I don't get any idea about the "dsqrt2_pdf = ?" value for E_e = 60 GeV? I sometime try with "10" but not sure why and how much should be the value. Can you also give some idea here?

I do not know that type of physics enough to be able to comment on that.

> Can you provide the link from where I could get "MG_1_5_15" ?

you can use bazaar to get back to old version of the code:
bzr branch lp:mg5amcnlo
then go to the mg5amcnlo directory
and do
bzr revert -r XXXX
where XXXX is the bazaar number corresponding to the version that you want:
see here https://bazaar.launchpad.net/~madteam/mg5amcnlo/series2.0/changes

> On 15 May 2021, at 09:00, SUBHASISH BEHERA <email address hidden> wrote:
>
> define p = p b b~
> define j = p
> generate p a > b b~ j /h t~ t QED<=99
>
> lpp2 = 3

Revision history for this message
SUBHASISH BEHERA (subhparasara) said :
#2

Thanks Olivier Mattelaer, that solved my question.