mg272 and mg273 give different xs for longitudinally polarized processes

Asked by xiao jie on 2020-07-17

Dear authors,

I found mg273 and mg272 give different cross sections for longitudinally polarized VBS processes.

For WLZL:
    set process:
        generate p p > w+{0} z{0} j j QED=4 QCD=0, w+ > l+ vl, z > l+ l- @ 1
        add process p p > w-{0} z{0} j j QED=4 QCD=0, w- > l- vl~, z > l+ l- @ 2
    and set reference frame:
        3,4,5,6 = me_frame
    The cross section under mg273 is 0.001368 pb
    The cross section under mg272 is 0.00158 pb
    mg273 is 13.4% less than mg272

For WLWL:
    set process:
        generate p p > w+{0} w+{0} j j QED=4 QCD=0, w+ > l+ vl @ 1
        add process p p > w-{0} w-{0} j j QED=4 QCD=0, w- > l- vl~ @ 2
    and set reference frame:
        3,4,5,6 = me_frame
    The cross section under mg273 is 0.003051 pb
    The cross section under mg272 is 0.003286 pb
    mg273 is 7.2% less than mg272

For WLWL no decay:
    set process:
        generate p p > w+{0} w+{0} j j QED=4 QCD=0 @ 1
        add process p p > w-{0} w-{0} j j QED=4 QCD=0 @ 2
    and set reference frame:
        3,4 = me_frame
    The cross section under mg273 is 0.02858 pb
    The cross section under mg272 is 0.02858 pb
    mg273 is same as mg272

Do you know reason?

Best,
Jie

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2020-07-17
Last reply:
2020-07-29

Hi,

This should be related to this message in the UpdatesNotes:

OM: Fix a bug in the longitudinal polarization for off-shell effect, leading to deviation at large invariant mass.

Cheers,

Olivier

Can you help with this problem?

Provide an answer of your own, or ask xiao jie for more information if necessary.

To post a message you must log in.