MadGraph5_aMC@NLO

Error while generating events with b in the final state at NLO

Asked by Antara Sarkar

Dear MG5 experts,

I am trying to generate b+photon+jets from p-p collision at NLO using the following commands:

import model loop_sm-no_b_mass
define p = 21 2 4 1 3 -2 -4 -1 -3 5 -5 # pass to 5 flavors
define j = p
generate p p > b a [QCD]
add process p p > b~ a [QCD]
add process p p > b a j [QCD]
add process p p > b~ a j [QCD]
output ba_qcd_nlo

My purpose is to study this as background for two b-jets and photon in the final state. However, on giving this command for output folder, the following error comes :
INFO: ... Done
INFO: Writing files in P0_gb_ab (1 / 40)
INFO: Creating files in directory V0_gb_ab
ALOHA: aloha creates FFV1 set of routines with options: L2,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g b > a b QCD<=1 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: g b > a b QCD<=1 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bg_ab (2 / 40)
INFO: Creating files in directory V0_bg_ab
ALOHA: aloha creates FFV1 set of routines with options: L2,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b g > a b QCD<=1 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b g > a b QCD<=1 QED<=1 [ all = QCD ]
INFO: Writing files in P0_gbx_abx (3 / 40)
INFO: Creating files in directory V0_gbx_abx
ALOHA: aloha creates FFV1 set of routines with options: L1,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g b~ > a b~ QCD<=1 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: g b~ > a b~ QCD<=1 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bxg_abx (4 / 40)
INFO: Creating files in directory V0_bxg_abx
ALOHA: aloha creates FFV1 set of routines with options: L1,P0
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b~ g > a b~ QCD<=1 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b~ g > a b~ QCD<=1 QED<=1 [ all = QCD ]
INFO: Writing files in P0_gg_abbx (5 / 40)
INFO: Creating files in directory V0_gg_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g g > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: g g > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_gb_abg (6 / 40)
INFO: Creating files in directory V0_gb_abg
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: g b > a b g QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: g b > a b g QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_uux_abbx (7 / 40)
INFO: Creating files in directory V0_uux_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: u u~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: u u~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_ub_aub (8 / 40)
INFO: Creating files in directory V0_ub_aub
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: u b > a u b QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: u b > a u b QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_ddx_abbx (9 / 40)
INFO: Creating files in directory V0_ddx_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: d d~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: d d~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_db_adb (10 / 40)
INFO: Creating files in directory V0_db_adb
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: d b > a d b QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: d b > a d b QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_uxu_abbx (11 / 40)
INFO: Creating files in directory V0_uxu_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: u~ u > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: u~ u > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_uxb_auxb (12 / 40)
INFO: Creating files in directory V0_uxb_auxb
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: u~ b > a u~ b QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: u~ b > a u~ b QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_dxd_abbx (13 / 40)
INFO: Creating files in directory V0_dxd_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: d~ d > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: d~ d > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_dxb_adxb (14 / 40)
INFO: Creating files in directory V0_dxb_adxb
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: d~ b > a d~ b QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: d~ b > a d~ b QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bg_abg (15 / 40)
INFO: Creating files in directory V0_bg_abg
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b g > a b g QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b g > a b g QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bu_abu (16 / 40)
INFO: Creating files in directory V0_bu_abu
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b u > a b u QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b u > a b u QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bd_abd (17 / 40)
INFO: Creating files in directory V0_bd_abd
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b d > a b d QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b d > a b d QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bux_abux (18 / 40)
INFO: Creating files in directory V0_bux_abux
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b u~ > a b u~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b u~ > a b u~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bdx_abdx (19 / 40)
INFO: Creating files in directory V0_bdx_abdx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b d~ > a b d~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b d~ > a b d~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bb_abb (20 / 40)
INFO: Creating files in directory V0_bb_abb
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b b > a b b QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b b > a b b QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bbx_abbx (21 / 40)
INFO: Creating files in directory V0_bbx_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b b~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b b~ > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Writing files in P0_bxb_abbx (22 / 40)
INFO: Creating files in directory V0_bxb_abbx
ALOHA: aloha creates FFV1 set of routines with options: L2
INFO: Computing diagram color coefficients
INFO: Drawing loop Feynman diagrams for Process: b~ b > a b b~ QCD<=2 QED<=1 [ all = QCD ]
INFO: Generating born Feynman diagrams for Process: b~ b > a b b~ QCD<=2 QED<=1 [ all = QCD ]
Command "output ba_qcd_nlo" interrupted with error:
OSError : [Errno 17] File exists: 'P0_gg_abbx'
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in 'MG5_debug'.
Please attach this file to your report.

Am I making any mistake in giving the commands? Could you please suggest how to successfully have two b's and one photon in the final state, at NLO?

Thanks and Regards,
Antara

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Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

The first issue here is that you are mixing four and five flavour computation.
In a five flavor computation, you can not ask to have one "b" in the final state.

So I guess that you need to change your model to use a four flavour model.

Cheers,

Olivier

Revision history for this message
Antara Sarkar (antara-s) said : 		#2

Thanks Olvier for your reply,

Yes, I agree that using a four flavour model did not produce any error while I was studying this process at LO. However, I now, need the cross section at NLO, where at first, a b and a photon are being produced from gluon and b. Thus, for QCD corrections in this process, we need to work in 5-flavour model. So, you mean if I have a b in my jet definition (j), then this process (with two b's and a photon in final state) would be accounted for. Is that sufficient?
Is there any way here, so that we can get more constribution, in particular, for the b's in the final state as I am interested in studying them, or there is no way out other than producing statistically very high number of events? Your insights would be very helpful.

Regards,
Antara

Revision history for this message
Antara Sarkar (antara-s) said : 		#3

Hi Olivier,

I tried generating the events at NLO in the five flavour model as follows:

import model loop_sm
define p = 21 2 4 1 3 -2 -4 -1 -3 # pass to 4 flavors
define j = p
define p = p b b~
define j = j b b~
generate p p > b a [QCD]
add process p p > b~ a [QCD]
add process p p > b a j [QCD]
add process p p > b~ a j [QCD]
output ba_bkgd_13tev_nlo

However, on doing so the following error shows up and it is getting stuck:

INFO: Starting run
INFO: Compiling the code
INFO: Using built-in libraries for PDFs
INFO: Compiling source...
INFO: ...done, continuing with P* directories
INFO: Compiling directories...
INFO: Compiling on 6 cores
INFO: Compiling P0_gb_ab...
INFO: Compiling P0_bg_ab...
INFO: Compiling P0_gbx_abx...
INFO: Compiling P0_bxg_abx...
INFO: Compiling P0_gg_abbx...
INFO: Compiling P0_gb_abg...
STOP pz is not conserved (flag:CT692)
STOP pz is not conserved (flag:CT692)
STOP pz is not conserved (flag:CT692)
STOP pz is not conserved (flag:CT692)
INFO: P0_gb_abg done.
INFO: P0_gbx_abx done.
INFO: Compiling P0_uux_abbx...
INFO: Compiling P0_ub_abu...
STOP pz is not conserved (flag:CT692)
WARNING: fct <function compile_dir at 0x7f7682f371d0> does not return 0. Stopping the code in a clean way. The error was:
A compilation Error occurs when trying to compile /home/ad/my_computation/MG5_aMC_v2_7_2/ba_bkgd_13tev_nlo/SubProcesses/P0_uux_abbx.
The compilation fails with the following output message:
    gfortran -O -fno-automatic -ffixed-line-length-132 -c -I. -I../../lib/ montecarlocounter.f
    born_leshouche.inc:16:25:

           DATA (MOTHUP(2,I, 4),I=1, 5)/ 0, 0, 2, 2, 2/
                             1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 3
    born_leshouche.inc:16:25:

           DATA (MOTHUP(2,I, 4),I=1, 5)/ 0, 0, 2, 2, 2/
                             1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 3
    born_leshouche.inc:16:12:

           DATA (MOTHUP(2,I, 4),I=1, 5)/ 0, 0, 2, 2, 2/
                1
    Error: Data element above array upper bound at (1)
    born_leshouche.inc:15:25:

           DATA (MOTHUP(1,I, 4),I=1, 5)/ 0, 0, 1, 1, 1/
                             1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 3
    born_leshouche.inc:15:25:

           DATA (MOTHUP(1,I, 4),I=1, 5)/ 0, 0, 1, 1, 1/
                             1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 3
    born_leshouche.inc:15:12:

           DATA (MOTHUP(1,I, 4),I=1, 5)/ 0, 0, 1, 1, 1/
                1
    Error: Data element above array upper bound at (1)
    born_leshouche.inc:14:19:

           DATA (IDUP(I,4),I=1,5)/4,-4,22,5,-5/
                       1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 2
    born_leshouche.inc:14:19:

           DATA (IDUP(I,4),I=1,5)/4,-4,22,5,-5/
                       1
    Warning: Array reference at (1) is out of bounds (4 > 2) in dimension 2
    born_leshouche.inc:14:12:

           DATA (IDUP(I,4),I=1,5)/4,-4,22,5,-5/
                1
    Error: Data element above array upper bound at (1)
    born_leshouche.inc:13:25:

           DATA (MOTHUP(2,I, 3),I=1, 5)/ 0, 0, 2, 2, 2/
                             1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 3
    born_leshouche.inc:13:25:

           DATA (MOTHUP(2,I, 3),I=1, 5)/ 0, 0, 2, 2, 2/
                             1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 3
    born_leshouche.inc:13:12:

           DATA (MOTHUP(2,I, 3),I=1, 5)/ 0, 0, 2, 2, 2/
                1
    Error: Data element above array upper bound at (1)
    born_leshouche.inc:12:25:

           DATA (MOTHUP(1,I, 3),I=1, 5)/ 0, 0, 1, 1, 1/
                             1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 3
    born_leshouche.inc:12:25:

           DATA (MOTHUP(1,I, 3),I=1, 5)/ 0, 0, 1, 1, 1/
                             1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 3
    born_leshouche.inc:12:12:

           DATA (MOTHUP(1,I, 3),I=1, 5)/ 0, 0, 1, 1, 1/
                1
    Error: Data element above array upper bound at (1)
    born_leshouche.inc:11:19:

           DATA (IDUP(I,3),I=1,5)/2,-2,22,5,-5/
                       1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 2
    born_leshouche.inc:11:19:

           DATA (IDUP(I,3),I=1,5)/2,-2,22,5,-5/
                       1
    Warning: Array reference at (1) is out of bounds (3 > 2) in dimension 2
    born_leshouche.inc:11:12:

           DATA (IDUP(I,3),I=1,5)/2,-2,22,5,-5/
                1
    Error: Data element above array upper bound at (1)
    makefile:73: recipe for target 'montecarlocounter.o' failed
    make: *** [montecarlocounter.o] Error 1

Please try to fix this compilations issue and retry.
Help might be found at https://answers.launchpad.net/mg5amcnlo.
If you think that this is a bug, you can report this at https://bugs.launchpad.net/mg5amcnlo
INFO: P0_gg_abbx done.
INFO: P0_bg_ab done.
INFO: P0_bxg_abx done.
INFO: P0_gb_ab done.

Could you tell what is going wrong here, I am not able to understand the meaning of this error. How do I correct this?

Looking forward to your advise in this matter.

Thanks & Regards,
Antara

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#4

Funny that you did not get the same error as above since you are still mixing four and five flavor computation since you use
define p = p b b~
define j = j b b~
In four flavor computation the "b" is massive and can be distinguished for the other light quark and therefore is not include in the NLO computation in the same way as the other quark since the pole are protected by the finite b mass.
The cost is obviously that your cross-section will have an uncertainty of the order of log(mb^2/shat) which can be large.
At LO, you can be inconsistent between four and five flavor and the code will return a number (which might not always be easy to understand theoretically due to the missmatch of flavor scheme, especially if you add parton-shower to the sample) but at NLO, since you include one order more to the computation you will be sensitive to the gluon splitting to b b~ already at matrix-element level and therefore you need to be 100% consistent to have an NLO accurate cross-section .

Now you might need to change your process definition to have something consistent with the four flavor computation since like with the "top" you have to produce them by pair in the four flavor scheme.

Cheers,

Olivier

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