could not convert string to float: b' cannot extract last t-channel invariant

If i try your process with the LTS version, it just crash due to the fact that you try to decay an initial state particles.
Not sure why such crash has been removed from the 3.5.x version,

Your crash in 3.5.X indicates that we fail to change consistently the mass of the final state (due to massive initial state). So we are back to the issue of inconsistency with the PDF which assumes that the top is massless. I do not have the motivation to study what is the physics inconsistency that trigger this and if they are a way to aleviate this in a reasonable way.

Maybe the best is to use madgraph for the decay:
define light = l+ l- ta+ ta- u c d s u~ c~ d~ s~ b b~ vl vl~
generate p p > t h z, (t > w+ b, w+ > light light), h > b b~, Z > light light

If you really want madspin, then keep the top exactly onshell (offshell effect are smaller than top mass effect that you assume negligeable anyway for using such PDF) might be a solution as well -- so using onshell mode --

Cheers,

Olivier

> On 2 May 2024, at 23:45, Kamran Ahmad <email address hidden> wrote:
>
> New question #812425 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/812425
>
> Hello, I'm encountering this error when i turn Madspin Decay On, how can i resolve this problem:
>
> Command "generate_events run_08" interrupted with error:
> ValueError : could not convert string to float: b' cannot extract last t-channel invariant 5491.5842784514825 -5491.5836414333562 \n'
> Please report this bug on https://bugs.launchpad.net/mg5amcnlo
> More information is found in '/home/kami/1Me/Tools/MG5_aMC_v3_5_4/htz/run_08_tag_1_debug.log'.
> Please attach this file to your report.
>
> #************************************************************
> #* MadGraph5_aMC@NLO/MadEvent *
> #* *
> #* * * *
> #* * * * * *
> #* * * * * 5 * * * * *
> #* * * * * *
> #* * * *
> #* *
> #* *
> #* VERSION 3.5.4 2024-04-05 *
> #* *
> #* The MadGraph5_aMC@NLO Development Team - Find us at *
> #* https://server06.fynu.ucl.ac.be/projects/madgraph *
> #* *
> #************************************************************
> #* *
> #* Command File for MadEvent *
> #* *
> #* run as ./bin/madevent.py filename *
> #* *
> #************************************************************
> generate_events run_08
> Traceback (most recent call last):
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1546, in onecmd
> return self.onecmd_orig(line, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1495, in onecmd_orig
> return func(arg, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/madevent_interface.py", line 2402, in do_generate_events
> self.run_generate_events(switch_mode, args)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/common_run_interface.py", line 7771, in new_fct
> original_fct(obj, *args, **opts)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/madevent_interface.py", line 2656, in run_generate_events
> self.exec_cmd('decay_events -from_cards', postcmd=False)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1575, in exec_cmd
> stop = Cmd.onecmd_orig(current_interface, line, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1495, in onecmd_orig
> return func(arg, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/common_run_interface.py", line 4120, in do_decay_events
> madspin_cmd.import_command_file(path)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1694, in import_command_file
> self.exec_cmd(line, precmd=True)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1575, in exec_cmd
> stop = Cmd.onecmd_orig(current_interface, line, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/interface/extended_cmd.py", line 1495, in onecmd_orig
> return func(arg, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/madgraph/various/misc.py", line 109, in f_with_no_logger
> out = f(self, *args, **opt)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/MadSpin/interface_madspin.py", line 673, in do_launch
> generate_all.run()
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/MadSpin/decay.py", line 2125, in run
> self.get_max_weight_from_event(decay_mapping)
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/MadSpin/decay.py", line 3275, in get_max_weight_from_event
> weight = self.get_max_weight_from_fortran(decay['path'], event_map,numberps,self.options['BW_cut'])
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/MadSpin/decay.py", line 3409, in get_max_weight_from_fortran
> max_weight = self.loadfortran('maxweight',
> File "/home/kami/1Me/Tools/MG5_aMC_v3_5_4/MadSpin/decay.py", line 3463, in loadfortran
> maxweight=float(external.stdout.readline())
> ValueError: could not convert string to float: b' cannot extract last t-channel invariant 5491.5842784514825 -5491.5836414333562 \n'
> Run Options
> -----------
> stdout_level : 20 (user set)
>
> MadEvent Options
> ----------------
> automatic_html_opening : False (user set)
> notification_center : True
> run_mode : 2
> cluster_queue : None (user set)
> cluster_time : None (user set)
> cluster_size : 100
> cluster_memory : 100 (user set)
> nb_core : 12 (user set)
> cluster_temp_path : None
>
> Configuration Options
> ---------------------
> pythia8_path : /home/kami/1Me/Tools/MG5_aMC_v3_5_4/HEPTools/pythia8 (user set)
> hwpp_path : None (user set)
> thepeg_path : None (user set)
> hepmc_path : None (user set)
> madanalysis_path : None (user set)
> madanalysis5_path : /home/kami/1Me/Tools/MG5_aMC_v3_5_4/HEPTools/madanalysis5/madanalysis5 (user set)
> pythia-pgs_path : None (user set)
> td_path : None (user set)
> delphes_path : /home/kami/1Me/Tools/MG5_aMC_v3_5_4/Delphes (user set)
> exrootanalysis_path : None (user set)
> syscalc_path : None (user set)
> rivet_path : None
> yoda_path : None
> lhapdf : /home/kami/1Me/Tools/MG5_aMC_v3_5_4/HEPTools/lhapdf6_py3/bin/lhapdf-config (user set)
> lhapdf_py2 : None
> lhapdf_py3 : None
> timeout : 60
> f2py_compiler : None
> f2py_compiler_py2 : None
> f2py_compiler_py3 : None
> web_browser : None
> eps_viewer : None
> text_editor : None
> fortran_compiler : None
> cpp_compiler : None
> auto_update : 7 (user set)
> cluster_type : condor
> cluster_status_update : (600, 30)
> cluster_nb_retry : 1
> cluster_local_path : None
> cluster_retry_wait : 300
> #************************************************************
> #* MadGraph5_aMC@NLO *
> #* *
> #* * * *
> #* * * * * *
> #* * * * * 5 * * * * *
> #* * * * * *
> #* * * *
> #* *
> #* *
> #* VERSION 3.5.4 2024-04-05 *
> #* *
> #* The MadGraph5_aMC@NLO Development Team - Find us at *
> #* https://server06.fynu.ucl.ac.be/projects/madgraph *
> #* *
> #************************************************************
> #* *
> #* Command File for MadGraph5_aMC@NLO *
> #* *
> #* run as ./bin/mg5_aMC filename *
> #* *
> #************************************************************
> set group_subprocesses Auto
> set ignore_six_quark_processes False
> set low_mem_multicore_nlo_generation False
> set complex_mass_scheme False
> set include_lepton_initiated_processes False
> set gauge unitary
> set loop_optimized_output True
> set loop_color_flows False
> set max_npoint_for_channel 0
> set default_unset_couplings 99
> set max_t_for_channel 99
> set zerowidth_tchannel True
> set nlo_mixed_expansion True
> import model sm
> define p = g u c d s u~ c~ d~ s~
> define j = g u c d s u~ c~ d~ s~
> define l+ = e+ mu+
> define l- = e- mu-
> define vl = ve vm vt
> define vl~ = ve~ vm~ vt~
> define p=p t t~ b b~
> generate p p > h t z
> output htz
> ######################################################################
> ## PARAM_CARD AUTOMATICALY GENERATED BY MG5 ####
> ######################################################################
> ###################################
> ## INFORMATION FOR MASS
> ###################################
> BLOCK MASS #
> 5 4.700000e+00 # mb
> 6 1.730000e+02 # mt
> 15 1.777000e+00 # mta
> 23 9.118800e+01 # mz
> 25 1.250000e+02 # mh
> 1 0.000000e+00 # d : 0.0
> 2 0.000000e+00 # u : 0.0
> 3 0.000000e+00 # s : 0.0
> 4 0.000000e+00 # c : 0.0
> 11 0.000000e+00 # e- : 0.0
> 12 0.000000e+00 # ve : 0.0
> 13 0.000000e+00 # mu- : 0.0
> 14 0.000000e+00 # vm : 0.0
> 16 0.000000e+00 # vt : 0.0
> 21 0.000000e+00 # g : 0.0
> 22 0.000000e+00 # a : 0.0
> 24 8.041900e+01 # w+ : cmath.sqrt(mz__exp__2/2. + cmath.sqrt(mz__exp__4/4. - (aew*cmath.pi*mz__exp__2)/(gf*sqrt__2)))
> ###################################
> ## INFORMATION FOR SMINPUTS
> ###################################
> BLOCK SMINPUTS #
> 1 1.325070e+02 # aewm1
> 2 1.166390e-05 # gf
> 3 1.190025e-01 # as (note that parameter not used if you use a pdf set)
> ###################################
> ## INFORMATION FOR YUKAWA
> ###################################
> BLOCK YUKAWA #
> 5 4.700000e+00 # ymb
> 6 1.730000e+02 # ymt
> 15 1.777000e+00 # ymtau
> ###################################
> ## INFORMATION FOR DECAY
> ###################################
> DECAY 6 1.491500e+00 # wt
> DECAY 23 2.441404e+00 # wz
> DECAY 24 2.047600e+00 # ww
> DECAY 25 6.382339e-03 # wh
> DECAY 1 0.000000e+00 # d : 0.0
> DECAY 2 0.000000e+00 # u : 0.0
> DECAY 3 0.000000e+00 # s : 0.0
> DECAY 4 0.000000e+00 # c : 0.0
> DECAY 5 0.000000e+00 # b : 0.0
> DECAY 11 0.000000e+00 # e- : 0.0
> DECAY 12 0.000000e+00 # ve : 0.0
> DECAY 13 0.000000e+00 # mu- : 0.0
> DECAY 14 0.000000e+00 # vm : 0.0
> DECAY 15 0.000000e+00 # ta- : 0.0
> DECAY 16 0.000000e+00 # vt : 0.0
> DECAY 21 0.000000e+00 # g : 0.0
> DECAY 22 0.000000e+00 # a : 0.0
>
> #*********************************************************************
> # MadGraph5_aMC@NLO *
> # *
> # run_card.dat MadEvent *
> # *
> # This file is used to set the parameters of the run. *
> # *
> # Some notation/conventions: *
> # *
> # Lines starting with a '# ' are info or comments *
> # *
> # mind the format: value = variable ! comment *
> # *
> # To display more options, you can type the command: *
> # update to_full *
> #*********************************************************************
> #
> #*********************************************************************
> # Tag name for the run (one word) *
> #*********************************************************************
> tag_1 = run_tag ! name of the run
> #*********************************************************************
> # Number of events and rnd seed *
> # Warning: Do not generate more than 1M events in a single run *
> #*********************************************************************
> 10000 = nevents ! Number of unweighted events requested
> 0 = iseed ! rnd seed (0=assigned automatically=default))
> #*********************************************************************
> # Collider type and energy *
> # lpp: 0=No PDF, 1=proton, -1=antiproton, *
> # 2=elastic photon of proton/ion beam *
> # +/-3=PDF of electron/positron beam *
> # +/-4=PDF of muon/antimuon beam *
> #*********************************************************************
> 1 = lpp1 ! beam 1 type
> 1 = lpp2 ! beam 2 type
> 7000.0 = ebeam1 ! beam 1 total energy in GeV
> 7000.0 = ebeam2 ! beam 2 total energy in GeV
> # To see polarised beam options: type "update beam_pol"
>
> #*********************************************************************
> # PDF CHOICE: this automatically fixes alpha_s and its evol. *
> # pdlabel: lhapdf=LHAPDF (installation needed) [1412.7420] *
> # iww=Improved Weizsaecker-Williams Approx.[hep-ph/9310350] *
> # eva=Effective W/Z/A Approx. [2111.02442] *
> # edff=EDFF in gamma-UPC [eq.(11) in 2207.03012] *
> # chff=ChFF in gamma-UPC [eq.(13) in 2207.03012] *
> # none=No PDF, same as lhapdf with lppx=0 *
> #*********************************************************************
> lhapdf = pdlabel ! PDF set
> 230000 = lhaid ! if pdlabel=lhapdf, this is the lhapdf number
> # To see heavy ion options: type "update ion_pdf"
> #*********************************************************************
> # Renormalization and factorization scales *
> #*********************************************************************
> False = fixed_ren_scale ! if .true. use fixed ren scale
> False = fixed_fac_scale1 ! if .true. use fixed fac scale for beam 1
> False = fixed_fac_scale2 ! if .true. use fixed fac scale for beam 2
> 91.188 = scale ! fixed ren scale
> 91.188 = dsqrt_q2fact1 ! fixed fact scale for pdf1
> 91.188 = dsqrt_q2fact2 ! fixed fact scale for pdf2
> -1 = dynamical_scale_choice ! Choose one of the preselected dynamical choices
> 1.0 = scalefact ! scale factor for event-by-event scales
>
>
> #*********************************************************************
> # Type and output format
> #*********************************************************************
> False = gridpack !True = setting up the grid pack
> -1.0 = time_of_flight ! threshold (in mm) below which the invariant livetime is not written (-1 means not written)
> average = event_norm ! average/sum. Normalization of the weight in the LHEF
> # To see MLM/CKKW merging options: type "update MLM" or "update CKKW"
>
> #*********************************************************************
> #
> #*********************************************************************
> # Phase-Space Optimization strategy (basic options)
> #*********************************************************************
> 0 = nhel ! using helicities importance sampling or not.
> ! 0: sum over helicity, 1: importance sampling
> 2 = sde_strategy ! default integration strategy (hep-ph/2021.00773)
> ! 1 is old strategy (using amp square)
> ! 2 is new strategy (using only the denominator)
> # To see advanced option for Phase-Space optimization: type "update psoptim"
> #*********************************************************************
> # Customization (custom cuts/scale/bias/...) *
> # list of files containing fortran function that overwrite default *
> #*********************************************************************
> = custom_fcts ! List of files containing user hook function
> #*******************************
> # Parton level cuts definition *
> #*******************************
> 0.0 = dsqrt_shat ! minimal shat for full process
> #
> #
> #*********************************************************************
> # BW cutoff (M+/-bwcutoff*Gamma) ! Define on/off-shell for "$" and decay
> #*********************************************************************
> 15.0 = bwcutoff ! (M+/-bwcutoff*Gamma)
> #*********************************************************************
> # Standard Cuts *
> #*********************************************************************
> # Minimum and maximum pt's (for max, -1 means no cut) *
> #*********************************************************************
> 20.0 = ptj ! minimum pt for the jets
> -1.0 = ptjmax ! maximum pt for the jets
> {} = pt_min_pdg ! pt cut for other particles (use pdg code). Applied on particle and anti-particle
> {} = pt_max_pdg ! pt cut for other particles (syntax e.g. {6: 100, 25: 50})
> #
> # For display option for energy cut in the partonic center of mass frame type 'update ecut'
> #
> #*********************************************************************
> # Maximum and minimum absolute rapidity (for max, -1 means no cut) *
> #*********************************************************************
> 5.0 = etaj ! max rap for the jets
> {} = eta_min_pdg ! rap cut for other particles (use pdg code). Applied on particle and anti-particle
> {} = eta_max_pdg ! rap cut for other particles (syntax e.g. {6: 2.5, 23: 5})
> #*********************************************************************
> # Minimum and maximum DeltaR distance *
> #*********************************************************************
> #*********************************************************************
> # Minimum and maximum invariant mass for pairs *
> #*********************************************************************
> {} = mxx_min_pdg ! min invariant mass of a pair of particles X/X~ (e.g. {6:250})
> {'default': False} = mxx_only_part_antipart ! if True the invariant mass is applied only
> ! to pairs of particle/antiparticle and not to pairs of the same pdg codes.
> #*********************************************************************
> # Inclusive cuts *
> #*********************************************************************
> 0.0 = ptheavy ! minimum pt for at least one heavy final state
> #*********************************************************************
> # maximal pdg code for quark to be considered as a light jet *
> # (otherwise b cuts are applied) *
> #*********************************************************************
> 6 = maxjetflavor ! Maximum jet pdg code
> #*********************************************************************
> #
> #*********************************************************************
> # Store info for systematics studies *
> # WARNING: Do not use for interference type of computation *
> #*********************************************************************
> True = use_syst ! Enable systematics studies
> #
> systematics = systematics_program ! none, systematics [python], SysCalc [depreceted, C++]
> ['--mur=0.5,1,2', '--muf=0.5,1,2', '--pdf=errorset'] = systematics_arguments ! see: https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/Systematics#Systematicspythonmodule
>
> --
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