NLL-fast

The successor to NLL-fast is now available. Please click here to return to the NNLL-fast webpage!

NLL-fast is a computer program which computes the squark and gluino hadroproduction cross sections including next-to-leading order (NLO) supersymmetric QCD corrections and the resummation of soft gluon emission at next-to-leading-logarithmic (NLL) accuracy. NLL-fast also provides an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions. The program reads in grid files with NLO and NLO+NLL results, the scale uncertainty and the pdf and alphas error and uses a fast interpolation routine to provide predictions for any value of squark and gluino masses in the mass ranges specified below. The results for the LHC collision energy of 13 TeV can be obtained with the latest 3.1 version, whereas earlier 2.1 (1.2) versions deliver cross sections for 8 (7) TeV. Results are obtained with the MSTW2008NLO (MSTW2008LO for the LO results), the CTEQ6.6M (CTEQ6L1) pdfs, and for version 3.1 also with the NNPDF3.0NLO (NNPDF3.0LO) set. Results for selected processes of squark and gluino production for 14, 33, and 100 TeV collision energy are also available in NLL-fast, see below.

This figure as eps or in a version without errors eps.

NLL-fast is based on results obtained by many authors over the years. In alphabetical order, the contributions were provided by: Wim Beenakker, Silja Brensing-Thewes, Christoph Borschensky, Michael Krämer, Anna Kulesza, Leszek Motyka, Eric Laenen and Irene Niessen. Additionally, NLL-fast uses NLO results obtained with Prospino. Therefore we ask to cite the following papers when referring to NLL-fast:

Squark and gluino production:

• Squark and Gluino Production at Hadron Colliders, W. Beenakker, R. Höpker, M. Spira, P.M. Zerwas, Nucl. Phys. B492 (1997) 51-103
• Threshold resummation for squark-antisquark and gluino-pair production at the LHC, A. Kulesza, L. Motyka, Phys. Rev. Lett. 102 (2009) 111802
• Soft gluon resummation for the production of gluino-gluino and squark-antisquark pairs at the LHC, A. Kulesza, L. Motyka, Phys. Rev. D80 (2009) 095004
• Soft-gluon resummation for squark and gluino hadroproduction, Wim Beenakker, Silja Brensing, Michael Krämer, Anna Kulesza, Eric Laenen, Irene Niessen, JHEP 0912 (2009) 041
• Squark and gluino hadroproduction, W. Beenakker, S. Brensing, M. Krämer, A. Kulesza, E. Laenen, L. Motyka, I. Niessen, Int. J. Mod. Phys. A26 (2011) 2637-2664

Stop (sbottom) production:

• Stop Production at Hadron Colliders, W. Beenakker, M. Krämer, T. Plehn, M. Spira, P.M. Zerwas, Nucl.Phys. B515 (1998) 3-14
• Supersymmetric top and bottom squark production at hadron colliders, Wim Beenakker, Silja Brensing, Michael Krämer, Anna Kulesza, Eric Laenen, Irene Niessen, JHEP 1008(2010)098
• Squark and gluino hadroproduction, W. Beenakker, S. Brensing, M. Krämer, A. Kulesza, E. Laenen, L. Motyka, I. Niessen, Int. J. Mod. Phys. A26 (2011) 2637-2664

When using NLL-fast version 3.1, please additionally cite:

• NLO+NLL squark and gluino production cross-sections with threshold-improved parton distributions, W. Beenakker, C. Borschensky, M. Krämer, A. Kulesza, E. Laenen, S. Marzani, J. Rojo, Eur.Phys.J. C76 (2016) 2, 53

NEW: NLL-fast, version 3.1 (LHC @ 13 TeV)

• Main program and grids in one package nllfast-3.1. For grids for stop/sbottom production SUSY parameters other that stop/sbottom masses correspond to CMSSM benchmark point 40.2.5 as defined in arXiv:1109.3859.
• This version of NLL-fast is an update of version 3.0, now also including predictions with the NNPDF3.0NLO (NNPDF3.0LO for LO) set.
• Please note that the output format for the NNPDF predictions is slightly different, as the PDF and AlphaS error are already given in a combined format.

NLL-fast for LHC @ 14 TeV and LHC @ 33 TeV

• Limited versions for 14 TeV and for 33 TeV covering only the processes of stop production and squark and gluino production in the decoupling limits.
• For stop production, SUSY parameters other that stop masses correspond to CMSSM benchmark point 40.2.5 as defined in arXiv:1109.3859. For stop masses lower than gluino mass and with the gluino mass lower than the one in the benchmark point 40.2.5, results differ from results given by NLL-fast by less than 1%. Other choices of SUSY parameters will lead to bigger differences with NLL-fast results (however, by not more than 10%). In particular, in the case of stop-production in the limit of all other sparticles decoupled, the results of NLL-fast are accurate within 1% for stop masses up to ~1.5 TeV. Please contact us if you need precise results for other choices of SUSY parameters.

NLL-fast, version 3.0 (LHC @ 13 TeV)

• main program and grids in one package nllfast-3.0. For grids for stop/sbottom production SUSY parameters other that stop/sbottom masses correspond to CMSSM benchmark point 40.2.5 as defined in arXiv:1109.3859.

NLL-fast, version 2.1 (LHC @ 8 TeV)

• main program: nllfast-2.1.f.
• grids for inclusive squark and gluino production, stop (sbottom) production and production of squark and gluinos in the decoupling limits: nllfast-2.11grids.tar. For grids for stop/sbottom production SUSY parameters other that stop/sbottom masses correspond to CMSSM benchmark point 40.2.5 as defined in arXiv:1109.3859.

NLL-fast, version 1.2 (LHC @ 7 TeV)

• main program: nllfast-1.2.f. A version of the code which reads in SLHA files using the SLHA library written by Thomas Hahn is also available: nllfast_slha-1.2.F (see the header for instructions how to compile this version of NLL-fast).
• grids for inclusive squark and gluino production, stop (sbottom) production and production of squark and gluinos in the decoupling limits: nllfast-1.21grids.tar. For grids for stop/sbottom production SUSY parameters other that stop/sbottom masses correspond to CMSSM benchmark point 40.2.4 as defined in arXiv:1109.3859.

NLL-fast is written in the Fortran programming language, so most Fortran compilers should be able to compile the code. One that it has been tested with is the free GNU Fortran compiler gfortran. On a Linux terminal, the command to compile the code is:

gfortran nllfast.f -o name_of_the_executable

where nllfast.f has to be replaced by the correct Fortran source file, depending on the version of NLL-fast.

c After compiling the code, it should be called in the following way for all four squark and gluino
c production processes:
c
c ./name_of_the_executable process pdf squark_mass gluino_mass
c
c or, for the case of stop-antistop (sbottom-antisbottom) production:
c
c ./name_of_the_executable st pdf stop_mass
c
c or, for the case of gluino production in the limit of large squark masses (decoupling limit):
c
c ./name_of_the_executable gdcpl pdf gluino_mass
c
c or, for the case of squark production in the limit of large gluino masses (decoupling limit):
c
c ./name_of_the_executable sdcpl pdf squark_mass

The command line attributes above can take the following values:

c  - process: 
c      sb     squark-antisquark production,
c      ss     squark-squark production,
c      gg     gluino-gluino production,
c      sg     squark-gluino production,
c  - pdf:
c      cteq   CTEQ6.6M NLO (CTEQ6L1 for LO predictions) parton distribution functions,
c      mstw   MSTW2008NLO  (MSTW2008LO for LO predictions) parton distribution functions
c      nnpdf  NNPDF3.0NLO  (NNPDF3.0LO with AlphaS = 0.130 for LO predictions) parton distribution functions (only available for NLL-fast 3.1)

Ranges of gluino and squark masses (squark_mass, gluino_mass, stop_mass) covered by various version differ. For the version for 100 TeV they are:

c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 15000 GeV
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 15000 GeV
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 10000 GeV  other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.5 as defined in arXiv:1109.3859, see also the comments above.

For the version for 33 TeV they are:

c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 6500 GeV
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 6500 GeV
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 5000 GeV  other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.5 as defined in arXiv:1109.3859, see also the comments above.

For the version for 14 TeV they are:

c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 3500 GeV
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 3500 GeV
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 2500 GeV  other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.5 as defined in arXiv:1109.3859, see also the comments above.

For the version 3.1 (13 TeV) they are:

c   for gluino-pair production:
c       200 GeV  <= gluino mass <= 3000 GeV    and   200 GeV <= squark mass <= 5000 GeV,
c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 3000 GeV
c    for squark-gluino  production:
c       200 GeV  <= gluino mass <= 3000 GeV    and   200 GeV <= squark mass <= 5000 GeV,
c    for squark-antisquark and squark-pair production:
c       200 GeV  <= squark mass <= 3000 GeV    and   200 GeV <= gluino mass <= 3000 GeV
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 3000 GeV
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 2500 GeV  and stop_mass <= gluino mass 
c                                             (other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.5 as defined in arXiv:1109.3859.)

For the version 2.1 (8 TeV) they are:

c    for gluino-pair production:
c       200 GeV  <= gluino mass <= 2500 GeV    and   200 GeV <= squark mass <= 4500 GeV,
c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 2500 GeV 
c    for squark-gluino  production:
c       200 GeV  <= gluino mass <= 2500 GeV    and   200 GeV <= squark mass <= 4500 GeV,
c    for squark-antisquark and squark-pair production:
c       200 GeV  <= squark mass <= 2500 GeV    and   200 GeV <= gluino mass <= 2500 GeV
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 2500 GeV
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 2000 GeV  and stop_mass <= gluino mass 
c                                             (other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.5 as defined in arXiv:1109.3859.)

and for the version 1.2 (7 TeV) they are:

c    for gluino-pair production:
c       200 GeV  <= gluino mass <= 1500 GeV    and   200 GeV <= squark mass <= 4500 GeV,
c       1500 GeV <  gluino mass <= 2000 GeV    and   200 GeV <= squark mass <= 2000 GeV,
c    for gluino production in the decoupling limit (large squark mass)
c       200 GeV  <= gluino_mass <= 2000 GeV 
c    for squark-gluino  production:
c       200 GeV  <= gluino mass <= 1500 GeV    and   200 GeV <= squark mass <= 3500 GeV,
c       1500 GeV <  gluino mass <= 2000 GeV    and   200 GeV <= squark mass <= 2000 GeV,
c    for squark-antisquark and squark-pair production:
c       200 GeV  <= squark mass <= 2000 GeV    and   200 GeV <= gluino mass <= 2000 GeV,
c    for squark production in the decoupling limit (large gluino mass)
c       200 GeV  <= squark mass <= 2000 GeV
c    for the sum of the four processes ('tot')
c      200 GeV  <= squark mass <= 2000 GeV    and   200 GeV <= gluino mass <= 2000 GeV,
c    and for stop-antistop production:
c       100 GeV  <= stop mass   <= 1000 GeV  (other SUSY parameters according to CMSSM benchmark 
c                                                    point 40.2.4 as defined in arXiv:1109.3859.)

# LHC @ 13 TeV, MSTW2008NLO (MSTW2008LO for LO)
# process: gg   
# ms[GeV]  mg[GeV]  LO[pb]     NLO[pb]    NLL+NLO[pb]  d_mu+[pb]  d_mu-[pb]   d_pdf+[%]  d_pdf-[%]  d_as+[%] d_as-[%]  K_NLO   K_NLL
------------------------------------------------------------------------------------------------------------------------------------
  1000.    1000.    0.136E+00  0.201E+00  0.220E+00    0.120E-01  -0.153E-01     9.3      -10.1       3.3      -3.5    1.48    1.09

• main program: nllfast-2.0.f.
• grids for inclusive squark and gluino production and production of gluinos in the decoupling limit: nllfast-2.0grids.tar.

If you have questions/comments or want to report a problem regarding the code, please contact Anna Kulesza or Christoph Borschensky.