N³LL q_T² resummation for color-singlet processes in MCFM

Authors: Thomas Becher, Tobias Neumann

CuTe-MCFM is a program and framework for q_T² resummation at N³LL accuracy for color-singlet processes based on a factorization theorem in SCET. It is fully differential in the Born kinematics and matches to large-q_T² fixed-order predictions in MCFM at relative order α_s². It provides an efficient way to estimate uncertainties from fixed-order truncation, resummation, and parton distribution functions. In addition to W,Z and H production, also the diboson processes γγ,Zγ,ZH and WH are available, including decays.

References for CuTe-MCFM

The program is based on the publication

Fiducial q_T² resummation of color-singlet processes at N³LL+NNLO,
Thomas Becher, Tobias Neumann, JHEP 03 (2021) 199, 2009.11437

We release CuTe-MCFM and MCFM as a combined code: Please refer to it as CuTe-MCFM if you use the resummation and simply as MCFM otherwise.

A quickstart manual for CuTe-MCFM is included in the distribution in Doc/cute-mcfm.pdf and an online version is also available. The manual for MCFM itself is included in Doc/manual.pdf. Example input files for all color-singlet processes are included in the Bin/ directory and can be used to reproduce the results in our publication.

Release history

• Release MCFM 10.2.1 / CuTe-MCFM 1.1 (May 2022)
• Release MCFM 10.1 / CuTe-MCFM 1.1 (January 2022) with q_T² resummation for Diphoton production at N³LL^′+NNLO including implementation of three-loop beam functions 2107.12478
• Initial release MCFM 10.0.1 / CuTe-MCFM 1.0.1 (March 2021, updated May 2021)

Please feel free to contact the authors for any questions.

Theoretical formalism

The implemented formalism is based on the resummation derived in SCET in the following publications:

• Electroweak Gauge-Boson Production at Small q_T²: Infrared Safety from the Collinear Anomaly,
  Thomas Becher, Matthias Neubert and Daniel Wilhelm, JHEP 1202 (2012) 124, 1109.6027
• Higgs-Boson Production at Small Transverse Momentum,
  Thomas Becher, Matthias Neubert and Daniel Wilhelm, JHEP 1305 (2013) 110, 1212.2621

The code CuTe resulting from these publications can be used for fully inclusive boson production (i.e. no decay of the boson and no fiducial cuts) and provides equivalent results to CuTe-MCFM.

See also the following publication for an interface of this formalism at N²LL to MadGraph5_aMC@NLO:

Event-Based Transverse Momentum Resummation,
Thomas Becher, Monika Hager, Eur.Phys.J. C79 (2019) no.8, 665 1904.08325