Chapter 14
New features in MCFM-10

14.1 Downloads of earlier versions, MCFM-10

• MCFM-10.2.2.tar.gz (May 19th, 2022, updated November 4th, 2022)

• MCFM-10.1.tar.gz (January 10th, 2022)

  • C++ interface to tree and one-loop amplitudes as a replacement of OpenLoops and Recola [2107.04472]
  • t-channel single-top-quark production at NNLO [2012.01574], see also [2109.10448]
  • $q_T^2$ resummation for Diphoton production at N${}^3$LL${}^{\prime }$+NNLO [2107.12478]

• MCFM-10.0.1.tar.gz (March 29th, 2021, updated May 27th, 2021)

  • N${}^3$LL+NNLO $q_T^2$ resummation for the single boson processes $W^{\text{+}},W^{\text{−}},Z$ and $H$ and diboson processes $\mathit{\gamma \gamma },\mathit{Z\gamma },\mathit{ZH\gamma \gamma },\mathit{Z\gamma },\mathit{ZH}$ and $\mathit{WH}$. See the CuTe-MCFM site for further details.
  • Support for histograms with custom binning.
  • Streamlined compilation process into single CMake script.

14.2 New features in MCFM-10.2

Version 10.2 of the code introduces the ability to compute diboson processes to NNLO. It also allows all NNLO calculations to be performed using two variants of slicing: using 0-jettiness (as in previous versions) or $q_T$ (new). Benchmark results are reported in Section 8.

This version also extends the capabilities of the interface to allow a calculation of one-loop amplitudes representing diboson+jet production with a variety of $W$ and $Z$ boson decays, including all appropriate interferences. The calculation of diboson amplitudes (without the presence of an additional jet) has also been extended to include additional processes that include interference contributions. The new scattering amplitudes available are:

d u~ e- ve~ e+ e-
u d~ e+ ve e+ e-
u u~ e- e+ ve ve~
d u~ e- ve~ a g
u d~ e+ ve a g
u u~ e- e+ a g
u u~ e- ve~ mu+ vmu g
d u~ e- ve~ mu+ mu- g
u d~ e+ ve mu+ mu- g
u u~ e- e+ mu+ mu- g
u u~ e- e+ e- e+ g
u u~ e- e+ vmu vmu~ g
u u~ e- e+ ve ve~ g

where, in addition, all relevant combinations of quark flavors are included.

A description of the new features added in recent releases (v9.0 onwards) is given in Section 15.

14.3 New features in MCFM-10.0

For using the $q_T$ resummation of CuTe-MCFM please refer to cute-mcfm.pdf and ref. [100].

New plotting infrastructure. MCFM-10.0 implements a new plotting infrastructure that allows for much easier setup and custom-binned histograms. The new style histograms can be enabled by setting newstyle = .true. in the [histogram] section of the input file. An example for $Z$ production with resummation and custom binning is given in src/User/nplotter_Z_new.f90. Each plotter implements a new Fortran module with a function setup() that is called once at the beginning of MCFM to set up the histogram binnings. The function book(p,wt,ids,vals,wts) is called for each phase space point, calculates the observables based on the jet four-momenta in p and returns them in the vals array. The wts array is typically filled with wt for each observable, but can be modified to return a different weight to the histogramming routine. This is used in the example file to implement a transition function for the resummed and fixed-order components.

To adopt a new process to the new histograms, the file src/Mods/mod_SetupPlots.f90 can be modified. More precisely, the function setup_plots needs to import the plotting module of the process, call the setup routine for the process, and set the pbook pointer to the actual book routine of the new plotting module.