HpT-N3LO computes the approximation of the N3LO contribution to the Higgs boson production from gluon fusion by combining the small-pt and threshold resummations.

HpT-N3LO relies on the following libraries:

• HpT-MON: for the computation of the exact FO (up to NNLO) results. The instruction on how to install HpT-MON is described in the README file.

• Complex Bessel: for the computation of various Bessel functions with complex arguments. This is not currently being used yet but might be useful in the future (plus stripping it away from the rest of the code also demands some time).

Thanks to meson, compiling the code is straightforward:

meson setup builddir
cd builddir
meson compile

This will generate two executables called higgs-pt and higgs-n in the builddir directory. To run the code, use one of the run cards in the runcards folder as follows:

./higgs-n ../runcards/Mellin-HpT-as-N.yaml    (for results as a function of N)
./higgs-pt ../runcards/Mellin-HpT-as-pt.yaml  (for results as a function of pt)

Every time changes are made, the code can be re-compiled by running meson compile inside the builddir directory.

Finally, in case one wants to install the header files and library system-wide, this can be done by running the following:

meson install

This, by default, will install the header files in /{prefix}/include/higgs-fo and add higgsfo.pc to the PKG path.