Documentation¶

Installation¶

To be able to compile the code you need to have the following softwares/libraries installed

LHAPDF6
GSL
Python Version >= 2.7
gcc >= 4.8

To compile and install, simply run

./install.sh

Code Usage¶

The install script installs the bbHFONLL code into a single library that can be called from python. An Example on how the program can be run is available in ./examples/test.py.

Input parameters are passed through a .info file in Yaml style. Have a look at ./examples/test.info for more details.

In addition to the desired computational parameters, a file containing the 4F scheme calculation, corresponding to the desired setup, must be provided, as this code only computes the massless contribution to the FONLL matched cross section.

4F scheme results¶

4F scheme results must be provided using the following convention:

    MH  XS  muR  muF

separated by a tab character, also the header must be included.

As an example we provide the set of tabulated cross sections that were used for the benchmark presented in chapter IV.2.2.e of the
Yellow Report 4 (Figure 264). The tabulated cross sections can be found here. To reproduce the numbers, one should run the code to generate events for Higgs production in association with bottom quarks at LHC in the MG5_aMCatNLO framework with the latest parameters recommended by the HXSWG
(bbH_4FS_yb2_save_central_v2.3.0.tar.gz and bbH_4FS_ybyt_save_central_v2.3.0.tar.gz) bbH, with the following settings: $m_H$ = 125.09 GeV, $m_b$ = 4.58 GeV, $\mu_F=\mu_F = (m_H+2m_b)/4$, at $\sqrt{S}= 13$ TeV. As input PDF we used the central PDF set (with $\mu_b$=4.58,m_b=4.58) in the LHAPDF6 format kindly provided by M. Bonvini that can be found at this page here.
If you use these numbers or run the code, please cite this paper

Higgs production in association with bottom quarks
Wiesemann, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, P. Torrielli. Sep 18, 2014. 33 pp.
arXiv:1409.5301

In order to perform a FONLL-B (NNLL+NLO) calculation three files have to be provided:

  * 4F_LO.txt, a Leading Order calculation in the 4F scheme,
  * 4F_gg.txt, a Leading Order calculation in the gluon-gluon channel in the 4F scheme,
  * 4F_NLO.txt, the full NLO calculation in the 4F scheme.

Example 4F scheme tables can be found in the ./examples folder.

Run the script¶

To run the code with python symply add the following lines in your preamble

import sys
   sys.path.append('<path_to_bbhfonll>/lib')
   sys.path.append('<path_to_bbhfonll>/src/python')

   import fonll

   calc = fonll.fonll('<path_to_param_card.info>')
   res  = calc.calc_fonll(125,125,125)

with the .info file in the form:

order_5f    : 2                                    # order of the 5F calc
   order_fonll : 2                                    # select 1 for fonll-A (LL matching)
   mur         : 125.                                 # renormalisation scale (central)
   muf         : 125.                                 # factorisation scale (central)
   mh          : 125.                                 # mass of the Higgs boson
   mb          : 4.58                                 # pole mass of the b-quark
   sqrts       : 13000.                               # center of mass energy
   iter        : 100000                               # number of vegas points per iteration
   pdf_set     : 'PDF4LHC15_nnlo_mc__mb4.58_mub4.58'  # pdf set