HELL
High Energy Large Logarithms
A small-x resummation code
Authors: Marco Bonvini, Tiziano Peraro
Developers: Marco Bonvini
Contributors: Simone Marzani, Claudio Muselli, Luca Rottoli, Federico Silvetti
HELL is a code which resums the dominant small-x logarithms in DGLAP splitting functions (at LL and NLL)
and in coefficient functions (at relative LL only, which is absolute NLL in DIS).
The processes for which the resummation of coefficient functions is already included in HELL are
- Deep Inelastic Scattering (DIS) with massless quarks
- Deep Inelastic Scattering (DIS) with massive quarks
- matching functions for variable flavour number schemes
- inclusive cross section for Higgs production in gluon fusion (since version 3.0)
For both speed and size issues, a light version of HELL, called HELL-x, bases on pre-tabulated resummed splitting and coefficient functions, is also available.
We suggest the use of HELL-x for all applications. HELL-x has also been interfaced to APFEL (for DGLAP evolution and DIS structure functions).
We provide the code and the interpolation tables in separate tarballs. Code version X.Y should use tables version X.
HELL-x (recommended for applications)
Latest version: HELL-x v3.0
Latest tables: HELL-x-data v3
Instructions: Download the tarballs above, or wget them directly:
> wget https://www.roma1.infn.it/~bonvini/hell/downloads/HELLx.v3.0.tgz
> wget https://www.roma1.infn.it/~bonvini/hell/downloads/HELLx-data.v3.tgz
then untar them, make and run
> tar xzf HELLx.v3.0.tgz
> tar xzf HELLx-data.v3.tgz
> cd HELLx
> make -j
> ./examples/test_hellx
Version history
- 18-05-2018: code: HELL-x v3.0
tables: HELL-x-data v3
Correction to the BFKL kernel used.
New version of resummation of Pqg and coefficient functions using the full NLL anomalous dimension rather than the LL' one (still selectable).
Matching to N3LO.
Added the ggH production process.
Added a table version check.
- 23-10-2017: code: HELL-x v2.0
tables: HELL-x-data v2
Full version 2.0. It now contains all the neutral-current and charged-current DIS coefficient functions.
Also corrects a minor bug in the theta function for massive contributions.
- 28-08-2017: code: HELL-x v2.0beta
tables: HELL-x-data v2beta
New version with improved treatment of running coupling resummation and matching of the evolution to NNLO.
Released with arXiv:1708.07510
- 14-07-2016: code: HELL-x v1.1
tables: HELL-x-data v1
Simplified the class for variable nf
- 11-07-2016: code and tables: HELL-x v1.0
Initial release
HELL (for advanced users only)
Latest version: HELL v3.1
Latest tables: HELL-data v3
Latest auxiliary tables: HELL-data-aux v3.1 (these can be computed with HELL itself, and are needed for the resummation of coefficient functions)
Instructions: Download the tarballs above, or wget them directly:
> wget https://www.roma1.infn.it/~bonvini/hell/downloads/HELL.v3.0.1.tgz
> wget https://www.roma1.infn.it/~bonvini/hell/downloads/HELL-data.v3.tgz
> wget https://www.roma1.infn.it/~bonvini/hell/downloads/HELL-data-aux.v3.tgz (optional)
then untar them, make (some adjustments to the makefile may be needed, e.g. the path to CUBA) and run
> tar xzf HELL.v3.0.1.tgz
> tar xzf HELL-data.v3.tgz
> tar xzf HELL-data-aux.v3.tgz
> cd HELL
> make -j
> ./examples/test_hell (needs aux data)
> ./examples/create_deltaP_tables -a 0.2 -n 4 (does not need aux data)
Note: To understand the workflow of HELL, better dropping me an email...
Version history
- 21-11-2022: code: HELL v3.1
tables: HELL-data v3
auxiliary tables: HELL-data-aux v3.1
Introduced differential observables (heavy quark pair production).
Various edits for better performances.
- 11-09-2018: code: HELL v3.0.1
tables: HELL-data v3
auxiliary tables: HELL-data-aux v3
Factorization scale dependence implemented also for DIS.
Improved error handling when table files are missing.
- 18-05-2018: code: HELL v3.0
tables: HELL-data v3
New resummation of anomalous dimensions, including the collinear implementation of running-coupling resummation
and a couple of corrections to the BFKL kernel used.
New version of resummation of Pqg and coefficient functions using the full NLL anomalous dimension rather than the LL' one.
Matching to N3LO.
Added all the neutral-current and charged-current DIS coefficient functions, matching conditions, and finally the ggH production process.
Added a table version check.
- 14-07-2016: code: HELL v1.0
tables: HELL-data v1
Initial release
Dependencies
HELL-x has only standard dependencies.
HELL depends on the following libraries:
- GSL - Gnu Scientific Libraries
- Cuba 4.x (from version 3)
Citation Policy
When you use the HELL and/or HELL-x code, please cite this webpage and the original publications:
\cite{Bonvini:2016wki,Bonvini:2017ogt,Bonvini:2018xvt,Bonvini:2018iwt}
Contacts
For any problem, request or suggestion, contact us
- marco.bonvini [at] roma1.infn.it