ONELOOP is a program to evaluate the one-loop scalar 1-point, 2-point, 3-point and 4-point functions, for all kinematical configurations relevant for collider-physics, and for any non-positive imaginary parts of the internal squared masses. It deals with all UV and IR divergences within dimensional regularization. Furthermore, it provides routines to evaluate these functions using straightforward numerical integration.

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Andreas van Hameren

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Software Download

   ONELOOP Current Version can be found here

Previous Versions:

Version 3.6 (18 February 2015):

Version 3.5 (14 May 2014): 

Version 3.4 (3 January 2014):  

Version 3.3.2 (6 November 2013): 

Version 3.3.1 (22 October 2012):

Version 3.3 (
15 September 2012): 

Version 3.1 (
12 May 2012):  OneLOop-3.1.tgz

Version 3.0  (17 April 2012):

Version 2.2  (26 August 2011)OneLOop-2.2.tgz

Version 1.2 
(10 May 2011):  OneLOop-1.2.tgz

Version 1.1 
(10 September 2010):  OneLOop-1.1.tgz

Version 1.0 (28 July 2010): 

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The following paper should be cited while using ONELOOP package

ONELOOP: for the evaluation of one-loop scalar functions

A. van Hameren

Comput.Phys.Commun. 182 (2011) 2427-2438

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News & Developments & Bug Report

  Changes in OneLOop Version 3.6

    Some minor bugs have been corrected. The python scripts have been made compatible both with Python-2 and Python-3

  Changes in OneLOop Version 3.5

    The derivative of the one-loop two-point scalar function is included

  Changes in OneLOop Version 3.4

     A bug in the 2-point function and in the build script have been cured

  Changes in OneLOop Version 3.3.2

     A few minor bugs have been cured

  Changes in OneLOop Version 3.3.1

     The tensor 1-point and 2-point functions up to rank 4 have been included. The scripts have been updated to create a dynamic library

  Changes in OneLOop Version 3.3
     A few minor bugs have been cured. All scripts to build the source code and the library are now in Python. An interface cavh_olo.h is
     provided to use OneLOop in C++ with the gcc compiler family

  Changes in OneLOop Version 3.1

     A minor bug has been fixed. OneLOop-3.1 can now also be used in combination with ddfun90 or qd

  Changes in OneLOop Version 3.0

     OneLOop-3.0 can be used with any precision your compiler supplies, and in
combination with mpfun90 or arprec for multi-precision

  Bug fix for OneLOop Version 2.2

     This bug does not exist in older versions.
In "subroutine box16", the line
     sm1 = cmplx(abs(rmu)) should be replaced by sm1 = cmplx(abs(rmu),kind=kindc2)

     The script can be used to corrects the source. It can take the directory with the source files as argument, e.g.

     ./   yourprojects/OneLOop-2.2/src

     or a complete source file, eg

     ./   yourprojects/avh_olo.f90

  Changes in OneLOop Version 2.2

     OneLOop-2.2 is a Fortran 95 program. It can be used as the previous versions, as a library providing a number of top-level 

      routines. Alternatively, it can also be used via a module, providing one-loop functions and auxiliary routines as module-routines

  Changes in OneLOop Version 1.2

     This version can also be used with compilers that do not accept "cd-functions" like "cdlog" and "cdsqrt", but do have the equivalent
     functions generically available. Furthermore, a few numerical instabilities have been cured

  Changes in OneLOop Version 1.1

     Some bugs in the finite complex mass 4-point function removed

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Contact us

If you have a question, comment, suggestion or bug report, please e-mail us at:


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Last modified by Malgorzata Worek
Thu, 14 June 2018