# The former ZFITTER homepage

## After relocation [12 July 2011], the ZFITTER webpage is yet under reconstruction.

We would like to thank DESY for hosting the ZFITTER homepage for about 20 years. The reference address at DESY for ZFITTER might stay valid.

### 28 December 2013 - Collegues who are interested in the ZFITTER/Gfitter copyright and plagiarism conflict, until April 2013: See zfitter-gfitter-conflict.html 01 May 2014 - For later updates, see zfitter-gfitter-conflict-since-april_2013.html

 1983 - 2013 We may look back to 30 years of fruitful collaboration in the Dubna-Zeuthen group. One of the major projects is ZFITTER. For an overview see "ZFITTER 1985-2013", http://arxiv.org/pdf/1302.1395v2, accepted for publication. In October 2013, Peter Higgs and Francois Englert were awarded the Nobel Prize in Physics ... for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider''. See "Press release from Royal Swedish Academy of Sciences", 8 October 2013, available from here. The accompanying advanced public information Scientific Background on the Nobel Prize in Physics 2013: The BEH-Mechanism, Interactions with Short Range Forces and Scalar Particles'', compiled by the Class for Physics of the Royal Swedish Academy of Sciences, available here, reproduces the Blue-band plot (March 2012) of the LEPEWWG on page 16. The plot relies on ZFITTER v.6.43. Since 20 June 2013, this webpage is the official ZFITTER home page. In a legal sense, this webpage is private property of Dr. Tord Riemann, ZFITTER spokesperson, who is responsible for its content. There is also a ZFITTER homepage at DESY, Zeuthen, edited by Dr. Sabine Riemann. The Board of Directors of Deutsches Elektronen-Synchrotron DESY is legally responsible for the content. ZFITTER main authors, July 2012: From left to right: Lida Kalinovskaya, Pena Christova, Dima Bardin, Tord Riemann, Sabine Riemann, Andrej Arbuzov Photograph made on occasion of 5th Helmholtz International Summer School "Calculations for Modern and Future Colliders", July 23 - August 2, 2012, Dubna, Russia, CALC 2012. Right: Sasha Olshevsky and Arif Akhundov Foto: © tordriemann@googlemail.com 2012 Foto: © tordriemann@googlemail.com 2011 Fotos: © JINR, Dubna, 2012 + A. Akhundov (priv.)

"ZFITTER - 20 years after"
Tord Riemann, DESY, Zeuthen, Germany
Talk on the ZFITTER history, held at LL2012, Int. Workshop "Loops and Legs in Quantum Field Theory", 15-20 April 2012, Wernigerode, Germany

ZFITTER
is a Fortran package for the evaluation of radiative corrections (quantum corrections), as predicted in the Standard Model of elementary particles, to a variety of observable quantities, notably those related to the Z-boson resonance peak studied at LEP, CERN.

It is supported since about 1985.

Authors of ZFITTER:
A. Akhundov, A. Arbuzov, M. Awramik, D. Bardin, M. Bilenky, A. Chizhov, P. Christova, M. Czakon, O. Fedorenko, A. Freitas, M. Grünewald, M. Jack, L. Kalinovskaya, A. Olshevsky, S. Riemann, T. Riemann, M. Sachwitz, A. Sazonov, Yu. Sedykh, I. Sheer, L. Vertogradov, H. Vogt.

ZFITTER
has been used for many experimental and phenomenological studies.
The actual version is ZFITTER v. 6.43 (released 17 June 2008).
ZFITTER authors claim to hold personal copyrights and licence rights.
ZFITTER v.6.44 has been prepared for release.
After clarification of copyright and licence problems, a release might become possible.

The creation of ZFITTER would have been impossible without the generous help of the community and the long-term co-operation with G. Passarino and the TOPAZ0 team (G.P. and G. Montagna, O. Nicrosini, F. Piccinini, R. Pittau), because the complexity of the standard model's fortranization deserves more than one independent implementation.
For those who want to know more about the complexity of the theoretical framework, we recommend the book "The Standard Model in the Making: Precision Study of the Electroweak Interactions", Oxford University Press, USA (December 9, 1999) by D. Bardin and G. Passarino.
Other helpful documents are e.g. "Electroweak Working Group Report", a part of: D. Bardin, W. Hollik, G. Passarino (eds.), "Reports of the working group on precision calculations for the Z resonance", CERN 95-03 (31 March 1995), and "Precision Calculation Project Report" by D. Bardin, M. Grunewald, G. Passarino.

PDG
The PDG -Particle Data Group with its regularly updated survey The Review of Particle Physics uses since many years for the determination of the Z boson properties and the analysis of the Standard Model, among other material, ZFITTER. For examles, see rpp2011-rev-z-boson, rpp2011-rev-standard-model, rpp2011-list-z-boson. .

LEPEWWG - the LEP electroweak working group
The perhaps most important applications for the elementary particle physics community may be found at the webpage of the LEP electroweak working group LEPEWWG. The prediction of the Higgs mass, assuming the Standard Model being valid, derived from radiative corrections to precision observables measured at LEP and other facilities, is visualized in the popular Blue Band Plot of the LEPEWWG.
s10_blueband.eps
s10_blueband.pdf

The plot is made with the ZFITTER package v. 6.43 [2008].
Updates may be found here too, e.g. under the subject "LEP/TEV EW WG Plots for Summer 2011"; version 6.43 of ZFITTER is furtheron used.
The Cracow/Knoxville Monte Carlo Generator Family
An important class of applications are precision Monte Carlo programs: Some of them link parts of ZFITTER.
E.g. the "Precision Monte-Carlo Event Generator KK For Two-Fermion Final States In e+e- Collisions" by S. Jadach, B. Ward, Z. Was, see hep-ph/9912214", Comput.Phys.Commun. 130 (2000) 260-325.
This collaboration uses the ZFITTER library dizet v.6 for the calculation of higher order corrections in the electroweak/QCD Standard Model
SMATASY, ZEFIT, BHAGENE etc.
There are a variety of projects with use of the ZFITTER package by so-called interfaces [written by the users] and, of course, with a correct reference to ZFITTER, usually with indication of the exact number of the ZFITTER version used.
We like to mention:
SMATASY - a project of M. Grunewald, S. Kirsch, T. Riemann, J. Rose for the description of the Z boson line shape in a model-independent approach (inspired by S-matrix theory)
ZEFIT - a project of A. Leike and S. Riemann for a model-independent approach to some classes of theories beyond the Standard Model with extra gauge degrees of freedom and thus with additional, heavy neutral gauge bosons
BHAGENE - a Monte-Carlo program of J. Field and T. Riemann for Bhabha scattering at LEP
H. Stenzel's modifications to ZFITTER v.6.42 - unpublished interface for ZFITTER v.6.42 with a proper implementation of the QCD renormalization scale. A study of variation of the mu-scale indicates a perturbative uncertainty of about 1 % for hadronic observables at the Z pole. Reference: H.Stenzel, " Theoretical uncertainties for measurements of alpha_s from electroweak observables", JHEP 0507:0132,2005.
Why the headline "Wo ZFITTER drin ist, soll auch ZFITTER draufstehen"?

[In English by google translator: "Where there is ZFITTER should also stand upon ZFITTER".]
Or simpler: "What contains ZFITTER should also cite ZFITTER"

Many of the ZFITTER authors never applied the package by themselves for e.g. a physical analysis -- despite the fact that its creation, description and support deserve a lot of time and of intellectual effort.
Since about 1985, and with continous support by JINR Dubna, Russia, we care about ZFITTER for the benefit of the scientific community and in order to support scientific progress.
Besides many other publications, descriptions of the software have been published several times, notebly a total of about 350 pages in the following articles:
• D. Bardin, M. Bilenky, T. Riemann, M. Sachwitz, H. Vogt
"Dizet: A Program Package for the Calculation of Electroweak One Loop Corrections for the Process e+ e- -> f+ f- Around the Z0 Peak"
Comput.Phys.Commun. 59 (1990) 303-312, PHE-89-09 (Jun 1989), 17 pp.
• D. Bardin, M. Bilenky, A. Chizhov, O. Fedorenko, S. Ganguli, A. Gurtu, M. Lokajicek, G. Mitselmakher, A. Olshevsky, J. Ridky, S. Riemann, T. Riemann, M. Sachwitz, A. Sazonov, A. Schaile, Yu. Sedykh, I. Sheer, L. Vertogradov
"ZFITTER: An Analytical program for fermion pair production in e+ e- annihilation"
CERN-TH-6443-92 (May 1992), 75 pp., E-Print: hep-ph/9412201 [unpublished];
• D. Bardin, L. Kalinovskaya, S. Riemann, T. Riemann et al.
Section 4.4 "ZFITTER basics"
pp. 86-92 of: D. Bardin et al., "Electroweak working group report", CERN-95-03A, Sep 1997, 158 pp., e-Print: hep-ph/9709229. Published in: D. Bardin et al., "Reports of the working group on precision calculations for the Z resonance", pp. 7-162.
• D. Bardin, P. Christova , M. Jack, L. Kalinovskaya, A. Olchevski, S. Riemann, T. Riemann
"ZFITTER v.6.21: A Semianalytical program for fermion pair production in e+ e- annihilation"
Comput.Phys.Commun. 133 (2001) 229-395, DESY-99-070 (Aug 1999), 192 pp., E-Print: hep-ph/9908433
• A. Arbuzov, M. Awramik, M. Czakon, A. Freitas, M. Grunewald, Klaus Monig, S. Riemann, T. Riemann
"ZFITTER: A Semi-analytical program for fermion pair production in e+ e- annihilation, from version 6.21 to version 6.42"
Comput.Phys.Commun. 174 (2006) 728-758, DESY-05-034 etc. (Jul 2005), 60 pp., E-Print: hep-ph/0507146

As a payback for the activities around ZFITTER, we expect from the scientific community that users of ZFITTER give fair reference to the software package and its roots.
This was clearly expressed since many years on this homepage:
See here.
In addition, there are two CPC license agreements, see at http://cpc.cs.qub.ac.uk/summaries/ADMJ, for the articles describing ZFITTER, Comp. Phys. Commun. 133 (2001) 229-395 and Comput. Phys. Commun. 174 (2006) 728-758.

Gfitter

Since 2007, the well-known C++ package Gfitter is another application of the ZFITTER software package.
Unfortunately, this had not been expressed by Gfitter's webpages or by the Gfitter software [which is handled as being proprietary although the formal licence is of the open-source type] or by the more than 35 publications between Dec 4, 2007 and July 4, 2011.

The content below the horizontal red double line is unchanged compared to the status as of Fr 24 Jul 15:26:51 CEST 2009. It is documented in the IT group at DESY.

There are nevertheless changes: all links to software are deactivated.
• The ZFITTER version 6.44 (20 January 2013) is not yet made public.
Presently, there are controversial positions concerning ZFITTERS ‘conditions of use’ and the ZFITTER software licence granted to the authors by Elsevier’s Computer Physics Communications Program Library - Programs in Physics & Physical Chemistry. Until the issue is settled, actualized versions of ZFITTER will stay at the beta level and cannot be released. Further information from tordriemann at google.com or from sabine.riemann at desy.de.
• The ZFITTER version 6.43 (17 June 2008) may be obtained by everybody on request from tordriemann at google.com or from sabine.riemann@desy.de - link has been deactivated
• The ZFITTER version 6.42 (18 May 2005) may be obtained by everybody on request from tordriemann at google.com or from sabine.riemann@desy.de - link has been deactivated

ZFITTER is a Fortran package for the evaluation of radiative corrections (quantum corrections), as predicted in the Standard Model of elementary particles, to a variety of observable quantities, notably those related to the Z-boson resonance peak studied at LEP, CERN.

These predictions depend on the masses of the particles in the Standard Model and on a coupling constant.
So there was the possibility to predict, assuming the validity of the Standard Model, the masses of the top quark and of the Higgs boson from quantum corrections, prior to their discoveries by a direct production.
The top quark has been discovered at the Tevatron, Fermilab, while we are searching yet for the Higgs boson at Fermilab and at LHC, CERN.

ZFITTER has been used for many experimental and phenomenological studies.
The perhaps most important applications for the elementary particle physics community may be found at the webpage of the LEP electroweak working group LEPEWWG.
The prediction of the Higgs mass, assuming the Standard Model being valid, derived from radiative corrections to precision observables measured at LEP and other facilities, is visualized in the popular Blue Band Plot.

s08_blueband.eps - s08_blueband.pdf

The plot is made with the ZFITTER package, in its latest version of 2008 with ZFITTER v. 6.43.

• Since May 18, 2005, ZFITTER is supported by the 'ZFITTER support group'.
With an explicit agreement of the ZFITTER authors, we decided to organize the support of the ZFITTER code starting with v.6.42 in such a way that the original author staff remains untouched, but that also the supporting collegues get the credit for their dedication.
The composition of the ZFITTER support group may change.

ZFITTER support group (June 2008):
Andrej Arbuzov, Michal Czakon, Ayres Freitas, Martin Grünewald, Klaus Mönig, Sabine Riemann, Tord Riemann

• ZFITTER Authors (1999 - today):
Dima Bardin, Penka Christova, Mark Jack, Lida Kalinovskaya, Sasha Olshevsky, Sabine Riemann, Tord Riemann

• Fortran code:

The only changes compared to ZFITTER version 6.42 are in the files zfusr6_43.f and dizet6_43.f.
Thanks to Daisuke Nomura for indicating a bug in dizet6_42.f.
Packeting Tord Riemann, test running Martin Grünewald.
A quick fit shows a negligible effect of 0.9 MeV (!) on the central MH value due to the correction.

An information from Matthias Steinhauser (1 May 2006, private information),
concerning the 4-loop QCD singlet-contribution to the rho-parameter (which is not evaluated in ZFITTER):
the numerical effect on the W-mass and on the effective weak mixing angle is unexpectedly small. This points to a good convergence of the perturbative series. If the situation met at three loops repeats for 4 loops, then the non-singlet corrections should be much smaller.
Reference: Y. Schröder, M. Steinhauser: "Four-Loop Singlet Contribution to the rho Parameter" Phys.Lett. B622 (2005) 124-130, hep-ph/0504055,

An information from Hasko Stenzel (26 Feb 2007, private information):
There exists a 'private' version of the ZFITTER code, based on v.6.42, with an implementation of the renormalization scale. A variation of the mu-scale indicates a perturbative uncertainty of about 1 % for hadronic observables at the Z pole.
Reference: H.Stenzel, " Theoretical uncertainties for measurements of alpha_s from electroweak observables", JHEP 0507:0132,2005.

• Program description:
ZFITTER: a semi-analytical program for fermion pair production in e+ e- annihilation, from version 6.21 to version 6.42

[hep-ph/0507146]
Comput. Phys. Commun. 174 (2006) 728-758.
A correct citation of the ZFITTER package will include both this reference, but also the description of ZFITTER v.6.21 (August 1999), [hep-ph/9908433], published in Comp. Phys. Commun. 133 (2001) 229

See also the "Memorandum on ZFITTER/Gfitter", the so-called one-page-memo of 4 Nov 2012.

## Descriptions of older versions of ZFITTER

• Program description update of ZFITTER v.6.30 (June 2000): A short (but complete) description of the changes of ZFITTER v.6.30 (June 2000) compared to the last described version v.6.21 (August 1999) may be found in: "Reports of the working groups on precision calculations for LEP2 physics":
When quoting this version, please refer to both the workshop write-up and the description of the program in Comput. Phys. Commun. 133 (2001) 229 [hep-ph/9908433]

• Program description of ZFITTER v.6.21 (August 1999):
Published in Comp. Phys. Commun. 133 (2001) 229

• Program description of version 4.5 (19 April 1992):
This program description remained unpublished.

## Older versions of the ZFITTER package

For changes of the program compared to foregoing versions see beginning of files zfitr6_xy.f.
The programs are also available from: /afs/cern.ch/user/b/bardindy/public/ZF6_xy/.
• version 6.30.02 (26 June 2000) click here. This version was used for the numerical contributions to the 2f subgroup of the LEP 2 Monte Carlo Workshop (2000), published as CERN Yellow Report CERN-2000-09-D (July 2000) [hep-ph/0007180]

Yet older versions:
It is also available from: /afs/cern.ch/user/b/bardindy/public/ZF6_06/. It replaces v.6.04 (of 21 April 1999)
For changes compared to v.6.04 see beginning of file zfitr6_06.f. We only mention that package acol.f was heavily improved, got much shorter and few bugs have been removed. The corresponding numerics is practically unchanged.
It is also available from: /afs/cern.ch/user/b/bardindy/public/ZF6_04/. It replaces v.5.21 (of 09 March 1999)
Changes compared to v.5.21 include:
corrected treatment of acollinearity cut options; for details see DESY 99-015 (hep-ph/9902408) to appear in Phys. Letters B, DESY 99-037 (in preparation) and references therein

Versions of ZFITTER older than v.6 may be found here:
It is also available from: /afs/cern.ch/user/b/bardindy/public/ZF5_21/. It replaces v.5.20 (of 17 Feb 1999)
Changes compared to v.5.20 include:
New treatment of ZMIN cut
Subroutine ZUCUTS: argument list is modified

It is also available from: /afs/cern.ch/user/b/bardindy/public/ZF5_20/. It replaces v.5.15 (of 02 Dec 1998)
Changes compared to v.5.15 are many. This program version is used for the preparation of a "Precision Calculation Project Report" written by D. Bardin, M. Grünewald and G. Passarino, hep-ph/9902452

It is also available from: /afs/cern.ch/user/b/bardindy/public/ZF5_15/. It replaces v.5.14 (of 27 Oct 1998)
Changes compared to v.5.14 include:
From 5.13 to 5.15 several bug fixes; for more details see begin of file zfitr5_15.f
It is also available from CERN afs ~/bardindy/public/ZF5_14/. It replaces v.5.13 (of 21 Oct 1998)
Changes compared to v.5.13 include:
1. flag IQCD=3: Kniehl's exact and CPU saving calculation of O(alfa_em x alfa_s) corrections
2. many real numbers made explicitely double precise
3. funny bug for IGAMS=0 fixed
For a short presentation of developments which led to v.5.14: click here
This replaces v.5.12 (of 16 June 1998)
Changes compared to v.5.12 are commented at top of file zfitr5_13.f; they concern:
0. Lepton masses;
1. Running \alpha_{em} - \Delta\alpha^{(5)}_{had} is released for fits instead of ALQED;
2. Fermi constant;
3. \rho_f.
This replaces v.5.12 (of 15 June 1998) - a bug was found.
Changes compared to v.5.11 and v.5.10 are mentioned at top of file zfitr5_12.f
• version 5.11 (of 08 June 1998): debugged and replaced by v.5.12
Changes compared to v.5_beta are mentioned at top of file zfitr5_10.f

Versions of ZFITTER older than v.5 may be found here:
• ZFITTER v.4.9
(used for D. Bardin et al., Electroweak Working Group Report, in "Reports of the working group on precision calculations at the Z resonance", CERN 95-03 (March 1995), hep-ph/9709229
and used for F. Boudjema et al., Standard Model Processes, in "Physics at LEP2", CERN 96-01 (Feb 1996), hep-ph/9601224):
• ZFITTER v.4.5 (19 April 1992) - described in CERN-TH. 6443/92 (1992) [hep-ph/9412201] click here
• very ancient versions of ZFITTER click here; version 4.00 is dated as of June 1991, older versions seem to be lost.

## Auxiliary material

New programming for predictions with acollinearity cut (1999):
The changes are valid since versions 6.04 (April 1999), 6.06 (May 1999) and correspond to:
At LEP1 energies - for tables click here (from talk at CERN LEP2 WS, March 1999).
At LEP2 energies - for figures click here (from talks at CERN LEP2 WS, March 1999, at Oxford LC WS, April, and at Sitges LC WS, May 1999).

Related programs:
• ZEFIT - a program hold by Sabine Riemann
for the study of extensions of the Standard Model by additional Z' bosons or contact interactions: click here
• SMATASY - a program hold by Martin Grünewald, Stefan Kirsch and Tord Riemann
for the model-independent study of the Z boson resonance: click here or here or here
• GAPP - a program hold by Jens Erler and Paul Langacker
"... short for the Global Analysis of Particle Properties. It is devoted to the calculation of pseudo-observables, i.e. observables with experiment specific corrections (such as initial state radiation or detector specifics) removed. The reduction of raw data to pseudo-observables is performed by the experimenters with available packages (e.g. ZFITTER for Z pole physics)." click here