Known Issues

Mac OS X:

Compilation of VBFNLO on MacOSX only works with static libraries. This can be requested with the configure-option --enable-shared=no. With this option the current version of Vbfnlo has been compiled successfully on different versions of MacOSX between 10.6.8 and 10.12.3 using GFortan 5 or 6 from Homebrew. However, linking with the library LoopTools, which is only needed for the calculation of the electroweak corrections in the Hjj process, is known to fail.

32-bit compilers:

If you want to compile VBFNLO with a 32-bit compiler (e.g. ifort) on a 64-bit machine, the following configure command should work:

FC=ifort CFLAGS=-m32 CXXFLAGS=-m32 LDFLAGS=-m32 ./configure

followed by your standard configure options (e.g. --prefix=)

VBFNLO on clusters:

When VBFNLO is linked to LHAPDF version 5 it can require more memory than some clusters allow (although VBFNLO version 2.7.0 needs significantly less memory than previous versions). The amount of memory required can be decreased (slightly) by only enabling certain processes at compilation – e.g.

./configure --enable-processes=vbf

LHAPDF 5 can also be reconfigured such that it only stores one PDF set per initialisation (in the LHAPDF code, set nmxset=1 in src/parmsetup.inc or configure with the option -with-max-num-pdfsets=1, as described here).

Alternatively, the new LHAPDF version 6 can be used, which is rewritten in C++ with dynamical memory allocation. This new version needs much less memory than previous LHAPDF versions.

The full list of bugfixes can be found in the ChangeLog.

NLO calculations of W-jj, W-Zjj, W-gamma jj production

A bug in the PDF convolution of the QCD-induced production processes $W^-jj$, $W^-Zjj$ and $W^-\gamma jj$ has been fixed. The size of the effect, which can be observed both in the real-emission part of the NLO calculation and the corresponding LO+jet processes, can reach several percent, depending on the parameter settings.

VBF cuts for HHjj

VBF cuts now also apply to VBF production of a Higgs pair.

Reading in slha-file fails sometimes: FIXED IN VERSION 2.7.0

In version 2.6.3 VBFNLO crashes on some computers when reading in slha-files. This will be fixed in the next release. If you stumble on this problem, please contact us for a solution.

Color flow in LHE output for process W-W-jj in VBF: FIXED IN VERSION 2.7.0

In version 2.6.3 the color flow information in Les Houches event output is set up incorrectly. This issue will be fixed in the next release. If you need a patch beforehand, please contact us.

gfortran 4.8: FIXED IN VERSION 2.7.0

Unfortunately, the gfortran versions 4.8.x (which are included e.g. in openSUSE 13.1 and Ubuntu 13.10) seem to have a bug during optimization, resulting in a much longer compile time of the VBFNLO loop functions. Additionally, up to 3 GB of RAM are needed during compilation.

The next release will include a workaround for the memory requirements, and will compile significantly faster than previous releases (however still not as fast as with gfortran 4.7).

Les Houches event output: FIXED IN VERSION 2.6.3

There are some small problems in the les Houches output of the current VBFNLO release:

• The inclusion of the tau mass gives wrong particle momenta for the H→WW and H→ZZ processes.
• The helicity information output is wrong for all Higgs decay processes and processes with a final state photon.

These issues will be fixed in the next release.

ZZZ production (process 450): FIXED IN VERSION 2.6.2

The QCD real emission part of the NLO computation gives no reliable result due to a problem with the dipole subtraction. This issue will be fixed in the next release.

LesHouches event output for processes with more than one phase space: FIXED IN VERSION 2.6.2

At the moment the fraction of events coming from the different phase spaces is not sampled correctly (process list: WA, ZA, WA+j, ZA+j, ZZZ, WWA, WAA, WZA, ZAA, AAA, WAA+j). This will be fixed in the next release.

Distributions and cross section for H→WW in VBF and GF: FIXED IN VERSION 2.6.2

In the current release the distributions and cross section for Higgs decaying in W bosons in vector boson fusion and gluon fusion production processes (IDs 105, 115, 2105, 4105) are slightly off. This will be fixed in the next release.

User generated ROOT histograms: FIXED IN VERSION 2.6.1

The NLO histograms for the root-only histograms do not include the virtual contributions. This will be fixed in the next release.

Symmetry factors for processes 4106 and 2106: FIXED IN VERSION 2.6.1

Processes 4106 ($pp \rightarrow Hjj \rightarrow ZZjj \rightarrow \ell_{1}^{+} \ell_{1}^{-} \ell_{1}^{+} \ell_{1}^{-} jj$ via gluon fusion) and 2106 ($pp \rightarrow H \gamma jj \rightarrow ZZ \gamma jj \rightarrow \ell_{1}^{+} \ell_{1}^{-} \ell_{1}^{+} \ell_{1}^{-} \gamma jj$ via vector boson fusion) are incorrect a factor of 2 if identical lepton pairs are chosen. (This is the default setting.) This will be fixed in the next release.

Anomalous HVV couplings: FIXED IN VERSION 2.6.1

When working with anomalous HVV couplings in VBF processes, the factors multiplying the SM HWW and HZZ couplings are not properly taken into account if the default settings (TREEFACW=TREEFACZ=1) are not used. This problem will be fixed in the next release. To fix this problem

• Download and unpack the file qqhqq.tar.gz
• Place the new file in the amplitudes/vvjj/ subdirectory
• Do make all install (there is no need to make clean beforehand)