HiggsBounds
With the discovery of the Higgs boson at the LHC and the precise measurements of its mass and couplings to other particles, a new era of high energy physics has started. Today, many SUSY models have not only be confronted with the exclusion limits from direct searches, but they have also to reproduce the Higgs properties correctly. The agreement with respect to the mass can be easily read off a spectrum file. For the rates this is usually not so easy. One can parametrize how ’SM-like’ the couplings of a particular scalar are by considering the ratio
r^{ϕXY} = (c_{ϕXY}^{SUS**Y}/c_{hXY}^{S**M})^{2} .
Here, c_{ϕXY}^{SUS**Y} is the calculated coupling between a scalar ϕ and two SM particles X and Y for a particular parameter point in a particular model. This coupling is normalized to the SM expectation for the same interaction. Nowadays, all r^{ϕXY} are constrained to be rather close to 1 if ϕ should be associated with the SM Higgs. SARAH uses the information which is already available from the calculation of the decays to obtain also values for r^{ϕXY}. Of course, also here the γ**Z channel is missing and r^{ϕγZ} is therefore put always to 0.
HiggsBounds is a tool to test the neutral and charged Higgs sectors against the current exclusion bounds from the Higgs searches at the LEP, Tevatron and LHC experiments. The required input consists of the masses, width and branching ratios of the Higgs fields. In addition, it is either possible to provide full information about production cross sections in e^{+}e^{−} and p**p collisions, or to work with a set of effective couplings.
HiggsBounds can be downloaded from
http://projects.hepforge.org/higgsbound
Although HiggsBounds supports a LesHouches interface, this functionality is restricted so far to at most 5 neutral Higgs fields, and therefore we don’t use it. Instead, a SPheno module generated by SARAH can create all necessary input files needed for a run of HiggsBounds with effective couplings (option whichinput=effC). To write these file, the flag 76 in the block SPhenoInfo in the LesHouches input file has to be set to 2 (the value 1 corresponds to versions of HiggsBounds prior to version 5):
Block SPhenoInput #
76 2 # Write files for HiggsBounds
Unfortunately, we can not provide all information which can be used by HiggsBounds to check the constraints. So far, the effective couplings H → γ**Z and H → ggZ are not calculated by SPheno and therefore they are set to zero in the output. In addition, as already mentioned, the SPheno version created by SARAH does not include the calculations of e^{+}e^{−} cross sections. For this reason, also the LEP production cross section of charged Higgs fields is not available for SPheno and it sets this value also to 0 in the output. However, it is of course possible to calculate this cross section as well as all other cross sections needed for the options (whichinput=hadr or whichinput=part) of HiggsBounds using CalcHep , Madgraph or WHIZARD .
The following files are created by SPheno
- MH_GammaTot.dat: Masses and widths of all neutral Higgs fields
- MHplus_GammaTot.dat: Masses and widths of all charged Higgs fields
- BR_H_NP.dat: Branching ratios for neutral Higgs fields into invisible and other neutral Higgs fields.
- BR_Hplus.dat: Branching ratios of charged Higgs fields into c**s̄, c**b̄ and τ**ν̄ final states
- BR_t.dat: Branching ratios of top quark into bottom quark and a W boson or charged Higgs
- effC.dat: effective couplings of neutral Higgs fields to s**s̄, c**c̄, b**b̄, t**t̄, μ**μ̄, τ**τ̄, γ**γ, g**g, γ**Z, ggZ as well as to all other neutral Higgs fields.
Other files are not produced; e.g.
- LEP_HpHm_CS_ratios.dat: LEP production cross section of charged Higgs.
HiggsBounds5 can cope with their absence.
To run HiggsBounds , use in the HiggsBounds directory
> ./HiggsBounds LandH effC [NN] [NC] '[SPheno Directory]'
where has to be replaced by the number of neutral Higgs particle, and by the number of the charged ones. For more information, see also the HiggsBounds manual. The results of the check are written to the file HiggsBounds_results.dat in the directory from which HiggsBounds has been called.