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2nd Meeting of MSSM neutral WG
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Europe/Zurich
EVO only (CERN)
EVO only
CERN
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Minutes of the 2nd meeting of the MSSM neutral Higgs group (29.3.2010)
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People present (on EVO): Monica Vazquez Acosta, Daniela Rebuzzi, Sven Heinemeyer, Michael Spira, Georg Weiglein, Markus Warsinsky
- M.W. gave a short talk on the status of the numbers for bb->H:
The program bbh@nnlo (Harlander/Kilgore)
Cross sections are available for 7 TeV in parametric form
The same for for the scale uncertainties and PDF uncertainties.
A cross check at NLO was done for the PDF sets: For MSTW2008nlo a pdf set with alpha_s fixed to the CTEQ6.6 value was chosen. The two calculations agree within their respective pdf ucnertainties nicely. Using MSTW2008nlo with its default alpha_s gives a small k-factor, but within combined PDF+alpha_s uncertainties, it agrees with the NLO calculations.
The SM values for the cross section are reweighted using an effective coupling approach. This can be shown by another calculation of bb->H in NLO QCD but also including SUSY corrections to give agreement within a few % with the reqeighting results.
Plan is to compare this calculation consistently with the 4-flavor calculation (gg->bbH) for the Freiburg meeting.
It was remarked that although for some MSSM-parameter changes (e.g. mu->-mu) the production cross section can change, but this can cancel mostly my the branching fraction to tau tau or mu mu, which changes in the opposite direction.
- M.S. is in the process of setting up a SM-like Grid for the gg->bbH process (4-flavor calculation)
- M.A. summarized the status of the SM-like Grids for the gg->H process:
Interpolations based on Higlu are available for top-loop, bottom-loop and the interference term for scalar and pseudoscalar Higgs bosons. In addition the NNLO correction to the top-loop only is considered.
These can then be rescaled using the effective couplings.
For the moment only the MHMAX scenario is considered.
- It was discussed on how to improve on this approximation, i.e. how to consider also SUSY particles in the production mechanism. The squark-loops are known and will shortly be made available in HIGLU, however, as the squarks are heavy in the MHMAX scenario, these are only of small importance. This needs to be revisited if other benchmark scenarios are considered. 2-loop SUSY contributions are being worked on at the moment. An alternative approach working with amplitudes and of the SM-like contributions, adding SUSY-contributions and k-factors for the different amplitudes was discussed (this is currently implemented in Feynhiggs). It was decided that in this direction more work is needed and this should be discussed in more detail in the Freiburg workshop.
- It was decided that M.W. will give a summary talk at the Freiburg meeting summarizing the progress made and showing plans.
- The next meeting was decided to be held on wednesday, 7.4., 16:00.
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