140 likes | 151 Views
This presentation discusses the resolution study of MSSM Higgs bosons using ExHuME and FAMOS software. It explores the missing mass spectrum, resolution, likelihood fit, and the requirements for resolving the Higgses.
E N D
FP420 Collaboration meeting CERN September 28, 2006 What is needed to resolve MSSM Higgses? Dmitry Zaborov (ITEP-Moscow)
The idea • Consider an example MSSM model with CP-violation • Generate some Higgs->bb events with ExHuME 1.3.3 (not-yet-official version provided by Andrew Pilkington) • Run them through FAMOS 1.4.0 • See how good resolution and how much statistics are needed to resolve peaks from (different) Higgs bosons D. Zaborov, FP420 Collaboration meeting CERN
The model • An example model implemented in ExHuME 1.3.3 Apparently, parameters are as in hep-ph/0502251 Φ3 = - 10° D. Zaborov, FP420 Collaboration meeting CERN
Missing mass spectrum generated 1 pot 2 pots smeared D. Zaborov, FP420 Collaboration meeting CERN
Missing mass resolution σ = 2.5 GeV M ~ 120 GeV Defined by FAMOS parameterization (FastTotem module by Marek) D. Zaborov, FP420 Collaboration meeting CERN
Missing mass resolution (continued) Missing mass resolution is a product of fractional momentum loss resolution σ = 2.0 GeV Low asymmetry events σ = 2.9 GeV High asymmetry events Better resolution for events with equal sharing of momentum losses between the two protons D. Zaborov, FP420 Collaboration meeting CERN
Artificial Gaussian smearing 0.5 GeV can see the peak 1.0 GeV can see a bump 1.5 GeV (no comments) D. Zaborov, FP420 Collaboration meeting CERN
Likelihood fit: single vs. double peak 100 events 300 events 1000 events 3000 events 100000 events 10000 events D. Zaborov, FP420 Collaboration meeting CERN
Testing likelihood ratio 100 equivalent experiments shown ~ 90% significance level 1 GeV smearing No background Binned likelihood From 100 to 1000 events needed depending on good luck D. Zaborov, FP420 Collaboration meeting CERN
So what is needed to resolve the Higgses? • Discover them first • Missing mass resolution as good as possible • A lot of statistics D. Zaborov, FP420 Collaboration meeting CERN
FP420 Collaboration meeting CERN September 28, 2006 Technicalities concerning the RP420 resolution study with ExHuME and FAMOS Dmitry Zaborov (ITEP-Moscow)
Interfacing ExHuME with FAMOS • A simple C++ implementation of CMKIN nTuple has been developed • Based on cfortran.h • No dependence on any particular framework • Requires cernlib and cfortran.h only • Events are written to disk and then read by FAMOS D. Zaborov, FP420 Collaboration meeting CERN
Usage … #include "StandAloneCmkinNtuple.hh“ … … StandAloneCmkinNtuple ntuple(“higgses.ntpl"); for(unsigned int i=0; i!= 100000; i++) { … ntuple.fill( hepevt_.nevhep, hepevt_.nhep, hepevt_.isthep, hepevt_.idhep, hepevt_.jmohep, hepevt_.jdahep, hepevt_.phep, hepevt_.vhep); } Compile with StandAloneCmkinNtuple.o and `cernlib packlib` D. Zaborov, FP420 Collaboration meeting CERN
Bug in FastTotem (FAMOS 1.4.0) 0.017 > ξ1 > 0.021 0.0137 > ξ2 > 0.021 No smearing in certain ξ regions for RP420 D. Zaborov, FP420 Collaboration meeting CERN