FTK Studies H hh bbbb FTK Physics Case
FTK Studies: H hh bbbb FTK Physics Case Meeting 12/15/05 Erik Brubaker University of Chicago Nov 3, 2005 FTK Physics Case Meeting
Double Higgs—Process • Resonant production of lightest MSSM neutral scalar Higgs h 0 through the heavier H 0. • Previous study (ATL-PHYS-97 -104) – For MH=300 Ge. V and tan(b)=3, S/sqrt(B) of 5. 7 can be reached using 300 fb-1; this requires 4 jets with ET>40 Ge. V and |h|<2. 5. – For lower integrated luminosity, more tricks are needed and jets down to 20 Ge. V are preferred. – They concluded trigger rates probably prohibitive. Nov 3, 2005 FTK Physics Case Meeting 2
Signal sample • Match jets to b quarks – Assume b tag req’d using FTK tracks at LVL 2 – So set thresholds based on kinematics of b jets. • Bottom right plot is pt of 4 th-highest jet matched to b quark. If <4 jets matched, fill a 0. – How would you set thresholds? Nov 3, 2005 FTK Physics Case Meeting 3
Signal sample • Without matching: still j 4 has low p. T. – No “zeros” in plot. • Consider multiple trigger thresholds. Nov 3, 2005 FTK Physics Case Meeting 4
SHERPA event generator • Recall: two problems w/ SHERPA multijets: – Don’t see much difference btw 2 2 and 2 2 + 2 3, etc. • Matching cut too high? – How to set scale of events, since kinematic cuts can bias distributions? • No solution yet, similar problem with ALPGEN. Nov 3, 2005 SHERPA, please generate: • jet jet -> jet jet jet • jet -> jet jet ME/PS matching at 25 Ge. V. • Add’l cuts bias kinematics through interaction with matching scale. • Thus matching also sets scale of interaction by defining “jet”. FTK Physics Case Meeting 5
Sample L 1 rates from SHERPA • Caveats: 2 2 only; uncertainties. • Implies very low generation threshold needed for 4 j@40. Matching (Ge. V) Eff. x 104 for L 1 4 j@40 Ge. V s (mb) from SHERPA Rate @ 1033 (Hz) 15 20 0. 0000096 1. 1 2200 780 0. 0021 85. 8 25 30 35 40 45 75 1. 2 2. 4 3. 2 5. 1 9. 8 55 340 170 95 56 35 4. 4 40. 8 30. 4 28. 6 34. 3 24. 2 Nov 3, 2005 FTK Physics Case Meeting 6
Next Steps • Generate large sample of SHERPA multijets over holidays. – Some fraction full simulation? – Input from other analyses ASAP to determine parameters of generation. • Reproduce (at some level) the earlier ATLAS study of H hh bbbb. Nov 3, 2005 FTK Physics Case Meeting 7
- Slides: 7