1. Joint IPPP-Imperial Workshop 28th May 2009 Jonathan Hays
SUSY DØ
Joint IPPP-Imperial Workshop
28th May 2009
Jonathan Hays

2. Outline Introducing the group Our activities SUSY Higgs @ DØ
Latest results
Plans and Prospects

3. DØ @ IC Gavin Davies DØ@IC-PI, Higgs Group Convener Rick Jesik
Trigger board chair
Jon Hays
TEVNPHWG, SUSY-Higgs Combinations and hb→bbb
Per Jonsson
L3 Trigger and Higgs BSM Sub-group convener and hb→bbb
Ray Beuselinck
Level 3 track trigger and computing
Tim Scanlon
Developer of NN b-tagging, b-ID Convener
hb→bbb moving to ZH→bb
Phil Vint
writing up his thesis
Theo Christoudias
ZH→bb - writing up!
Nicolas Osman
hb→bbb – not writing up just yet…

6. SUSY @ DØ Integrated Luminosity
Current public results
28th May 2009
Coming this summer

7. SUSY Higgs @ DØ Currently searches in three signatures
Currently searches in three signatures
h→ : eµ, µhad, ehad
bh→b : µhad, (+ehad in the future)
bh→bbb : 3,4,5 jet final states
Generally search in model independent way
95% CL limit on ×Br
Then interpret within some MSSM scenario

8. Limit Setting Define test statistic using ratio of Poisson likelihoods
MC Pseudo-experiments used to generate PDFs for s+b and b hypotheses
Systematics introduced using Baysian approach with (generally) gaussian prior.
Profile likelihood technique for dealing with nuisance parameters offers improved sensitivity
CLs+b
1-CLb
Jonathan Hays
Imperial College

9. b-tagging Identify jets originating from b-quarks Make use of
Identify jets originating from b-quarks
Make use of
soft-lepton tagging
impact parameter
secondary vertex
Combine outputs in NN
to optimise identification
Jonathan Hays
Imperial College

10. Inclusive di-tau Isolated electron or muon + hadronic tau (NN tau-ID)
Visible mass distribution used for limit setting
PRL (2008) – RunIIa

11. Higgs with associated b-quark di-tau channel
Isolated muon + hadronic tau + b-tagged jet
NN and likelihood select against ttbar and QCD backgrounds – 2D distribution used for limit setting
Earlier results: Phys. Rev. Lett. 102, (2009)   

12. Higgs with associated b-quark bb channel
Require 3 b-tagged jets
Multijet background modelled from data
Mbb used as input distribution to limit setting
Δb effects significant
Width can be larger than experimental resolution
large variation with sign of µ

13. Plans and Prospects Combinations! – with current data
DØ combination currently in review
all three channels – results from ICHEP08
aiming for approval in time for SUSY09 …
CDF-DØ h→ combination in progress
CDF-DØ all three channels – coming soon

14. Plans and Prospects
New data – new results, plots shown for up to 2.6fb-1 New results using up to 4.1fb-1 coming this Summer Could get 10fb-1 per experiment by end of RunII plenty of room for extending the limits Go further… add in other Tevatron constraints on SUSY in broader context?
28th May 2009

15. SUSY Models Choose mhmax and no-mixing scenarios as benchmarks
MSUSY = 1TeV
µ=±200 GeV
M2 = 200 GeV
Xt = 2 MSUSY
At = Ab
M~g = 0.8MSUSY
MSUSY = 2TeV
µ=±200 GeV
M2 = 200 GeV
Xt = 0
At = Ab
M~g = 0.8MSUSY
28th May 2009