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Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 1
SUSY status at Karlsruhe
W. de Boer, M. Niegel, A. Vest, V. Zhukov
Universität Karlsruhe (TH)
SUSY/MSSM
Trileptons from direct neutralino-chargino production
Semileptonic gluino decays at large m0
Summary
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 2
Supersymmetry (SUSY) / MSSM parameters
SM particles spin SUSY partners spin
½ 0½ 01 ½0 ½
g 1 g ½
qL , qR qL , qR
lL , lR lL , lR
g, Z0, W+/- c01, c
02, c
03, c
04
h0, H+/-, H0, A0 c+/-1 , c
+/-2
~
~ ~~ ~
~
~ ~~
~ ~} {MSSM: 105 + 25(SM) parameters, but
The masses and couplings of , and are determined by the parameters
Gaugino mass parameters unify to at the GUT scale
Sfermion masses are free parameters
Each SUSY decay chain ends up in the LSP, e.g.
mSUGRA model:
common mass for scalar fields (gauginos) at the GUT scale
REWSB → model completely determined by
i0
10
g j±
m0m1/2
, tan , M 2
m0 , m1/2 , tan , sign , A0
M 1 , M 2 , M 3 m1/2
SUSY transformation Q:converts a fermionic stateinto a bosonic state and vice versa
Q |fermion> = |boson>Q |boson> = |fermion>
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 3
SUSY benchmark point LM9
m0=1450GeV
m1/2=175GeV
tan=50sign=1A0=0
⇒M 10≈65GeV
mSUGRA parameters:
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 4
Trileptons from direct neutralino-chargino production
Trilepton (e, ) LO cross sections (ISAJET7.69 + Pythia 6.225) of direct c
1±c2
production (xsecs of other pairs c1,2± c3,4
much smaller)
KNLO
~ 1.3(Prospino 2.0)W. Beenaker et al.
May be discovery channel for Lint
> 30 fb -1 ( > 10 fb) Up to 20 % of thetotal susy cross section (at large m
0)
cross-section cross-section
pp201
±
The only region with 2 body decays
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 5
Trileptons from direct neutralino-chargino production
Typical selection criteria:
3 isolated leptons with 2 OSSF
no central jets
Some missing ET
Only e, considered, not
3 body decay: 2 body decay:
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 6
Dilepton invariant masses, BR's
3 body decay:Minv
max= mc20
-mc10
2 body decay:M2inv
max= (m2
c20-m2
~l)(m2
~l-m2
c10)/m2
~l
BR
BR
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 7
Simulated data samples: signal and background
'preliminary' analysis with full and fast simulationGenerator : PYTHIA 6.225 +ISAJET(ISASUGRA) 7.69 (TopRex for ttbar,Wt)
CMS full : OSCAR 3.6.0 + ORCA 8.7.1 (DST)
CMS fast : FAMOS 1.2.0
mSUGRA parameter space scan and for LM9
LO
(pb)
KNLO/LO
3l
NLO(pb) NNLO
(30 fb-1) Nsim
full Nsim
fast
ZZ 11.8 1.34 0.16 4800 104 104
ZW 30.0 1.72 1.68 5. 104 5*104 5*104
ttbar 486 1.71 88 2.6*106 104 1.5*106
Zbbar 746 2.0 149 4.4*106 104 106 Wtj 60 1.7 10 3*105 104 2.5*105
SUSY(LM9) 25 1.6 13.1 4*105 104 3*105 lm9_3l 4.6 1.3 0.124 3.7*103 104 104
mSUGRA scan ( ~200 points) 104
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 8
Trileptons from direct neutralino-chargino production
LM9 and ZZ/W bkgr simulated in full, others in fast simulation
No pileup in OSCAR but event pileup implemented in FAMOS
Data samples produced in Karlsruhe (not published)
Same analysis code for ORCA and FAMOS
Default algorithms
Lepton isolation implemented in FAMOS
Electron isolation implemented in ORCA
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 9
Reconstruction
ORCA FAMOS selectionmuons GlobalMuobReconstructor L3MuonReconstructor Pt > 10 GeV MuIsoByTrackerPt(1.5) no tracks > 1.5 GeV 24 MuIsoByCaloEt(5.) R < 0.3 Ecal < 5 GeV in R < 0.3
electrons ElectronCandidate ElectronCandidate Pt > 10 GeV no tracks Pt>1.5 GeV R < 0.3 no tracks Pt > 1.5 GeV R < 0.3 24 Ecal/Hcal > 0.8 Ecal/Hcal > 0.8 jets IterativeCone(R = 0.5) IterativeCone(R = 0.5) Et > 20 GeV EcalPlusHcalTowerInput EcalPlusHcalTowerInput 24
JetsPlusTrack JetsPlusTrack MET METfromEcalPlusHcalTower METfromCaloTower LeptonCorrection LeptonCorrection
tracks CombinatorialTrackFinder CombinatorialTrackFinder Pt > 0.8 GeV 24
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 10
Event selection (without MET cut)
● L1 Trigger (for ORCA): dimuons 3 Gev, dielectrons 12 GeV
● 3 isolated leptons with 2 OSSF (Mll < 75 GeV)
● : Pt > 10 GeV, 24 ● e : Pt > 15 Gev, 24
● No Jets with ET > 20 GeV, 24
● No MET cut
Ntot (30fb-1) Nj=0 2m+l 2e+l 3ltot ZZ 4800 3245 56 118 174 ZW 5*104 3.4*104 223 480 703 ttbar 2.6*106 2.2*105 396 178 574 Zbbar 4.4*106 3.7*106 171 154 325 Wt 3*105 1.2*105 58 39 97 SUSY 4*105 1.7 *105 42 23 65 lm9_3l 3750 2720 265 146 411
2 + ,e
Significance = 8.9
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 11
Event selection (with MET cut)
● L1 Trigger (for ORCA): dimuons 3 Gev, dielectrons 12 GeV
● 3 isolated leptons with 2 OSSF (Mll < 75 GeV)
● : Pt > 10 GeV, 24 ● e : Pt > 15 Gev, 24
● No Jets with ET > 20 GeV, 24
● MET > 18 GeV
↓
Significance increases
from 8.9 to 10.5
2 + ,e
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 12
Discovery reach
>3 significance plot for Lint = 30 fb-1 (FAMOS scan)
5 5
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 13
Status / To do list
Still missing:
Trigger study (will be done soon)
Uncertanities (gen and rec, not covered)
some more bkg (ZWjets)
Cut optimisation (use of MET -> Valerie)
Martin Niegel will continue...
By now:
CMS internal note („Trilepton from direct neutralino chargino production in mSUGRA“)
PTDR draft
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 14
Semileptonic gluino decays at large m0
Semileptonic (gluino decay) dileptons at large m0 intresting from the Dark Matter search (W. de Boer et al.)
Large m0 and lowest m1/2 are the focus point -> LM9
Potentially much better significance than other topologies
look at the final state (next slide) !!
Edge in Minv of the dileptons from the Neutralino decay is the only discovery signature at the LHC
Also interesting for indirect Dark Matter search due to the large annihilation cross section
Valerie is working on the reconstruction now
Dominant SM Background: ttbar, QCD, Drell-Yan...
A better understanding by October; collaborating with Catania.
something for PTDR ??
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 15
Semileptonic gluino decays at large m0
3 body decays:
2 body decays:
Advantage over trileptons:MET is significant since the neutralinosare produced by decays of heavy gluinos-> MET cut reduces most of the SM BG
Anja Vest, Uni Karlsruhe (TH) DCMS Meeting in Aachen October 2005 16
Summary
Trileptons from direct neutralino-chargino production (LM9) on the way to PTDR
Dileptons from semileptonic gluino decays (LM9) just started (PTDR?)
The 'bulk' region (low m0, LM1, LM2, LM5 points):
under investigation (Italy, Greece, Straßbourg) (we collaborate)
but: event topology is different
New Diploma student Christophe Saout (started 2 weeks ago)
New topics to come....