Trilepton from direct neutralinochargino production in mSUGRA

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Trilepton from direct neutralino-chargino
productionin mSUGRA
V.Zhukov W. de Boer, M.Niegel University
Karlsruhe
-see previous talks at BSM meetings CERN
11/01, FNAL 11/04, CERN 12/05 -CMS internal note
is submitted - status at www-ekp.physik.uni.ka
rlsruhe/zhukov/Trileptons/Trileptons.html
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Introduction
Signal signatures two cases
Branching ratios to l
Dileptons invariant mass
Minvmax mc20-mc10
3 body
M2invmax (m2c20-m2l)(m2l-m2c10)/m2l
2 body
l mostly stau

• Typical selection criteria
• 3 isolated leptons with 2 OSSF
• no central jets
• some missing ET

Only e, m are considered for the signal not t
( important for 2 body)
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Previous studies
Reasonable estimate
CMS CMS Note 1997-007 I.Iashvili,A.Kharchilava,
K.Mazumdar CMSJET based, scan over mSUGRA many
relevant backgrounds are considered. SNs /vNbkg
30fb-1 40 (m0100, m1/2100, tanb2)
7 (m02000,
m1/2175,tanb2)
ATLAS PTDR 1998 simulations 5s reach at 10
fb-1 ATLFAST(simple detector parametrisation) not
all backgrounds considered.
No complete trileptons analysis at the LHC (I
found) so far...
2fb-1 10fb-1 30fb-1
Tevatron CDF/D0 experimental search for 200
pb-1 nothing observed so far simulation 5s
reach at different Lint
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mSUGRA parameters and constrains
mSUGRA m1/2, m0, tanb, A0, sgnm
Where to scan?
EWSB constrains define upper limit of m1/2 at
large m0
mg2.7m1/2 , mc100.4m1/2, mc200.8m1/2
mass limits low limit m1/2 at low m0 mhgt 114.4
GeV , mc?gt 103 GeV
b-gtsg low limit m1/2at low A0 A0 changes
interplay between mh limit and bsg
Dam upper limit on m1/2 (only 2s effect)
Agree on standard constrains?
Relic density neutralino is LSP WMAPSRN
??h2 0.094 -0.129 Indirect search (EGRET)
m1/2lt 250 GeV Calculation of the RD is model
dependant this constrain is indicative (at high
tanb and m0)
tanb50 A00
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Cross sections
Trilepton (e, m) LO cross sections
(ISAJET7.69Pythia 6.225) from direct
?1??? production (other pairs ?1,2?3,4?
much less.)
KNLO1.3 (Prospino2.0) W.Beenaker et al
the only region with 2 body decays
no EWSB
no EWSB
Up to 20 of the total susy cross section (at
large m0)
Can be a Discovery channel for Lintgt30 fb-1
(s gt10 fb)
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Benchmark points
2 body
Mostly 2 body, via staus
3 body
Not distinguished from bkg, c20-gtZ
Not distinguished from bkg, c20-gtZ
2 body
3 body
Not distinguished from bkg, c20-gtZ
3 body
LM1, LM3, LM6, LM7, LM9 Scan over mSUGRA plain
LM9 used for the detailed study
Z peak
Dmm c20- mc10 vs m1/2 tanb50 m01400
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Simulated samplessignal and backgrounds
Generator 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
LM9 and ZZ/W bkgr are simulated in full, others
in fast simulation
Data samples are produced in Karlsruhe (not
published)
No pileup in OSCAR but event pileup is
implimented in FAMOS
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Reconstruction
Same analysis code for ORCA and FAMOS
Default algorithms were used leptons
isolation was implimented in FAMOS and for
electrons in ORCA
ORCA
FAMOS selection muons
GlobalMuobReconstructor
L3MuonReconstructor Ptgt10 GeV/c
MuIsoByTrackerPt(1.5
) no tracksgt1.5GeV
h lt2.4
MuIsoByCaloEt(5.) Rlt0.3 Ecallt5GeV in
Rlt0.3 electrons ElectronCandidate
ElectronCandidate
Ptgt10 GeV/c no
tracks Ptgt1.5GeV Rlt0.3 no tracks
Ptgt1.5GeV Rlt0.3 h lt2.4
Ecal/Hcalgt0.8
Ecal/Hcalgt0.8 jets
IterativeCone(R0.5)
IterativeCone(R0.5) Etgt20
GeV EcalPlusHcalTowerInput
EcalPlusHcalTowerInput h lt2.4
JetsPlusTrack
JetsPlusTrack
MET METfromEcalPlusHcalTower
METfromCaloTower
LeptonCorrection
LeptonCorrection tracks
CombinatorialTrackFinder
CombinatorialTrackFinder Ptgt0.8 GeV/c



h lt2.4
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Reconstruction leptons
electrons
muons
Ntot leptons reconstructed per event
Rapidity distribution for leptons from c20 decays
(LM9)
Dpt pt-ptmc/pt for leptons from c20 decay
Bremss. losses
Efficiency for leptons from c20
Eorca84 Efamos80
Eorca77 Efamos73
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Reconstruction Jets
Number of jets(Etgt20GeV) per event for LM9 and
ttbar MC- PYTHIA PYCELL 7 difference between
FAMOS and ORCA
MET for LM9 different methodes
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Reconstruction invariant mass
Use high Pt combinations of Opposite Sign Same
Flavor (OSSF) pairs. Low Pt combinations
can increase the background LM9 and ZW for all
and high Pt pairs.
The simulated and reconstructed (high Pt
OSSF) invariant mass for muons and electrons
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Event Selection
Very conservative cuts.
No MET cut is used (see backup slides)
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Invariant mass
LM9 and different backgrounds for dimuons and
dielectron pairs
DFOS is not subtracted
Use only dimuons lepton in this analysis the
dielectron requires further optimisation.
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Benchmark points
Significance (SLv 2lnQ) for different
benchmark points (LM9, LM7, LM1, LM3) in
dimuon invariant mass.
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Discovery reach
gt3 s significance plot for Lint 30 fb-1 at
low luminosity (FAMOS scan)
Z peak
Z peak
5s
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Pileup
Event pileup is implimented in FAMOS uses
mu05b_MBforPU samples
8 signal loss at LL 43 signal reduction at
HL (but also the backgrounds)
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SummaryConclusion
Trilepton (dimuonslepton) from ?1??? can be
seen at Lintgt30fb-1 with SLgt5 at m1/2 lt250
GeV with rather conservative event selections
and considering most of the backgrounds. Larger
m1/2 are limited by the decay of c20 into on
shell Z or Dmmc20-mc10 in the Z peak. The 2
body decay is available only in very narrow
region at small m0.
The Z/W/g/jets and ttbar bkg can be suppressed by
using MET and btagging, improving significance
by30
The use of electrons requires the optimisation of
the Pt selection cuts and isolation as well as
the energy loss recovery.
The kinematical end point (m1/2) can be
reconstructed with an accuracy of 10 GeV(to
be studied)
Better significance can be obtained with
semileptonic decays where MET cut can be used.
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Plans
to be done - optimisation of lepton cuts and
isolations, (electrom object) - use of the MET
selection - trigger performance, HLT menu -
consider inclusive Z/gamma jets (ALPGEN) -
reconstruction of the endpoints and masses,
accuracies, significance, systematic - event
topology reconstruction - stau in 2 body decays
Contribute to the PTDR v.II Physics at 30
fb-1 16.14 Direct c0c production in
tri-leptons
Working group is formed University Karlsruhe
W.de Boer, V.Zhukov, M.Niegel UC Davis
M.Chertok, A.Soha, A.Stromberg Tata Institute
K.Mazumdar Mugla U K.Cankocak
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Backup slides
Total susy cross section(LO)
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Backup slides
Pt distibution for reconstructed muons and
electrons at LM9 ordered by Pt
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Backup slides
Using METcut METgt18 GeV and btagging (Eeff50)
for ttbar. Dimuons invariant mass for LM9 and
backgrounds
SL11