susy status at karlsruhe - tu dresdenvest/talks/susy_dcms_okt05.pdf · anja vest, uni karlsruhe...

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


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>


SUSY benchmark point LM9

m0=1450GeV

m1/2=175GeV

tan=50sign=1A0=0

⇒M 10≈65GeV

mSUGRA parameters:



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



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:


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


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



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


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


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


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


Discovery reach

>3 significance plot for Lint = 30 fb-1 (FAMOS scan)

5 5


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



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 ??



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


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....

susy status at karlsruhe - tu dresdenvest/talks/susy_dcms_okt05.pdf · anja vest, uni karlsruhe...

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