C.Collard 26/02/03 Exotic Signals at Hadron Colliders 1 Randall Sundrum KK Graviton at CMS Caroline Collard, LLR, Ecole Polytechnique, France Work in collaboration.

26/02/03Exotic Signals at Hadron Colliders

1C.Collard

Randall Sundrum KK Graviton at CMS

Caroline Collard, LLR, Ecole Polytechnique, France

Work in collaboration with M.-C. Lemaire, P. Traczyk and G. Wrochna


2C.Collard

Overview• Extra Dimensions & Randall Sundrum Model

• Search for RS graviton in the CMS detector– The CMS detector– Signal & Background– First Analysis: 5 discovery limit– The photon radiation with PHOTOS – If no signal? 95% CL signal exclusion– If a signal? Spin-2 analysis

• Conclusions


3C.Collard

Extra Dimensions

No new Physics

Small Compact ED

New particles:KK Gravitons(continuum)

Deviation from Newton's Law

many dimensionswith symmetrical configuration

New particles:KK Gravitons

(same separation space),KK fermions or gauge bosons

Deviation from Newton's Law

many dimensionswith antisym configuration

Large Compact ED

New particles:KK Gravitons

(different separation space),KK fermions or gauge bosons,...

No deviation from Newton's Law

only one extra dimension

Warped ED

Why? • Unification of gravitation with other forces.• Hierarchy problem : MEW and MPL

Different models of ED


4C.Collard

Warped EDThe Randall-Sundrum Model:

– only one extra dimension 5D Anti-de-Sitter Spacetime

– metric: e-2kr dx dx + r2 d2

– k (~ MPL): AdS5 curvature, r: compactification radius,

r : new coordinate and x: traditional 4D coordinates

– Gravity Scale: =MPL e-kr no hierarchy if kr≈12

Planck brane SM brane

r = 0 r = r

bulkr


5C.Collard

Warped EDThe Randall-Sundrum Model:

– Two parameters in the model: e-kr and k/MPL

– Graviton in 5D KK graviton excitations in 4D Experimental measurement of the 1st KK graviton

M1 [Mn = k xn e-kr with J1(xn)=0]

1 [n = Mn xn2 (k/MPL)2 with (open decay mode)]

– Other parameter choice:

M1 and c= k/MPL

c is related to 1 and also to the coupling


6C.Collard

Variation of c

d/

dM

MG

0.01 ≤ c ≤ 0.1

c = 0.1

c = 0.05c = 0.02c = 0.01


7C.Collard

The CMS detector

• pp collider:14 TeV in cms

• Start in 2007• 1 year @ low

lumi: 10 fb-1

• 1 year @ high lumi: 100 fb-1

Higgs Discovery and Search for New Physics


8C.Collard

Analysis• Signal:

– ffbar, gg G (B.R.= 4 %)– ffbar, gg G e+e-, +- (B.R.= 2

%)

Generation with PYTHIA

Photon Radiation with PYTHIA or PHOTOS

Detector response with CMSJET (Fast Simulation)


9C.Collard

CMS Performance in CMSJET

• ECAL: For electron and detection

Barrel (||<1.56) E/E = 3% /√E + 0.2/E + 0.55%

Endcap (1.65<| |< 3) E/E = 6% /√E + 0.9/E + 0.55%

• Tracker: For muon detection p/p = 4% √p


10C.Collard

Analysis• Backgrounds:

– For : ffbar, gg (+ photon-jet: ffbar g,

fg f, gg g + dijet: ff ff, ffbar ffbar,

ffbar gg, fg fg, gg ffbar, gg gg)

No K factor for .

– For e+e-, +-: pp Z/ l+l- (Drell Yan)

K factor =1.38 from comparison between PYTHIA MC and

CDF data

M (GeV)

# E

ven

ts

CMSJET


11C.Collard

MG= 1500 GeV, c=0.01,Lumi=100 fb-1

G

M (GeV)

# E

ven

tsCMSJET


12C.Collard

5 Discovery Limit

G c =0.01

100 fb-1

MG (GeV)

.B

(fb

)CMSJET


13C.Collard

MG= 1000 GeV, c=0.01,Lumi=100 fb-1

Difference in resolution for e (Energy in calo) and (Momentum in tracker) => Different mass windows

CMSJET


14C.Collard

5 Discovery Limit

G e+e-

c =0.01

.B

(fb

)

MG (GeV)

CMSJET


15C.Collard

Radiation with PHOTOS

Use of PHOTOS to generate radiation, in place of PYTHIA

Dependence on the input parameters used in PHOTOS: E fraction, Double Bremsstrahlung flag, Interference flag

With E fraction= 0.01, Double Bremsstrahlung flag = T, Interference flag=F, Mass Limits for 5 Discovery:

=> Results in agreement!

Lumi PYTHIA PHOTOS

300 fb-1 2300 GeV 2350 GeV

100 fb-1 2000 GeV 2080 GeV


16C.Collard

CMSJET

Use of PHOTOS

PHOTOS (0.01, F, F) PHOTOS (0.02, T, T)

PHOTOS (0.01, T, F) PYTHIA

RMS= 42.44 RMS= 40.01

RMS= 39.92 RMS= 41.32

Impact of input parameters:

Mee (GeV)

# E

ntr

ies


17C.Collard

5 Discovery Limit with PHOTOS

G e+e-

c

MG (GeV)

Theoretical constraint on curvature

Theroretical constraintfor no new hierarchy CMSJET


18C.Collard

If there is no signal …• NS: number of expected signal events• NB: number of background events

• Nobs:number of “observed” events

• 95% CL Exclusion Limit


19C.Collard

95% CL Exclusion Limit

Signal Exclusionat 95% CL

MG (GeV)

c

Excluded

|R5| < M52

= 10 TeV

Region of interest

Muons Electrons

Photons

CMSJET


20C.Collard

If there is a signal …

• How to be sure it is a RS Graviton?– Graviton? not a Z’?

– RS model?

MG=2000 GeV,c=0.01

CMSJET


21C.Collard

Angular Distribution• Graviton = spin 2

pp G +-

MG=1000 GeV c=0.1

Cos

qqbar G ll:1-3cos2+4cos4

gg G ll:1-cos4

After cut:( | | < 3.0 for e | | < 2.4 for )

CMSJET


22C.Collard

How different from Z’?• Kolmogorov-Smirnov Test

• Rem: No mode for Z’

Z’ 1+ cos2

G

M= 2000 GeV

Cos

For G:number of events corresponding to Lumi, randomly chosen

CMSJET


23C.Collard

95% CL Exclusion Limit

MG (GeV)

cSpin 1 rejection

with 90% probability at 95% CL

Excluded

|R5| < M52

= 10 TeV

Region of interest

Electrons

Leptons

CMSJET


24C.Collard

Detector acceptance

Importance of the pattern recognition in the endcap regions!

|| < 2.4 || < 1.5

Cos

CMSJET


25C.Collard

RS model?Davoudiasl, Hewett, Rizzo

hep-ph/0006041

c=1.c=0.5

c=0.1c=0.05c=0.01

If the 1st graviton is found, there is a prediction where to find the next resonances for c not too big.

Mll (GeV)

d/

dM


26C.Collard

Conclusions

• Signal? Test of Randall Sundrum model after 1 year data taking at the high luminosity design

• Graviton? channel or angular distributions of lepton decay products

• Next Step: Full simulation-reconstruction chain

C.Collard 26/02/03 Exotic Signals at Hadron Colliders 1 Randall Sundrum KK Graviton at CMS Caroline Collard, LLR, Ecole Polytechnique, France Work in collaboration.

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