cdf searches overview

Tracey Pratt EuroGDR, Frascati, Italy November 2004

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CDF

Searches Overview

Tracey PrattLiverpool University

Extra Dimensional Models and their Signatures Introduction to the Tevatron and CDF Search channels, Search Strategy Comparison of Background Expectation to Data Preliminary Results Summary and Outlook


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Curvature of the extra dimension

Gravity localised in the EDScale of physical phenomena on the TeV-brane is specified by the exponential warp factor:

= MPle-kRc

~ TeV if kRc ~11-12.

Planck TeV brane1 highly curved extra dimension

Extra Dimensional Solutions the Hierarchy Problem

(MEW << MPlanck?)

Taking compact space to be very large

G

Gravity freely propagates in the

MPl(4+n) ~ 1 TeV

MPl2 = VnMPl(4+n)

(2+n)

many large extra dimensions (n>2)

To solve hierarchy:

hep-ph 9905221hep-ph 9803315


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CDF @ Tevatron pp Collider

Highest energy collider operating in the world!

D0

pp

CDF

Run I (1992-1996)√s 1.8 TeV, 110 pb-1

Run II (2001-2009)√s 1.96 TeVPhysics Analyses use ~200-345pb-1 collected between 02/02 and 07/04

days

Delivered To Tape

700

600

500

400

300

200

100

0

pb-1 Total Luminosity


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RS model

Dilepton channel

400 600 800 1000

Tevatron 700 GeV KK graviton

K/MPl

10.70.50.30.20.1

d/dM (pb/GeV)

10-2

10-4

10–6

10-8

Mll (GeV)

Experimental Signatures for

Since gravitons can propagate in the bulk, energy and momentum are not conserved in the GKK emission from the point of view of our 3+1 space-time

Since the spin 2 graviton in generally a has a bulk momentum component , its spin from the point of view of our brane can appear as 0, 1 or 2

Mll (GeV)

Run I =+1

Graviton emission

&

Graviton exchangeSearch for deviations in cross sections

and asymmetries of SM processes

g,q

g,q

f,V

f,V

G

g,q

g,q jet,V

G

Search for ET + jet(s), ET + V

M (GeV) Mll (GeV)


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CDF ED Search Channels

Completed On their way!

Search StrategyAim to make generic signature-based searches (e.g. ee channel)Perform general searches comparing data to expectationSo we can interpret data according to many new models

(e.g. G: RS and ADD, Z’: SM, E6; RPV )!

So use same data for ee ADD and RS model

Channel

Run I Run II Run II Emission

+ ET

jet + ET

Virtual Graviton Exchange

ee

ee &

& ee

jet-jet

ZZ


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G Emission: +Et

Limitsn=4 MD > 0.55 TeV

n=6 MD > 0.58 TeV

n=8 MD > 0.60 TeV

qq GKKSearch Selection - One with ET > 55 GeV and ||<1 - ET > 45 GeV - No jets with ET > 15 GeV - No tracks with pT > 5 GeV

ResultsExpected background: 11.0 2.3 Observed: 11

Cosmic ray muons 6.3 2.0

Z0+ 3.2 1.0

W e (““) 0.9 0.1

Prompt diphotons 0.4 0.1

W () 0.3 0.1

Main backgrounds

87 pb-1 Run I


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G Emission: jet(s)+Et

from Pythia

prediction from Giudice, Rattazi and Wells (hep-ph9811291)

falls as 1/MDn+2 for all subprocesses

Tevatron s=2 TeV MD = 1.2 TeV

n=4

n=2

pTmin (GeV)

gggGKK

qggGKK

qqgGKKdominate sub-process for n>2

q q q q q q

q

qq gg gg

GKKGKKGKK

gg

gg

g

gg

g

g

g

g

GKKGKKGKK

GKKGKK GKK

q

qqq

qqq

gg gg

q q

g


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Search Selection jet ET

1st 80 GeV, || <1.1 and ET>80 GeV

a second jet is allowed if ET2nd > 30 GeV

no isolated tracks in event (pT10 GeV)

Main background Z()+jets, W()+jets.

CDF Run I : Best limits from the Tevatron from

searches for direct graviton emission

G Emission: jet(s)+ET

ResultsExpected: 27416 Observed: 284 events.Relative uncertainty on the signal acceptance 25 %

Limits95 % C.L. upper limit on number of signal events: 62

84 pb-1 Run Ib

Run I : MD (TeV) > Run II 85pb-1

n CDF

(K=1.0)

D(K=1.0)

D(K=1.34)

D(K=1.3)

4 0.77 0.66 0.73 0.68

6 0.71 0.63 0.65 0.66

Predicted Data

Predicted invisible Z

Observed (84pb-1)

ET (GeV)


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G Exchange: ee

Search selection2 two isolated e, ET > 25 GeV 2 central e (CC) or 1 central and 1 forward e (CP)

Main Backgrounds

~12500 candidates

COT

Plug Calorimeter

Time-of-Flight

Central Calorimeter

Solenoid

Silicon Tracker

|| < 1

1<||<3

Nexp=11.1 Nobs=14 for Mee>300 GeV/c2

Nexp= 4.6 Nobs= 9 for Mee>350 GeV/c2

Apply energy dependent cuts for high mass efficiency

Extra Dimensions Standard Modell+

l-Z/ l+

l-

l+

l-


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G Exchange:7500 candidates

Search Selection2 isolated PT>20 GeV |1|<1, |2|<1.5*

Veto cosmic rays using track-timing cuts

Muon System

COTTime-of-Flight

Solenoid

Silicon Tracker

|| < 1.5

|| < 1

2 may include tracks w/o chamber information

Nexp=5.2 ± 0.3 Nobs=6 for Mee>300 GeV/c2



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G Exchange:

Backgrounds • Standard Model diphoton production (dominant at very high masses)• Fakes: -jet and jet-jet, where jet fragments into a hard 0

Search Selection2 isolated ET>15 GeV 2 central (CC)

Nexp=4.2±1.0 Nobs=1 for Mee>300 GeV/c2

Nexp=1.5±0.5 Nobs=1 for Mee>350 GeV/c2

Standard Model

Extra Dimensions


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Extracting G Exchange ll, Limits

95 % C.L. lower limits on string scale and upper limits on .BR(G→ll) and are placed using binned likelihood method

ni i

ni!L(/)=i i e

ni : observed eventsi= Ni

sig + Nibkg (Resonant particles)

i= Nisig() + Ni

bkg (LED spectrum)Likelihoods are integrated to give the final limits, taking into account the signal and background systematic uncertainties

Sources of systematic uncertainties:Luminosity Acceptance (PDF, MC statistics...)Energy/Momentum scale resolutionSelection EfficienciesBackground statistics and normalisation

95 % C.L. upper limits on .BR(G→) are placed using ± 3 search windows around MG

N95%=95%Nsig

95%= N95%

AÕ


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G Exchange: jet jet

•Fit the mass spectrum with a simple background parameterization and •Search for bumps comparable with the mass resolution.

No significant evidence for a new particle

Search Selection2 highest ET jets selectedfrom inclusive jet samples


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ADD ee Limits

Set a limit on the effective Planck scale (Ms4)

using invariant mass spectrum (1D fit)

Parameterise the cross section in terms of =/ s

4, where =±1 (Hewett) = SM + INT + 2 KK

CDF Run I: 780 768

987 959


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RS Graviton Limits

for k/M_Pl=0.05 masses less than 500 GeV are ruled out at 95% C.L..

Channel Luminosity

(pb-1)

MG(GeV/c2)

K/MPl=0.01

MG(GeV/c2)

K/MPl=0.1

ee 200 200 640

200 170 610

ee+ 200 200 700

345 220 690

jetjet 75pb-1 exclude 220-840 GeV: k/MPl=0.3


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Angular Distributions: ee

cos* in Collins-Soper frame

1-D fits performed, but also study angular distributions

Good agreement with SM prediction


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Angular Distributions: &

cos* in Collins-Soper frame


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Summary and Outlook

Searches for ED have been performed in many channels at CDF No evidence of deviations from Standard Model expectation observed Best limits obtained

ADD jets+ET, ee + ~ 1 TeV

RS (345pb-1)m1 ~ 220 to 690 GeV for k/MPl 0.01 to 0.1

ee + (200pb-1) m1 ~ 200 to 700 GeV for k/MPl 0.01 to 0.1 Many new results and publications on their way…. ee PP search ZZ channel Tevatron Run IIa (2 fb-1) has a promising observation potential and should be in a position to discover ED, if they exist,

ADD: up to about MS = 2 TeV

RS: m1 from 0.5 to1 TeV for k/MPl 0.01 to 0.1 Look out for CDF results!


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ee(PP): Comparison to Expectation

New for Run II: Plug ee increase acceptance!

Search selection2 two isolated e, ET > 25 GeV 2 forward e (PP)

QCD dijets: jet is misidentifiedLarger effect in the plug region than in central

Main Non-Drell-Yan Background



limits being obtained!


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Summary and Outlook

Searches for ED have been performed in many channels at CDF No evidence of deviations from Standard Model expectation observed Best limits obtained

ADD jets+ET, ee + ~ 1 TeV

RS (345pb-1)m1 ~ 220 to 690 GeV for k/MPl 0.01 to 0.1

ee + (200pb-1) m1 ~ 200 to 700 GeV for k/MPl 0.01 to 0.1 Many new results and publications on their way…. ee PP search ZZ channel Tevatron Run IIa (2 fb-1) has a promising observation potential and should be in a position to discover ED, if they exist,

ADD: up to about MS = 2 TeV

RS: m1 from 0.5 to1 TeV for k/MPl 0.01 to 0.1 Look out for CDF results!


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Spin-0 Dilepton Limits

RP sneutrino

`

l+

l-

2xBR


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CDF Run L(pb-1) Mass Limit @ 95 %

Z' SM ee Run IA(92-93) 20 505Run IB(94-94) 90 640 590IIA (winter 04) 200 750 735

Run I limits exceeded!

Z' bosons

E6 Z'

E6 Model Z`:del Aguilia et al., Nuc Phys B287 (87)Unification of strong and EWK forces at GUT

E6→(SO(10)→SU(5)xU(1))xU(1)

Z` = Z sinE6 + Z cosE6

Z,ZIE6 = sin-1√3/8, sin-1√5/8

Sequential Z`: Reference model with SM-like couplings to fermionsFree parameter M(Z`)


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Little Higgs Z'

Solve fine-tuning and hierarchy by canceling divergences of Higgs mass

SU(2) ZH coupling parameter cot

Littlest Higgs ZH (→ee)

M(ZH)>800 GeV/c2 for cot=1.0

M(ZH)>755 GeV/c2 for cot=0.9

Arkani-Hamed, Cohen, Georgi, Phys. Lett. B 513, 232, 2001Han, Logan, McElrath, Wang, Phys. Rev. D 67, 095004, 2003

First limits set!


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Technicolor


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Spin-dependent Acceptance

spin-0 spin-1 spin-2

Angular distribution and therefore acceptance of decay products depends on the spin of the decaying particle.


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CDF Run I search for LED

Search Selection

2 with Et > 22 GeV,

CC or CP: central (|| < 1), plug (1<|| <2.4)

Main backgrounds: fakes from -jet and jet-jet

Results Observed: 287 Central Central events

192 Central Plug eventsLimits Using a maximum likelihood fit method

CC 100 pb-1, CP 87 pb-1

Plug

Central

95 % C.L. MS > 899 / 797 GeV KLED = 1.0

( = -1/+1, Hewett)

Mhighest = 288 GeV/c2


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CDF Run I ee search for LED2 high Et isolated electrons (> 25 GeV) (CC and CP)

95 % C.L. MS > 780 / 768 GeV KLED = 1.0

95 % C.L. MS > 826 / 808 GeV KLED = 1.3

( = -1/+1, Hewett)

Main Backgrounds: Drell-Yan, QCD di-jet, diboson production, Z,tt-bar production

500 GeV

CC: 3319 CP: 3825

Channel 95 % C.L. MS (Hewett) GeV/c2

KLED = 1.0

= -1

= +1

ee 780 768 899 815

ee and 905 826


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Davoudiasl, Hewett, Rizzo hep-ph 0006041

constraints

m1 (GeV)

K/MPl

0.20

0.10

0.07

0.05

0.03

0.02

0.01

Tevatron 110 pb-1

Dijet and dilepton data

1000 2000 3000 4000 5000

Oblique Parameters

< 10 TeVSolve hierarchy

|R5| < M52

Curvature of 5th dimension

LHC 10 fb-1

Dilepton data

Allowed Region

2 fb-1

Sridhar hep-ph 0103055

Diphoton data

2 fb-1


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Diphoton constraints

hep-ph 0103055

200 220 240 260 280m0 (GeV)

K/MPl 0.1

0.08

0.06

0.04

0.02

s = 2 TeV

L = 2fb-1

Run II a, b

95 % C.L. m0 (GeV)

K/MPl 0.1

0.08

0.06

0.04

0.021000 1100 1200 1300 1400

s = 14 TeV

L = 100fb-1

95 % C.L.

m1 : 700-1150 GeV m1 : 3.5-5.5 TeV

Tevatron LHC

||<1.2 for both ||<2.5 for both Using (KLED=1.3) for full

cdf searches overview

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