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Müge Karagöz Ünel

CERN24th Jan 2008

Extra Dimensions @

the LHC

• Based on a talk given in 2007, so most ATLAS and TeV results not updated. Sorry!

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History Illustrated1687 1915

~1960

1925

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• Not a new idea!– Kaluza and Klein tried to unify

electromagnetism and General Relativity in the ‘20s by adding a 4th spatial dimension

• In late ‘90s, models attempt to solve the hierarchy problem (MPl >> MEW)

• A lot of variations since then…• Searches at current colliders

boomed..

Extra Dimensions

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“Modifying” Gravitational Law• Obtain size of the ED (compactification

radius) from the gravitational potential (Gauss’ law)

• n=1 R~1013 cm: deviations of Newtonian gravity over solar distances; excluded.

• n=2 (R~ 100m - 1mm): within reach, ruled out by Eot-Wash table-top (<150m)

• n>2, gravity modified at distances we can probe at colliders.

V (r) 1

MPl2

m1m2

r

1

MPl(3n )(n2)

m1m2

rn1 for r << R

V (r) 1

MPl2

m1m2

r

m1m2

MPl(3n )(n2) Rn

1

r for r >> R

R ~ 1030

n 17cm

1TeV

mEW

12

n

MPl ~ 1019 GeV, MPl(4+n)~MEW

22

(4 )

11/

( )N DPL n

G MM

2 2 n nPl DM M R

• Assume MPl(4+n) ~ mEW,

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Large Extra Dimensions (LED, ADD):• n > 0 (n > 2), compactified, flat• Graviton in bulk• Could be as large as 0.1mmTeV-1 ED (DDG):• n ≥ 1 (n = 1)• Gauge bosons in bulk as wellWarped Extra Dimensions (RS):• n = 1, highly curved• 2-branes solution: RS1• k/MPl, k: curvature, warp factorUniversal Extra Dimensions (UED):• n = 1, flat, MUED: only1 ED• KK-number conservation • All SM particles in the bulk• Lots of KK spectra

Searches Concentrated onE

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Dienes, Dudas, GherghettaNucl Phys B537 (99)

Randall, SundrumPhys Rev Lett 83 (99)

Arkani-Hamed, Dimopoulos, Dvali Phys Lett B429 (98)

Appelquist, Cheng, DobrescuPhys. Rev. D 64 (01)

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Large ED (ADD):● Graviton in bulk● DY interference, or missing ET

TeV-1 ED (DDG):● Gauge Bosons and Higgs in bulk●

spin-1 KK resonances● DY interference

Warped ED (RS):● Graviton resonances

llZZqq

jet+MET

+MET

Virtual or resonanceexchange

emission

Bosonic KK modes: simpler signatures

Universal ED (UED):● spin-1 KK resonances

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• Flat large EDs generate tower of KK gravitons with mass splitting ~ 1/RC

continuum of graviton states• SM fields localized within 3D-brane• Size of ED determined by the fundamental scale MD and # ED

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Large Extra Dimensions (ADD)

2 2 n nPl DM M R

SM

int

s

Hewett

Effective for continuum G

• n<=2 ruled out (by Eot-Wash)• MD < 1TeV ruled out by Tevatron

Signatures: • Virtual production with DY interference excess above continuum• Real graviton emission with jet or photon

R ~ 1030

n 17cm

1TeV

mEW

12

n

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Warped Extra Dimensions

222 dydxdxeds vuuv

ky

Randall Sundrum (Type I)• Brane metric scales as function of

bulk position• Coupling constant:

c= k/MPl, k: curvature scale

• Well separated narrow-width graviton mass spectrum with masses

mn=kxnekrcπ (J1(xn)=0)

Bulk (y)

TeV

Plan

ck

c>0.1 forbidden

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From Tevatron to LHCE

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Most stringent limits to date from colliders:• CDF : k/MPl= 0.1, mG > 889 GeV (comb +ee)• D0 : k/MPl = 0.1, mG > 865 GeV (diEM)

• But we huge BSM reach increase from 2TeV to 14 TeV!

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Virtual Exchange Searches (LED)

• 2 OS muons & Mμμ>1 TeV• Bkgrd: mainly Irreducible DY•PYTHIA + CTEQ6L, Kf=1.38

Belotelov et al.,CMS PTDR 2006SM

Signal

• Di-photon/dilepton invariant mass• Manageable backgrounds• Min invariant mass cut extends

reach

Kabachenko et al.ATL-PHYS-2001-012

ATLAS Sensitivity for n=5..2

100fb-1: MD ~6.3-7.9 TeV

CMS 5 Sensitivity for n=6..3• 1 fb-1: ~4.0-5.5 ТеV• 100 fb-1: ~5.5-8.2 ТеV

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LED from Graviton EmissionE

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CMS NOTE 2006/129

MD= 1– 1.5 TeV, n<7, 1 fb-1

2 - 2.5 TeV, n<7, 10 fb-1 3 - 3.5 TeV, n<6, 100 fb-1

L.Vacavant, I.HinchcliffeJ. Phys G 27 (01)

pp→jet+G

• Signature: high ET jet + MET (from escaping G)• Bkgrnd: irreducible jet+Z/W via invisible decays

# ED, n 2 3 4

MD (TeV) 9.1 7.0 6.0

RC (m) 8 - 10-6

ATLAS sensitivity in 100 fb-1

• much lower rates than mono-jet signature • Signature: high-pT photon + MET

• Bkgrnd: irreducible Zγ → , and reducible fakes

pp→+ G

Rates for MD≥ 3.5TeV are too low for 5σ discovery with systematics

CMS sensitivity

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M=1.5, 1.75, 2 TeVNo Kf for signal

SM

WED RS1 SearchesE

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Allanach et al, hep-ph 0006114ATLAS Spin exploitation• Use cosdistribution of the dilepton system• Determine Spin-2 nature of graviton at 90% C.L.

up to MG = 1720 GeV with 100 fb-1

CMS PTDR results• Use ll and : B(G->) = 2* B(G->ee/)• Reach in ee and similar (unmanageable

bkgrnd) (also not enough stats) • CMS can detect at 5 up to 1.8 TeV (c=0.01)

and 3.8 TeV (c=0.1) with 100 fb-1

• Uncertainties’ effect in mass ~150 GeV

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TeV-1 Searches in DileptonsE

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• 1 ED with small enough compactification for gauge bosons to travel in bulk• All fermions localized at a fixed point (M1)

destructive interference with SM GB cKK = √2 cSM

• q and l at opposite points (M2) constructive interference

• V(k) appear as resonances: Mk = √(M0

2+k2/R2), k=1,2,…• search for anomaly/bump in dilepton invariant mass

ppZ1 ) /1)e+e-

Azuelos, PoleselloEPJ D C39 Sup.2 (04)

• ATLAS 5 reach in Mll (fast simulation): MC = 5.8 TeV in 100 fb-1

-If no peak, limit ~13 TeV in 300 fb-1

• CMS 5 reach in Mee (full simulation): MC = 6.0 TeV in 80 fb-1

Clerbaux et al, 06 Z(1) can be discriminated from Z’ for up to ~5 TeV with 300fb-1

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Is it a Z’ or RS Graviton?

Handles: • Mass little info about models (unless blessed enough to observe series of KK bumps)• Cross section info about couplings• BR test couplings & universality (G has well-defined ratio between ll//ZZ and Z’ has no coupling )• Angular distribution/asymmetries spin and couplings (even then various Z’ are not easy to tell)

J Aguilar

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4 TeV

6 TeV

ATLAS W(1) SearchesE

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Polesello, Patra EPJ Direct C 32 Sup.2 (04)

TeV-1 searches in lepton+MET

• Feasibility using fast simulation for

• Search for a peak in MT(l)

• Analysis challenges: – MET measurement,

– for muons, the edge washed out.

• In 100 fb-1

– detect a peak, if MC(= R-1)<6 TeV

– fermionic couplings measured,

if MC <~ 5 TeV

• If none observed, – use -ve interference with SM W (e

only)

– a limit of MC < 11.7 TeV

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Those -Blackholes

Webber et al, 2005 BH from LED, possible from RS

as well

• If the impact parameter of a 2-parton collision < Schwarzschild radius Rs, then a black hole with MBH is formed.

)1/(1

1

4

1n

BHBHH M

n

R

nT

Parton

Parton

2

2

c

GMR BHs

MBH = √S

Rs

Formation

Nick Brett

• Arise from models with ED

• Could be produced when ECM > MPl

• Need QT of gravity as MBH approaches MPl

• σ ~ πRS2 ~ 1 TeV-2 ~ 10-38 m2 ~ O(100)pb

• LHC Black Hole Factory, rates as high as 1Hz!

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-Blackhole Detection at ATLAS

“I have never won the national lottery, so go for it!” – anony, on BH threat from LHC!

• Distinguishing features– High Multiplicity, ΣET,

Sphericity, MPT

– Democratic Decay• Theory estimates limit

systematics• Charybdis event generator

6.1 TeV MBH

J. Tanaka , “Search for Black Holes”, 24/05/03 Athens

DecayGiddings,Thomas PRD65(2002)056010

• BH lifetime ~ 10-27 – 10-25 seconds!

• Decays with equal probability to all particles via Hawking Radiation (roughly a blackbody spectrum)

• evaporates into (hadron : lepton)= (5 : 1) accounting for t, W, Z and H decays

Harris, et al.JHEP05 (2005) 053

N=6 gives a larger yield than n=2

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Minimal Universal ED• SM particles propagate in bulk with 1 ED• KK-parity conservation

– Leads to stable LKP as DM candidate– Pair of KK modes, no virtual KK modes Limits are weaker due to small cross sections

600

570

g1

Q1

Z1

L1

1

LEP + TeVatron limits: MC > 300-400 GeV

CMS g1g1/G1Q1/Q1Q1 analysis:• 4 low-pT isolated leptons (2 pairs of OS same flavour) l + m jets (m=4,3,2) + MET (from 2 undetected 1)• Irreducible background:

tt + m jets, 4 b-jets, ZZ, Zbb• Discovery reach: MC ~600 GeV for 1 fb-1

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Thick brane Universal ED• Thick brane solutions: One UED

embedded in (SUSY) LED

• Gravity-matter interactions break PKK

• Pair of KK partons decaying to SM parton+graviton: g1/g1->q/g+G

• Measure excess of dijets with large MET

• Main backgrounds: dijets + Z/W decaying invisibly

MET (GeV)

Signal

BG

200 600 1000 1400

MKK=1.3TeV

Beauchemin, Azuelos

ATL-PHYS-PUB-2005-003

Sensitivity:• if MC = 1.3 TeV, clear probing with 6 pb-1

• 5σ up to 2.7 TeV with 100 fb-1

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Is it SUSY or UED?E

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UED decays are similar to SUSY: how to separate?• Look for 2nd level KK modes (SUSY has none) - might be too heavy to observe• UED KK states are same spin of SM particles (SUSY are not) - use dilepton invariant mass - use asymmetry in lq mass

• use q or qbar, near and far lepton invariant mass• Success of method SUSY point dependent• Expected to work at 100-150 fb-1

SUSY

q 02

~l

~

01

~UED

q near

l

farl1Q1Z

1l

1

~

Matchev

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RS with Custodial Symmetry• Favourite model building in warped space

– Gauge hierarchy problem, unification– Fermion masses (localizations in the bulk)– Dark Matter candidate, “LZP”, CHAMP-like signatures

• Ingredients of model building: – embed into SU(2)LxSU(2)RxU(1) (hep-ph/0612048)

• Additional custodial symmetry in SU(2)LxSU(2)R to protect EW observables (Z→bb)

– Light degenerate KK fermions (“custodians”) with no zero modes bR,L, Q = 2/3, -1/3, 5/3

• Strategy:– KK quarks searches and related

signatures through multi-W events of bR

decays• Uncommon in SUSY searches• Stay as inclusive as possible

– Multi-W events are generally interesting (WW scattering etc..)

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Production & Decay

• Strong interaction pair production dominates

• Simulate tW decay modes of bR, Scale up for total rate

• In 10fb-1 of data 22k tW from q5/3 at 500 GeV

• Count Ws in hadronic decays• Overwhelming background: ttbar

Signature: 4W + 2b-jets

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Conclusions

• ED spectra is much wider now wrt a few years ago.

• If ED exists at the TeV scale, we will be able to observe inclusive signatures.

• CMS and ATLAS reaches for KK resonances are similar.

• With < 60 fb-1 LHC is expected to completely cover the RS1 region of interest.

• Many exclusive studies will be carried out with few fb-1 data…

• Blackholes may be the “smoking gun” from early data as well as resonances.

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Flatland: A Romance of Many DimensionsWith Illustrations

by the Author, A SQUARE[Edwin Abbott Abbott]

Dedication To

The Inhabitants of SPACE IN GENERALAnd H.C. IN PARTICULAR

This Work is DedicatedBy a Humble Native of Flatland

In the Hope thatEven as he was Initiated into the Mysteries

Of THREE DimensionsHaving been previously conversant

With ONLY TWOSo the Citizens of that Celestial Region

May aspire yet higher and higherTo the Secrets of FOUR FIVE OR EVEN SIX Dimensions

Thereby contributingTo the Enlargement of THE IMAGINATION

And the possible DevelopmentOf that most and excellent Gift of MODESTY

Among the Superior RacesOf SOLID HUMANITY

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BACKUP

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Tevatron: Other SignaturesE

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LED Graviton emission search• Monojet + MET • Backgrounds: Z→+jets, W→l+jets, QCD dijet. • Expected 819±71, Observed 779.• LEP still better at low MD and n

RS Graviton resonance search• B(G→ZZ) = 0.05 (x2 B(G→ee))• 4 very isolated electrons in ZZ• consistent with null observation at MG > 500 GeV• not yet sensitive for limits, need more luminosity

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PP Motivations Ilustrated

mewb

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46 m

22 m

the Detectors

• Inner Inner Tracking (||<2.5, 2T solenoid) :• Silicon pixels and strips• Transition Radiation (e/ separation)

• Calorimetry (||<5) :• EM : Pb-LAr, Accordion shape• HAD: Fe/scintillator (centr), Cu/W-LAr (fwd)

• Muon Spectrometer (||<2.7, 4T toroid) : • air-core toroids with muon chambers

• Tracking (||<2.5, 4T solenoid) : • Silicon pixels and strips

• Calorimetry (||<5) :• EM : PbWO4 crystals• HAD: brass/scintillator (centr+ end-cap), Fe/Quartz (fwd)

• Muon Spectrometer (||<2.5) : • return yoke of solenoid with mu chambers

Tracker: /pT 1.5 10-4 pT 0.005EM Cal: /E 3%/E(GeV) 0.5%Hadron Cal: /E 100% / E(GeV) 5%

Mu Spec: /pT 5% at 1 TeV/c (from Tracker)

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S Ferrag

Mc= 6 TeV2,4,6 ED

How well do we know?The apparatus:

• Detector effects need to be understood

• 5 discovery reach for RS gravitons in needs ~50% less data if alignment is optimal!

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The theory:

• For LED, PDF uncertainties claimed to cancel reach above MC=4TeV

• NLO corrections ~1.6

C = 0.01 (coupling constant)

C =0.1First data

Long term

Dimuon Mass

(1-5 fb-1)

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First Physics Run in 2008E

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How many events per experiment at the beginning ?

1 fb-1 6 month at 1032, =50%

10 pb-1 1 month at1030 and < 2 weeks

at 1031, =50%

100 pb-1 few days at 1032 , =50%

similar statisticsto CDF, D0 today

l e or Assumed selection efficiency:W l, Z ll : 20%tt l+X : 1.5% (no b-tag, inside mass bin)

+ lots of min-bias and jets (107 events in 2 weeks of data taking if 20% of trigger bandwidth allocated)

5 fb-1 3 month at 1032 and3 month at 1033, =50%

~ 105 J/Psi + Y ll

• Large statistics of EW sample in a few weeks!

F. Gianotti, Ichep06

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RS ED & Z(n)E

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Gokhan Unel, Athens07

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Experimental Bounds on MD [TeV] at 95% CL

Karina F. Loureiro, C2CR07

AUGER

n xmin=1 xmin=3 xmin=1 DiMuonDiElectron DiPhoton

2 3.2 1.09 1.673 1.27 1.704 > 1.3 - 1.5 > 1.0 - 1.1 3.0* 1.07 1.435 0.97 1.296 2.0 0.90 1.207 > 1.6 - 1.8 > 1.1 - 1.3 0.85 1.14

GRW 1.07 1.43Hewett 0.96/0.93 1.28

CDF (ADD) LEP

n (K=1.3) (Avg.) 1 TeV 3 TeV 5 TeV

2 1.33 1.60 1 ± 1% 3 ± 3.3% 5 ± 40% > 600 - 18003 1.09 1.20 1 ± 1% 3 ± 7.5% 5 ± 48% > 10 - 1004 0.99 0.94 1 ± 1% 3 ± 9.5% 5 ± 54%5 0.92 0.77 1 ± 1% 3 ± 17%6 0.88 0.66 1 ± 1% 3 ± 23%7 1 ± 1% 3 ± 24%

ASTROPHYS.

AGASA D0 (ADD) [HLZ]

Fit Fails

LHC (ADD)

EOT-WASH

1. *For n ≥ 42. GRW: Giudice-Rattazzi-Wells3. HLZ: Han-Lykken-Zhang

DØ Note 4336-Conf - FINAL Version 2/25/04DØ Note 4349-Conf - Version 2.1 FINAL 3/17/04arXiv:hep-ex/0506063 v2 16 Nov 2005

AUGER

n xmin=1 xmin=3 xmin=1 DiMuonDiElectron DiPhoton

2 3.2 1.09 1.673 1.27 1.704 > 1.3 - 1.5 > 1.0 - 1.1 3.0* 1.07 1.435 0.97 1.296 2.0 0.90 1.207 > 1.6 - 1.8 > 1.1 - 1.3 0.85 1.14

GRW 1.07 1.43Hewett 0.96/0.93 1.28

CDF (ADD) LEP

n (K=1.3) (Avg.) 1 TeV 3 TeV 5 TeV

2 1.33 1.60 1 ± 1% 3 ± 3.3% 5 ± 40% > 600 - 18003 1.09 1.20 1 ± 1% 3 ± 7.5% 5 ± 48% > 10 - 1004 0.99 0.94 1 ± 1% 3 ± 9.5% 5 ± 54%5 0.92 0.77 1 ± 1% 3 ± 17%6 0.88 0.66 1 ± 1% 3 ± 23%7 1 ± 1% 3 ± 24%

ASTROPHYS.

AGASA D0 (ADD) [HLZ]

Fit Fails

LHC (ADD)

EOT-WASH

1. *For n ≥ 42. GRW: Giudice-Rattazzi-Wells3. HLZ: Han-Lykken-Zhang

DØ Note 4336-Conf - FINAL Version 2/25/04DØ Note 4349-Conf - Version 2.1 FINAL 3/17/04arXiv:hep-ex/0506063 v2 16 Nov 2005