search for extra-dimensions at pp and ep colliders

ICHEP ’04, Beijing, August 20, 2004

Eric Kajfasz, CPPM/D0 1

Search for Search for Extra-DimensionsExtra-Dimensions

at pp and ep Collidersat pp and ep Colliders

Eric Kajfasz, CPPM/[email protected]

for the CDF, D0, H1 and Zeus collaborations

__



Extra Dimensions: OutlineExtra Dimensions: Outline

• Extra Dimension Models and Signatures studied at CDF & D0 Run II, H1 and ZEUS

• Preliminary results on virtual graviton/gauge boson exchange and direct graviton emission

• Summary and Conclusions

• Why ED?o come “naturally” with string theoryo provide mechanism to explain why MEW <<

MPL

o ...



Extra Dimensions: Models Extra Dimensions: Models ExploredExplored

focus on n extra dims in models where SM fermions live on a D3-brane:• Large Extra Dimensions (LED) Arkani-Hamed,Dimopoulos,Dvali Phys Lett B429 (98)

o MPL ~ 1019GeVo n >= 2 compact and flat - MS : string/fundamental scale

M2PL ~ Rn MS

n+2 => MS can be lowered to TeV scaleo gravitons propagate in the bulk => Kaluza-Klein tower G(k)

o can’t resolve successive modes (0.01eV:n=2; 1MeV:n=3; 100MeV:n=6)=> expect:

• virtual exchange of graviton KK modes• real graviton emission

• TeV-1 Extra Dimension (TeV-1) Dienes,Dudas,Gherghetta Nucl Phys B537 (99)

o MC : compactification scale (~ TeV)o gauge fields can propagate in the bulk => KK towers of gauge bosonso modes with nearly equal energy spacing ~TeVo lower GUT scale by changing running of the couplings=> expect:

• resonances at high energies (LHC ...)• virtual exchange (Hera, Tevatron)



• Warped Extra Dimension (RS) Randull,Sundrum Phys Rev Lett 83 (99)

o ED of size R, highly curved, compactified on S1/Z2 orbifold: y = R.

o Zero mode graviton G(0) localized at the Planck-brane (y = 0) o SM fields localized on TeV-brane (y = R)o metric: ds2 = e-2kR dxdx – R2d2

k: curvature scalefor kR ~ 11-12, = MPLe-kR~ TeV

o consistency => 0.01 < k/MPL 0.1

o Gravitons propagate in the bulk => KK tower G(n) of modes of mass mn = xnke-kR (xn: 1st Bessel func. zeros i.e. 3.83, 7.02, 10.17, ...)=> well separated modes

= m1MPL/(kx1) => model characterized by m1 and k/MPL

o => Look for first graviton resonance

Extra Dimensions: Models Extra Dimensions: Models Explored ...Explored ...

yy=0 y=R



Extra Dimensions: Topologies Extra Dimensions: Topologies ExploredExplored

KK

q

q_

ee, ,

G

q

q_ g(jet),

jet(s) + MET+ MET

ExchangeVirtual Gravitons(LED,TeV-1,RS)

Emission ofReal Gravitons

(LED)

KKee

jetp

Tevatron

Tevatron

Hera



Large Extra DimensionsLarge Extra DimensionsVirtual Graviton ExchangeVirtual Graviton Exchange

G(n) G(n)

_/Z f

f

G(n) f

f

G(n) f

f

_ _

dilepton channel(Tevatron)

diphoton channel(Tevatron)

DIS channel(Hera)

G(n)

SM

SM

SM



Large Extra DimensionsLarge Extra DimensionsVirtual Graviton ExchangeVirtual Graviton Exchange

• Effect of ED parameterized by a single variable:

• different formalisms have different definitions of MS:o Hewett: (Hewett, Phys Rev Lett 82, 4765 (99) )

F = 2/ with = ± 1

o GRW: (Giudice, Rattazzi, Wells, hep-ph/9811291)

F = 1

o HLZ: (Han, Lykken, Zhang, hep-ph/9811350)

F = log(MS2/s) for n = 2

F = 2/(n-2) for n > 2

G= F/ MS4

= SM + Gint + G2KK



Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange

• 2 isolated e’s, ET> 25 GeV

• e’s coming from luminous region• MET significance cut• CC = 92.4 ± 0.4% CP = 79.2 ± 0.5%

• for Mee > 350 GeV: Nexp = 4.6, Nobs = 8

• Mee distrib. used in binned likelihood => Limits on G=/MS

4

CC+CP

C(entral): ||<1 P(lug) : 1<||<3

Mee

95% CL limits on MS (TeV)

eeee




• diEM = combine ee and o 2 EM objects, ET > 25 GeV

with track isolationo overall ID efficiency: 85 ± 1 %

• for MdiEM > 350 GeV:Nexp = 9.7 (1.6 QCD), Nobs = 8

• Systematics: ~ 12%

CC-CC + CC-EC

CC: ||<1.1 EC: 1.5<||<2.4

signal for G = 0.6

200pb-1

diEMdiEM

QCD D-Y+direct +QCDCC-CC + CC-EC




Run II

Run I+II

• Data agree with SM predictions =>

• MdiEM vs|cos*| distrib. used

in 2D Binned Likelihood

• =>Set limits on G alone orin combination with Run I results

• => give 95% CL limits on MS (TeV)

• Most stringent constraints on LED for n > 2 to date among all experiments.

200pb-1

diEMdiEM




250pb-1

• 2 ’s with PT > 15 GeVo isolated, ||<2.0o cosmic vetoo M > 50 GeV

• for M > 300 GeV:Nexp = 6.4 and Nobs = 5

• Systematics: ~ 13%D0 RunII Preliminary

Mvs|cos*| distr. used

in 2D Binned Likelihood=> Set limits on G

=> 95% CL limits on MS (TeV)



Large Extra Dimensions:HERALarge Extra Dimensions:HERA Virtual Graviton Exchange Virtual Graviton Exchange

G(k) Virtual exchange in t-channel interferes with Deep Inelastic Scattering (DIS)

Small contribution ~ O(1%) from eg -> eg G(k) exchange affects the Q2 distribution at high Q2

Compare d/dQ2 to what is expected from SM

Q2 = (k-k’)2 = -q2

,KK




Hewett formalis

m

DISDIS

H1 s1/2(GeV) Lint(pb-1)

e+

p301 36

e+

p319 65

e- p 319 162 fit of d/dQ2

no deviation from SM=> Set limits on G




Large Extra Dimensions: Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange

Hewett formalism:

= - 1 : MS > 0.79 TeV = + 1 : MS > 0.78 TeV

DISDIS

Zeus s1/2(GeV) Lint(pb-1)

e+ p 301/319 112

e- p 319 16

d/dQ2 used in binned

likelihood=> Set limits on G




Large Extra Dimensions:Large Extra Dimensions:Direct Graviton EmissionDirect Graviton Emission

• Graviton produced along with a jet disappears in the bulk, undetected => mono-jet like topology with high MET

n = 6 and MS = 0.7 TeV

• Final Selection:o MET > 150 GeVo PT(jet1) > 150 GeV, || < 1o PT(jet2) < 50 GeV(MET,jet1) > 30o

• Nexp = 100.2 ± 6.3 (stat) ± 7.5 (theo) + 50 - 30 (JES)• Nobs = 63 (~ 5% efficiency)

QCD

MC SM bkg: mostlyZ->+jet(s)

85pb-1

MS

n

(K = 1)

updated analysis with 200pb-1

and new JES in process ...

limits on MS

~ 660-680 GeV

jet(s)+METjet(s)+MET



TeVTeV-1-1 Extra Dimension: Extra Dimension:Virtual Exchange of Z/Virtual Exchange of Z/ KK states KK states

• (> 1 EM w/ track match)

• same procedure as for LED analysis but with virtual Z/ KK states effects parameterized by:

C = 2/3MC2

• Nexp = 12.1 (4.3 QCD), Nobs = 9

• => Limit set as done for LED: C < 2.63 TeV-2 =>

MC > 1.12 TeV @ 95% CL

KK states modify the Z/ propagators:1/Q2 -> 1/Q2 + C

1/(Q2+MZ2) -> 1/(Q2+MZ

2) + C

Fit to e+p and e-p data =>

MC > 1.0 TeV @ 95% CL

D0: D0: eeee

H1: DISH1: DIS

200pb-1

signal for C = 5 TeV-2

from combined precision EW measurements: MC > 6.6 TeV

LEPLEP

QCD D-Y+ QCD



RS Extra DimensionRS Extra Dimension

• Graviton KK states well separated => resonant graviton search:

• CDF analyses:o ee and : binned likelihood methodo counting limits using 3 mass window around resonance

• D0 analysis:o diEM: using 3 mass window method




ee

data agree with expected SM bkg ...

ee, ee, , ,

ee:• 2 isolated e’s w/ ET>25GeV• CC or CP

:• 2 isolated ’s w/ PT>20GeV• |1| <1, |2|<1.5• cosmic veto

:• 2 isolated ’s w/ ET>15GeV• CC




ee

ee, ee, , ,

• cross-section limits computed from binned likelihood (ee,) and 3- mass window ()• compare to R-S cross-section for different values of the k/MPL parameter.

=> exclusion contour plot ...




Lower limits on MG (GeV) for k/MPL = 0.1

ee

620 605 690

ee, ee, , ,

Further improvement can be achieved by:• using mass window method for dilepton channels• combining channels




signal RS Graviton MG = 300 GeV

same diEM data set as for LED search

data agree with expected SM background => set limits with mass window method

diEMdiEM

200pb-1

785 GeV

QCDD-Y+direct + QCD

CC-CC + CC-EC



SummarySummary

LED = -1MS(TeV) >

= +1MS(TeV) >

CDF 0.99 0.96

D0diEM

1.10 1.22

D0/I+IIdiEM

1.16 1.28

D0

0.95 0.97

H1 0.78 0.82

ZEUS 0.79 0.78

RS MG(GeV) >@k/MPL=0.1

CDF

605

CDFee

620

CDF

690

D0ee

660

D0diEM

785

TeV-1 MC(TeV) >

D0 1.12

H1 1.0

LEP 6.6

n

MS

(K = 1)



ConclusionsConclusions

• Tevatron, CDF&D0 working well• CDF&D0 have by now each ~ 450pb-1 on tape• Tevatron and HERA are great tools to start looking for

ED’s• Very competitive results and even most stringent limits

are starting to come out• There is still room for improvement, so stay tuned. • However, for the final word on some models, we may

very well need to wait for LHC ...

search for extra-dimensions at pp and ep colliders

Documents

hlarge extra dimensions

mew extra dimensions

extra dimension tev

n extra dims

virtual graviton exchangediem

virtual graviton exchangedata

tevatronextra dimensions

extra dimension rs randull