Search for Extra Dimensions at ATLAS

Ambreesh Gupta

University of Chicago

PASCOS 2003

T.I.F.R, Mumbai, 3-8 January 2003

Spectrum of ATLAS Studies

Large Extra Dimensions KK Graviton Direct Production Missing ET

KK Graviton Virtual Production Drell-Yan

TeV-1 Extra Dimensions KK Gauge Bosons Multi-TeV Resonance

Randall-Sundrum Models KK Graviton TeV Resonance Radion Higgs Like Signature

Other Scenario (E)LED + MSSM RGE and Di-Jet cross section LED + singlet neutrino + 2HDM-II H

Large Extra Dim.: Graviton Direct Production The apparent weakness of gravity could be due

to diffusion of its field in extra dimension. Gravitons will appear as tower of massive

Kaluza Kline states from 4D point of view. G(k) as external leg => Missing Energy in 4D.

ATLAS studies for sensitivity on scale MD and number

of extra dimension .L. Vacavant and I. Hinchliffe, J. Phys. G: Nucl. Part. Phys. 27 (2001) 1839

Large Extra Dim.: Graviton Direct Production

Disentangle and MD

- Run at two different energies

e.g 10 TeV and 14 TeV =>

need 50 fb-1.

Large Extra Dim.: Graviton Virtual Exchange

Signal: Deviation in DY cross section, Asymmetries. ATLAS studies with the photon and lepton pair production.

V. Kabachenko, A. Migakov, A Zenin, ATL-PHYS-2001-012

Large enhancement in

di-lepton cross section.

(similarly in di-photon)

Large Extra Dim.: Graviton Virtual Exchange

TeV-1 Size Extra Dimension & KK Gauge Boson Kaluza-Kline excitation of SM

Gauge possible in presence of

small extra dimension R ~ 1 TeV-1

Indirect constraint from LEP

R > 4 TeV-1. ATLAS studies

- Study the di-lepton resonance from (1)/Z(1)

- Implemented in PYTHIA ( M.E from T. Rizzo)

G. Azuelos and G. Polesello, hep-ph/0204031.

TeV-1 Size Extra Dimension & KK Gauge Boson

Reach: Possible to detect resonance up to 5.8 TeV

In absence of peak a 95% CL of 13.5 TeV can be achieved

TeV Scale Gauge Coupling Unification

KK excitation of Gauge boson affect the evolution of

gauge couplings. LHC studies

- Signal: Modified Di-Jet cross section

C. Balzas, B. Laforge, hep-ph/0110217

Reach: 5 signal measurable for scale 5-10 TeV

Geometric property of space-time is

used to solve the hierarchy problem. Kaluza-Kline excitations could be

observed as well separated narrow resonance. Atlas study on signal sensitivity and spin determination.

Signal: G(k) e+e-, +-, (WW, ZZ, tt)

- Model implemented in HERWIG.

- Studies done for the electron channel (also +-, )

- One year of high luminosity run; 100 fb-1.

Randall-Sundrum Model: Narrow Resonance

B.C Allanach, K. Odagiri, A. Parker and B. Webber, JHEP 9 (2000) 19.

Randall-Sundrum Model: Narrow Resonance

mG = 1.5 TeV

5 sensitivity up to

2.1TeV of graviton

mass.

Spin-1 ruled out with

90 CL up to 1.7 TeV

of graviton mass.

Randall-Sundrum Model: RadionsIn order to stabilize the size of extra dimension

an additional scalar , the Radion, is proposed.

The Radion has couplings similar to SM Higgs, and

mixes with it. ATLAS studies for various Radion decay modes.

Goldberger and Wise, PRL 83 (1999) 4922.

G. Azuelos, D. Cavalli, H. Przysiezniak, L. Vacavant, hep-ph/0204031.

Randall-Sundrum Model: Radions , ZZ 4l

- SM Higgs study re- interpreted

for 100 fb-1 data.

hh bb

- Study similar to MSSM. Negligible background.

hh - High Backgrounds.

Reach: 4.6, 5.7 TeV for m = 300, 600 GeV.

Reach: 1.1 TeV with m = 600 GeV

Summary

LHC will be able to probe a number of Models. Studies

done on

- Large Extra Dimension.

- Warped Extra Dimensions.

- TeV-1 Size Extra Dimension. Studies in progress for – blackholes and trans planckian

scattering, universal extra dimension,…