sreerup raychaudhuri tifr extra dimensions and collider physics workshop on synergy between high...

Sreerup Raychaudhuri

TIFR

Extra Dimensions and Collider Physics

Workshop on Synergy between High Energy and High Luminosity FrontiersTata Institute of Fundamental Research, Mumbai

January 10, 2011

Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR

Extra Compact Dimensions

Ancient Age1914-1975

Mediæval Age

1970-1998

Modern Age1998-

Attempts to unify gravitation with electromagnetism :Kaluza-Klein theory

Compact dimensions lead to Yang-Mills theories

Largely abandoned In 1950’s and 1960’s

Relativistic string theory requires D = 26 or D = 10

Compactification on Calabi-Yau manifolds or orbifolds led to gauge theory

Discovery of D-branes and AdS-CFT

Large extra dimensionsproposed to solve hierarchy problem

Warped extra dimensions as a more natural solution: use of AdS-CFT ideas

Universal extra dimensions : ‘bosonic’ supersymmetry


Compact Dimensions

RC

CRx ~

CRx

two-dimensional

one-dimensional


Large Extra Dimensions

Antoniadis, Arkani-Hamed, Dimopoulos, Dvail 1998

SM fields are confined to the braneOnly graviton can access the bulk

brane

bulk

nSM )1()4(


Cn R

nM

Kaluza-Klein tower of

states

0CR


Each graviton KK mode couples very weakly with SM matter, but collective effect of many modes builds up to electroweak strength

G

G2

~ G

GM

real virtual


Graviton-induced processes :

KKSS

SM MM

8int4

11

DØ


MS (

TeV)

Constraining the string scale :


Laboratory Black Holes

b

If impact parameter b < RS Schwarzschild radius for M = 2 mp ,a micro-black hole is formed

Decay by Hawking radiation with lifetime ~ 10-25 s

Spectacular spherically-distributed signals

Cross section (semiclassical) : pb10~2SR

At least 105 micro black holes at the 14-TeV LHC with 10 fb-1

Einstein gravity gives 10-28 pb


Probability of accretion:

3009 10~10exp


Warped Extra Dimension

Randall, Sundrum 1999

Planck brane

TeV brane

AdS5 ‘throat’

Metric contracts exponentially along AdS5

‘throat’ Gravitons acquire TeV masses2222

dRdxdxeds CKRC

2)1()4( / ZSM


CKRe Warp factor controls the entire RS phenomenology:

)GeV100(~ n

KRnn xKexM C

Kaluza-Klein tower of states

Each graviton couples as:

0.1 to0.01~PM

Kc

Graviton KK modes behave like WIMPs…


Decay modes of RS gravitons


2 40 0

( )( )

CkRs

n n n n

xeD s

s M iM m

0s

sx

m

Sum over propagators


Graviton resonances in Drell-Yan dileptons


ATLAS dilepton

CMS dielectron

inaccessible

inaccessible5

X

CDF


ATLAS

Allanach et al (2000)

Resonant production of G1

Final state : dielectrons


RS Variants

CKRe Warp factor: Must choose KRC = 11.7Dynamic generation of hierarchy : Goldberger-WiseReplace KRC = T(x) ; potential in T(x) is flat

Introduce a bulk scalar with 𝛷4 couplings

k T

( )V ky

11.7


Residue is a light scalar – the radion

Invoke AdS-CFT correspondence: bulk RS model is equivalent to a composite SM on the TeV brane

Keep only Higgs fields localised to TeV brane and let all other SM fields go into the bulk

Each will have KK modes, just as the graviton has in RSStrongest signal will be from the g1 decaying to t t

TeV32g1 M

FCNC

Tevatron GeV800g1 M


Universal Extra Dimension

Appelquist, Cheng, Dobrescu 2001

; metric is flat


Collider bound: R-1 > 728 GeVDark Matter constraint:


Bounds from non-discovery are easy, but ….


many other possibilities…


SUMMARY

• If SUSY is the Standard BSM theory, Extra Dimensions have become the Standard non-SUSY theory

• Three main paradigms: ADD, RS, UED

• Each has interesting collider phenomenology

• LHC has the potential to discover all of the models…unless they decouple

• Next few years may be exciting!

Thank You

sreerup raychaudhuri tifr extra dimensions and collider physics workshop on synergy between high...

Documents

graviton kk modes

sm fields

warped extra dimensionrandall

braneonly graviton

sm matter

bulk rs model

entire rs phenomenology

composite sm