Transcript ppt - Tata Institute of Fundamental Research

Extra Dimensions and Collider Physics
Sreerup Raychaudhuri
TIFR
Workshop on Synergy between High Energy and High Luminosity Frontiers
Tata Institute of Fundamental Research, Mumbai
January 10, 2011
Extra Compact Dimensions
Ancient Age
1914-1975
Mediæval Age
1970-1998
Modern Age
1998-
Attempts to unify
gravitation with
electromagnetism :
Kaluza-Klein theory
Relativistic string
theory requires
D = 26 or D = 10
Large extra dimensions
proposed to solve
hierarchy problem
Compact dimensions
lead to Yang-Mills
theories
Compactification on
Calabi-Yau manifolds
or orbifolds led to
gauge theory
Warped extra
dimensions as a more
natural solution: use of
AdS-CFT ideas
Largely abandoned
In 1950’s and 1960’s
Discovery of D-branes
and AdS-CFT
Universal extra
dimensions : ‘bosonic’
supersymmetry
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Compact Dimensions
RC
x ~ RC
two-dimensional
x  RC
one-dimensional
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Large Extra Dimensions
Antoniadis, Arkani-Hamed, Dimopoulos, Dvail 1998
 
M ( 4)  S (1)
n
bulk
SM fields are confined to the brane
Only graviton can access the bulk
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
n
Mn 
RC
Kaluza-Klein
tower of
states
Extra Dimensions and Collider Physics
RC  0
Sreerup Raychaudhuri, TIFR
Each graviton KK mode couples very weakly with SM
matter, but collective effect of many modes builds up to
electroweak strength
real
   G
G
Extra Dimensions and Collider Physics
virtual
~
M
2
G
G
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Graviton-induced processes :
   SM
1
1
 4  int  8  KK
MS
MS
Extra Dimensions and Collider Physics
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MS (TeV)
Constraining the string scale :
Extra Dimensions and Collider Physics
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Laboratory Black Holes
b
If impact parameter b < RS Schwarzschild radius for M = 2 mp ,
a micro-black hole is formed
Cross section (semiclassical) :
   RS2 ~ 10pb
Einstein gravity gives 10-28 pb
At least 105 micro black holes at the 14-TeV LHC with 10 fb-1
Decay by Hawking radiation with lifetime ~ 10-25 s
Spectacular spherically-distributed signals
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Probability of accretion:


exp 109 ~ 10300
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Warped Extra Dimension
Randall, Sundrum 1999
M ( 4)  S (1) / Z 2
AdS5 ‘throat’
Metric contracts exponentially along AdS5
‘throat’  Gravitons acquire TeV masses
ds  e
2
Extra Dimensions and Collider Physics
2 KRC
 dx dx  RC2 d 2
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 KRC
e
Warp factor
controls the entire RS phenomenology:
M n  xn KeKRC ~ xn  (100 GeV)
Kaluza-Klein tower of states
Each graviton couples as:
K
c
~ 0.01 to 0.1
MP
Graviton KK modes behave like WIMPs…
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Decay modes of RS gravitons
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Sum over propagators

D(s)  
 e kR 
C
n 0 s  M  iM n  n
2
n

 ( xs )
m04
s
xs 
m0
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Graviton resonances in Drell-Yan dileptons
Extra Dimensions and Collider Physics
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Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Extra Dimensions and Collider Physics
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ATLAS dilepton
CDF
inaccessible
5X
inaccessible
CMS dielectron
Extra Dimensions and Collider Physics
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Allanach et al (2000)
Resonant
production
of G1
ATLAS
Final state :
dielectrons
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
RS Variants
Warp factor: e  KRC
Must choose KRC = 11.7
Dynamic generation of hierarchy : Goldberger-Wise
Replace KRC = T(x) ; potential in T(x) is flat
Introduce a bulk scalar with 𝛷4 couplings
V (ky)
11.7
Extra Dimensions and Collider Physics
k T
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Residue is a light scalar – the radion
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
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 RS
Strongest signal will be from the g1 decaying to t t
Tevatron
M g1   800 GeV
FCNC
M g1   2  3 T eV
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Universal Extra Dimension
Appelquist, Cheng, Dobrescu 2001
; metric is flat
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Collider bound:
R-1 > 728 GeV
Dark Matter constraint:
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Bounds from non-discovery are easy, but ….
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
many other possibilities…
Extra Dimensions and Collider Physics
Sreerup Raychaudhuri, TIFR
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!
Extra Dimensions and Collider Physics
Thank You
Sreerup Raychaudhuri, TIFR