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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 Sreerup Raychaudhuri, TIFR Graviton-induced processes : SM 1 1 4 int 8 KK MS MS Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR MS (TeV) Constraining the string scale : Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR 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 ~ 10300 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 Sreerup Raychaudhuri, TIFR KRC e Warp factor controls the entire RS phenomenology: M n xn KeKRC ~ 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 Sreerup Raychaudhuri, TIFR Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR ATLAS dilepton CDF inaccessible 5X inaccessible CMS dielectron Extra Dimensions and Collider Physics Sreerup Raychaudhuri, TIFR 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 Sreerup Raychaudhuri, TIFR 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
