Extra Dimensions Primer (see S. Hossenfelder) LED in many dimensions JLH, Lillie, Rizzo...
-
date post
21-Dec-2015 -
Category
Documents
-
view
215 -
download
0
Transcript of Extra Dimensions Primer (see S. Hossenfelder) LED in many dimensions JLH, Lillie, Rizzo...
Extra Dimensions
• Primer (see S. Hossenfelder)
• LED in many dimensions JLH, Lillie, Rizzo
hep-ph/0503178
SUSY05 Durham J. Hewett
Models with Large Extra DimensionsArkani-Hamed, Dimopoulos, Dvali 1998
•Gravity in the bulk D = 4 + n•SM confined to brane•Fundamental scale of gravity in bulk = M*
Gauss’ Law:
M* ~ TeV ‘solves’ hierarchy !
Rc ~ 0.1 mm to 1 fm for n = 2 - 6Graviton KK states finely spacedmKK
2 = n2/Rc2
m1 ~ eV to MeV for n = 2 - 6
Collider Signatures
•Graviton KK Emission•Graviton KK Exchange•Black Hole Production
Current Experimental Constraints
• MD ~ 1 TeV from Graviton exchange and emission at LEP II and Tevatron: Updates this afternoon!
• Tabletop:
Rc < 130 microns for = 2, orMD > 1.7 TeV
Hoyle etal hep-ph/0405262
Astrophysics Constraints: Reexamined
• Supernova CoolingNN NN + Gn can cool supernova too rapidly
• Cosmic Disfuse Gamma-raysGn (Expect Big improvements from GLAST!)
• Neutron Star Heat ExcessNN NN + Gn becomes trapped in neutron star halo
Hannestad and Raffelt (See also Casse etal)
TeV-1 Extra Dimensions
The Standard Model goes into the bulk!Many model building choices:
– Gauge fields in the bulk– Higgs in bulk or brane– Fermions: located at orbifold fixed points localized at specific points: Split Fermions propagate freely through bulk: Universal ED
Phenomenology greatly depends on fermionlocations!
Experimental Constraints on TeV-1 ED
• Fermions at orbifold fixed points– Precision EW with KK gauge exchange: Mc > 4 TeV
– LEP II indirect KK gauge exchange: Mc > 3 TeV
• Split Fermions– Precision EW with KK gauge exchange: Mc > 2-3 TeV
– Tree-level FCNC with KK gauge exchange: Generally Mc > 100’s TeV, but can arrange for Mc > few
TeV
• Universal ED (KK parity is conserved)– Precision EW from loop contributions: Mc > 300 GeV
– Pair production of KK states: Mc > few 100 GeV
(Updates this afternoon?)Huge number of contributing authors!
Randall-Sundrum model of Localized Gravity
Graviton KK states:
mn = xn k/MPl; J1(xn) =0
TeV-scale masses withTeV-1 couplings to SM
Bulk is slice of AdS5
ds2 = e-2ky dxdx -dy2
= e-kr MPl (
= TeV-scale
Experimental Constraints on RS Gravitons
• Graviton resonances in Drell-Yan and diphoton– Updates this afternoon!
• Indirect Graviton searches
LEP II
Tevatron
LED: Is the hierarchy problem really solved?
M*Rc > 108 for n = 2-6Disparate values for gravity and EWK scales traded for disparate values of M* and Rc
However,1 < M*Rc < 10 forn = 17 - 40
Large n offers true solution to hierarchy!
Collider Signatures Change
Graviton KK states are now ‘invisible’•m1 ~ TeV•Couplings are still MPl
-1
Collider searches are highly degraded!
For n = 2, M* up to 10 TeVobservable at ILC, LHC
Drops to < 1 TeV for n = 20
Only viable collider signature is Black Hole production!
Black Hole Production @ LHC:
Black Holes produced when s > M*
Classical Approximation: [space curvature << E]
E/2
E/2b
b < Rs(E) BH forms
MBH ~ s^
Geometric Considerations:
Naïve = Rs2(E), details show this holds up to a factor
of a few
Dimopoulos, LandsbergGiddings, Thomas
Potential Corrections to Classical Approx:
1. Distortions from finite Rc as Rs Rc
2. Quantum Gravity EffectsHigher curvature term corrections
Critical point forinstabilities for n=5:(Rs/Rc)2 ~ 0.1 @ LHC
Gauss-Bonnet term
RS2/(2Rc)2
n = 15 - 40
n = 2 - 20
n2 ≤ 1 in string models
Potential Corrections to Classical Approx:
1. Distortions from finite Rc as Rs Rc
2. Quantum Gravity EffectsHigher curvature term corrections
Critical point forinstabilities for n=5:(Rs/Rc)2 ~ 0.1 (@ LHC)
RS2/(2Rc)2
n = 15 - 40
n = 2 - 20
n2 ≤ 1 in string models
Note: This defines M*
Decay Properties of Black Holes (after Balding):Decay proceeds by thermal emission of Hawking
radiation
At fixed MBH, higher dimensional BH’s are hotter:
N ~ 1/T
higher dimensional BH’s emit fewer quanta, with each quanta having higher energy
Harris etal hep-ph/0411022
Multiplicity for n = 2 to n = 6
n determined to n = 0.75 @ 68% CL for n=2-6 from TH and This procedure doesn’t work for large n
pT distributions of Black Hole decays
Provide good discriminating power for value of n
Generated using modified CHARYBDIS linked to PYTHIA with M* = 1 TeV
Determination of Number of Large Extra Dims Perform 2 fit assuming M* = 1 TeV and n = 21 Generated 300k events (~ 10 fb-1)
•Used pT missing distb’n only•Discrimination improves when jet pT included as well•n < 6(7) excluded at 5 for n > 13
Excellent resolution power for large values of n!
Motivations for determining value of n:
• It’s a property of Extra Dims that we will want to know; provides a handle on the physics of Quantum Gravity• Distinguishes BH’s from large flat extra dims from
those in Randall-Sundrum warped models (n = 1)• Provides null test of Critical String Theory!!!
If string theory is correct, large extra dims will be embedded in it and Ms ~ TeV
String resonances may be produced at LHC (if weak heterotic strings), but do not provide determination of n
CST requires n = 6(7) for anomaly cancellationDetermination of n > 6(7) from Black Hole production would
exclude CST as a string theory candidate!
Black Holes provide collider information on string theory