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Flat large extra dimensions: implications for
Dark matter direct detection
Bo Qin (秦波 )
National Astronomical Observatories, CAS
(中国科学院国家天文台)
with Glenn Starkman (CWRU) & Joe Silk (Oxford)
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Gravity
Newtonian
New gravity
R
Four interactions in Nature
Strong interaction 1 Electromagnetic 10-2
Weak interaction 10-15
Gravity 10-39
Could gravity play a dominant role between elementary particles?(1) extra dimensions (2) dark matter particles? (strong, EM forces absent)
Extra dimensions
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The question
Theory
Large extra dimensions (ADD)
Enhance
DM—baryon interaction
Experiments
WIMP DM direct detections
Put limit on
DM—baryon cross section
compare
test
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Searches for Dark Matter
Direct Detection Indirect DetectionColliders: LHC
Fuzzy CDM 10-22 eV • Axions (CDM) 10-6 eV WDM keV MeV CDM MeV• WIMPs (SUSY, neutralino) 10-1000 GeV
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Dark matter detection
2a DM
V
S dVIndirect Direct
nuclear recoils
nrS Nearest MH ~0.1pc5x brighter than Draco
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Gravity —experimental
Gravity has only been accurately measured at
~1cm Solar system (Pluto)
But was extrapolated 33 orders of mag. down to ~10-33cm
12 orders o.m., up to 1000 Mpc
Gravity in large scales (cosmological) & weak regimes:
Modified Newtonian Dynamics (MOND) Milgrom 1983 ApJ, Sanders 2002, ARA&A, Bekenstein 2004 PRD
a = GM/r2 , (a>a0) a0 ~10-8 cm s-2
a = (GMa0)1/2 /r , (a<a0)
Pioneer Anomaly:
Anderson et al 1998 PRL, Turyshev 2005 Am.J.Phys.
Negative energy? Henry-Couannier et al
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Bullet cluster—End of MOND?
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Pioneer Anomaly —A Mystery?
20-70 AU
ap ~8*10-8 cm s-2
constant, toward the Sun
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Experimental tests of Newton’s law of gravity at sub-mm scales
& Searches for extra dimensions
Long et al., Nature (2003)
Hoyle et al., PRL (2001); PRD (2004)
Chiaverini et al. PRL (2003)
(& e.g. hep-ph/0402168 for a review)
• No deviation from Newtonian has been found
from ~1cm down to ~20μm
Gravity—Experimental (small distance scales):
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Extra Dimensions: Klein, Kaluza, 1920’
• String theory
Gravitational behavior at small distance scales, r<R• Size of extra dimensions: Planck scale ~10-33 cm
• Large Extra Dimensions: 3 + n + m = 9
Arkani-Hamed, Dimopoulos & Dvali (ADD) 1998, Phys. Lett. B
Gravity: F ~ r-(2+n) at r<R,
R~10(30/n)-17 cm (for n=2, R~1mm)
Randall & Sundrum (1999)
Opens New Window: Experimental test of string theory + Searches for extra dimensions, by precise measurement of gravity at sub-mm scales
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ADD Scenario
Size of large extra dimensions:
R~10(30/n)-17 cm (TeV /MD)1+2/n
n=2, R=10-2 cm (TeV /MD)2
n=3, R=10-7 cm (TeV /MD)5/3
n=4, R=10-9.5 cm (TeV /MD)3/2
n=5, R=10-11 cm (TeV /MD)7/5
n=6, R=10-12 cm (TeV /MD)4/3
New Fundamental scale: MD-1
~ 10-17 cm, (MD=TeV)
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1/r2+n—law “New” Gravity
in (ADD) large extra dimensions
R: size of large extra dimension
Newtonian
New gravity
R
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Gravitational scattering cross section —Classical
1
2
2
nx
n
v
mGRA
A=[(n+1)/(n-1)] (n-1)/(n+1) ~1
4
22
v
mG Newtonian:
1/r2+n—law “New” Gravity :
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Gravitational scattering cross section —Quantum
1
2
2
nx
n
v
mGRA
A=[(n+1)/(n-1)] (n-1)/(n+1) ~1
de Broglie wavelength > R or b Q.M. treatment
Q.M. cross section = 2 Classical cross section (for bosons) = 1/2 Classical cross section (for fermions)
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Conclusions
• Large extra dimensions (LED) greatly enhance gravity in small distance scales
• LED could greatly increase the cross section between DM and baryons
• Current DM detection experiments give stringent constraints on flat LED (ADD)
• ADD in apparent contradiction with DM direct detection limits
• Either ADD scenario incorrect • or DM mass not in 10GeV-10TeV range• MeV CDM, or WDM (~keV) ?