Flat large extra dimensions: implications for Dark matter direct detection Bo Qin ( 秦波 )...
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Transcript of Flat large extra dimensions: implications for Dark matter direct detection Bo Qin ( 秦波 )...
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)
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
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
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
Dark matter detection
2a DM
V
S dVIndirect Direct
nuclear recoils
nrS Nearest MH ~0.1pc5x brighter than Draco
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
Bullet cluster—End of MOND?
Pioneer Anomaly —A Mystery?
20-70 AU
ap ~8*10-8 cm s-2
constant, toward the Sun
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):
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
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)
1/r2+n—law “New” Gravity
in (ADD) large extra dimensions
R: size of large extra dimension
Newtonian
New gravity
R
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 :
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)
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) ?