1. Christopher M. Savage University of Michigan – Ann Arbor
Can WIMP Spin Dependent Couplings explain DAMA? Limits from DAMA and Other Experiments
Christopher M. Savage
University of Michigan – Ann Arbor
Katie Freese (University of Michigan)
Paolo Gondolo (University of Utah)
astro-ph/
11/29/2018
IDM Spin Dependent Limits

2. IDM 2004 - Spin Dependent Limits
Overview
DAMA/NaI positive signal and CDMS II null result are not compatible for spin-independent couplings (assuming the standard halo model)
WIMPs may alternatively have spin-dependent couplings; examine if this case has parameter space consistent with the DAMA signal and the null results of other experiments
P. Ullio, M. Kamionkowski, and P. Vogel, JHEP 0107, 044 (2001).
F. Giuliani, arXiv:hep-ph/
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IDM Spin Dependent Limits

3. IDM 2004 - Spin Dependent Limits
Direct Detection
Detector
WIMP
Scatter
Elastic scattering of WIMP off detector nuclei
Rate:
Recoils:
Efficiencies, quenching, multiple elements
CDMS, CRESST, Edelweiss, SIMPLE, ZEPLIN, etc.
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IDM Spin Dependent Limits

4. IDM 2004 - Spin Dependent Limits
Annual Modulation
30 km/s
232 km/s
WIMP Halo Wind
Earth’s motion
With disk (June) Against disk (December)
Modulation Amplitude:
DAMA
Nma = ± /kg/day/keVee (2-6 keVee)
Elegant V, etc.
(R. Bernabei et al., 2003)
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IDM Spin Dependent Limits

5. IDM 2004 - Spin Dependent Limits
Indirect Detection n
WIMP
Gravitational capture  Annihilation
Neutrino-induced muons
Sun: WIMP-proton cross-section
BAKSAN, Super-K, etc.
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IDM Spin Dependent Limits

6. Spin-Dependent Cross-Section
Nuclear structure functions
Odd proton: Spp >> Snn
Odd neutron: Snn >> Spp
Finite momentum transfer
q = 0  SD  (ap + an)2  (<Sp> ap + <Sn> an)2
q  0: larger masses
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IDM Spin Dependent Limits

7. Spin-Dependent Limits
Null Result:
Positive Signal:
A, B, C
Depend on detector parameters, WIMP mass
Relative magnitude dependent upon Spp, Spn, Snn
Conics
Parallel lines
Ellipse
Multiple Elements
EOGM
OGM
q  0
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IDM Spin Dependent Limits

8. Spin-Dependent Limits
Proton only coupling (an = 0)
Neutron only coupling (ap = 0)
General couplings
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IDM Spin Dependent Limits

9. WIMP-Proton Cross-Section Limits (for an = 0)
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IDM Spin Dependent Limits

10. WIMP-Neutron Cross-Section Limits (for ap = 0)
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IDM Spin Dependent Limits

11. IDM 2004 - Spin Dependent Limits
Allowed Couplings
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IDM Spin Dependent Limits

12. Allowed Couplings (Low Mass)
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IDM Spin Dependent Limits

13. IDM 2004 - Spin Dependent Limits
Results
WIMP masses of 5-13 GeV:
Parameter spaces still remain which are compatible with DAMA signal and all null results
Allows for comparable proton and neutron couplings
(e.g. ap = an = 2.0 at 10 GeV)
All solutions have
No MSSM candidates
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IDM Spin Dependent Limits

14. IDM 2004 - Spin Dependent Limits
Conclusions
DAMA can still be explained by a WIMP with spin-dependent couplings, although at masses lower too low for MSSM.
Extending analysis of Super-K (BAKSAN) results to lower masses could confirm or rule out the remaining spin-dependent parameter space for DAMA (for standard halo). Odd-Z experiments (CRESST I, SIMPLE) will also be able to examine this remaining space.
11/29/2018
IDM Spin Dependent Limits