12/9/04KICP - Spin Dependent Limits 1 Can WIMP Spin Dependent Couplings explain DAMA? Limits from...
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Transcript of 12/9/04KICP - Spin Dependent Limits 1 Can WIMP Spin Dependent Couplings explain DAMA? Limits from...
12/9/04 KICP - Spin Dependent Limits 1
Can WIMP Spin Dependent Can WIMP Spin Dependent Couplings explain DAMA?Couplings explain DAMA?
Limits from DAMA and Other ExperimentsLimits from DAMA and Other Experiments
Christopher M. SavageUniversity of Michigan – Ann Arbor
Katie Freese (University of Michigan)
Paolo Gondolo (University of Utah)
astro-ph/0408346
to appear in Phys. Rev. D
12/9/04 KICP - Spin Dependent Limits 2
Overview
DAMA/NaI positive signal and CDMS II null result are not compatible for spin-independent couplings (assuming the standard halo model)
With exceptions – Gelmini & Gondolo (2004)
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/0404010.
12/9/04 KICP - Spin Dependent Limits 3
Direct Detection
Elastic scattering of WIMP off detector nuclei
Rate:
Recoils:
Efficiencies, quenching, multiple elements
CDMS, CRESST, Edelweiss,SIMPLE, ZEPLIN, NAIAD, etc.
DetectorWIMP
WIMPScatter
2
1
),()(2
)(2
E
EtEq
mdEtR
RTMN rec det
maxNN rec
Goodman &Witten (1985)
12/9/04 KICP - Spin Dependent Limits 4
Annual Modulation
Earth’s motion With disk (June)
Against disk (December)
Modulation Amplitude:
DAMA (R. Bernabei et al., 2003)
Nma = 0.0200 ± 0.0032 /kg/day/keVee (2-6 keVee) Elegant V, etc.
30 km/s
232 km/s
WIMP Halo Wind
)]2 Dec()2 June([21 RRNma
Drukier, Freese & Spergel (1986)
12/9/04 KICP - Spin Dependent Limits 5
Indirect Detection
Gravitational capture Annihilation
Neutrino-induced muons
Sun: WIMP-proton cross-section
Baksan, Super-K, ANTARES, etc.
WIMP anti-WIMP, asymmetry Halo model dependence
WIMP
)(max,max pWIMPSun
Silk, Olive & Srednicki (1985)Freese (1986)
12/9/04 KICP - 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
)]()()([12
32)( 22
22
qSaqSaaqSaJ
Gq nnnpnnpppp
FSD
22224, pFpSD aG
22224, nFnSD aG
12/9/04 KICP - 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
22nnpp aCaaBaAN
maxNN
maxmin NNN OGMEOGMq 0Multiple Elements
12/9/04 KICP - Spin Dependent Limits 8
Spin-Dependent Limits
Proton only coupling (an = 0)
Neutron only coupling (ap = 0)
General couplings
12/9/04 KICP - Spin Dependent Limits 9
WIMP-Proton Cross-Section Limits(for an = 0)
NAIAD, etc.
12/9/04 KICP - Spin Dependent Limits 10
WIMP-Neutron Cross-Section Limits(for ap = 0)
Zeplin I (Preliminary)V. Kudryavtsev et al., IDM 2004
ap = -3
12/9/04 KICP - Spin Dependent Limits 11
Allowed Couplings
12/9/04 KICP - Spin Dependent Limits 12
Allowed Couplings (Low Mass)
12/9/04 KICP - Spin Dependent Limits 13
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 = 2.5 at 8 GeV)
All solutions have
No MSSM candidates LEP: M > 30 GeV (Abbiendi et al. [OPAL], 2000)
pb5.01 , pWIMPpa
12/9/04 KICP - Spin Dependent Limits 14
Results (12/8)
WIMP masses of 5-10 GeV:Super-K extended analysis
S. Desai for Super-K(private correspondence)
12/9/04 KICP - Spin Dependent Limits 15
Conclusions
DAMA can still be explained by a WIMP with spin-dependent couplings, although at masses 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) – (IN PROGRESS). Odd-Z experiments (CRESST I, SIMPLE/PICASSO, COUPP,etc.) will also be able to examine this remaining space.
Thresholds more important than exposure