Can WIMP Spin Dependent Couplings explain DAMA? Limits from DAMA and Other Experiments

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/0408346 to appear in Phys. Rev. D KICP - 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) 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. KICP - Spin Dependent Limits

Detector WIMP Scatter WIMP Direct Detection Goodman &Witten (1985) • Elastic scattering of WIMP off detector nuclei • Rate: • Recoils: • Efficiencies, quenching, multiple elements • CDMS, CRESST, Edelweiss,SIMPLE, ZEPLIN, NAIAD, etc. KICP - Spin Dependent Limits

WIMP Halo Wind 30 km/s 232 km/s Annual Modulation Drukier, Freese & Spergel (1986) • 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. KICP - Spin Dependent Limits

n WIMP Indirect Detection Silk, Olive & Srednicki (1985) Freese (1986) • Gravitational capture Annihilation • Neutrino-induced muons • Sun: WIMP-proton cross-section • Baksan, Super-K, ANTARES, etc. • WIMP  anti-WIMP, asymmetry • Halo model dependence KICP - Spin Dependent Limits

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 KICP - Spin Dependent Limits

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

Spin-Dependent Limits • Proton only coupling (an = 0) • Neutron only coupling (ap = 0) • General couplings KICP - Spin Dependent Limits

WIMP-Proton Cross-Section Limits(for an = 0) NAIAD, etc. KICP - Spin Dependent Limits

ap = -3 Zeplin I (Preliminary) V. Kudryavtsev et al., IDM 2004 WIMP-Neutron Cross-Section Limits(for ap = 0) KICP - Spin Dependent Limits

Allowed Couplings KICP - Spin Dependent Limits

Allowed Couplings (Low Mass) KICP - 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 = 2.5 at 8 GeV) • All solutions have • No MSSM candidates • LEP: M > 30 GeV (Abbiendi et al. [OPAL], 2000) KICP - Spin Dependent Limits

Results (12/8) • WIMP masses of 5-10 GeV: Super-K extended analysis S. Desai for Super-K (private correspondence) KICP - Spin Dependent Limits

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 KICP - Spin Dependent Limits

Can WIMP Spin Dependent Couplings explain DAMA? Limits from DAMA and Other Experiments