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

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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.

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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)

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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)

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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)

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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

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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

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Spin-Dependent Limits

Proton only coupling (an = 0)

Neutron only coupling (ap = 0)

General couplings

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WIMP-Proton Cross-Section Limits(for an = 0)

NAIAD, etc.

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WIMP-Neutron Cross-Section Limits(for ap = 0)

Zeplin I (Preliminary)V. Kudryavtsev et al., IDM 2004

ap = -3

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Allowed Couplings

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Allowed Couplings (Low Mass)

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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

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Results (12/8)

WIMP masses of 5-10 GeV:Super-K extended analysis

S. Desai for Super-K(private correspondence)

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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