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Dark Matter Consistent with DAMA

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(1)

Dark Matter Consistent with DAMA

Spencer Chang (UC Davis) work in collaboration with

(2)

Dark Matter Mystery

Dark matter implied by astronomy and cosmology, but

mysterious from

particle physics view

Many experiments will probe it: collider, direct and indirect

detection experiments

(3)

DAMA/NaI and DAMA/LIBRA

DAMA only experiment focusing on modulation

Has seen an

excess consistent with expected

behavior of DM

25 NaI detectors w/ 2 PMT's each

(4)

Modulation

Due to earth's (and sun's) orbit, velocity distribution changes seasonally

Dec 2nd

Minimum June 2nd

Maximum

232 km/s

30 km/s

Drukier, Freese, Spergel

(5)

Modulation (cont.)

dR/dER = S0 + Sm cos[2π(t-t0)/T]

Expect T = 1 year, t0 = June 2nd

(152nd day), Sm

positive (negative) for large (small)

Dec 2nd

June 2nd

=

mN E R

βmin

(6)

Data Consistent with DM modulation

Expectations 1 152

(7)

Modulation Spectra

Most events expected at low energy

(8)

Consistent Models vs DAMA

DAMA/LIBRA data is now detailed

enough to pin down parameter space of dark matter candidates

Can check if those models are allowed by other data

Consider spin-independent scattering

Elastic case, requires light dark matter

Inelastic dark matter

(9)

Elastic DM

DAMA spectra for different masses (GeV)

12

7 2

77

SC, Pierce, Weiner

See also Fairbairn, Schwetz and Freese et.al.

Data points pick out preferred mass regions

Fact that the first few points are “low” drives

the fit

(10)

LDM Plots

Spectral information disfavors m < 10 GeV Need nonstandard astrophysics/expt'l issues for consistency

SC, Pierce, Weiner

DAMA 68,90,99%CL

Regions

Envelope is 2 bin DAMA fit

(11)

Inelastic Dark Matter

Models where dark matter scatters dominantly inelastically off nuclei

Adds extra parameter δ, mass splitting to heavier state

Kinematics produces a few effects

Originally proposed to reconcile CDMS and DAMA

Smith, Weiner

SC, Kribs, Smith, Weiner

(12)

Preference for Heavy Targets

Threshold velocity in order to excite to higher DM state

Heavier targets sample lower

velocities, giving enhanced rates

min= 1

2 mN E R

mN NER 

threshold=

2N

CDMS DAMA

e.g.

m=100 GeV, δ=120 keV

(13)

Distinct Spectra

Low energy recoils require higher

velocities

Full expt'l spectra is important,

model, constraints depend strongly

on event

min= 1

2 mN E R

mN NER 

(14)

Enhanced Modulation

Sampling of higher velocity tail, means more modulation

Expt: Dates of data taking crucial to

setting limits. Can

search for enhanced modulation

Modulation in observed DAMA range

Preferred Splitting

(15)

Benchmark Values

(16)

DAMA Spectra Benchmarks

For different dark matter masses, each fit prefers a range for δ, as it shifts the peak

(17)

IDM Plots

Constraints CRESST

(18)

XENON Data

Analysis region

(< 27 keV) misses most of the IDM recoils

(19)

CRESST Data

Seven events observed, lower than we expect, but inconsistent with expected

(20)

Conclusions

DAMA's new data is predictive enough to set up a non-moving target

Light Dark Matter

Low threshold expts: CDMS, CoGeNT, and even XENON will probe further

Inelastic Dark Matter

Heavy target expts: CRESST, XENON, LUX, KIMS, ZEPLIN should see high

energy events and possibly modulation

(21)
(22)

Extra Slides

(23)

Direct Detection Rates (SI)

Astrophysics

Particle Physics

Experimental

Total convolution must be unraveled to connect to

fundamental physics

(24)

Models of IDM

Sneutrino with lepton number violation

Pseudo-Dirac Neutrino

 ∂ Z ⊃ R ∂ I −R ∂ I  Z

= Ri I /2

  Z⊃ Z

=

±=± Mass splitting technically

natural due to breaking of

U(1) symmetry

(25)

Theory of Dark Matter

Dark matter mass due to ATIC is 800 GeV – 1 TeV

Attempts to get DAMA by inelastic scattering

Plots from before rule out m > 250 GeV

However, the inelastic scattering is

mediated by light vector φ, giving 1/(q2- m 2)2 in rate

(26)

Preliminary Results: Pushes to larger δ mφ ~ 8 MeV mφ ~ 80 MeV

CDMS CRESST

參考文獻

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