No combined analysis of all experiments available

Transcription

1 Compatibility between DAMA-CDMS CDMS-Edelweiss-Xenon10 - KIMS? No combined analysis of all experiments available However, some trivial considerations: * for m χ 25 GeV capture on DAMA is dominated by the I target WIMPS above threshold in DAMA are also above threshold in CDMS - Edelweiss Ge, Xe in XENON10 or CsI in KIMS for m χ 25 Ge capture on DAMA is dominated by the Na target WIMPS above threshold in DAMA can be below threshold in the CDMS - Edelweiss Ge, Xe in Xenon10 or CsI in KIMS What about quantitively? neglecting channeling

2 Uncertainties in signal predictions

3 The function I(v min ) for different halo models v esc =650 km/sec corotation, counter-rotation

4 A couple of comments on the dependence d of the expected rate on the DF rate is proportional to local density ρ loc low m χ high v min strong variation in detection rate due to exponential tail in I(v min ) ratio of two different exclusion plots: ratio of corresponding local densities ρ loc v 0 =270/v 0 =220 v 0 =170/v 0 =220 dependence is stronger than density ratio at low m χ

5 x

6 [Belli, Cerulli, Fornengo, Scopel, PRD66(2002)043503] (NB: each curve in the previous slide corresponds to one of the models above)

7 Uncertainties due to hadronic matrix elements - The example of the scalar contribution to the neutralino-nucleon cross section Higgs-exchange squark-exchange squark exchange (four-fermi approx): propagators: couplings:

8 Higgs-exchange contribution: neutralino-higgs couplings: α=higgs-mixing angle: quark-higgs couplings: radiative corrections to down-type Yukawa couplings:

9 The hadronic matrix elements: introduce uncertainties in the final result [Bottino, Donato, Fornengo, Scopel, Astrop.Phys. 18(2002)205; ibidem 13(2000)215] The Higgs-nucleon couplings can be rewritten as: with:(l=light quark h=heavy quark): σ πn = pion-nucleon sigma term (size of SU(3) symmetry breaking)

10 Relevant parameters: r~25 30 MeV<σ 0 <40 MeV Two determinations of σ πn : (A. Bottino et al., Astrop. Phys. 13 (2000) 215) (M. M. Pavan et al., PiN Newslett. 16(2002)110, hep-ph/ ) 41 MeV < σ πn < 57 MeV 55 MeV < σ πn < 73 MeV N.B.: combining various measurements, the quantity (squark content of the nucleon) can be sizeable (y<0.6) cross section depends on g d2, factor ~(600/100) 2 ~36 uncertainty!

11 Quenching can be higher! Channeling effect in crystals (Dobryshevsky, arxiv: , Bernabei et al., arxiv: ) critical angle: C 2 ~3, d=interatomic spacing a 0 =0.529 Å (Bohr radius) anomalous deep penetration of ions into crystalline targets discovered a long time ago (1957, 4 kev 134 CS + observed to penetrate λ~ 1000 Å in Ge, according to Lindhard theory λ~ 44 Å) when the ion recoils along one crystallographic axis it only encounters electrons long penetration depth and q~1

12 Quenching can be higher! Channeling effect in crystals the channeling effect is only relevant at low recoil energies (<150 kev) detector response enhanced smaller WIMP cross sections needed to produce the same effect smaller threshold on recoil energy and sensitivity to lighter masses N.B.: this effect was neglected so far in the analysis of WIMP searches. It is expected in crystal scintillators and ionizators (Ge, NaI) no enhancement in liquid noble gas experiments (XENON10, ZEPLIN) channeled events are lost using PSD in scintillators channeled events are lost using double read-out discrimination (CDMS, Edelweiss) quenching measurements are not sensitive enough to see channeled events (q=1 peak broadened by energy resolution)

13 The WIMP interpretation of DAMA/NaI and other constraints Isothermal sphere, no channeling in NaI, DAMA/NaI maximal hadronic eff-mssm matrix elements in σ (nucleon) scalar, no GUT KIMS XENON10 CDMS relation between M 1 and M 2 Standard assumptions ρ loc =0.3 GeV cm -3 v 0 =220 km sec -1 v esc =650 km sec -1 N.B.:first direct check using Iodine (same target as DAMA) from KIMS Disfavored, but large uncertainties involved (e.g.: efficiencies in background subtraction, astrophysics, scaling laws among different materials, etc.)

14 Neutralino-nucleon cross section & CDM limit (including uncertainties from astrophysics and hadronic matrix elements) C3 A0 B1 solid: v esc =650 km/sec long dashes: v esc =450 km/sec counterrotation eff-mssm (including uncertainties due to hadronic matrix elements)

15 Comparing the model with latest DAMA/Libra data [Bottino, Donato, Fornengo, Scopel, Phys.Rev.D78:083520,2008, arxiv: ] DAMA/Libra 6.5 σ away from null ipothesis, convoluted on different halo models channeling not included eff-mssm (including uncertainties due to hadronic matrix elements) scatter plot: reference choice of hadronic matrix elements

16 Comparing the model with latest DAMA/Libra data [Bottino, Donato, Fornengo, Scopel, Phys.Rev.D78:083520,2008, arxiv: ] DAMA/Libra 6.5 σ away from null ipothesis, convoluted on different halo models(private communication) eff-mssm (including uncertainties due to hadronic matrix elements) channeling included scatter plot: reference choice of hadronic matrix elements

17 Compatibility of DAMA/LIBRA region with low mass neutralinos [Bottino, Donato, Fornengo, Scopel, arxiv: ] (Evan s logarithmic model (A1), R c =5 kpc) v 0 =v 0,min OK v 0 =v 0,central OK OK v 0 =v 0,max no channeling, lowmedium range of v 0 and ρ 0 disfavoured ρ=ρ min ρ=ρ max

18 Compatibility of DAMA/LIBRA region with low mass neutralinos [Bottino, Donato, Fornengo, Scopel, arxiv: ] (Evan s logarithmic model (A1), R c =5 kpc) v 0 =v 0,min OK OK v 0 =v 0,central OK v 0 =v 0,max channeling included, low-medium range of v 0 and ρ 0 favoured ρ=ρ min ρ=ρ max

19 Channeling DAMA region moves to lower masses and cross sections less tension between DAMA and other experiments In the DAMA region at low mass scattering dominated by Iodine, not Sodium KIMS might be sensitive to the light WIMP window!

20 Examples of alternative explanations pseudoscalar and scalar light bosons (axion-like) (Bernabei et al., PRD73(2006)063522) (total conversion of incoming particle in EM radiation, no nuclear recoil involved rejection techniques of other experiments ineffective, high quenching DM) inelastic Dark Matter (Smith, Weiner, PRD64 (2001) ) N N δ~15 kev may reconcile DAMA and CDMS mirror matter (Foot, arxiv: ) He (H ) dominated halo with small O component enhances sensitivity to lower threshold compared to WIMPS

21 Summary of direct detection processes: Scatterings on nuclei detection of nuclear recoil energy DMp N DMp Ionization: Ge, Si Bolometer: TeO 2, Ge, CaWO 4,... Scintillation: NaI(Tl), LXe,CaF 2 (Eu), Inelastic Dark Matter:W W + N W* + N W has Two mass states χ+, χ- with δ mass splitting Kinematical constraint for the inelastic scattering of χ- on a nucleus 1 2 µv2 δ v v thr = 2δ µ Excitation of bound electrons in scatterings on nuclei detection of recoil nuclei + e.m. radiation Conversion of particle into e.m. radiation detection of γ, X-rays, e - Interaction only on atomic electrons detection of e.m. radiation DMp e -... even WIMPs e.g. sterile ν also other ideas a X-ray Interaction of ligth DMp (LDM) on e - or nucleus with production of a lighter particle detection of electron/nucleus recoil energy e - γ e.g. signals from these candidates are completely lost in experiments based on rejection procedures of the e.m. component of their rate and more

22 Main consequences of inelastic Dark Matter: 1. overall suppression of signal 2. energy-dependent suppression of signal 3. enhancement of modulated signal relative to unmodulated one can reconcile DAMA with constraints from other (lighter) nuclei but KIMS constraint on I is not affected