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					          The Status of DAMA and Direct
               Detection of WIMPs
              Limits from DAMA and Other Experiments


                                   Christopher M. Savage
                                 Fine Theoretical Physics Institute
                                      University of Minnesota


                                         Katie Freese (University of Michigan)
                                         Graciela Gelmini (UCLA)
                                         Paolo Gondolo (University of Utah)

                                                   arXiv:0808.3607



8/29/08           Cosmo 08 - DAMA and Direct Detection                           1
 Overview

     DAMA/NaI (1996-2002)
             Observes annual modulation (6.3)
                  first claimed signal for direct detection of WIMPs
             Apparent incompatibilities with other experiments in standard
              frameworks
             Many proposed explanations, including spin-dependent
              couplings

     DAMA/LIBRA (2003+)
             Confirms annual modulation (8.2)
             Can WIMP scattering still explain both DAMA signal and null
              results of other experiments?



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 Outline

     WIMP direct detection & modulation

     DAMA modulation signal

     Explanations and detector effects

     Compatibility with other experiments
      (effective WIMP-nucleon couplings)




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 Elastic Scattering and WIMP Detection

     Direct detection

     Annual modulation

     Indirect detection (Sun/Earth)




8/29/08              Cosmo 08 - DAMA and Direct Detection   4
                                             Talk by Uwe Oberlack
 Direct Detection
                                                                               Detector
              Goodman & Witten (1985)                    WIMP



     Elastic scattering of WIMP                                     Scatter
                                                                                          WIMP
      off detector nuclei
                                 E2       
     Rate:          R(t )          dE        X (q)  ( E , t )        X = Ge, Xe, …
                              E1         2m 2


     Recoils: N rec  M det T R

     Efficiencies, quenching, multiple elements

             CDMS, XENON, CRESST, TEXONO,                            N rec  N max
              CoGeNT, COUPP, etc.


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 Direct Detection
     Recoil spectrum




8/29/08             Cosmo 08 - DAMA and Direct Detection   6
 Annual Modulation                                     WIMP Halo Wind
                                                                        30 km/s
          Drukier, Freese & Spergel (1986)


     Earth’s motion
              With disk (June)                            ~300 km/s
               Against disk (December)




8/29/08                          Cosmo 08 - DAMA and Direct Detection             7
 Annual Modulation




8/29/08      Cosmo 08 - DAMA and Direct Detection   8
 Annual Modulation


 R( E , t )  R0 ( E )  Rm ( E , t )

 Rm (t )  S m cos[ (t  June 2)]

 S m  1 [ R(June 2)  R(Dec 2)]
       2




     DAMA/NaI & DAMA/LIBRA                        (R. Bernabei et al., 2008)
          Modulation amplitude: Sm = 0.0131 ± 0.0016 /kg/day/keVee (2-6 keVee)


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 Indirect Detection
          Silk, Olive & Srednicki (1985), Freese (1986)



              Elastic scattering of WIMP off Sun/Earth nuclei
                 gravitational capture
                 annihilation (neutrinos)
                                                                         n
              Flux   X            X = H, He, …

               Sun  max        W IMP, p   max
                                                           WIMP

              SuperK, AMANDA/IceCube, etc.




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 Indirect Detection

     Cross-sections
             Gravitational capture                  scattering
             Annihilation                           ann



     Assumptions

             No large WIMP/anti-WIMP asymmetry                       Majorana ()
                                                                    Relic abundance
             Annihilation cross-section large “enough”             <ann v> ~ 10-26 cm3/s

             Annihilation not to light quarks                        Majorana ()


8/29/08                      Cosmo 08 - DAMA and Direct Detection                            11
 Effective Coupling

     Effective Lagrangian (-quark):

          L    2 q   5  q   5q  3q  q q

                     Axial vector                      Scalar
                   (spin-dependent)             (spin-independent)




     SUSY  2q, 3q


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 Scattering Cross-Section
     Spin-independent (SI)
           SI (q)   SI ,0 F (q)
                              2
                                             SI ,0 
                                                        4 2
                                                         
                                                               Zf   p  ( A  Z ) fn 
                                                                                          2

                  Couples to scalar density of quarks and gluons
                  Scales as A2
                  MSSM: fp  fn             only one parameter: SI,p


     Spin-dependent (SD)
                  32  2GF 2
                         2
       SD ( q)           [a p S pp ( q)  a p an S pn ( q)  an Snn ( q)]
                                                                2

                   2J  1
                  Couples to spin
                  Multiple form factors due to spins of proton and neutron groups
                  Does not scale with A

8/29/08                        Cosmo 08 - DAMA and Direct Detection                           13
 Scattering Cross-Section

     Total           tot   SI   SD

     Couplings
             fp , fn , ap , an                 SI,p , SI,n , SD,p , SD,n (+ 2 signs)


     SD scattering cross-section for a nucleon typically much
      larger (102 - 104+) than SI cross-section in CMSSM
             Indirect detection: Sun is primarily hydrogen
             Direct detection: SI A2 boost




8/29/08                           Cosmo 08 - DAMA and Direct Detection                       14
 DAMA Modulation

     DAMA/NaI (1996-2002)
          R. Bernabei et al., Riv. Nuovo Cim. 26N1, 1 (2003)

             Observes annual modulation (6.3)
                first claimed signal for direct detection of WIMPs



     DAMA/LIBRA (2003+)
          R. Bernabei et al., arXiv:0804.2741 [astro-ph]

             Confirms annual modulation (8.2)




8/29/08                         Cosmo 08 - DAMA and Direct Detection   15
 DAMA Modulation

     DAMA/NaI (6.3)
                                                          Bernabei et al. (2003)




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 DAMA Modulation

     DAMA/NaI + DAMA/LIBRA (8.2)
                                                         Bernabei et al. (2008)




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 DAMA Modulation




8/29/08     Cosmo 08 - DAMA and Direct Detection   18
 DAMA Modulation
     Requirements for DM signal
          1)    Cosine modulation
          2)    1 year period
          3)    Phase ~ June 2nd (standard halo)
          4)    Modulation at low energies only
          5)    Modulation in single scatter events only (not in multiples)
          6)    Modulation amplitude  ~7%

     Multiple hits
               2-6 keVee         -0.0004 ± 0.0006 cpd/kg/keVee
     High energies
              90+ keV           -0.05 ± 0.19 cpd/kg         (one cycle)

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 DAMA Modulation

     Backgrounds/systematics
             Temperature
             Neutrons + other backgrounds
             Radon
             Muon flux modulation
             Detector noise



     None reproduce all signal characteristics
      or capable of producing level of signal



8/29/08                    Cosmo 08 - DAMA and Direct Detection   20
 DAMA/NaI


     Incompatible?



     Standard framework
             Spin-independent
             Isothermal halo


     Cutoff: mass > 30 GeV



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 DAMA/NaI
     Explanations/effects
             Low mass WIMPs
                     • P. Gondolo & G. Gelmini, PRD 71, 123520 (2005)
             Streams/caustics
                     • Gondolo & Gelmini (Ibid)
             Spin-dependent couplings
                     • CS, P. Gondolo & K. Freese, PRD 70, 123513 (2004)
                     • F. Giuliani & T.A. Girard, PRD 71, 123503 (2005)
                     • P. Ullio, M. Kamionkowski & P. Vogel, JHEP 0107, 044 (2001)
             Inelastic scattering
                     • D. Tucker-Smith & N. Weiner, PRD 72, 063509 (2005)
             Mirror matter
                     • R. Foot, PRD 74, 023514 (2006)
             Etc.

             Channeling effect
             Migdal effect


8/29/08                         Cosmo 08 - DAMA and Direct Detection                 22
 Low mass WIMPs
             Relax 30 GeV mass cut – scattering off Na
               P. Gondolo & G. Gelmini, PRD 71, 123520 (2005)




8/29/08                     Cosmo 08 - DAMA and Direct Detection   23
 Spin-dependent
             Spin-dependent couplings

               CS, P. Gondolo & K. Freese, PRD 70, 123513 (2004)
               F. Giuliani & T.A. Girard, PRD 71, 123503 (2005)
               P. Ullio, M. Kamionkowski & P. Vogel, JHEP 0107, 044 (2001)




8/29/08                     Cosmo 08 - DAMA and Direct Detection             24
 Channeling

     Nuclear recoil energy (keV)
             Electrons – ionization/scintillation
                  electron equivalent (keVee)
             Other nuclei – phonons/heat


     Quenching factor Q:
             fraction of recoil energy into measured channel          Eee  QE rec
             QNa  0.3, QI  0.09

                2 keVee DAMA event from:
                     •   6.7 keV Na recoil
                     •   22 keV I recoil



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 Channeling
     Ion channeling                      (R. Bernabei et al., 2008)
             Recoils along channels in crystal
             Energy dependent fraction of recoils have Q  1




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 DAMA Channeling                       Bernabei et al. (2008)




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 Migdal Effect
          Migdal (1941)

              Velocity change of recoiling nucleus
                 excited/ionized electrons                           Bernabei et al. (2007)



              Extra EM energy
               (ionization/scintillation)




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 DAMA Migdal Effect                     Bernabei et al. (2008)




8/29/08      Cosmo 08 - DAMA and Direct Detection                29
 DAMA/LIBRA
     DAMA/LIBRA analyses (selected)

                  CS, G. Gelmini, P. Gondolo & K. Freese, arXiv:0808.3607 [astro-ph]
                  F. Petriello & K.M. Zurek, arXiv:0806.3989 [hep-ph]
                  S. Chang, A. Pierce & N. Weiner, arXiv:0808.0196 [hep-ph]
                  D. Hooper, F. Petriello, K.M. Zurek & M. Kamionkowski,
                   arXiv:0808.2464 [hep-ph]



     Assumptions
             Isothermal spherical halo model
             Elastic scattering



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 DAMA/LIBRA
     Binning

     Channeling

     Statistical methods

     Spin-independent (SI)

     Spin-dependent (SD)
             Proton-only coupling (an = 0)
             Neutron-only coupling (ap = 0)
             Equal magnitude (an = ±ap)
             General couplings

8/29/08                     Cosmo 08 - DAMA and Direct Detection   31
 DAMA Binning

     DAMA/NaI: 2 bins
             Low energy
                  2-4 keVee        0.0252 ± 0.0050 cpd/kg/keVee
                  2-5 keVee        0.0215 ± 0.0039 cpd/kg/keVee
                  2-6 keVee        0.0200 ± 0.0032 cpd/kg/keVee
             High energy
                  6-14 keVee       -0.0009 ± 0.0019 cpd/kg/keVee


     DAMA/NaI + DAMA/LIBRA: 36 bins
             Low energy (2-5 keVee): positive modulation signal
             High energy (~6-20 keVee): consistent with zero modulation



8/29/08                         Cosmo 08 - DAMA and Direct Detection       32
 DAMA Binning




8/29/08     Cosmo 08 - DAMA and Direct Detection   33
 DAMA Binning




8/29/08     Cosmo 08 - DAMA and Direct Detection   34
 DAMA Binning




8/29/08     Cosmo 08 - DAMA and Direct Detection   35
 DAMA Channeling




8/29/08     Cosmo 08 - DAMA and Direct Detection   36
 DAMA Channeling




8/29/08     Cosmo 08 - DAMA and Direct Detection   37
 DAMA Statistical Tests

     Likelihood ratio confidence region
             Parameter estimation – preferred region




     2 goodness of fit (g.o.f.)
             Excluded region



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 DAMA Statistical Tests




8/29/08       Cosmo 08 - DAMA and Direct Detection   39
 DAMA Statistical Tests




8/29/08       Cosmo 08 - DAMA and Direct Detection   40
 Null Experiments




8/29/08       Cosmo 08 - DAMA and Direct Detection   41
 Spin-independent




8/29/08      Cosmo 08 - DAMA and Direct Detection   42
 Spin-independent




8/29/08      Cosmo 08 - DAMA and Direct Detection   43
 Spin-independent




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 Spin-dependent: proton-only (an = 0)




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 Spin-dependent: proton-only (an = 0)




8/29/08       Cosmo 08 - DAMA and Direct Detection   46
 Spin-dependent: proton-only (an = 0)




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 Spin-dependent: neutron-only (ap = 0)




8/29/08       Cosmo 08 - DAMA and Direct Detection   48
 Spin-dependent: neutron-only (ap = 0)




8/29/08       Cosmo 08 - DAMA and Direct Detection   49
 Spin-dependent: neutron-only (ap = 0)




8/29/08       Cosmo 08 - DAMA and Direct Detection   50
 Spin-dependent (an = ap)




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 Spin-dependent (an = ap)




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 Spin-dependent (an = -ap)




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 Spin-dependent (an = -ap)




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                                                a=2       N  1 pb
 Spin-dependent couplings                       a = 20    N  100 pb




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                                                a=2       N  1 pb
 Spin-dependent couplings                       a = 20    N  100 pb




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 SuperK Analysis

     Original:
          S. Desai et al. [SuperK Collaboration], PRD 70, 083523 (2004)
                Analysis down to 10 GeV WIMP mass
                No neutrino oscillations



     Reanalysis:
          D. Hooper, F. Petriello, K.M. Zurek & M. Kamionkowski,
            arXiv:0808.2464 [hep-ph]
                Low WIMP masses
                Neutrino Oscillations                 Talk by Kathryn Zurek
                Spin-independent




8/29/08                      Cosmo 08 - DAMA and Direct Detection              57
                                              (from Kathryn Zurek)
 SuperK Analysis




8/29/08      Cosmo 08 - DAMA and Direct Detection               58
                                              (from Kathryn Zurek)
 SuperK Analysis




8/29/08      Cosmo 08 - DAMA and Direct Detection               59
 Results

     Parameter spaces still remain which are compatible with
      DAMA signal and all null results
             Spin-independent:                   7-10 GeV (SuperK constrained)
             Spin-dependent (proton only):       3-10 GeV (SuperK constrained)
             Spin-dependent (neutron only):      7-9 GeV
             Spin-dependent (mixed):             3-10 GeV (SuperK constrained)



     Allows for comparable proton and neutron couplings
          (e.g. ap = an = 2.5 at 5 GeV)




8/29/08                  Cosmo 08 - DAMA and Direct Detection                     60
 Conclusions

     DAMA can still be explained by low mass WIMPs with spin-
      independent and/or spin-dependent couplings
             Isothermal halo


     SuperK further constrains couplings (if valid)
             Spin-dependent neutron coupling survives


     Probing compatible parameter space:
             Odd-Z experiments (SIMPLE/PICASSO, COUPP, KIMS, etc.)
             Thresholds more important than exposure




8/29/08                         Cosmo 08 - DAMA and Direct Detection   61

				
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