Distinguishing Dark Matter Candidates from Direct Detection Experiments

Transcription

1 Distinguishing Dark Matter Candidates from Direct Detection Experiments Chung-Lin Shan Department of Physics, National Cheng Kung University International Workshop on DM, DE and Matter-Antimatter Asymmetry November 20, 2009 in collaboration with M. Drees and M. Kakizaki

2 Introduction Dark Matter candidates Direct Dark Matter detection Theoretical predictions Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining ratios of the WIMP-nucleon cross sections Summary C. L. Shan, NCKU Physics p. 1

3 Introduction Dark Matter candidates Dark Matter candidates C. L. Shan, NCKU Physics p. 2

4 Introduction Dark Matter candidates Dark Matter candidates Particles of typical supersymmetric models Normal particles SUSY partners Name Symbol Name Symbol up-quarks u, c, t up-squarks ũ L, ũ R, c L, c R, t L, t R down-quarks d, s, b down-squarks dl, d R, s L, s R, b L, b R leptons e, µ, τ sleptons ẽ L, ẽ R, µ L, µ R, τ L, τ R neutrinos ν e, ν µ, ν τ sneutrinos ν e, ν µ, ν τ gluons g gluinos g photon γ photino γ Z boson Z 0 Z-ino Z light scalar Higgs h 0 neutralinos χ 0 1, χ0 2, χ0 3, χ0 4 heavy scalar Higgs H 0 neutral higgsinos h 0, H 0 pseudoscalar Higgs A 0 charged Higgs H ± charged higgsinos H ± W bosons W ± W-inos W ± charginos χ ± 1, χ± 2 graviton G gravitino G axion a axino ã C. L. Shan, NCKU Physics p. 3

5 Introduction Dark Matter candidates Dark Matter candidates In supersymmetric (SUSY) models: The lightest neutralinos, gravitinos, axinos, sneutrinos,... In Universal Extra Dimensions (UED) models: The first Kaluza-Klein (KK) mode of the hypercharge gauge boson,... In Little Higgs (LH) models: The lightest T-odd particles,... Other possible candidates: Axions, heavy fourth-generation Dirac and Majorana neutrinos, massive neutrinos, sterile neutrinos, fermionic DM, leptophilic DM, (singlet) scalar DM, WIMPless DM, MeV DM, mirror DM, two components DM, unparticle DM, FIMP DM [arxiv: ], itimp DM [arxiv: ], massive astrophysical compact halo objects (MACHOs), Q-balls,... C. L. Shan, NCKU Physics p. 4

6 Introduction Direct Dark Matter detection Direct Dark Matter detection C. L. Shan, NCKU Physics p. 5

7 Introduction Direct Dark Matter detection Direct Dark Matter detection DM should have small, but non-zero interactions with ordinary matter. p, e DM p, e + DM DM e, ν µ, γ DM e +, p, γ DM DM ( ) q q Colliders Indirect detection Direct detection C. L. Shan, NCKU Physics p. 6

8 Introduction Direct Dark Matter detection Direct Dark Matter detection Differential event rate for elastic WIMP-nucleus scattering dr vmax [ ] f1(v) dq = AF 2 (Q) dv v min v Here v min = α Astrophysics Q is the minimal incoming velocity of incident WIMPs that can deposit the recoil energy Q in the detector. A ρ0σ0 mn α m 2m χmr,n 2 2mr,N 2 r,n = mχm N 6 m χ + m N Particle Physics ρ 0 : WIMP density near the Earth σ 0 : total cross section ignoring the form factor suppression F (Q): elastic nuclear form factor f 1 (v): one-dimensional velocity distribution of halo WIMPs C. L. Shan, NCKU Physics p. 7

9 Introduction Direct Dark Matter detection Direct Dark Matter detection Spin-independent (SI) WIMP-nucleus cross section ( ) [ ] σ SI 4 2 ( 0 = m 2 4 r,n Zf p + (A Z)f n π π ( ) σ SI 4 χp/ m 2 r,p π fp 2 f p, f n: effective SI WIMP-proton/neutron couplings ) m 2 r,n A2 f p 2 = A 2 ( mr,n m r,p ) 2 σ SI χp Exclusion limits on the SI WIMP-nucleon cross section [ C. L. Shan, NCKU Physics p. 8

10 Introduction Direct Dark Matter detection Direct Dark Matter detection Spin-dependent (SD) WIMP-nucleus cross section σ SD 0 = ( 32 ) G 2 F m2 r,n ( J + 1 ) [ a p S p + a n S n π J ( ) ( ) σ SD 32 χp/n = G 2 3 F π m2 r,p/n a 2 p/n 4 J, S p, S n : total nuclear spin, expectation values of the proton/neutron group spin a p, a n: SD effective WIMP-proton/neutron couplings Exclusion limits on the SD WIMP-proton cross section ] 2 [ C. L. Shan, NCKU Physics p. 9

11 Introduction Direct Dark Matter detection Direct Dark Matter detection Spin-dependent (SD) WIMP-nucleus cross section σ SD 0 = ( 32 ) G 2 F m2 r,n ( J + 1 ) [ a p S p + a n S n π J ( ) ( ) σ SD 32 χp/n = G 2 3 F π m2 r,p/n a 2 p/n 4 J, S p, S n : total nuclear spin, expectation values of the proton/neutron group spin a p, a n: SD effective WIMP-proton/neutron couplings Exclusion limits on the SD WIMP-neutron cross section ] 2 [ C. L. Shan, NCKU Physics p. 10

12 Introduction Direct Dark Matter detection Direct Dark Matter detection Spin-dependent (SD) WIMP-nucleus cross section σ SD 0 = ( 32 ) G 2 F m2 r,n ( J + 1 ) [ a p S p + a n S n π J ( ) ( ) σ SD 32 χp/n = G 2 3 F π m2 r,p/n a 2 p/n 4 J, S p, S n : total nuclear spin, expectation values of the proton/neutron group spin a p, a n: SD effective WIMP-proton/neutron couplings Exclusion limits on the a p and a n couplings ] 2 [V. N. Lebedenko et al., arxiv: ] C. L. Shan, NCKU Physics p. 11

13 Theoretical predictions C. L. Shan, NCKU Physics p. 12

14 Theoretical predictions msugra (minimal Supergravity; CMSSM, constrained MSSM) A narrow range for the SD cross section on proton [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 13

15 Theoretical predictions Singlet Higgs extension of the MSSM (xmssm) A lighter neutralino with a much larger SD cross section [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 14

16 Theoretical predictions Scalar singlet extended SM (xsm) A spin-0 singlet Higgs boson with only a smaller SI cross section [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 15

17 Theoretical predictions Right-hand Dirac neutrino A relatively larger SI cross section, a smaller SD cross section [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 16

18 Theoretical predictions Minimal Universal Extra Dimensions (mued) The smallest SI cross section, a narrow range for SD cross section and mass [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 17

19 Theoretical predictions Littlest Higgs with T-parity (LHT) A much smaller SI and the smallest SD cross section [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 18

20 Theoretical predictions Comparison of different models Distinguishing different models by σ SD p/n vs. σ SI p/n planes [V. Barger, W. Y. Keung, and G. Shaughnessy, PRD 78, (2008)] C. L. Shan, NCKU Physics p. 19

21 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section C. L. Shan, NCKU Physics p. 20

22 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section Differential event rate for elastic WIMP-nucleus scattering dr vmax [ ] f1(v) dq = AF 2 (Q) dv v Here v min v min = α Q is the minimal incoming velocity of incident WIMPs that can deposit the recoil energy Q in the detector. ρ0σ0 A 2m χmr,n 2 α mn 2m 2 r,n m r,n = mχm N m χ + m N ρ 0 : WIMP density near the Earth σ 0 : total cross section ignoring the form factor suppression F (Q): elastic nuclear form factor f 1 (v): one-dimensional velocity distribution of halo WIMPs C. L. Shan, NCKU Physics p. 21

23 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section Normalized one-dimensional velocity distribution function f 1 (v) = N { d 2Q dq N = 2 { [ 1 1 α 0 Q F 2 (Q) [ 1 F 2 (Q) ( dr dq ( )] dr dq dq )]} } 1 Q=v 2 /α 2 Moments of the velocity distribution function ( α v n n+1 = N (Q thre ) 2 N (Q thre ) = 2 α [ 2Q 1/2 thre F 2 (Q thre ) [ I n(q thre ) = Q (n 1)/2 Q thre ) [ 2Q (n+1)/2 thre F 2 (Q thre ) ( ) dr + (n + 1)I n(q thre ) dq Q=Q thre ( ) ] 1 dr + I 0 (Q thre ) dq Q=Q thre 1 F 2 (Q) ( )] dr dq dq ] [M. Drees and CLS, JCAP 0706, 011] C. L. Shan, NCKU Physics p. 22

24 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section Ansatz: reconstructing the measured recoil spectrum in the nth Q-bin ( ) dr r n e kn(q Qs,n) dq expt, Q Q n r n Nn b n Logarithmic slope and shifted point in the nth Q-bin Q Q n n 1 N n ( ) bn (Q n,i Q n) = coth N n 2 i=1 Q s,n = Q n + 1 [ ] sinh(knbn/2) ln k n k nb n/2 ( knb n 2 ) 1 k n Estimating the moments of the WIMP velocity distribution [ 1/2 2Q v n = α n min r ] 1 [ ] (n+1)/2 min 2Q F 2 (Q min ) + I min r min 0 F 2 + (n + 1)I n (Q min ) I n = a Q (n 1)/2 a F 2 (Q a) r min = ( ) dr = r 1 e k 1(Q min Q s,1) dq expt, Q=Q min [M. Drees and CLS, JCAP 0706, 011] C. L. Shan, NCKU Physics p. 23

25 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section Determining the WIMP mass m χ v n = mx m Y m X R n R n m X /m Y R n = 2Q(n+1)/2 min,x r min,x /FX 2 (Q min,x ) + (n + 1)I n,x 2Q 1/2 min,x r min,x /FX 2 (Q min,x ) + I 0,X 1/n ( X Y ) 1 (n 0) With the assumption of a dominant SI WIMP interaction m χ σ = (m X /m Y ) 5/2 m Y m X R σ R σ (m X /m Y ) 5/2 R σ = E Y E X 2Q1/2 min,x r min,x /F 2 X (Q min,x ) + I 0,X 2Q 1/2 min,y r min,x /F 2 Y (Q min,y ) + I 0,Y [CLS and M. Drees, arxiv: ] [M. Drees and CLS, JCAP 0806, 012] C. L. Shan, NCKU Physics p. 24

26 Our works Determining the WIMP mass/si WIMP-nucleon cross section Determining the WIMP mass and the SI WIMP-nucleon cross section Estimating the SI WIMP-nucleon coupling [ ( )] f p 2 = 1 π ρ E Z A 2 2Q1/2 min,z r min,z Z mz FZ 2(Q + I 0,Z (m χ + m Z ) min,z ) [M. Drees and CLS, arxiv: ] f p 2 rec m χ,rec (Q max < 100 kev, 76 Ge (+ 28 si + 76 ge), σ SI χp = 10 8 pb, 1(3) 50 events) [M. Drees and CLS, arxiv: ; in progress] C. L. Shan, NCKU Physics p. 25

27 Our works Determining ratios of the WIMP-nucleon cross sections Determining the WIMP-nucleon cross sections C. L. Shan, NCKU Physics p. 26

28 Our works Determining ratios of the WIMP-nucleon cross sections Determining the WIMP-nucleon cross sections Determining the ratio of two SD WIMP-nucleon couplings ( ) SD an a p ±,n = Sp X ± S p Y ( RJ,n,X /R J,n,Y ) S n X ± S n Y ( RJ,n,X /R J,n,Y ) [M. Drees and CLS, arxiv: ] (a n /a p ) SD rec,n (5 100 kev, 73 Ge + 37 Cl, 50 events each, m χ = 100 GeV or a n/a p = 0.7) [M. Drees, M. Kakizaki and CLS, arxiv: ; in progress] C. L. Shan, NCKU Physics p. 27

29 Our works Determining ratios of the WIMP-nucleon cross sections Determining the WIMP-nucleon cross sections Determining the ratio of two SD WIMP-nucleon couplings ( ) SI+SD an a p ± = ( c p,x s n/p,x c p,y s n/p,y ) ± cp,x c p,y sn/p,x s n/p,y c p,x s 2 n/p,x c p,y s 2 n/p,y (a n /a p ) SI+SD rec [M. Drees and CLS, arxiv: ] (5 100 kev, 19 F I + 28 Si, σ SI χp = 10 8 /10 10 pb, a p = 0.1) [M. Drees, M. Kakizaki and CLS, arxiv: ; in progress] C. L. Shan, NCKU Physics p. 28

30 Our works Determining ratios of the WIMP-nucleon cross sections Determining the WIMP-nucleon cross sections Determining the ratio of two WIMP-proton cross sections σχp SD σχp SI = F 2 SI,Y (Q min,y )(R m,x /R m,y ) F 2 SI,X (Q min,x ) C p,x F 2 SD,X (Q min,x ) C p,y F 2 SD,Y (Q min,y )(R m,x /R m,y ) ( [M. Drees and CLS, arxiv: ] ) σχ(p,n)/σ SD χp SI rec (19 F I + 28 Si vs. 76 Ge + 23 Na/ 131 Xe, σχp SI = 10 8, a p = 0.1) [M. Drees, M. Kakizaki and CLS, arxiv: ; in progress] C. L. Shan, NCKU Physics p. 29

31 Summary Summary C. L. Shan, NCKU Physics p. 30

32 Summary Summary Once two or more experiments with different target nuclei observe positive WIMP signals, we could estimate WIMP mass m χ SI WIMP-proton coupling f p 2 ratio between the SD WIMP-nucleon couplings, a n /a p ratios between the SD and SI WIMP-nucleon cross sections, σ SD χp/n /σsi χp These analyses are independent of the velocity distribution, the local dentity, and the mass/couplings on nucleons of halo WIMPs (none of them is yet known). For a WIMP mass of 100 GeV, these quantities could be estimated with statistical errors of 10 40% with only O(50) events from one experiment. C. L. Shan, NCKU Physics p. 31

33 Summary Summary These information will help us to constrain the parameter space distinguish the (neutralino) LSP from the (first KK hypercharge) LKP [G. Bertone et al., PRL 99, (2007); V. Barger et al., PRD 78, (2008);] G. Belanger et al., PRD 79, (2009); R. C. Cotta et al., NJP 11, (2009)] identify the particle produced at colliders to be indeed halo WIMP predict the WIMP annihilation cross section σ anni v... (Online interactive) simulation/data analysis system: AMIDAS [CLS, arxiv: , ] Thank you very much for your attention [ cshan/publications/talks/] C. L. Shan, NCKU Physics p. 32