Dark matter: evidence and candidates Astrophysical evidences - - PowerPoint PPT Presentation

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Dark matter: evidence and candidates

Zhao-Huan Yu (余钊焕)

Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, CAS

March 14, 2014

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 1 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Dark matter (DM) in the Universe

Dark matter exists at various scales in the Universe. (galaxies, clusters, large scale structures, cosmological scale) However, its microscopic property remains unknown.

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 2 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Coma cluster (后发座星系团)

后发 猎犬 牧夫 北冕 室女 大熊 狮子 小狮

In 1933, Fritz Zwicky found that the velocity dispersion of galaxies in the Coma cluster was far too large to be supported by the luminous matter.

Mass-to-light ratio

[Kent & Gunn, 1982]

Typical spiral galaxy:

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 3 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Coma cluster (后发座星系团)

后发 猎犬 牧夫 北冕 室女 大熊 狮子 小狮

In 1933, Fritz Zwicky found that the velocity dispersion of galaxies in the Coma cluster was far too large to be supported by the luminous matter.

Mass-to-light ratio

[Kent & Gunn, 1982]

Typical spiral galaxy:

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 3 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Coma cluster (后发座星系团)

后发 猎犬 牧夫 北冕 室女 大熊 狮子 小狮

In 1933, Fritz Zwicky found that the velocity dispersion of galaxies in the Coma cluster was far too large to be supported by the luminous matter.

Mass-to-light ratio ΥComa ∼ 260Υ⊙

[Kent & Gunn, 1982]

Typical spiral galaxy: O(10)Υ⊙

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 3 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Spiral galaxies: rotation curves

In the 1970s, Vera Rubin and her collaborators measured the rotation curves of spiral galaxies and also found evidence for non-luminous matter.

Triangulum galaxy M33 [Corbelli & Salucci, astro-ph/9909252]

According to Newton’s law, the relation between the rotation velocity and the mass within radius should be . .

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 4 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Spiral galaxies: rotation curves

In the 1970s, Vera Rubin and her collaborators measured the rotation curves of spiral galaxies and also found evidence for non-luminous matter.

Triangulum galaxy M33

dark matter halo stellar disk gas

M33

[Corbelli & Salucci, astro-ph/9909252]

According to Newton’s law, the relation between the rotation velocity and the mass within radius should be . .

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 4 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Spiral galaxies: rotation curves

In the 1970s, Vera Rubin and her collaborators measured the rotation curves of spiral galaxies and also found evidence for non-luminous matter.

Triangulum galaxy M33

dark matter halo stellar disk gas

M33

[Corbelli & Salucci, astro-ph/9909252]

According to Newton’s law, the relation between the rotation velocity v and the mass M(r) within radius r should be . . v2 r = GN M(r) r2 M(r) = constant ⇒ v ∝ r−1/2 M(r) ∝ r ⇒ v = constant

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 4 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus ⇓ Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus ⇓ Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus ⇓ Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus ⇓ Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury ⇓ Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How can we explain an anomalous phenomenon?

Unexpected movement of Uranus ⇓ Perturbed by Neptune (discovered in 1846)

Search for new objects/substances responsible for it!

Anomalous perihelion precession of Mercury ⇓ Update Newtonian mechanics to general relativity

Modify known physical laws!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 5 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How about the anomalous phenomena here?

Modify physical laws ⇒ MOdified Newtonian Dynamics (MOND)

[Milgrom, ApJ, 1983]

Difficult to coherently explain data at all scales with one model. Consider new objects MAssive Compact Halo Objects (MACHOs) (baryonic dark matter: brown dwarfs, jupiters, stellar black-hole remnants, white dwarfs, neutron stars, ...) MACHO fraction in the Galactic dark matter halo: (95% C.L.)

[EROS-2 coll., astro-ph/0607207]

Consider new substances Nonbaryonic Dark Matter (not constituted by baryons)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 6 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How about the anomalous phenomena here?

Modify physical laws ⇒ MOdified Newtonian Dynamics (MOND)

[Milgrom, ApJ, 1983]

Difficult to coherently explain data at all scales with one model. Consider new objects ⇒ MAssive Compact Halo Objects (MACHOs) (baryonic dark matter: brown dwarfs, jupiters, stellar black-hole remnants, white dwarfs, neutron stars, ...) MACHO fraction in the Galactic dark matter halo: < 8% (95% C.L.)

[EROS-2 coll., astro-ph/0607207]

Consider new substances Nonbaryonic Dark Matter (not constituted by baryons)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 6 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

How about the anomalous phenomena here?

Modify physical laws ⇒ MOdified Newtonian Dynamics (MOND)

[Milgrom, ApJ, 1983]

Difficult to coherently explain data at all scales with one model. Consider new objects ⇒ MAssive Compact Halo Objects (MACHOs) (baryonic dark matter: brown dwarfs, jupiters, stellar black-hole remnants, white dwarfs, neutron stars, ...) MACHO fraction in the Galactic dark matter halo: < 8% (95% C.L.)

[EROS-2 coll., astro-ph/0607207]

Consider new substances ⇒ Nonbaryonic Dark Matter (not constituted by baryons)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 6 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Bullet cluster: disfavor MOND

Fluid-like X-ray emitting plasma (visible matter) Mass distribution

• bserved by weak

gravitational lensing (DM dominated) An 8σ significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law.

[Clowe et al., astro-ph/0608407]

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 7 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Big bang theory

According to the big bang theory, ∼ 13.8 billion years ago, the Universe was extremely hot and dense. Every- thing was in thermal equilibrium and inter- acted with each other. As it expanded, the Universe cooled down. Its constituents decou- pled from the thermal bath one by one.

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 8 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Structure formation: hot, cold, and warm dark matter

Small initial fluctuations + Gravitational instability ⇒ Decoupled matter generates cosmological structures Baryonic matter decoupled too late. Only baryonic matter ⇒ Galaxies would not be formed! ⇒ Needs nonbaryonic dark matter which decoupled much earlier Hot dark matter (such as neutrinos): relativistic when it decoupled structure forms by fragmentation (top-down) Cold dark matter (CDM): nonrelativistic when it decoupled structure forms hierarchically (bottom-up) Galaxies are older than clusters Favors cold dark matter theory Milky Way dwarf satellites: (observed) vs. (CDM predicted) “Missing satellites problem” Warm dark matter?

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 9 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Structure formation: hot, cold, and warm dark matter

Small initial fluctuations + Gravitational instability ⇒ Decoupled matter generates cosmological structures Baryonic matter decoupled too late. Only baryonic matter ⇒ Galaxies would not be formed! ⇒ Needs nonbaryonic dark matter which decoupled much earlier Hot dark matter (such as neutrinos): relativistic when it decoupled ⇒ structure forms by fragmentation (top-down) Cold dark matter (CDM): nonrelativistic when it decoupled ⇒ structure forms hierarchically (bottom-up) Galaxies are older than clusters ⇒ Favors cold dark matter theory Milky Way dwarf satellites: (observed) vs. (CDM predicted) “Missing satellites problem” Warm dark matter?

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 9 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Structure formation: hot, cold, and warm dark matter

Small initial fluctuations + Gravitational instability ⇒ Decoupled matter generates cosmological structures Baryonic matter decoupled too late. Only baryonic matter ⇒ Galaxies would not be formed! ⇒ Needs nonbaryonic dark matter which decoupled much earlier Hot dark matter (such as neutrinos): relativistic when it decoupled ⇒ structure forms by fragmentation (top-down) Cold dark matter (CDM): nonrelativistic when it decoupled ⇒ structure forms hierarchically (bottom-up) Galaxies are older than clusters ⇒ Favors cold dark matter theory Milky Way dwarf satellites: ∼ 20 (observed) vs. ∼ 500 (CDM predicted) “Missing satellites problem” ⇒ Warm dark matter?

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 9 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Standard cosmology: ΛCDM model

0.0 0.5 1.0 0.0 0.5 1.0 1.5 2.0 Flat BAO CMB SNe No Big Bang

[Kowalski et al., 0804.4142] [WMAP Science Team]

In the ΛCDM model, the Universe contains a cosmological constant Λ (dark energy) and cold dark matter (CDM). The evolution of the Universe is governed by the Friedmann equation: . . k H2R2 = ΩΛ + Ωm + Ωr − 1

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 10 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Cosmic microwave background (CMB)

2 10 50 1000 2000 3000 4000 5000 6000

Dℓ[µK2]

90◦ 18◦ 500 1000 1500 2000 2500

Multipole moment, ℓ

1◦ 0.2◦ 0.1◦ 0.07◦

Angular scale

Planck Coll. 1303.5062

WMAP Planck

Dark matter 22.7% 26.8% Ordinary matter 4.5% 4.9% Dark energy 72.8% 68.3%

. .

t ∼ 380 000 yr, T ∼ 3000 K Electrons + protons → hydrogen atoms Photons decoupled

cools ⇓ down . . Today, ∼ 2.7 K microwave background CMB anisotropies encode the information from the early Universe. The shape of anisotropy power spectrum depends on cosmological parameters, such as ΩΛ, Ωm, Ωb, ...

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 11 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Big bang nucleosynthesis (BBN): t ∼ 1 sec − 1 hour

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12

0.2 0.1 0.05 0.02 0.01

T (MeV) log( ) YP log[ (gcm )]

B

• 3
• log(

/ )

A H

N N

1/2=10.6min

=310

• 10
• =3
• 4He

2D 3He 3T 7Li 7Be

• B

1min 3min 1h

n

[Kolb & Turner, The Early Universe]

• 3He/H p

4He 2 3 4 5 6 7 8 9 10 1

0.01 0.02 0.03 0.005

CMB BBN Baryon-to-photon ratio η × 1010 Baryon density Ωbh2 D ___ H

0.24 0.23 0.25 0.26 0.27 10−4 10−3 10−5 10−9 10−10 2 5

7Li/H p

Yp D/H p

[Cyburt et al., 0808.2818]

Primordial abundances of light elements ⇓ Baryon density Ωb (consistent with CMB observations) ⇓ The majority of matter is nonbaryonic

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 12 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Inferred properties of dark matter

Dark (electrically neutral): no light emitted from it Nonbaryonic: BBN & CMB observations Long lived: survived from early eras of the Universe to now Colorless: otherwise, it would bind with nuclei Cold: structure formation theory Abundance: more than 80% of all matter in the Universe ρDM ∼ 0.4 GeV/cm3 near the earth

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 13 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Standard model (SM) of particle physics

Higgs Boson Photon Weak Gluons Quarks Leptons Bosons

e μ τ ν ν ν

e μ τ

q g W Z γ H

SU(3)C × SU(2)L × U(1)Y gauge symmetry Spontaneous symmetry breaking of the Higgs field ⇒ Electroweak symmetry breaking & generating fermion masses

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 14 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Are there dark matter candidates in the standard model? Nonbaryonic Colorless Electrically neutral Long lived Massive Hot DM: neutrinos Cold DM: none

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 15 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

WIMP miracle

[Feng, arXiv:1003.0904]

The relic density of dark matter can be calculated by the Boltzmann equation: ˙ nχ + 3Hnχ = −σannv[n2

χ − (nEQ χ )2]

⇒ Ωχh2 ≃ 3 × 10−27 cm3 s−1 σannv Observed relic density Typical value of weak interactions

Weakly interacting massive particles (WIMPs) are wonderful candidates

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 16 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

WIMP miracle

[Feng, arXiv:1003.0904]

The relic density of dark matter can be calculated by the Boltzmann equation: ˙ nχ + 3Hnχ = −σannv[n2

χ − (nEQ χ )2]

⇒ Ωχh2 ≃ 3 × 10−27 cm3 s−1 σannv Observed relic density ⇓ σannv ∼ O(10−26) cm3 s−1 Typical value of weak interactions ⇓

Weakly interacting massive particles (WIMPs) are wonderful candidates

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 16 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Problem of the standard model

A ∼125 GeV Higgs boson has been discovered at the LHC

[ATLAS Coll., 1207.7214; CMS Coll., 1207.7235]

In the standard model, the quantum correction of the Higgs boson mass ∆m2

H suffers from the quadratic divergence

⇓ Hierarchy problem ⇓ New physics at the TeV scale (Supersymmetry, extra dimensions, little Higgs, ...) ⇓ New physics models often involve candidates for WIMP dark matter

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 17 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Supersymmetry (SUSY)

A symmetry between fermions and bosons . . . . e, µ, τ leptons ↔ sleptons ˜ e, ˜ µ, ˜ τ νe, νµ, ντ neutrinos ↔ sneutrinos ˜ νe, ˜ νµ, ˜ ντ d, u, s, c, b, t quarks ↔ squarks ˜ d, ˜ u, ˜ s, ˜ c, ˜ b, ˜ t g gluon ↔ gluino ˜ g W ±, H± charged bosons ↔ charginos ˜ χ±

1 , ˜

χ±

2

B, W 3, H0

1, H0 2

neutral bosons ↔ neutralinos ˜ χ0

1, ˜

χ0

2, ˜

χ0

3, ˜

χ0

4

Not to violate baryon number

• r lepton number

R-parity conserved SUSY [ ] The lightest SUSY particle (LSP) is stable An attractive candidate for non-baryonic dark matter

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 18 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Supersymmetry (SUSY)

A symmetry between fermions and bosons . . . . e, µ, τ leptons ↔ sleptons ˜ e, ˜ µ, ˜ τ νe, νµ, ντ neutrinos ↔ sneutrinos ˜ νe, ˜ νµ, ˜ ντ d, u, s, c, b, t quarks ↔ squarks ˜ d, ˜ u, ˜ s, ˜ c, ˜ b, ˜ t g gluon ↔ gluino ˜ g W ±, H± charged bosons ↔ charginos ˜ χ±

1 , ˜

χ±

2

B, W 3, H0

1, H0 2

neutral bosons ↔ neutralinos ˜ χ0

1, ˜

χ0

2, ˜

χ0

3, ˜

χ0

4

Not to violate baryon number B or lepton number L ⇒ R-parity conserved SUSY [PR = (−1)3(B−L)+2s] ⇒ The lightest SUSY particle (LSP) is stable ⇒ An attractive candidate for non-baryonic dark matter

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 18 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: (the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

SUSY particles

Nonbaryonic Colorless Electrically neutral Long lived Not excluded by experiment Cold DM: χ0

1

(the lightest neutralino)

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 19 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

More candidates

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0 10 3 10 6 10 9 10 12 10 15 10 18

mass (GeV)

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10

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10

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10

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10

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10

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10

• 3

10 10

3

10

6

10

9

10

12

10

15

10

18

10

21

10

24

σint (pb) Some Dark Matter Candidate Particles

neutrinos

neutralino KK photon branon LTP

axion

axino gravitino KK graviton SuperWIMPs :

wimpzilla WIMPs : Black Hole Remnant Q-ball fuzzy CDM

[Baer & Tata, 0805.1905]

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 20 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Conclusions and discussions Dark matter Cosmology A s t r

• p

h y s i c s Particle physics

Dark matter connects our knowledge of the Universe from the largest to the smallest scales.

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 21 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Conclusions and discussions

DM DM SM SM

Unknown physics

Direct detection Inirect detection Collider detection

Current and near future dark matter searching experiments are promising to solve the mystery of dark matter.

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 22 / 23

. . . . . . Astrophysical evidences . . . . . Cosmological considerations . . . . . . . . Particle candidates . . . Conclusions

Thanks for your attentions!

Zhao-Huan Yu (IHEP) Dark matter: evidence and candidates Mar 2014 23 / 23