Direct and Indirect Detection of Dark Matter Zhao-Huan Yu School of - - PowerPoint PPT Presentation

▶
direct and indirect detection of dark matter
SMART_READER_LITE
LIVE PREVIEW

Direct and Indirect Detection of Dark Matter Zhao-Huan Yu School of - - PowerPoint PPT Presentation

Nov 11, 2022 336 likes •975 views

Dark Matter Direct Detection Indirect Detection Direct and Indirect Detection of Dark Matter Zhao-Huan Yu School of Physics, Sun Yat-Sen University http://yzhxxzxy.github.io June 18, 2019 Zhao-Huan Yu (SYSU) Direct and

slide-1
SLIDE 1

Dark Matter Direct Detection Indirect Detection

Direct and Indirect Detection of Dark Matter

Zhao-Huan Yu（余钊焕）

School of Physics, Sun Yat-Sen University http://yzhxxzxy.github.io

June 18, 2019

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 1 / 56

slide-2
SLIDE 2

Dark Matter Direct Detection Indirect Detection

Dark Matter in the Universe

dark matter halo stellar disk gas

M33

Bullet Cluster Bullet Cluster Spiral galaxy M33 Spiral galaxy M33 Cluster Abell 2218 Cluster Abell 2218 CMB CMB

Dark matter (DM) makes up most of the matter component in the Universe, as suggested by astrophysical and cosmological observations

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 2 / 56

slide-3
SLIDE 3

Dark Matter Direct Detection Indirect Detection

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 ∼ 0.3 − 0.4 GeV/cm3 near the earth

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 3 / 56

slide-4
SLIDE 4

Dark Matter Direct Detection Indirect Detection

DM Relic Abundance

10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 0.1 1 10 10-3 10-2 10-1 100 101 102 103

Y = n / s

Ωχ h2

T (GeV) DM freeze out, mχ = 100 GeV, g* = 86

10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 0.1 1 10 10-3 10-2 10-1 100 101 102 103 3 × 10-25 〈σv〉 = 3 × 10-26 cm3/s 3 × 10-27 Equilibrium

If DM particles (χ) were thermally produced in the early Universe, their relic abundance would be determined by the annihilation cross section 〈σannv〉: Ωχh2 ≃ 3 × 10−27 cm3 s−1 〈σannv〉 Observation value Ωχh2 ≃ 0.1 ⇒ 〈σannv〉 ≃ 3 × 10−26 cm3 s−1 Assuming the annihilation process consists of two weak interaction vertices with the SU(2)L gauge coupling g ≃ 0.64, for mχ ∼ O(TeV) we have 〈σannv〉 ∼ g4 16π2m2

χ

∼ O(10−26) cm3 s−1 ⇒ A very attractive class of DM candidates: Weakly interacting massive particles (WIMPs)

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 4 / 56

slide-5
SLIDE 5

Dark Matter Direct Detection Indirect Detection

Experimental Approaches to Dark Matter

DM DM SM SM

Unknown physics

Direct detection Inirect detection Collider detection

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 5 / 56

slide-6
SLIDE 6

Dark Matter Direct Detection Indirect Detection

WIMP Scattering ofg Atomic Nuclei

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 6 / 56

slide-7
SLIDE 7

Dark Matter Direct Detection Indirect Detection

Direct Detection

[Bing-Lin Young, Front. Phys. 12, 121201 (2017)] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 7 / 56

slide-8
SLIDE 8

Dark Matter Direct Detection Indirect Detection

WIMP Velocity Distribution

Galactic disk and dark halo

[Credit: ESO/L. Calçada]

During the collapse process which formed the Galaxy, WIMP velocities were “thermalized” by fmuctuations in the gravitational potential, and WIMPs have a Maxwell-Boltzmann velocity distribution in the Galactic rest frame: ˜ f (˜ v)d3˜ v =

  • mχ

2πkBT 3/2 exp

  • −

mχ ˜ v2 2kBT

  • d3˜

v = e−˜

v2/v2

π3/2v3 d3˜ v, v2

0 ≡ 2kBT

mχ

〈˜ v〉 = ∫ ˜ v ˜ f (˜ v)d3˜ v = 0,

  • ˜

v2 = ∫ ˜ v2 ˜ f (˜ v)d3˜ v = 3 2 v2

Speed distribution: ˜ f (˜ v)d˜ v = 4˜ v2 πv3 e−˜

v2/v2

0 d˜

v For an isothermal halo, the local value of v0 equals to the rotational speed of the Sun: v0 = v⊙ ≃ 220km/s

[Binney & Tremaine, Galactic Dynamics, Chapter 4]

Velocity dispersion:

  • 〈˜

v2〉 =

  • 3/2v0 ≃ 270km/s

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 8 / 56

slide-9
SLIDE 9

Dark Matter Direct Detection Indirect Detection

Earth Rest Frame

Sun WIMP wind Earth

J u n e D e c e m b e r v⊕ = 30 km/s Cygnus v⊙ ≃ 220 km/s δ = 30.7◦

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 100 200 300 400 500 600 700 800

f (v) (10-3 km-1 s) v (km s-1) Speed distributions

vobs = 0 vobs = 205 km/s vobs = 235 km/s 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 100 200 300 400 500 600 700 800

The WIMP velocity distribution f (v) seen by an observer on the Earth can be derived via Galilean transformation ˜ v = v + vobs, vobs = v⊙ + v⊕ Velocity distribution: f (v) = ˜ f (v + vobs) Speed distribution: f (v)dv = 4v2 πv3 exp

  • −

v2 + v2

  • bs

v2

  • ×

˜ v2 2vvobs sinh

  • 2vvobs

v2

  • dv

Since v⊕ ≪ v⊙, we have (ω = 2π/year) vobs(t) ≃ v⊙ + v⊕ sinδcos[ω(t − t0)] ≃ 220 km/s + 15 km/s · cos[ω(t − t0)] ⇒ Annual modulation signal peaked on June 2 [Freese et al., PRD 37, 3388 (1988)]

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 9 / 56

slide-10
SLIDE 10

Dark Matter Direct Detection Indirect Detection

Nuclear Recoil

v WIMP χ Nucleus A vχ θχ χ vR θR A

Energy conservation: 1 2 mχ v2 = 1 2 mχ v2

χ + 1

2 mAv2

R

Momentum conservation: mχ v = mχ vχ cosθχ + mAvR cosθR mχ vχ sinθχ = mAvR sinθR ⇒ Recoil velocity vR = 2mχ v cosθR mχ + mA ⇒ Recoil momentum (momentum transfer) qR = mAvR = 2µχAv cosθR Reduced mass of the χA system µχA ≡ mχmA mχ + mA =        mA, for mχ ≫ mA 1 2mχ, for mχ = mA mχ, for mχ ≪ mA Forward scattering (θR = 0) ⇒ maximal momentum transfer qmax

R

= 2µχAv

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 10 / 56

slide-11
SLIDE 11

Dark Matter Direct Detection Indirect Detection

Nuclear Recoil

v WIMP χ Nucleus A vχ θχ χ vR θR A

Energy conservation: 1 2 mχ v2 = 1 2 mχ v2

χ + 1

2 mAv2

R

Momentum conservation: mχ v = mχ vχ cosθχ + mAvR cosθR mχ vχ sinθχ = mAvR sinθR ⇒ Recoil velocity vR = 2mχ v cosθR mχ + mA ⇒ Recoil momentum (momentum transfer) qR = mAvR = 2µχAv cosθR ⇒ Kinetic energy of the recoiled nucleus ER = q2

R

2mA = 2µ2

χA

mA v2cos2θR As v ∼ 10−3c, for mχ = mA ≃ 100 GeV and θR = 0, qR = mχ v ∼ 100 MeV, ER = 1 2mχ v2 ∼ 50 keV

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 10 / 56

slide-12
SLIDE 12

Dark Matter Direct Detection Indirect Detection

Event Rate

Event rate per unit time per unit energy interval: dR dER = NT ρ⊕ mχ ∫ vmax

vmin

d3v f (v)v dσχA dER Astrophysics factors Particle physics factors Detector factors NT: target nucleus number ρ⊕ ≃ 0.3 − 0.4 GeV/cm3: DM mass density around the Earth (ρ⊕/mχ is the DM particle number density around the Earth) σχA: DM-nucleus scattering cross section Minimal velocity vmin =

  • mAEth

R

2µ2

χA

1/2 : determined by the detector threshold

  • f nuclear recoil energy, Eth

R

Maximal velocity vmax: determined by the DM escape velocity vesc (vesc ≃ 544 km/s [Smith et al., MNRAS 379, 755])

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 11 / 56

slide-13
SLIDE 13

Dark Matter Direct Detection Indirect Detection

Cross Section Dependence on Nucleus Spin

There are two kinds of DM-nucleus scattering Spin-independent (SI) cross section: σSI

χA ∝ µ2 χA[ZGp + (A− Z)Gn]2

Spin-dependent (SD) cross section: σSD

χA ∝ µ2 χA

JA + 1 JA (SA

pG′ p + SA nG′ n)2

Nucleus properties: mass number A, atomic number Z, spin JA, expectation value of the proton (neutron) spin content in the nucleus SA

p (SA n)

G(′)

p

and G(′)

n : DM efgective couplings to the proton and the neutron

Z ≃ A/2 ⇒ σSI

χA ∝ A2[(Gp + Gn)/2]2

Strong coherent enhancement for heavy nuclei Spins of nucleons tend to cancel out among themselves:

SA

N ≃ 1/2 (N = p or n) for a nucleus with an odd number of N

SA

N ≃ 0 for a nucleus with an even number of N

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 12 / 56

slide-14
SLIDE 14

Dark Matter Direct Detection Indirect Detection

Three Levels of Interaction

Mediator χ χ q q

DM-parton interaction

M(χq → χq) ⇒

Mediator χ χ p, n p, n

DM-nucleon interaction

M(χN → χN) ⇒

Mediator χ χ A A

DM-nucleus interaction

M(χA → χA) As a variety of target nuclei are used in direct detection experiments, results are usually compared with each other at the DM-nucleon level The DM-nucleon level is related to the DM-parton level via form factors, which describe the probabilities of fjnding partons inside nucleons Relevant partons involve not only valence quarks, but also sea quarks and gluons

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 13 / 56

slide-15
SLIDE 15

Dark Matter Direct Detection Indirect Detection

Zero Momentum Transfer Limit

S χ χ q q

Q2 → 0 ⇒

χ χ q q χ χ p, n p, n

As the momentum transfer is typically much smaller than the underlying energy scale (e.g., mediator mass), the zero momentum transfer limit is a good approximation for calculation In this limit, the mediator fjeld can be integrated out, and the interaction can be described by efgective operators in efgective fjeld theory Scalar mediator propagator: i Q2 − m2

S

⇒ − i m2

S

Lagrangian: Lint = gχS ¯ χχ + gqS¯ qq ⇒ Leff = Geff ¯ χχ¯ qq, Geff = gχ gq m2

S Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 14 / 56

slide-16
SLIDE 16

Dark Matter Direct Detection Indirect Detection

Efgective Operators for DM-nucleon interactions

Assuming the DM particle is a Dirac fermion χ and using Dirac fjelds p and n to describe the proton and the neutron, the efgective Lagrangian reads Leff,N = ∑

N=p,n

∑

i j

GN,i j ¯ χΓ iχ ¯ NΓjN, Γ i,Γ j ∈ {1, iγ5,γµ,γµγ5,σµν}

[Bélanger et al., arXiv:0803.2360, Comput.Phys.Commun.]

Lorentz indices in Γ i and Γj should be contracted in pair Efgective couplings GN,i j have a mass dimension of −2: [GN,i j] = [Mass]−2 ¯ χχ ¯ NN and ¯ χγµχ ¯ NγµN lead to SI DM-nucleon scattering ¯ χγµγ5χ ¯ Nγµγ5N and ¯ χσµνχ ¯ NσµνN lead to SD DM-nucleon scattering The following operators lead to scattering cross sections σχN ∝ |Q2|: ¯ χiγ5χ ¯ Niγ5N, ¯ χχ ¯ Niγ5N, ¯ χiγ5χ ¯ NN, ¯ χγµχ ¯ Nγµγ5N, ¯ χγµγ5χ ¯ NγµN For a Majorana fermion χ instead, we have ¯ χγµχ = 0 and ¯ χσµνχ = 0, and hence the related operators vanish

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 15 / 56

slide-17
SLIDE 17

Dark Matter Direct Detection Indirect Detection

Higgs Portal for Majorana Fermionic DM

k1 k2 h q χ q χ p1 p2 Q k1 k2 q χ q χ p1 p2

Interactions for a Majorana fermion χ, the SM Higgs boson h, and quarks q: LDM ⊃ 1 2 gχh ¯ χχ LSM ⊃ − ∑

q

mq v h¯ qq, q = d,u,s, c, b, t The amplitude for χ(p1) + q(k1) → χ(p2) + q(k2): iM = igχ ¯ u(p2)u(p1) i Q2 − m2

h

  • −i

mq v

  • ¯

u(k2)u(k1) Zero momentum transfer ⇓ Q2 = (k2 − k1)2 → 0 iM = −i gχmq vm2

h

¯ u(p2)u(p1)¯ u(k2)u(k1) ⇓ Leff,q = ∑

q

GS,q ¯ χχ¯ qq, GS,q = − gχmq 2vm2

h Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 16 / 56

slide-18
SLIDE 18

Dark Matter Direct Detection Indirect Detection

Efgective Lagrangian: Scalar Type

Scalar-type efgective Lagrangian for a spin-1/2 fermion χ: LS,q = ∑

q

GS,q ¯ χχ¯ qq ⇒ LS,N = ∑

N=p,n

GS,N ¯ χχ ¯ NN GS,N = mN ∑

q=u,d,s

GS,q mq f N

q +

∑

q=c,b,t

GS,q mq f N

Q

  • The second term accounts for DM interactions with gluons through loops of

heavy quarks (c, b, and t): f N

Q = 2

27

  • 1 −

∑

q=u,d,s

f N

q

  • Form factor f N

q is the contribution of q to mN: 〈N| mq¯

qq |N〉 = f N

q mN

f p

u ≃ 0.020,

f p

d ≃ 0.026,

f n

u ≃ 0.014,

f n

d ≃ 0.036,

f p

s = f n s ≃ 0.118

[Ellis et al., arXiv:hep-ph/0001005, PLB]

The scalar type induces SI DM-nucleon scattering with a cross section of σSI

χN =

nχ π µ2

χN G2 S,N,

µχN ≡ mχmN mχ + mN , nχ = 1, for Dirac fermion χ 4, for Majorana fermion χ

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 17 / 56

slide-19
SLIDE 19

Dark Matter Direct Detection Indirect Detection

Z Portal for Majorana Fermionic DM

Interactions for a Majorana fermion χ, the Z boson, and quarks q: LDM ⊃ 1 2 gχ Zµ ¯ χγµγ5χ, LSM ⊃ g 2cW Zµ ∑

q

¯ qγµ(gq

V − gq Aγ5)q

gui

V = 1

2 − 4 3s2

W,

gdi

V = −1

2 + 2 3s2

W,

gui

A = 1

2 = −gdi

A , cW ≡ cosθW, sW ≡ sinθW

Z boson propagator −i Q2 − m2

Z

  • gµν −

QµQν m2

Z

  • Q2→0

− − − → i m2

Z

gµν Efgective Lagrangian in the zero momentum transfer limit: Leff,q = ∑

q

¯ χγµγ5χ(GA,q¯ qγµγ5q + GAV,q¯ qγµq), GA,q = gχ ggq

A

4cWm2

Z

GAV,q = − gχ g gq

V

4cWm2

Z

leads to σχN ∝ |Q2| and can be neglected for direct detection

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 18 / 56

slide-20
SLIDE 20

Dark Matter Direct Detection Indirect Detection

Efgective Lagrangian: Axial Vector Type

Axial-vector-type efgective Lagrangian for a spin-1/2 fermion χ: LA,q = ∑

q

GA,q ¯ χγµγ5χ¯ qγµγ5q ⇒ LA,N = ∑

N=p,n

GA,N ¯ χγµγ5χ ¯ Nγµγ5N GA,N = ∑

q=u,d,s

GA,q∆N

q ,

2∆N

q sµ ≡ 〈N| ¯

qγµγ5q |N〉 Form factors ∆N

q account the contributions of quarks and anti-quarks to the

nucleon spin vector sµ, and can be extracted from lepton-proton scattering data: ∆p

u = ∆n d ≃ 0.842,

∆p

d = ∆n u ≃ −0.427,

∆p

s = ∆n s ≃ −0.085

[HERMES coll., arXiv:hep-ex/0609039, PRD]

Neutron form factors are related to proton form factors by isospin symmetry The axial vector type induces SD DM-nucleon scattering: σSD

χN =

3nχ π µ2

χN G2 A,N,

nχ = 1, for Dirac fermion χ 4, for Majorana fermion χ

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 19 / 56

slide-21
SLIDE 21

Dark Matter Direct Detection Indirect Detection

Z Portal for Complex Scalar DM

χ χ Zµ p k = igχ(p + k)µ . k1 k2 Z q χ q χ p1 p2 Q

Interactions for a complex scalar χ, the Z boson, and quarks q: LDM ⊃ gχ Zµ(χ∗i← → ∂ µχ) LSM ⊃ g 2cW Zµ ∑

q

¯ qγµ(gq

V − gq Aγ5)q

iM = igχ(p1 + p2)µ −i(gµν − QµQν/m2

Z)

Q2 − m2

Z

×i g 2cW ¯ u(k2)γν(gq

V − gq Aγ5)u(k1) Q2→0

− − − → −i gχ g 2cWm2

Z

(p1 + p2)µ¯ u(k2)γµ(gq

V − gq Aγ5)u(k1)

Leff,q = ∑

q

(χ∗i← → ∂ µχ)(FV,q¯ qγµq + FVA,q¯ qγµγ5q) FV,q = − gχ g gq

V

2cWm2

Z

, FVA,q = gχ g gq

A

2cWm2

Z

(⇒ σχN ∝ |Q2|)

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 20 / 56

slide-22
SLIDE 22

Dark Matter Direct Detection Indirect Detection

Efgective Lagrangian: Vector Type

Vector-type efgective Lagrangian for a complex scalar χ: LV,q = ∑

q

FV,q(χ∗i← → ∂ µχ)¯ qγµq ⇒ LA,N = ∑

N=p,n

FV,N(χ∗i← → ∂ µχ) ¯ NγµN The relation between FV,N and FV,q refmects the valence quark numbers in N: FV,p = 2FV,u + FV,d, FV,n = FV,u + 2FV,d The vector type induces SI DM-nucleon scattering: σSI

χN = 1

πµ2

χN F 2 V,N

Vector-type efgective Lagrangian for a Dirac fermion χ: LV,q = ∑

q

GV,q ¯ χγµχ¯ qγµq ⇒ LA,N = ∑

N=p,n

GV,N ¯ χγµχ ¯ NγµN It also induces SI DM-nucleon scattering: σSI

χN = 1

πµ2

χN G2 V,N,

GV,p = 2GV,u + GV,d, GV,n = GV,u + 2GV,d

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 21 / 56

slide-23
SLIDE 23

Dark Matter Direct Detection Indirect Detection

Efgective Operators for DM-quark Interactions

Spin-1/2 DM Spin-0 DM SI ¯ χχ¯ qq, ¯ χγµχ¯ qγµq χ∗χ¯ qq, (χ∗i← → ∂ µχ)¯ qγµq SD ¯ χγµγ5χ¯ qγµγ5q, ¯ χσµνχ¯ qσµνq σχN ∝ |Q2| ¯ χiγ5χ¯ qiγ5q, ¯ χχ¯ qiγ5q ¯ χiγ5χ¯ qq, ¯ χγµχ¯ qγµγ5q ¯ χγµγ5χ¯ qγµq, ϵµνρσ ¯ χσµνχ¯ qσρσq χ∗χ¯ qiγ5q (χ∗i← → ∂ µχ)¯ qγµγ5q Spin-3/2 DM Spin-1 DM SI ¯ χµχµ¯ qq, ¯ χνγµχν¯ qγµq χ∗

µχµ¯

qq, (χ∗

νi←

→ ∂ µχν)¯ qγµq SD ¯ χνγµγ5χν¯ qγµγ5q, ¯ χρσµνχρ¯ qσµνq i( ¯ χµχν − ¯ χνχµ)¯ qσµνq i(χ∗

µχν − χ∗ νχµ)¯

qσµνq ϵµνρσ(χ∗

µ

← → ∂ν χρ)¯ qγσγ5q σχN ∝ |Q2| ¯ χµiγ5χµ¯ qiγ5q, ¯ χµχµ¯ qiγ5q ¯ χµiγ5χµ¯ qq, ¯ χνγµχν¯ qγµγ5q ¯ χµγµγ5χν¯ qγµq, ϵµνρσi( ¯ χµχν − ¯ χνχµ)¯ qσρσq ϵµνρσ ¯ χασµνχα¯ qσρσq, ( ¯ χµγ5χν − ¯ χνγ5χµ)¯ qσµνq ϵµνρσ( ¯ χµγ5χν − ¯ χνγ5χµ)¯ qσρσq χ∗

µχµ¯

qiγ5q (χ∗

νi←

→ ∂ µχν)¯ qγµγ5q ϵµνρσ(χ∗

µ

← → ∂ν χρ)¯ qγσq ϵµνρσi(χ∗

µχν − χ∗ νχµ)¯

qσρσq [Zheng, ZHY, Shao, Bi, Li, Zhang, arXiv:1012.2022, NPB; ZHY, Zheng, Bi, Li, Yao, Zhang, arXiv:1112.6052, NPB]

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 22 / 56

slide-24
SLIDE 24

Dark Matter Direct Detection Indirect Detection

Technologies and Detector Material

[From M. Lindner’s talk (2016)] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 23 / 56

slide-25
SLIDE 25

Dark Matter Direct Detection Indirect Detection

Technologies and Detector Material

[From M. Lindner’s talk (2016)] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 24 / 56

slide-26
SLIDE 26

Dark Matter Direct Detection Indirect Detection

Example: Dual-phase Xenon Time Projection Chamber

[From A. Cottle’s talk (2017)]

Upper: Xenon gas Lower: Liquid Xenon UV scintillation photons recorded by photomultiplier tube (PMT) arrays

  • n top and bottom

Primary scintillation (S1): Scintillation light promptly emitted from the interaction vertex Secondary scintillation (S2): Ionization electrons emitted from the interaction are drifted to the surface and into the gas, where they emit proportional scintillation light Experiments: XENON, LUX, PandaX

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 25 / 56

slide-27
SLIDE 27

Dark Matter Direct Detection Indirect Detection

PandaX-II Real Data: S1 versus S2

[PandaX-II coll., arXiv:1607.07400, PRL]

ER calibration median NR calibration median 99.99% NR acceptance

S1 and S2: characterized by numbers of photoelectrons (PEs) in PMTs The γ background, which produces electron recoil (ER) events, can be distinguished from nuclear recoil (NR) events using the S2-to-S1 ratio

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 26 / 56

slide-28
SLIDE 28

Dark Matter Direct Detection Indirect Detection

Backgrounds

[From P. Cushman’s talk (2014)]

Background suppression: Deep underground Shielded environments Cosmogenic backgrounds:

Cosmic rays and secondary reactions Activation products in shields and detectors

Radiogenic backgrounds:

External natural radioactivity: walls, structures of site, radon Internal radioactivity: shield and construction materials, detector contamination in manufacture, naturally occurring radio-isotopes in target material

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 27 / 56

slide-29
SLIDE 29

Dark Matter Direct Detection Indirect Detection

China JinPing Underground Laboratory (CJPL)

[Yue et al., arXiv:1602.02462]

Experiments: CDEX, PandaX

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 28 / 56

slide-30
SLIDE 30

Dark Matter Direct Detection Indirect Detection

Exclusion Limits for SI Scattering

[From J. Cooley’s talk (2017)]

Lower threshold Lighter target Fewer backgrounds More exposure Heavier target

Assuming isospin conservation (Gp = Gn) for SI scattering, we can treat protons and neutrons as the same species, “nucleons”

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 29 / 56

slide-31
SLIDE 31

Dark Matter Direct Detection Indirect Detection

Exclusion Limits for SI Scattering

[From J. Cooley’s talk (2017)]

Lower threshold Lighter target Fewer backgrounds More exposure Heavier target

Assuming isospin conservation (Gp = Gn) for SI scattering, we can treat protons and neutrons as the same species, “nucleons”

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 29 / 56

slide-32
SLIDE 32

Dark Matter Direct Detection Indirect Detection

Exclusion Limits for SD Scattering

CMSSM

[PICO coll., arXiv:1702.07666, PRL] [XENON1T coll., arXiv:1902.03234, PRL]

For SD scattering, specifjc detection material usually has very difgerent sensitivities to WIMP-proton and WIMP-neutron cross sections As there is no coherent enhancement for SD scattering, the sensitivity is lower than the SI case by several orders of magnitude

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 30 / 56

slide-33
SLIDE 33

Dark Matter Direct Detection Indirect Detection

DAMA/LIBRA Annual Modulation “Signal”

[Bernabei et al., arXiv:1308.5109, EPJC]

Highly radio-pure scintillating NaI(Tl) crystals at Gran Sasso, Italy Annual modulation signal observed over 14 cycles at 9.3σ signifjcance No background/signal discrimination

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 31 / 56

slide-34
SLIDE 34

Dark Matter Direct Detection Indirect Detection

DAMA/LIBRA Annual Modulation “Signal”

[XENON100 coll., arXiv:1207.5988, PRL]

Favored regions excluded by other direct detection experiments Highly radio-pure scintillating NaI(Tl) crystals at Gran Sasso, Italy Annual modulation signal observed over 14 cycles at 9.3σ signifjcance No background/signal discrimination

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 31 / 56

slide-35
SLIDE 35

Dark Matter Direct Detection Indirect Detection

Other Sources for DAMA/LIBRA Signal

The DAMA/LIBRA signal might be composed of neutrons liberated in the material surrounding the detector by two sources [Davis, arXiv:1407.1052, PRL] Atmospheric muons: fmux depends on the temperature of the atmosphere, peaked on June 21st Solar neutrinos: fmux depends on the distance between the Earth and the Sun, peaked on January 4th Objection: Klinger & Kudryavtsev, “muon-induced neutrons do not explain the DAMA data,” arXiv:1503.07225, PRL

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 32 / 56

slide-36
SLIDE 36

Dark Matter Direct Detection Indirect Detection

Further Test: SABRE Project

[From E. Barberio’s talk]

SABRE: Sodium iodide with Active Background REjection Complementary tests in both hemispheres: one part in Gran Sasso (Italy) and one part in Stawell (Australia) Developing low background scintillating NaI(Tl) crystals that exceed the radio-purity of DAMA/LIBRA A well‐shielded active veto to reduce internal and external backgrounds

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 33 / 56

slide-37
SLIDE 37

Dark Matter Direct Detection Indirect Detection

Low Mass Region

[CDEX-10, arXiv:1802.09016, PRL] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 34 / 56

slide-38
SLIDE 38

Dark Matter Direct Detection Indirect Detection

Near Future Prospect

[From A. Cottle’s talk (2017)] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 35 / 56

slide-39
SLIDE 39

Dark Matter Direct Detection Indirect Detection

Neutrino Backgrounds

[From J. Billard’s talk (2016)]

Direct detection experiments will be sensitive to coherent neutrino-nucleus scattering (CNS) due to astrophysical neutrinos [Billard et al., arXiv:1307.5458, PRD] Solar neutrinos

pp neutrinos: p + p → D + e+ + νe

7Be neutrinos:

e− + 7Be → 7Li + νe pep neutrinos: p + e− + p → D + νe

8B neutrinos: 8B → 8Be ∗ + e+ + νe

Hep neutrinos:

3He + p → 4He + e+ + νe

Atmospheric neutrinos Cosmic-ray collisions in the atmosphere Difguse supernova neutrino background (DSNB) All supernova explosions in the past history of the Universe

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 36 / 56

slide-40
SLIDE 40

Dark Matter Direct Detection Indirect Detection

Going beyond the Neutrino Floor

Diurnal modulation

Negative Ion Time Projection Chamber DRIFT experiment

[From J. Spooner’s talk (2010)]

Possible ways to reduce the impact of neutrino backgrounds: Reduction of systematic uncertainties on neutrino fmuxes Utilization of difgerent target nuclei [Ruppin et al., arXiv:1408.3581, PRD] Measurement of annual modulation [Davis, arXiv:1412.1475, JCAP] Measurement of nuclear recoil direction [O’Hare, et al., arXiv:1505.08061, PRD]

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 37 / 56

slide-41
SLIDE 41

Dark Matter Direct Detection Indirect Detection

Indirect Detection

Indirect detection looks for stable products (γ rays, cosmic rays, neutrinos) from dark matter annihilation or decay (if DM is not totally stable) in space

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 38 / 56

slide-42
SLIDE 42

Dark Matter Direct Detection Indirect Detection

Indirect Detection Experiments

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 39 / 56

slide-43
SLIDE 43

Dark Matter Direct Detection Indirect Detection

Dark Matter Source Function

Particle number per unit time per unit volume per unit energy interval of a stable species (γ, e±, ν, p, ¯ p, ···) produced from DM annihilation or decay: (Annihilation) Qann(x, E) = 〈σannv〉tot 2m2

χ

ρ2(x) ∑

i

Fi dN dE

  • i

(Decay) Qdec(x, E) = 1 τχmχ ρ(x) ∑

i

Bi dN dE

  • i

Astrophysics factors Particle physics factors ρ(x): DM mass density at the source position x (dN/dE)i: number per unit energy interval from a single event in the channel i 〈σannv〉tot: thermal average of the total annihilation cross section multiplied by the relative velocity between the two incoming DM particles Fi ≡ 〈σannv〉i/〈σannv〉tot: branching fraction of the annihilation channel i τχ ≡ 1/Γχ: mean lifetime of the DM particle Bi ≡ Γi/Γχ: branching ratio of the decay channel i

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 40 / 56

slide-44
SLIDE 44

Dark Matter Direct Detection Indirect Detection

γ rays from DM: Continuous Spectrum

dN/dEγ (GeV) Eγ (GeV)

µ+ µ− τ+τ− b b − Z0Z0

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102 10-2 10-1 100 101 102

Local Group of galaxies

DM pair annihilation or decay into e+e−, µ+µ−, τ+τ−, q¯ q, W +W −, Z0Z0, h0h0 ⇓ γ-ray emission from fjnal state radiation or particle decays Cut-ofg energy: mχ for DM annihilation mχ/2 for DM decay More promising to look at DM-dominated regions: Galactic Center Galactic halo dwarf galaxies clusters of galaxies

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 41 / 56

slide-45
SLIDE 45

Dark Matter Direct Detection Indirect Detection

γ-ray Observation of Dwarf Galaxies

101 102 103 104

DM Mass (GeV/c2)

10−27 10−26 10−25 10−24 10−23 10−22 10−21

σv (cm3 s−1)

b¯ b

4-year Pass 7 Limit 6-year Pass 8 Limit Median Expected 68% Containment 95% Containment

Thermal Relic Cross Section (Steigman et al. 2012)

101 102 103 104

DM Mass (GeV/c2)

10−27 10−26 10−25 10−24 10−23 10−22 10−21

σv (cm3 s−1)

τ +τ −

4-year Pass 7 Limit 6-year Pass 8 Limit Median Expected 68% Containment 95% Containment

Thermal Relic Cross Section (Steigman et al. 2012)

[Fermi-LAT coll., 1503.02641, PRL]

The space experiment Fermi-LAT searched for γ-ray emission from dwarf spheroidal satellite galaxies of the Milky Way and found no signifjcant signal Based on the 6-year data, upper limits on DM annihilation cross section are given

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 42 / 56

slide-46
SLIDE 46

Dark Matter Direct Detection Indirect Detection

GeV Excess at the Galactic Center?

[Daylan et al., 1402.6703, PDU]

Since 2009, several groups reported an excess of continuous spectrum γ-rays in the Fermi-LAT data after subtracting well-known astrophysical backgrounds, locating in the Galactic Center (GC) region and peaking at a few GeV Left: raw γ-ray maps Right: residual maps after subtracting the Galactic difguse model, 20 cm template, point sources, and isotropic template →

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 43 / 56

slide-47
SLIDE 47

Dark Matter Direct Detection Indirect Detection

Interpretation with Dark Matter Annihilation

DM annihilation into b¯ b mχ ≃ 30 − 40 GeV 〈σannv〉 ∼ 10−26 cm3 s−1 DM annihilation into τ+τ− mχ ∼ 9 GeV 〈σannv〉 ∼ 5 × 10−27 cm3 s−1

20 40 60 80 100 1026 1025

MDM GeV Σ v cm3 s1

KRA, gNFW Γ 1.26

b Χmin

2 dof 1.44

  • 100

101 102 1. 0. 1. 2. 3. 4.

EΓ GeV 106 EΓ

2 ddEΓd GeV cm2 s1 sr1

MDM 37.8 GeV Σ v 2.10 1026 cm3s1

5 10 15 20 25 30 1026 1025

MDM GeV Σ v cm3 s1

KRA, gNFW Γ 1.26

BRΤ 100 Χmin

2 dof 3.4

BRΜ 0 BRe 0

  • 100

101 102 1. 0. 1. 2. 3. 4.

EΓ GeV 106 EΓ

2 ddEΓd GeV cm2 s1 sr1

MDM 8 GeV Σ v 6.96 1027 cm3s1

[Cirelli et al., arXiv:1407.2173, JCAP] Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 44 / 56

slide-48
SLIDE 48

Dark Matter Direct Detection Indirect Detection

γ rays from DM: Line Spectrum

χ ¯ χ γ γ DM particles should not have electric charge and thus not directly couple to photons ⇓ DM particles may couple to photons via high order loop diagrams ⇓ Highly suppressed: branching fraction may be only ∼ 10−4 − 10−1 For nonrelativistic DM particles in space, the photons produced in would be mono-energetic A

  • ray line at energy

(“smoking gun” for DM particles)

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 45 / 56

slide-49
SLIDE 49

Dark Matter Direct Detection Indirect Detection

γ rays from DM: Line Spectrum

χ ¯ χ γ γ DM particles should not have electric charge and thus not directly couple to photons ⇓ DM particles may couple to photons via high order loop diagrams ⇓ Highly suppressed: branching fraction may be only ∼ 10−4 − 10−1 For nonrelativistic DM particles in space, the photons produced in χχ → γγ would be mono-energetic ⇓ A γ-ray line at energy ∼ mχ (“smoking gun” for DM particles)

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 45 / 56

slide-50
SLIDE 50

Dark Matter Direct Detection Indirect Detection

A γ-ray Line Signal at the Galactic Center?

5 10 15 20 25 30 35 40

Counts p-value=0.85, χ 2

red =14.3/21

Signal counts: 53.4 (4.26σ) 80.5 - 208.5 GeV Reg3 (ULTRACLEAN), Eγ =129.6 GeV

100 150 200

E [GeV]

  • 10

10

Counts - Model

[Weniger, 1204.2797, JCAP]

Residual map

180 90

  • 90
  • 180
  • 90
  • 45

45 90

  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2.5

  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2.5

keV cm-2 s-1 sr-1

[Su & Finkbeiner, 1206.1616]

Using the 3.7-year Fermi-LAT γ-ray data, several analyses showed that there might be evidence of a monochromatic γ-ray line at energy ∼ 130 GeV,

  • riginating from the Galactic center region (about 3 − 4σ)

It may be explained by DM annihilation with 〈σannv〉 ∼ 10−27 cm3 s−1

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 46 / 56

slide-51
SLIDE 51

Dark Matter Direct Detection Indirect Detection

Fermi-LAT Offjcial Results: Not Confjrmed with More Data

Events / 5.0 GeV

10 20 30 40 50 60 70

= 133.0 GeV

γ

P7_REP_CLEAN R3 2D E = 17.8 evts

sig

n σ = 3.3

local

s = 276.2 evts

bkg

n = 2.76

bkg

Γ (c) Energy (GeV)

60 80 100 120 140 160 180 200 220

) σ

  • Resid. (
  • 4
  • 2

2 4

[Fermi-LAT Coll., 1305.5597, PRD]

3.7 years 3.7-year data The most signifjcant fjt occurred at Eγ = 133 GeV and had a local signifjcance of 3.3σ, translating to a global signifjcance of 1.6σ 5.8-year data The local signifjcance has dropped to

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 47 / 56

slide-52
SLIDE 52

Dark Matter Direct Detection Indirect Detection

Fermi-LAT Offjcial Results: Not Confjrmed with More Data

Events / 5.0 GeV

10 20 30 40 50 60 70

= 133.0 GeV

γ

P7_REP_CLEAN R3 2D E = 17.8 evts

sig

n σ = 3.3

local

s = 276.2 evts

bkg

n = 2.76

bkg

Γ (c) Energy (GeV)

60 80 100 120 140 160 180 200 220

) σ

  • Resid. (
  • 4
  • 2

2 4

[Fermi-LAT Coll., 1305.5597, PRD]

3.7 years

Events / ( 5.0 GeV )

20 40 60 80 100 120 140

P8_CLEAN R3 5.8 yr = 133.0 GeV

γ

E = 2.47

bkg

Γ ) σ = 7.3 evts (0.7

sig

n 30 evts ± = 700

bkg

n Energy (GeV)

40 60 80 100 120 140 160 180 200 220

) σ Residual(

  • 2

2

[Fermi-LAT Coll., 1506.00013, PRD]

5.8 years 3.7-year data The most signifjcant fjt occurred at Eγ = 133 GeV and had a local signifjcance of 3.3σ, translating to a global signifjcance of 1.6σ 5.8-year data The local signifjcance has dropped to 0.72σ

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 47 / 56

slide-53
SLIDE 53

Dark Matter Direct Detection Indirect Detection

Neutrinos from DM

Dark matter may be captured and accumulated at the core of the Sun (or the Earth ), producing high energy neutrinos that could freely go out Change Rate of the number of DM particles in the Sun: dNχ dt = C⊙(σχH,σχHe) + A⊙(σann)N 2

χ

Capture rate C⊙ depends on DM scattering on Hydrogen and Helium Annihilation rate A⊙ = 〈σann〉/Veff depends on DM annihilation as well as the efgective volume of the solar core The age of the Sun is long enough (∼ 4.6 billion years) to make the capture and annihilation processes reach equilibrium: dNχ/dt = 0

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 48 / 56

slide-54
SLIDE 54

Dark Matter Direct Detection Indirect Detection

IceCube: South Pole Neutrino Observatory

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 49 / 56

slide-55
SLIDE 55

Dark Matter Direct Detection Indirect Detection

Searches for Neutrinos from DM Annihilation within the Sun

[IceCube Coll, 1612.05949, EPJC]

No signal detected in searches for neutrinos with energies of GeV − TeV from DM annihilation at the solar core Assuming equilibrium in the capture and annihilation processes, the constraints can be converted to those on the DM scattering cross section

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 50 / 56

slide-56
SLIDE 56

Dark Matter Direct Detection Indirect Detection

Cosmic Rays from DM

R R=20 kpc h=0.1 kpc r L=3-10 kpc =8.0 kpc z (axial symmetry around z)

R 0.6

( B )

β + β- R

  • 2.2
  • (H+He+...) ISM

(p,He)

Spallation

V1 V2 p1 p2 Þ1 Þ2

(Halo+Disc) (Disc) (Disc) (Halo+Disc) Diffusion on magnetic inhomogeneities Acceleration by shock waves ß disintegration Energy losses Reacceleration : Va

N

j

N l N k Z,A Z’,A’

(A,Z) (A,Z+1) (A,Z-1)

Vc Vc

Ec/n Ec/n

(Disc) (Disc)

[Maurin et al., astro-ph/0212111]

After produced in sources, Galactic cosmic rays difguse in the interstellar space, sufgering from several propagation efgects before they arrive at the Earth: difgusion, energy losses, convection, reacceleration, spallation, ··· Unlike γ rays and neutrinos, cosmic rays typically do not contain direction information of their sources

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 51 / 56

slide-57
SLIDE 57

Dark Matter Direct Detection Indirect Detection

Cosmic Ray Propagation Equation

The propagation equation for Galactic cosmic rays is ∂ ψ ∂ t = Q(x, p) + ∇ · (Dx x∇ψ − Vcψ) + ∂ ∂ p

  • p2Dpp

∂ ∂ p ψ p2

  • − ∂

∂ p

  • ˙

pψ − p 3(∇ · Vc)ψ

  • − ψ

τf − ψ τr ψ = ψ(x, p, t) : cosmic ray density per momentum interval Q(x, p) : cosmic ray source term Dx x : spatial difgusion coeffjcient Dpp : difgusion coeffjcient in the momentum space for reacceleration Vc : convection velocity ˙ p ≡ dp/dt : momentum loss rate τf : fragmentation time scale τr : radioactive decay time scale Numerical tools GALPROP: https://galprop.stanford.edu DRAGON: https://github.com/cosmicrays/DRAGON

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 52 / 56

slide-58
SLIDE 58

Dark Matter Direct Detection Indirect Detection

Cosmic-ray Positron Excess

[PAMELA Coll., 0810.4995, Nature] [AMS Coll., PRL 110, 141102 (2013)]

In 2008, the PAMELA experiment found an unexpected increase in the cosmic-ray positron fraction with E ≳ 10 GeV In 2013, the AMS-02 experiment confjrmed such a positron excess

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 53 / 56

slide-59
SLIDE 59

Dark Matter Direct Detection Indirect Detection

Interpretation: Dark Matter vs Pulsar

10-2 10-1 100 100 101 102 103 e+/(e-+e+) E (GeV) bkg dm total 10-2 10-1 100 100 101 102 103 e+/(e-+e+) E (GeV) AMS HEAT94+95 HEAT00 PAMELA AMS-02

[Yuan, Bi, et al., 1304.1482, APP]

e+/(e−+ e+) E (GeV) AMS HEAT94+95 HEAT00 PAMELA AMS02 Total Bkg Geminga 10-2 10-1 100 100 101 102 103

[Yin, ZHY, Yuan, Bi, 1304.4128, PRD]

Interpretation with Galactic DM annihilation into τ+τ− Interpretation with the nearby pulsar Geminga

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 54 / 56

slide-60
SLIDE 60

Dark Matter Direct Detection Indirect Detection

First Result from DAMPE

[DAMPE Coll., 1711.10981, Nature]

In November 2017, DAMPE (悟空) collaboration released their fjrst measurement of the cosmic-ray spectrum of electrons and positrons This measurement found a spectral break at ∼ 0.9 TeV

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 55 / 56

slide-61
SLIDE 61

Dark Matter Direct Detection Indirect Detection

Summary 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 Although several anomalous observations have been found in direct and indirect searches, there is no absolutely solid DM detection signal so far DM detection sensitivities are being improved quickly; it is very promising to detect robust DM signals in the near future

Thank you!

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 56 / 56

slide-62
SLIDE 62

Dark Matter Direct Detection Indirect Detection

Summary 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 Although several anomalous observations have been found in direct and indirect searches, there is no absolutely solid DM detection signal so far DM detection sensitivities are being improved quickly; it is very promising to detect robust DM signals in the near future

Thank you!

Zhao-Huan Yu (SYSU) Direct and Indirect Detection of Dark Matter June 2019 56 / 56