Zhao-Huan YU (余钊焕yzhxxzxy.github.io/slides/1312_DM_cld_search.pdf · (highly suppressed, the...

$: Zhao-Huan YU (余钊焕yzhxxzxy.github.io/slides/1312_DM_cld_search.pdf · (highly suppressed, the branching fraction may be only ˘ 10 4 10 1) For nonrelativistic DM particles, the$
. . . . . . . .Dark matter

. . . . . .Collider detection

. . . . . . . . . . .Monophoton signature

. . . . . .Mono-Z signature

. .Conclusions

Dark matter searches at high energy colliders

Zhao-Huan YU (余钊焕)

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

December 13, 2013

Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 1 / 34

. . . . . . . .Dark matter




. .Conclusions

Dark matter

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.


. . . . . . . .Dark matter




. .Conclusions

Dark matter

Different kinds of DM detections

DMDM

SMSM

Unknownphysics

Direct detection

Inirectdetection

Colliderdetection


. . . . . . . .Dark matter




. .Conclusions

Direct detection

DM direct detection

Detect recoil signals of nuclei scattered by DM particles(photons, phonons, ionization)

Work underground to reduce cosmic ray backgrounds


. . . . . . . .Dark matter




. .Conclusions

Direct detection

Direct detection results (spin independent)

]2WIMP Mass [GeV/c6 7 8 910 20 30 40 50 100 200 300 400 1000

]2W

IMP-

Nuc

leon

Cro

ss S

ectio

n [c

m

-4510

-4410

-4310

-4210

-4110

-4010

-3910

]2WIMP Mass [GeV/c6 7 8 910 20 30 40 50 100 200 300 400 1000

]2W

IMP-

Nuc

leon

Cro

ss S

ectio

n [c

m

-4510

-4410

-4310

-4210

-4110

-4010

-3910

]2WIMP Mass [GeV/c6 7 8 910 20 30 40 50 100 200 300 400 1000

]2W

IMP-

Nuc

leon

Cro

ss S

ectio

n [c

m

-4510

-4410

-4310

-4210

-4110

-4010

-3910

DAMA/I

DAMA/Na

CoGeNT

CDMS (2010/11)EDELWEISS (2011/12)

XENON10 (2011)

XENON100 (2011)

COUPP (2012)

SIMPLE (2012)

ZEPLIN-III (2012)

CRESST-II (2012)

XENON100 (2012)observed limit (90% CL)

Expected limit of this run:

expectedσ 2 ± expectedσ 1 ±

⇐ XENON100, arXiv:1207.5988

mWIMP (GeV/c2)

WIM

P−nu

cleo

n cr

oss

sect

ion

(cm

2 )

101 102 103

10−45

10−44

6 8 10 12

10−44

10−42

10−40

LUX, arXiv:1310.8214 ⇒ LUX

XENON100


. . . . . . . .Dark matter




. .Conclusions

Indirect detection

DM indirect detection

Search for products from DM annihilation or decay


. . . . . . . .Dark matter




. .Conclusions

Indirect detection

Indirect detection experiments


. . . . . . . .Dark matter




. .Conclusions

Indirect detection

Indirect detection results

10-2

10-1

100

100

101

102

103

e+/(

e- +

e+)

E (GeV)

bkgdm

total

10-2

10-1

100

100

101

102

103

e+/(

e- +

e+)

E (GeV)

AMSHEAT94+95

HEAT00PAMELAAMS-02

AMS-02 positron fraction interpretedby the DM annihilation into τ+τ−

[Yuan, Bi, et al., arXiv:1304.1482]

e+/(

e−

+ e

+)

E (GeV)

AMSHEAT94+95HEAT00PAMELA

AMS02TotalBkgGeminga

10-2

10-1

100

100

101

102

103

AMS-02 positron fraction interpretedby the nearby pulsar Geminga[Yin, ZHY, Yuan, Bi, arXiv:1304.4128]


. . . . . . . .Dark matter




. .Conclusions

Indirect detection

10−22

10−23

10−24

10−25

10−26

〈σv〉(

cm3

s−1)

e+e−

Observed Limit

Median Expected

68% Containment

95% Containment

10−22

10−23

10−24

10−25

10−26

〈σv〉(

cm3

s−1)

µ+µ−

101 102 103

Mass (GeV/c2)

10−22

10−23

10−24

10−25

10−26

〈σv〉(

cm3

s−1)

τ+τ−

uu

bb

101 102 103

Mass (GeV/c2)

W+W−

Fermi γ-ray observations on15 dwarf spheroidal satellitegalaxies of the Milky Wayhas set strict constraints onDM annihilations.

Reach down to the canonicalannihilation cross section ofthermal produced dark mat-ter (∼ 3× 10−26 cm3 s−1).

[arXiv:1310.0828]


. . . . . . . .Dark matter




. .Conclusions

Colliders

Past and current hadron colliders

TEVATRON: pp collider(Fermilab, 1987-2011)Circumference: 6.28 kmCollision energy: ps = 1.96 TeVLuminosity: ∼ 4.3× 1032 cm−2 s−1

Detectors: CDF, D;

LHC: pp collider (also pPb, PbPb)(CERN, 2009-)Circumference: 26.659 kmCollision energy: ps = 7, 8, 13, 14 TeVLuminosity: ∼ 50−500×1032 cm−2 s−1

Detectors: ATLAS, CMS, ALICE, LHCb


. . . . . . . .Dark matter




. .Conclusions

Colliders

Future e+e− colliders

ILC: International Linear ColliderCollision energy:p

s = 250, 350, 500, 1000 GeVLuminosity: ∼ 75−500×1032 cm−2 s−1

Detectors: SiD, ILD

CEPC: Circular Electron-Positron Collider (China)Collision energy: ps ∼ 250 GeV

CLIC: Compact Linear ColliderCollision energy: ps ∼ 1− 3 TeV


. . . . . . . .Dark matter




. .Conclusions

DM searching at colliders

Particle identification in collider detectors

How about DM particles? Missing energy (/E or /ET)(similar to neutrinos)


. . . . . . . .Dark matter




. .Conclusions


DM searching channels at colliders.

......

g

g

bχ02

ℓ−

g qχ+

1 νℓ′

g

g

bb

qq′

ℓ+

ℓ−

χ01

χ01

νℓ′

ℓ′+

.

......

q

q

g

χ

χ

q

Social DMAccompanied by other new particles

Complicated decay chainsVarious final states(jets+ leptons+ /ET, ...)

Maverick DMDM particle is the only new particle

reachable at the collision energyMono-X+ /E final states

(monojet, mono-γ, mono-W/Z , ...)

(Classified by Rocky Kolb)Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 13 / 34

. . . . . . . .Dark matter




. .Conclusions


Results from LHC

]2 [GeV/cχM1 10

210

310

]2

-Nucle

on C

ross S

ection [

cm

χ

-4610

-4410

-4210

-4010

-3810

-3610

-3410

-3210

-3010

-2810

-2710CMS 2012 Vector

CMS 2011 Vector

CDF 2012

XENON100 2012

COUPP 2012

SIMPLE 2012

CoGeNT 2011

CDMSII 2011

CDMSII 2010

CMS Preliminary = 8 TeVs

Spin Independent

-1L dt = 19.5 fb∫

2Λ

q)µγq)(χ

µγχ(

]2 [GeV/cχM1 10

2103

10

]2

-Nu

cle

on

Cro

ss S

ectio

n [

cm

χ

-4610

-4410

-4210

-4010

-3810

-3610

-3410

-3210

-3010

-2810

-2710CMS 2012 Axial Vector

CMS 2011 Axial Vector

CDF 2012

SIMPLE 2012

CDMSII 2011

COUPP 2012

-

W+

Super-K W-

W+IceCube W

CMS Preliminary = 8 TeVs

-1L dt = 19.5 fb∫

Spin Dependent

2Λ

q)5

γµγq)(χ5

γµ

γχ(

Constraints on DM-nucleon scattering cross section given by the CMSdark matter search in the monojet+ /ET final state with an integratedluminosity of ∼ 20 fb−1 at ps = 8 TeV

[CMS PAS EXO-12-048]Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 14 / 34

. . . . . . . .Dark matter




. .Conclusions


Expected sensitivity at the CEPC.

......

e

e−

e+

γ

χ

χ

e

e−

e+

χ

χ

γ

Oe =1Λ2 χΓχχ eΓee

Λ

(Ge

V)

mχ (GeV)

e+e

− collider, √s = 250 GeV

100 fb-1

1000 fb-1

Γχ = 1, Γe = 1

Γχ = γ5, Γe = γ5

Γχ = γ µ, Γe = γµ

Γχ = γ µγ5, Γe = γµγ5

0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100 120

< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

e+e

− collider, √s = 250 GeV

100 fb-1

1000 fb-1

Γχ = γ5, Γe = γ5

Γχ = γ µ, Γe = γµ

Fermi 4-year upper limit

10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

5 50 1 10 100

Expected sensitivities (3σ reaches) tointeractions between DM and electronsin the monophoton+ /E searchingchannel at the circular electron-positroncollider (CEPC)


. . . . . . . .Dark matter




. .Conclusions

γ-ray line spectrum

γ-ray emission from DM: line spectrum

In general, DM particles (χ) should not have electric chargeand not directly couple to photons

⇓DM particles may couple to photons via high order loop diagrams(highly suppressed, the branching fraction may be only ∼ 10−4− 10−1)

χ

χ

γ

γ

For nonrelativistic DM particles, thephotons produced in χχ → γγ would bemono-energetic

⇓A γ-ray line at energy ∼ mχ

(“smoking gun” for DM particles)


. . . . . . . .Dark matter




. .Conclusions


γ-ray emission from DM: line spectrum

In general, DM particles (χ) should not have electric chargeand not directly couple to photons

⇓DM particles may couple to photons via high order loop diagrams(highly suppressed, the branching fraction may be only ∼ 10−4− 10−1)

χ

χ

γ

γ For nonrelativistic DM particles, thephotons produced in χχ → γγ would bemono-energetic

⇓A γ-ray line at energy ∼ mχ

(“smoking gun” for DM particles)


. . . . . . . .Dark matter




. .Conclusions


A γ-ray line from the Galactic center region?

0

5

10

15

20

25

30

35

40

Counts

p-value=0.85, χ 2red=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

0

10

Counts - Model

Weniger, 1204.2797

Residual map

180 90 0 -90 -18000

-90

-45

0

45

90

00

-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 thatthere might be evidence of a monochromatic γ-ray line at energy∼ 130 GeV, originating from the Galactic center region (about 3− 4σ).It may be due to DM annihilation with

σannv�∼ 10−27 cm3 s−1.


. . . . . . . .Dark matter




. .Conclusions


(GeV)χm10 210

)-1 s3

95%

CL

Lim

it (c

mγγ

v>σ<

-3010

-2910

-2810

-2710

-2610

-25103.7 year R41 NFW Profile

Observed Upper LimitExpected LimitExpected 68% ContainmentExpected 95% Containment

Eve

nts

/ 5.0

GeV

0

10

20

30

40

50

60

70 = 133.0 GeVγP7_REP_CLEAN R3 2D E

= 17.8 evtssign

σ = 3.3 locals

= 276.2 evtsbkgn

= 2.76bkgΓ

(c)

Energy (GeV)60 80 100 120 140 160 180 200 220

)σR

esid

. (

-4-2024

Recently, the Fermi-LAT Collaboration has released its official spectralline search in the energy range 5− 300 GeV using 3.7 years of data.They did not find any globally significant lines and set 95% CL upperlimits for DM annihilation cross sections.Their most significant fit occurred at Eγ = 133 GeV and had a localsignificance of 3.3σ, which translates to a global significance of 1.6σ.

Fermi-LAT Collaboration, 1305.5597Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 18 / 34

. . . . . . . .Dark matter




. .Conclusions

Collider sensitivity

DM-photon interaction at e+e− colliders

χ

χ

γ

γ

⇒γ

e−

e+

χ

χ

γ

The coupling between DM particles and photons that induce theannihilation process χχ → γγ can also lead to the process e+e−→ χχγ.Therefore, the possible γ-ray line signal observed by Fermi-LAT may betested at future TeV-scale e+e− colliders.

DM particles escape from the detector⇓

Signature: a monophoton associating with missing energy (γ+ /E)Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 19 / 34

. . . . . . . .Dark matter




. .Conclusions


Effective operator approachIf DM particles couple to photons via exchanging some mediators whichare sufficiently heavy, the DM-photon coupling can be approximatelydescribed by effective contact operators.

For Dirac fermionic DM, consider OF =1

Λ3 χ iγ5χFµν Fµν :σannv�χχ→2γ ≃

4m4χ

πΛ6 , σ(e+e−→ χχγ)∼ s2

Λ6

Fermi γ-ray line signal ⇐⇒ mχ ≃ 130 GeV, Λ∼ 1 TeV

For complex scalar DM, consider OS =1

Λ2χ∗χFµν Fµν :

σannv�χχ∗→2γ ≃

2m2χ

πΛ4 , σ(e+e−→ χχ∗γ)∼ s

Λ4

Fermi γ-ray line signal ⇐⇒ mχ ≃ 130 GeV, Λ∼ 3 TeV


. . . . . . . .Dark matter




. .Conclusions


In the γ+ /E searching channel, the main background is e+e−→ ννγ:

e

Z0

e−

e+

ν

ν

γ

W

e

e−

e+

ν

ν

γ

W

W

e−

e+

ν

γ

ν

· · ·

Minor backgrounds: e+e−→ e+e−γ, e+e−→ τ+τ−γ, · · ·Simulation: FeynRules → MadGraph 5 → PGS 4

ILD-like ECAL energy resolution:∆E

E=

16.6%pE/GeV

⊕ 1.1%

Future e+e− colliders: ps = 250 GeV (“Higgs factory”),ps = 500 GeV (typical ILC), ps = 1 TeV (upgraded ILC & initial CLIC),ps = 3 TeV (ultimate CLIC)


. . . . . . . .Dark matter




. .Conclusions

Collider sensitivityd

σ /

θγ

(f

b /

de

gre

e)

θγ

e+e

− collider, √s = 500 GeV, γ + E ⁄

e+e

− → νν−γ

e+e

− → e

+e

−γFermionic DM

Scalar DM

10-2

10-1

100

101

102

0° 20° 40° 60° 80° 100° 120° 140° 160° 180°

dσ

/ p

Tγ (

fb /

Ge

V)

pTγ (GeV)

e+e


e+e

− → νν−γ

e+e

− → e

+e

−γFermionic DM

Scalar DM

10-2

10-1

100

101

102

0 50 100 150 200 250

dσ

/ m

mis

s

(fb

/ G

eV

)

mmiss = [ ( pe− + pe

+ − pγ )2 ]1/2

(GeV)

e+e


e+e

− → νν−γ

e+e

− → e

+e

−γFermionic DM

Scalar DM

10-2

10-1

100

101

102

0 100 200 300 400 500

Z0 pole

Cut 1 (pre-selection):Require a photon with Eγ > 10 GeVand 10◦ < θγ < 170◦Veto any other particle

Benchmark point: Λ = 200 GeV, mχ = 100 (50)GeV for fermionic (scalar) DM

Cut 2: Veto 50 GeV< mmiss < 130 GeV

Cut 3: Require 30◦ < θγ < 150◦

Cut 4: Require pγT >p

s/10


. . . . . . . .Dark matter




. .Conclusions


Cross sections and signal significances after each cutννγ e+e−γ Fermionic DM Scalar DMσ (fb) σ (fb) σ (fb) S/

pB σ (fb) S/

pB

Cut 1 2415.2 173.0 646.8 12.7 321.4 6.3Cut 2 2102.5 168.6 646.8 13.6 308.2 6.5Cut 3 1161.1 16.8 538.0 15.7 255.9 7.5Cut 4 254.5 1.9 520.7 32.5 253.9 15.8

Benchmark point: Λ = 200 GeV, mχ = 100 (50)GeV for fermionic (scalar) DM

Most of the signal events remaine+e−→ ννγ background: reduced by almost an order of magnitudee+e−→ e+e−γ background: only one percent survives

(ps = 500 GeV, 1 fb−1)


. . . . . . . .Dark matter




. .Conclusions

Collider sensitivityΛ

(G

eV

)

mχ (GeV)

Fermionic DM

√s = 250 GeV

√s = 500 GeV

√s = 1 TeV

√s = 3 TeV

102

103

104

5 50 500 10 100 1000

Fermi γ -ray line signal

Λ (G

eV

)

mχ (GeV)

Scalar DM

√s = 250 GeV

√s = 500 GeV

√s = 1 TeV

√s = 3 TeV

102

103

104

5 50 500 10 100 1000


< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

Fermionic DM

√s = 250 GeV

√s = 500 GeV

√s = 1 TeV

√s = 3 TeV

Fermi 3.7-year upper limit

10-35

10-34

10-33

10-32

10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

10-22

5 50 500 10 100 1000


< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

Scalar DM

√s = 250 GeV

√s = 500 GeV

√s = 1 TeV

√s = 3 TeV


10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

10-22

5 50 500 10 100 1000


Solid lines: 100 fb−1; dot-dashed lines: 1000 fb−1 (S/p

B = 3)[ZHY, Yin, Yan, arXiv:1307.5740]


. . . . . . . .Dark matter




. .Conclusions

Beam polarization

Beam polarizationFor a process at an e+e− collider with polarized beams,σ(Pe− , Pe+) =

14

�(1+ Pe−)(1+ Pe+)σRR+ (1− Pe−)(1− Pe+)σLL

+(1+ Pe−)(1− Pe+)σRL+ (1− Pe−)(1+ Pe+)σLR�

Positro

n p

ola

rization P

e+

Electron polarization Pe−

σ (e+e

− → νν

−γ ) [fb]

-1.0

-1.0

-0.5

0.0

0.5

1.0

-1.0 -0.5 0.0 0.5 1.0

8000

6000

4400

3000

2000

1200

750

500

500

Positro

n p

ola

rization P

e+


σ (e+e

− → χχ

−γ ) [fb], fermionic DM

-1.0

-1.0

-0.5

0.0

0.5

1.0

-1.0 -0.5 0.0 0.5 1.0

250

250

400

400

540

540

640

640700

700

800

800

940

940

1100

1100

Positro

n p

ola

rization P

e+


σ (e+e

− → χχ*γ ) [fb], scalar DM

-1.0

-1.0

-0.5

0.0

0.5

1.0

-1.0 -0.5 0.0 0.5 1.0

120

120

200

200

270

270

320

320350

350

400

400

470

470

550

550

▲ (Pe− , Pe+) = (0.8,−0.3) can be achieved at the ILC[ILC technical design report, Vol. 1, 1306.6327]


. . . . . . . .Dark matter




. .Conclusions

Beam polarization<

σa

nnv >

(c

m3 s

-1)

mχ (GeV)

Fermionic DM

Unpolarized, 200 fb-1


(Pe−, Pe

+) = (0.8, −0.3), 200 fb-1

(Pe−, Pe

+) = (0.8, −0.3), 2000 fb-1


10-33

10-32

10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

5 50 500 10 100 1000


√s = 1 TeV

< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

Scalar DM



(Pe−, Pe

+) = (0.8, −0.3), 100 fb-1

(Pe−, Pe

+) = (0.8, −0.3), 1000 fb-1


10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

5 50 500 10 100 1000


√s = 3 TeV

(S/p

B = 3)

Using the polarized beams is roughly equivalent to increasing theintegrated luminosity by an order of magnitude.

For fermionic DM (scalar DM), a data set of 2000 fb−1 (1000 fb−1)would be just sufficient to test the Fermi γ-ray line signal at an e+e−collider with ps = 1 TeV (3 TeV).

[ZHY, Yin, Yan, arXiv:1307.5740]


. . . . . . . .Dark matter




. .Conclusions

Mono-Z signature

Mono-Z signature: DM couplings to Z Z/Zγ

.

......

Z/γ

e−

e+

χ

χ

ZWe consider the following couplings:

OF1 =1

Λ31

χχBµνBµν +

1

Λ32

χχW aµνW

aµν

⊃ χχ(GZZZµνZµν + GAZAµνZµν)

OF2 =1

Λ31

χ iγ5χBµν Bµν +

1

Λ32

χ iγ5χW aµνW

aµν

⊃ χ iγ5χ(GZZZµν Zµν + GAZAµν Zµν)

OFH =1

Λ3 χχ(DµH)†DµH

→ m2Z

2Λ3 χχZµZµ

GZZ ≡ sin2 θW

Λ31

+cos2 θW

Λ32

GAZ ≡ 2sinθW cosθW

�1

Λ32

− 1

Λ31

�

The mono-Z channel at high energy e+e− collider can be sensitive tothe DM coupling to Z Z/Zγ.


. . . . . . . .Dark matter




. .Conclusions

Mono-Z signature

Mono-Z signature: DM couplings to electrons

.

......

e

e−

e+

Z

χ

χ

e

e−

e+

χ

χ

Z

This channel can also be sensitive to the DM coupling to electrons.

We consider the following couplings:

OFP =1

Λ2 χγ5χ eγ5e, OFA =1

Λ2 χγµγ5χ eγµγ5e


. . . . . . . .Dark matter




. .Conclusions

Event distributions

Lepton channel: Z → ℓ+ℓ− (ℓ= e,µ)

SM backgrounds: e+e−→ ℓ+ℓ−νν , e+e−→ τ+τ−, e+e−→ τ+τ−νν

Reconstructing the Z boson: require only 2 leptons (e’s or µ’s) withpT > 10 GeV and |η|< 3, and that they are opposite-sign same-flavor;require their invariant mass satisfying |mℓℓ−mZ |< 5 GeV.Reconstructing the recoil mass: mrecoil =

p(pe+ + pe− − pℓ1 − pℓ2)

2;veto the events with mrecoil < 140 GeV.


. . . . . . . .Dark matter




. .Conclusions

Event distributions

Lepton channel: Z → ℓ+ℓ− (ℓ= e,µ)D

iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mll (GeV)

e+e

− collider, √s = 500 GeV, ll + E ⁄

llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

SM backgrounds: e+e−→ ℓ+ℓ−νν , e+e−→ τ+τ−, e+e−→ τ+τ−ννReconstructing the Z boson: require only 2 leptons (e’s or µ’s) withpT > 10 GeV and |η|< 3, and that they are opposite-sign same-flavor;

require their invariant mass satisfying |mℓℓ−mZ |< 5 GeV.Reconstructing the recoil mass: mrecoil =

p(pe+ + pe− − pℓ1 − pℓ2)



. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mll (GeV)

e+e


llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

SM backgrounds: e+e−→ ℓ+ℓ−νν , e+e−→ τ+τ−, e+e−→ τ+τ−ννReconstructing the Z boson: require only 2 leptons (e’s or µ’s) withpT > 10 GeV and |η|< 3, and that they are opposite-sign same-flavor;require their invariant mass satisfying |mℓℓ−mZ |< 5 GeV.

Reconstructing the recoil mass: mrecoil =p(pe+ + pe− − pℓ1 − pℓ2)



. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mll (GeV)

e+e


llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

Diffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mrecoil (GeV)

e+e


llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

0 100 200 300 400 500

SM backgrounds: e+e−→ ℓ+ℓ−νν , e+e−→ τ+τ−, e+e−→ τ+τ−ννReconstructing the Z boson: require only 2 leptons (e’s or µ’s) withpT > 10 GeV and |η|< 3, and that they are opposite-sign same-flavor;require their invariant mass satisfying |mℓℓ−mZ |< 5 GeV.Reconstructing the recoil mass: mrecoil =

p(pe+ + pe− − pℓ1 − pℓ2)

2;

veto the events with mrecoil < 140 GeV.


. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mll (GeV)

e+e


llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

Diffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mrecoil (GeV)

e+e


llνν

ττ

ττνν

F1

F2

FH

FP

FA

10-5

10-4

10-3

10-2

10-1

100

0 100 200 300 400 500

SM backgrounds: e+e−→ ℓ+ℓ−νν , e+e−→ τ+τ−, e+e−→ τ+τ−ννReconstructing the Z boson: require only 2 leptons (e’s or µ’s) withpT > 10 GeV and |η|< 3, and that they are opposite-sign same-flavor;require their invariant mass satisfying |mℓℓ−mZ |< 5 GeV.Reconstructing the recoil mass: mrecoil =

p(pe+ + pe− − pℓ1 − pℓ2)



. . . . . . . .Dark matter




. .Conclusions

Event distributions

Hadron channel: Z → j j

SM backgrounds: e+e−→ j jνν , e+e−→ j jℓν , e+e−→ t t

Reconstructing the Z boson: require only 2 jets with pT > 10 GeV and|η|< 3; require their invariant mass satisfying 40 GeV< m j j < 95 GeV.

Reconstructing the recoil mass: mrecoil =p(pe+ + pe− − p j1 − p j2)



. . . . . . . .Dark matter




. .Conclusions

Event distributions

Hadron channel: Z → j jD

iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mjj (GeV)

e+e

− collider, √s = 500 GeV, jj + E ⁄

jjνν

jjlν

tt

F1

F2

FH

FP

FA

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600


Reconstructing the Z boson: require only 2 jets with pT > 10 GeV and|η|< 3;

require their invariant mass satisfying 40 GeV< m j j < 95 GeV.




. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mjj (GeV)

e+e


jjνν

jjlν

tt

F1

F2

FH

FP

FA

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600






. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mjj (GeV)

e+e


jjνν

jjlν

tt

F1

F2

FH

FP

FA

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

Fra

ctio

n o

f e

ve

nts

mrecoil (GeV)

e+e


jjνν

jjlν

tt

F1

F2

FH

FP

FA

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100

0 100 200 300 400 500




2;

veto the events with mrecoil < 200 GeV.


. . . . . . . .Dark matter




. .Conclusions

Event distributions


iffe

ren

tia

l cro

ss s

ectio

n (

fb /

Ge

V)

mjj (GeV)

e+e


jjνν

jjlν

tt

F1

F2

FH

FP

FA

10-4

10-3

10-2

10-1

100

101

0 100 200 300 400 500 600

Fra

ctio

n o

f e

ve

nts

mrecoil (GeV)

e+e


jjνν

jjlν

tt

F1

F2

FH

FP

FA

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100

0 100 200 300 400 500






. . . . . . . .Dark matter




. .Conclusions

Expected sensitivity

3σ sensitivity: DM couplings to Z Z/ZγΛ

(G

eV

)

mχ (GeV)

e+e

− collider, Operator F1

√s = 250 GeV, jj + E ⁄√s = 500 GeV, jj + E ⁄√s = 1 TeV, jj + E ⁄√s = 250 GeV, ll + E ⁄√s = 500 GeV, ll + E ⁄√s = 1 TeV, ll + E ⁄

101

102

103

5 50 500 1 10 100 1000

Λ

(Ge

V)

mχ (GeV)

e+e

− collider, Operator FH


101

102

5 50 500 1 10 100 1000

Λ

(Ge

V)

mχ (GeV)

e+e

− collider, Operator F2


101

102

103

5 50 500 1 10 100 1000

< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

χχ− → ZZ, Operator F2

√s = 500 GeV

√s = 1 TeV


10-29

10-28

10-27

10-26

10-25

10-24

10-23

10-22

10-21

10-20

500 100 1000

(with an integrated luminosity of 1000 fb−1, assuming Λ = Λ1 = Λ2 for OF1 and OF2)Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 31 / 34

. . . . . . . .Dark matter




. .Conclusions

Expected sensitivity

3σ sensitivity: DM couplings to electronsΛ

(G

eV

)

mχ (GeV)

e+e

− collider, Operator FP


101

102

103

5 50 500 1 10 100 1000

< σ

an

nv >

(c

m3 s

-1)

mχ (GeV)

χχ− → e+e

−, Operator FP

√s = 250 GeV

√s = 500 GeV

√s = 1 TeV


10-31

10-30

10-29

10-28

10-27

10-26

10-25

10-24

10-23

10-22

5 50 500 1 10 100 1000

Λ

(Ge

V)

mχ (GeV)

e+e

− collider, Operator FA


101

102

103

5 50 500 1 10 100 1000

(with an integrated luminosity of 1000 fb−1)Zhao-Huan YU (IHEP) Dark matter searches at high energy colliders Dec 2013 32 / 34

. . . . . . . .Dark matter




. .Conclusions

Conclusions and discussions

...1 As a frontier of cosmology, astrophysics, and particle physics, theresearch of dark matter connects our knowledge of the Universefrom the largest to the smallest scales.

...2 In addition to DM direct and indirect detection, collider detectionprovides an independent and complementary way to explore themicroscopic nature of DM particles.

...3 If there are other new particles accompanied with DM particles,collider detection is needed to acquire the most detailedinformation about the new physics containing DM particles.


. . . . . . . .Dark matter




. .Conclusions

Thanks for your attentions!


Zhao-Huan YU (余钊焕yzhxxzxy.github.io/slides/1312_DM_cld_search.pdf · (highly suppressed, the...

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Transcript of Zhao-Huan YU (余钊焕yzhxxzxy.github.io/slides/1312_DM_cld_search.pdf · (highly suppressed, the...