Closing in on mass-degenerate dark matter scenarios with ......Closing in on mass-degenerate dark matter scenarios with antiprotons and direct detection On the complementarity of direct

Closing in on mass-degenerate dark matterscenarios with antiprotons and direct detection

On the complementarity of direct and indirect detection

Stefan Vogl

with Mathias Garny (DESY), Alejandro Ibarra and Miguel Pato (TUM)to appear soon

S. Vogl (TU München) PASCOS 2012 8 June 2012 1 / 15

Outline

IntroductionParticle Physics FrameworkRelic DensityIndirect DetectionDirect DetectionResultsConclusion


Why consider compressed mass spectra?

Lets consider the case when the dark matter particle χ and the next to lightestbeyond the Standard Model particle η have a similar mass

∆m = mχ − mη . mχ.

Collidersminimal transverse momentum pT is required to distinguish jet

pT ≈ ∆m

low sensitivity to compressed mass spectra




∆m = mχ − mη . mχ.

thermal production

for mη

mχ

≈ 1.2 coannihilations become important




∆m = mχ − mη . mχ.

Indirect Detectioncompressed mass spectra exhibit very characteristic features

annihilation rates are enhanced for small ∆m

huge astrophysical uncertainties




∆m = mχ − mη . mχ.

Direct Detectionscattering rates are enhanced for small ∆m

less astrophysical uncertainties than in Indirect Detection

good experimental limits




∆m = mχ − mη . mχ.

Direct Detectionscattering rates are enhanced for small ∆m

less astrophysical uncertainties than in Indirect Detection

good experimental limits

But: We need to specify the model in order to compare observab les.


Particle Physics Framework

Begin with the SM and add news physics

ParticlesMajorana fermion χ as dark matter

a scalar η as the next to lightest beyond the Standard Model particle

Assign chargesχ is a singlet under SU(3)× SU(2) × U(1)

η is a triplet under SU(3) and (for simplicity) a singlet under SU(2)

u,d,s or b flavor quantum number for η

Interactionsa Yukawa interaction with the quarks: Lint = f χqRη


Particle Physics Framework

Begin with the SM and add news physics

ParticlesMajorana fermion χ as dark matter

a scalar η as the next to lightest beyond the Standard Model particle

Assign chargesχ is a singlet under SU(3)× SU(2) × U(1)

η is a triplet under SU(3) and (for simplicity) a singlet under SU(2)

u,d,s or b flavor quantum number for η

Interactionsa Yukawa interaction with the quarks: Lint = f χqRη

Notice: similar to SUSY with light squarks


thermal freeze outall particles are in thermal equilibrium in the early Universe

when temperature T ≪ mχ dark matter can’t be produced anymore→ dark matter freezes out


Coannihilations

for ∆mmχ

. 1.2 more particles need to be included in the Boltzmannequation

we use MicrOMEGAS for the calculation of the relic density

specifying mχ and ∆m yields constraint on f

Example: Coupling to u and mχ/mη = 1.1

100 200 500 1000 2000 5000 1 ´ 10410- 4

0.001

0.01

0.1

1

10

m Χ @GeVD

f

for mχ smaller that a certain scale the relic density can not be obtained


Majorana fermions annihilating into light quarks

thermally averaged cross section 〈σannv〉 can be expanded as

〈σannv〉 = a + bv2 +O(v4)

consider annihilations into quarks

s-wave annihilation is suppressed by chirality

〈σannv〉 ≈ a ≈m2

fm2

DM

p-wave suppressed by velocity

〈σannv〉 ≈ v2 ≈ 10−6


Lifting the chirality suppression

the suppression can be lifted by the emission of a boson, i.e. γ, W±, Z ora gluon

χ0

1u

η

g

η

χ0

1u

the fragmentation of the gluon increases the production of antiprotons


Constraints from Antiprotons

the p/p ratio measured by Pamela constrains σv

main uncertainty: halo model and cosmic ray propagation

Example: mη/mχ = 1.1

10−26

10−25

10−24

10−23

10−22

10−21

10−20

102 103 104

σv(χ

χ→

guu)[cm

3/sec]

mDM [GeV]

σv(χχ → guu)

MIN

MED

MAX

excluded fromPAMELA p/p

Isothermal

NFW

Einasto


Dark Matter Nucleon Scattering

dark matter nucleon scattering is induced microscopical by scattering ofquarks and gluons in the nucleus

χ

u

ηχ

u

interactions can be described in terms of effective Lagrangian

suppression scale Λ = m2η− (mχ + mq)

2

compressed spectrum → small Λ

recoil rate is enhanced

uncertainties: astrophysics (mainly neglected here) and composition ofthe nucleon


Putting everything together


The Direct Detection Planeu-couplingm Η�m Χ=1.1

therm al relicantiprotonsdirect detection

102 103 10410-46

10-45

10-44

10-43

10-42

10-41

10-40

m Χ @GeVD

Σp

SI@c

m2 D


The Indirect Detection Plane

100 200 500 1000 2000 5000 1 ´ 10410- 32

10- 30

10- 28

10- 26

10- 24

m Χ@GeVD

Σv@c

m3

s-1 D


Which constraint is strongest?


Conclusions

compressed mass spectra lead to enhanced signals for dark matterdetection experiments

probes region of parameter space inaccessible at colliders

direct detection experiments are cutting into the parameter space allowedby thermal production


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Documents

Closing in on mass-degenerate dark matter scenarios with ......Closing in on mass-degenerate dark matter scenarios with antiprotons and direct detection On the complementarity of direct