gamma rays from simple dark matter...

Gamma Rays from Simple Dark Matter Models

Michel H.G. TytgatUniversité Libre de Bruxelles

Belgium

IPM school and conference on Particle Physics (IPP15)Neutrino physics, dark matter and B-physicsTeheran, Iran, 31 August - 11 September 2015

I. VECTOR LIKE PORTAL

II. HEAVY MINIMAL DARK MATTER

Based on:

F. Giacchino, L. Lopez Honorez, M.T, arXiv:1307.6480 & arXiv:1405.6921A. Ibarra, F. Giacchino, L.Lopez Honorez, M.T, S. Wild, to appear

Based on:

C. Garcia-Cely, A. Ibarra, A. Lamperstorfer, M.T., arXiv:1507.05536

SM

SM

DM

DM

indirect detection(annihilation into gamma rays, neutrinos, antimatter, etc)

POSSIBLE TEST OF THE WIMP HYPOTHESIS

FERMI-LAT (gamma-ray space telescope)

Q: do you have strong chromostereopsis?

DM

DM

γ

γ

1. no astrophysical counterparts

2. MDM ~ Eγ

IDEAL INDIRECT SIGNATURES OF DM

➙

Annihilation into two mono-energetic gamma rays!

HESS collaborationPhys.Rev.Lett. 110 (2013) 041301

FERMI-LAT + HESS limits on gamma ray lines

CURRENT EXPERIMENTAL LIMITS

WMAP/Planck

ASTROPHYSICAL BACKGROUND

MORE GENERALLY, GAMMA RAY SPECTRAL FEATURES

VIRTUAL INTERNAL BREMSSTRAHLUNG

if peaks for

S

S

Ψf

f

Eγ ∼MShence

if peaks for

Eγ ∼MS

Eγ/MS

I. THE VECTOR-LIKE PORTAL

L ⊃ yl S Ψ lR + h.c.

Z2 symmetry

real singlet scalar vector-like charged lepton

S dark matter

We call it the Vector-like Portal following P. Fileviez Perez, M.B. Wise, arXiv:1303.1452

SM light lepton

ANNIHILATION CROSS SECTION

The annihilation cross section is d-wave in chiral limit(I don’t know of another instance. Do you?)

Takashi TomaarXiv:1307.6181Giacchino, Lopez Honorez & M.T. arXiv:1307.6480

r =MΨ

MS> 1

The annihilation cross section is d-wave in chiral limit(I don’t know of another instance. Do you?)

Takashi TomaarXiv:1307.6181Giacchino, Lopez Honorez & M.T. arXiv:1307.6480

r =MΨ

MS> 1

rχ =MΨ

Mχ> 1

Goldberg «Constraint on the Photino mass from cosmology»Phys.Rev.Lett. 50 (1983) 1419

As is well-known, Majorana annihilation is p-wave

ANNIHILATION CROSS SECTION

σv(χχ→ ll) =y4

l

48π

v2

M2χ

1 + r4χ

(1 + r2χ)4

S-WAVE INITIAL STATE FINAL STATE

➙S-WAVE ANNIHILATIONIS MASS SUPPRESSED


χ χ

Os−wave = mf χγ5χ ψfγ5ψf

σv ∝ y4f

m2f

M4χ➙

1S0(0−+)ψfγ5ψf

|S = 0� =12

(| ↓�| ↑� − | ↑�| ↓�)

2S+1LJ(JPC) =

chiral coupling

A DIGRESSIONANNIHILATION OF MAJORANA DM

INTO LIGHT SM FERMIONS

f f

P-WAVE INITIAL STATE FINAL STATE

σv ∝ y4f

v2

M2χ

➙P-WAVE IN CHIRAL LIMIT


3P1(1++)

χ χ

ψfγkγ5ψf

A DIGRESSIONANNIHILATION OF MAJORANA DM

INTO LIGHT SM FERMIONS

f f

S-WAVE INITIAL STATE FINAL STATE

D-WAVE INITIAL STATE FINAL STATE

OT = ∂µS∂νS ΘµνfR

FERMIONSTRESS-ENERGY TENSOR

OS = mf S2 ψfψf

S S1S0(0++)

➙

S S1D2(2++) Θij =

i

2ψf (γi−→∂ j − γj←−∂ i)ψf

d-wavein chiral limit ➙

ψfψf

chirally suppressed

REAL SCALAR IS D-WAVE. WHY?

f

f

f

f

2-BODY DM ANNIHILATION SUPPRESSED AT GC

NO INDIRECT DETECTION?

YES, LOOK FOR RADIATIVE CORRECTIONS!

power of and phase-space suppressed, but s-wave

�v2� ≈ 0.3

v ∼ 10−3GALACTIC CENTRE

EARLY UNIVERSE

α

MONOCHROMATIC GAMMA RAYS

VIB

Takashi TomaarXiv:1307.6181Giacchino, Lopez Honorez & M.T.arXiv:1307.6480

Barger, Keung & MarfatiaarXiv:1111.4523 x =

Eγ

MDM

r =MΨ

MS> 1

Same for scalar & Majorana!

σ(SS → ffγ)σ(χχ→ ffγ)

=8y4

l

g4l

SAME BUT CROSS SECTION DIFFER BY A FACTOR OF 8

while

huge enhancement of VIB for scalar DMw.r.t. Majorana DM

Takashi TomaarXiv:1307.6181Giacchino, Lopez Honorez & M.T.arXiv:1307.6480

➙

�σv�(SS → ff)�σv�(χχ → ff)

< 0.16y4

l

g4l

VIB ENHANCED

2-BODY SUPPRESSED

σvffγ

�σv�ff

r = M/MDM

O(100) to O(1000)enhancement

�v� = 0.3

VIB ENHANCEMENT

SCALARMAJORANA

Giacchino, Lopez Honorez & M.T.arXiv:1307.6480See alsoTakashi Toma, arXiv:1307.6181Ibarra, Toma, Totzauer & Wild, arXiv:1405.6917

Ibarra, Toma, Totzauer & WildarXiv:1405.6917

Ibarra, Toma, Totzauer & WildarXiv:1405.6917

CURRENT CONSTRAINTS FUTURE (CTA) CONSTRAINTS

L ⊃ yl S Ψ lR + h.c. A SINGLET SCALAR WITH VL LEPTONS

L ⊃ yq S ΨqR + h.c.

~ 40 (up-like quarks)

~ 150 (down-like quarks)

➙ABUNDANCE FROM

GLUON BREMSSTRAHLUNG and DI-GLUONS

+ DIRECT DETECTION + CONSTRAINTS FROM CR ANTI-PROTONS

+ LHC constraintsetc...

WHAT’S NEXT? A POSSIBLE EXTENSION

THE SAME WITH VL QUARKS

EVEN IN EARLY UNIVERSE

Work in progress, in collaboration with S. Wild, L. Lopez Honorez, F. Giacchino & A. Ibarro

�σv�qq � �σv�qqg

Work in progress, in collaboration with S. Wild, L. Lopez Honorez, F. Giacchino & A. Ibarro

Nice interplay between Direct & Indirect Detection and Collider Searches

Now I discuss DM candidates that are beyond the reach of DD and LHC

VLP

HEAVY MDM

II. HEAVY MINIMAL DARK MATTER

Cirelli, Fornengo, StrumiaarXiv:hep-ph/0512090

Inert Doublet

Wino-like

5-plet7-plet

Dirac Neutrino

*(χχχH†H)

Λ ∼ 1015GeV

Mχ ∼ TeVτχ ∼ 10−8s χ −→ −χ

Z2

Di Luzio, R. Grober, J. F. Kamenik, and M. Nardecchia, arXiv:1504.00359

7⊗ 7⊗ 7 = . . .⊕ 3S ⊕ . . . . . .

O5 =1Λ

(χ37)

a(H†τ

aH)

5-plet is naturally stable, not the 7-plet *

∆�Mχ

VIB must be important

In principle, we may determine the relic abundance,assuming thermal freeze-out, which would point to a

specific DM mass

Instead we considered the flux of gamma-rays for a range of possible masses (ie do not assume thermal FO)

and set constraints on the 5-plet (7-plet) abundance (from HESS and the future CTA)

Calculating the gamma-ray flux is complex because of the Sommerfeld effect

Furthermore we took into account VIB

Garcia-Cely, Ibarra, Lamperstorfer, M.T. (2015)

For the fermionic 5-plet, see Cirelli, Hambye, Panci, Sala, Taoso, arXiv:1507.05519

Sommerfeld effect (in brief)

DM annihilation is a NR process (relative v ~ 10-3)A light mediator may enhance/decrease the annihilation cross section

with

(massless mediator)attractive repulsive

V (r) =α

r

σv → S(α/v)σv

S (α/v) =πα/v

exp (πα/v)− 1

S

α/v

∝ |α|v

σv

Sommerfeld effect (in brief)Relevant if (a fortiori if intermediate charged particles)

Physics more transparent in SU(2)L x U(1) symmetric limit

T a2

with

e.g. singlet channel always attractive (higher isospin always repulsive)

γ, W, Z

DM, DM±, DM2±, . . .

V (r) =g2

rT1 · T2 ≡

g2

2r

�T 2 − T 2

1 − T 22

�

T = T1 ⊕ T2

W a

T a1

mdm � mW,Z

V (5)T=0 = −6

g2

rV (5)

T=2 = −3g2

rV (5)

T=4 = +4g2

r

In practice, especially for signals from the GC,

mass splitting (which lead to mixing between isospin eigenstates) and gauge bosons masses must be taken

into account!

One needs to solve a system of coupled Schroedinger equations. This turns out to be delicate.

Sommerfeld leads to peaks and dips in the annihilation cross sections

Strumia, Cirelli & Tambirini (2007)

Garcia-Cely, Ibarra, Lamperstorfer, M.T. arXiv:1507.05536See also Cirelli, Hambye, Panci, Sala, Taoso, arXiv:1507.05519

Components are nearly degenerate. We show that VIB is important, i.e. an O(100%) correction


Components are nearly degenerate. We show that VIB is important, i.e. an O(100%) correction!


HESS

CTA (artistic view)

300 GeV-30 TeV1° circle around GCwith |b|>0.3°

ΔE/E ~20-10%

10’s GeV-100 TeV ΔE/E ~10%

HESS LIMITS

HESS LIMITS

thermalDMVIB+LINES

SOFT

LINES ONLY (dashed)


HESS LIMITS

thermalDM

VIB+LINES

LINES ONLY (dashed)

HESS LIMITS

HESS LIMITS vs CTA FORECAST

CTA

HESS

assuming112 hoursexposure

&same region

as HESS

HESS LIMITS vs CTA FORECAST

CTA

HESS

thermal DM

I DISCUSSED SIMPLE MODELS (here VLP & MDM)WITH STRONG

GAMMA RAY FEATURES

INTERESTING BENCHMARK MODELS FOR CURRENT & FUTURE

GAMMA RAY OBSERVATORIES

FERMI-LAT (gamma-ray space telescope)

Q: do you have chromostereopsis?

gamma rays from simple dark matter...

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