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

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

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

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

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

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

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

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

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)

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

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

BCKUP

FERMI-LAT (gamma-ray space telescope)

Q: do you have chromostereopsis?