Gamma Rays from Simple Dark Matter Models Michel H.G. Tytgat Université Libre de Bruxelles Belgium IPM school and conference on Particle Physics (IPP15) Neutrino physics, dark matter and B-physics Teheran, Iran, 31 August - 11 September 2015
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
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
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
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
SCALARMAJORANA
Giacchino, Lopez Honorez & M.T.arXiv:1307.6480See alsoTakashi Toma, arXiv:1307.6181Ibarra, Toma, Totzauer & Wild, arXiv:1405.6917
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
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 *
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
thermalDMVIB+LINES
SOFT
LINES ONLY (dashed)
Garcia-Cely, Ibarra, Lamperstorfer, M.T. (2015)
I DISCUSSED SIMPLE MODELS (here VLP & MDM)WITH STRONG
GAMMA RAY FEATURES
INTERESTING BENCHMARK MODELS FOR CURRENT & FUTURE
GAMMA RAY OBSERVATORIES