gamma rays from simple dark matter...
TRANSCRIPT
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