WIMP DM & g-ray observations

Shigeki Matsumoto (Kavli IPMU)

From recent various experimental & theoretical observations,
the WIMP dark matter seems to be a fermionic particle which
carries the weak isospin. This fact indicates that DM searchusing g-ray observations will be the most important one!!!

WIMP DM & direct detections

1/8～ WIMP (Weakly interacting massive particle) hypothesis ～DM is a neutral and stable particle whose mass is O(0.1-1)TeV!

It is consistent with DM cosmology.

It is consistent with Particle Phys.

・ Why is DM weakly interacting?
・ Why is DM cold in present Univ.?
・ Why is abundance WDMh2 ～ 0.1?

BSM for EWSB often predicts WIMP
candidate. Its mass and the scale ofthe EWSB can have the same origin!

Direct detection

Indirect detection
DMSM

Indirect detections put alimit as sv < 1-10 pb・c.
Collider experiments (LHC)
put a limit as s < 1-10 fb.

DMSM
Production @ colliders

Direct detections put a limit
stringently as s < 1-10 zb!

WIMP DM & direct detections

2/8

Direct detection experiments put stringent limits on the WIMP scattering offa nuclei, so that those already give an important implication to its property.

When WIMP has DM-DM-h coupling of O(1), current limits already ruled out it.
Scalar and Vector WIMP have a dimension
4 interaction inducing the O(1) coupling.
Fermionic WIMP has the O(1) couplingwhen its state is given by the mixingof different weak-isospin states.
↓The coupling is suppressed for Fermionic
WIMP close to a weak-isospin eigenstate.

LUX 2013

3/8Fermionic WIMPs
Scientific name

SU(3)cSU(2)LU(1)YExamples

Singlet fermionDoublet fermion
Triplet fermion 1Triplet fermion 2…

11
1
1…

12
3
3…

0½
0
1…

BinoHiggsino
Wino…

Fermionic WIMP (weak-isospin singlet)
The singlet WIMIP does not have any
renormalizable interactions coupling
to SM particles directly.
Additional new particles with theirmasses of O(mWIMP) must exist. Or mWIMP must be tuned enough. [S. M., S. Mukhopadhyay, Y-L. Tsai, 1405.1859]

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Fermionic WIMPs
Fermionic WIMP (weak-isospin non-singlet)

The non-singlet WIMIP always has renormalizable interactions coupling to SM
particles directly, the SU(2)L gauge interactions. Thermal relics are consistent
with the PLANCK result when its mass is 1-3TeV. [Hisano, S.M., et.al., PLB, 2007]
Is the WIMP relevant to AMS-02 anomaly?
The WIMIP is not necessarily to be absolute stable and it may decay into SM
particles via e.g. GUT suppressed interactions. [Ibe, S.M., Shirai, Yanagida, 2014]

L int = (1/LGUT)2 cLLEc  t ～ 10-27 (1TeV/m)5 (LGUT/1016 GeV)4 [s]Positron fraction

Favored mass region

Fermionic WIMPs

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The non-singlet WIMP is theoretically favoredThe minimal SUSY breaking model
MSSM

Split-type SUSY Spectrum

SUGRA interaction
SUSYNo-singlets →Pure Gravity Mediation Model[Ibe, Yanagida, Moroi, PLB, 2007]

Merits obtained from the model• Higgs mass of 125 GeV• DM candidate exist• GUT unification works• Leptogenesis works• No Flavor/CP problems• No gravitino problem• No Plonyi problem

The LSP is the neutral wino, namely SU(2)L-triplet Majorana fermion!

SU(2)L non-singlet fermionic WIMPs

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DM mass: mc ～ 1-3TeV & Scattering cross section sSI(cN) ～ 10-11pb.
Continuum & line g-rays from the WIMP• Wino annihilates mainly into W bosons, and W-decay produces continuum g.
• Thanks to the existence of charged wino, wino annihilates also into line g.
Sommerfeld effect of Wino annihilation
When the wino mass is heavier than O(1)TeV,annihilation cross sections of all channels
are significantly boosted by the Sommerfeldenhancement. [Hisano, S.M. Nojiri, PRL, 2004]
The effect can be understood by the effectof long range forces (exchanging W, Z, g )which modify the initial wino wave functions.

g-ray observations of the WIMPdSphggdSph: Continuum g-ray obs. at satellite born experiments (Fermi-LAT, etc.)
G.C. : Line g-ray obs. at air Cherenkov type experiments (H.E.S.S., CTA, etc.)
TimedSph data
Present 4yrs Only CL. dSphs
Near future 10yrs CL. & UF. dSphs
Future 25yrs Updated data
In addition to continuing dSph obs.,
it is important to upgrade stellar
kinematical data of dSphs!
↓PFS of the SuMIRe project!
[Ibe, Ichikawa, Ishigaki, S.M., Sugai][Bhattacherjee, Ibe, Ichikawa,S.M., Nishiyama, JHEP, 2014]

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Summary• 様々なスピン及び量子数を持つＷＩＭＰ暗黒物質候補の中で、弱アイソスピンを持つフェルミオン暗黒物質が現在とても注目されている。
• このＷＩＭＰ暗黒物質は、その質量が１－３ＴｅＶ当たりと予言され。また対消滅過程がSommerfeld効果により増大し、ガンマ線の連続スペクトル及び線スペクトルを強い強度で放出する。
• そのため衛星実験（Fermi-LAT）や空気チェレンコフ実験(H.E.S.S.やCTA等)を用いた矮小楕円体銀河（dSphs)や銀河中心（G.C.)の観測は、最も有効な暗黒物質の検出方法である。

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EFT for the singlet WIMP

DMCPV

H~HDM
DMDM

H~H~HDMHZ

Hf~fDMf・ Only the mass dimension 5 operator OPS breaks the CP-symmetry.

・ Flavor blindness is assumed for each 4-Fermi (mass dimension 6) operators.
・ The regions of the cutoff L > 10mDM and 10mDM > L > 2mDM are considered.