The WIMP Hypothesis Today
Shigeki Matsumoto (Kavli IPMU)
Collaborators: Members in IPMU WIMP PROJECTThe WIMP hypothesis is now efficiently being tested by
the direct DM detection at under ground experiments.
✔ What kind of WIMP is now being ruled out?
✔ What kind of WIMP will be explored in near future?

✔ What kind of WIMP remain explored even in future?

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The WIMP hypothesis“Dark matter is a massive, stable and electrically neutral particle, andwas in a thermal equilibrium with SM particles in the early universe.”
From NeffWIMP dark matter

From unitarity

GeV
10 5

10 –3

There are many types of WIMP, depending on those quantum numbers.
 Classification of WIMP in terms of its spin and isospin!
After the WIMP spin fixed,WIMP

MixedSinglet-like

Weak-charged

We focus on fermionic WIMPs, for it is predicted in SUSY models!

Research strategy

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1. Constructing the minimal model in each WIMP quantum number(s).
The renormalizable one involving the least number of new fields.

2. Imposing all constraints on it & clarifying its present status.
From direct/indirect detections and lepton/hadron colliders.
MCMC scanning & Projecting the result on a appropriate plane.
3. Imposing near future-expected direct detection constraints.
2nd generation direct detections (LZ experiment) imposed.
Showing the result on the same plane as before for comparison.
4. Figuring out parameter regions not covered even in the future.
Judging whether or not the remaining regions are attractive.
Start considering what kind of experiments we need to cover it.

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Case mixed: Singlet-Doublets model
Typical WIMPin CMSSM[Z2 symmetry imposed]@ Present@ Near future

After LZ

[S. Banergee, S.M., K. Mukaida, Y-L Sming Tsai, JHEP (2016)]

Mixed WIMP ← Yukawa interactions → DM-DM-h(Z) couplings
The same conclusion holds for the most of mixed WIMPs.

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Case mixed: Singlet-Doublets model
Typical WIMPin CMSSM[Z2 symmetry imposed]@ Near future

Funnel regions@ Present

After LZ

[S. Banergee, S.M., K. Mukaida, Y-L Sming Tsai, JHEP (2016)]

Mixed WIMP ← Yukawa interactions → DM-DM-h(Z) couplings
The same conclusion holds for the most of mixed WIMPs.

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Case weak-charged: Triplet model
WIMP in the AMSB

3TeV

460GeV＆Favored

One of minimal DMs

Future LHC[Z2 symmetry imposed]@ Near Future[Sommerfeld effect: J. Hisano, S.M., M. Nojiri (2005-2017)]

Only indirect detection is possible to explore this DM in near future.
Refinement of the detection is required by updated astronomical data.

Case singlet-like with Heavy mediator

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Mediator particle must be introduced!

~[Simplified model involving all possible interactions reproducing above EFT is used.]@ Present

Light mediator regioncP = 0 & flavor blind 4-Fermi int.

BinoinMSSM@ Near future
After LZ

Light mediator region[S.M., S. Mukhopadhyay, Y-L Sming Tsai, (2014, 2016)]

Z-portal and leptophilic regions will remain unexplored in near future.
SD direct detection & lepton collider experiment play important role!

Case singlet-like with Heavy mediator

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Mediator particle must be introduced!

~@ PresentBinoinMSSM@ Near future
After LZ

4-FermiZ-funnelH-funnel[Simplified model involving all possible interactions reproducing above EFT is used.]

Light mediator regioncP = 0 & flavor blind 4-Fermi int.

Light mediator region[S.M., S. Mukhopadhyay, Y-L Sming Tsai, (2014, 2016)]

Z-portal and leptophilic regions will remain unexplored in near future.
SD direct detection & lepton collider experiment play important role!

Case singlet-like with Light mediator

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Light WIMP region!

[Scalar mediator case]@ PresentSinglino
inNMSSM@ Present＆[S.M., Y-L Sming Tsai, Po-Yan Tseng, (2017)]

Testing the scenario ← Light mediator → Physics of dark matter
For more details, go to the talk by Po-Yan Tseng this afternoon!

Summary

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Wide parameter regions are still there in all cases & should be explored!

Fermionic WIMP
Mixed

Singlet-likewill be tested + Heavy mediator
efficiently bydirect DM det,
will be tested
by high energy
lepton collider.

Weak-charged+ Light mediator will be tested
Many regions
will remain
unexplored.

by indirect DMdetections.

Backup (Classifying WIMPs)
After fixing its spin, the WIMP field is written by a linear combinationof colorless rep. of SU(2)L×U(1)Y involving a EM neutral component:

Singlet-like Patche.g.
Bino-like in SUSYKK photon in UED

Higgsino-like in SUSY
Inert Higgs in 2HDM

4½,
3

S-D Mixed Patche.g.
Bino-Higgsino WIMP

27…

D-T mixed Patche.g.
Higgsino-wino WIMP

Doublet-like Patch
e.g.

10

Triplet-like Patche.g.
Wino-like in SUSY
Quintet-like Patche.g.
Minimal dark matter

Backup (Mixed WIMP)
Simplest example = (Fermionic) singlet-doublet WIMP✓ Typical WIMP in the traditional natural SUSY.
✓ Minimal contents: 10, 2½, 2–½. (Anomaly cancel.)✓ 3 neutral Majorana and 1 charged Dirac fermions.
➢Lagrangian assuming Z2 symmetry making the WIMP stable is➢Parameter space are defined by [MS, MD, y1 = ycosq, y2 = ysin q],
corresponding to [M1, m, (g’/ 𝟐)cos b, (g’/ 𝟐)sin b] at the MSSM.
[DM interactions are assumed to preserve the CP symmetry.]➢Scanning parameter space using MCMC to clarify the current
status and future prospects of the WIMP, assuming |yi | ≦ 1.

Backup (Mixed WIMP)
SMSM

WIMP
Or
WIMP

SMZ

WIMP

SMDCoannihilation region

hResonance regions

WIMP

⊂

DegenerateSMγ, Z
DSMWIMPhH-blind spot region

WIMPPresent status(The likelihood function is now projected onto the (MDM, MD)-plane.)Backup (Triplet-like Fermion WIMP)
Simplest example = (Fermionic) triplet-like WIMP
✓ Predicted in High-scale SUSY and MPP scenarios.
✓ Minimal contents: 30 . (Just one representation.)✓ 1 neutral Majorana and 1 charged Dirac fermions.
➢Lagrangian assuming Z2 symmetry making the WIMP stable is➢Parameter space is simply defined by only one parameter MT.

➢Scanning parameter space is simple because of one parameter.

➢It is possible to include higher dimensional operators to takenew physics effects beyond the WIMP into account, however,those do not play important roles at WIMP’s phenomenology.

Backup (Triplet-like Fermion WIMP)
Field Theory Lagrangian of WIMP
|yon(r)|↓

Non-relativistic expansion andintroducing a ‘composite’ field
describing WIMP 2-body states.

w/o V(r)|yoff(r)|↓r0

The Schrodinger eq. is obtainedas EOM of the composite field.

[-∇2/m + V(r)]y(r) = 0w/ V(r)Wino↓

WIMP Annihilation cross section
is obtained by the formula:(sv)on = (|yon(0)|2/|yoff(0)|2) (sv)off(sv)off(sv)on↓

Weak long-range force increase
the wave function at origin, forit acts as a attractive force!!!

[J. Hisano, S. M., M. Nagai, M. Nojiri,
O. Saito, M. Senami, 2004-2007.]

Backup (S-like F-WIMP w/ H-mediator)
Simplest example = (Fermionic) singlet-like WIMP
✓ Predicted in all of the DS scenarios involving WIMP.
✓ Minimal contents: 10 + Mediator大事！

✓ 1 neutral Majorana and mediator states(s).

➢When the mediator is heavier enough than the WIMP and the EWscale, the phenomenology is effectively described by the EFT,

where L represents the typical mass scale of the mediator.
➢Parameter space is very complicated, ∃about 10 parameters.

➢Scanning parameter space using MCMC, assuming CP invarianceand the flavor blindness of the WIMP interaction with |c i | ≦ 1.

Backup (S-like F-WIMP w/ L-mediator)
Simplest example = (Fermionic) singlet-like WIMP
✓ Predicted in all of the DS scenarios involving WIMP.
✓ Minimal contents: 10 + Scalar/Vector Mediator.

✓ 1 neutral Majorana and mediator states.

↑大事！

Let us consider the case of a light singlet WIMP + a scalar mediator!
➢Lagrangian involving all possible renormalizable interactions:➢Parameter space is again very complicated, ∃8 parameters.

➢Scanning parameter space using MCMC, assuming CP invariance(cp = 0) with being |dimension-less(full) coupling| ≦ 1(1TeV).