Light Nonthermal Dark Matter: A Minimal Model & Detection Prospects

Rouzbeh Allahverdi

Collider and Dark Matter Physics Workshop Mitchell Institute for Fundamental Physics and Astronomy

Texas A&M University May12-15, 2014

Outline: • Introduction • Minimal model (non-supersymmetric version) • Detection prospects (direct, indirect, collider) • Minimal model (supersymmetric version) • Outlook

R.A., B. Dutta PRD 88, 023525 (2013) R.A., B. Dutta, R. N. Mohapatra, K. Sinha PRL 111, 051302 (2013) R.A., B. Dutta, Y. Gao arXiv:1403.5717

Based on the following works:

Introduction: The present universe according to observations: Two big problems to address: 1) Dark Matter (DM) What is the nature of DM? How was it produced? 2) Baryon Asymmetry of Universe (BAU) Why is it nonzero? How was it generated? Also, the coincidence puzzle: Why the DM and baryons have comparable energy densities?

Dark Energy 68%

Atoms 5%

Dark Matter 27%

Generation of BAU: B, C & CP, out of thermal equilibrium (Sakharov conditions): Occurred via out-of-equilibrium decay of some heavy state(s) produced after (or during) inflation

LRRL

RRLL

ffffffff

==

≠≠

,,

RRLL

LRRL

ffffffff

==

≠≠

,,

Production of DM: Thermal freeze-out (WIMP miracle): Nonthermal production:

20~ χm

Tf

fr TT <

scmvf

/103 326−×=σ

scmvf

/103 326−×≠σ

We adopt a bottom-up approach. We consider a minimal extension of the SM with renormalizable B interactions:

A Minimal Model:

NNmXmuNXddXL Ncii

cj

ciijnew 2

|| 22* +++′= αααααα λλ

:αX Iso-singlet color triplet scalars with Y =+4/3

:N Singlet fermion

R.A., B. Dutta PRD 88, 023525 (2013)

termskineticch ++ ..

The field content is the minimum required to generate nonzero baryon asymmetry via out-of-equilibrium decay of X Kolb, Wolfram NPB 172, 224 (1980); Erratum-ibid 195, 542 (1982)

)21(

||||

)Im(

81

12

22

21

21

,

21

21

,,212

*1

1

↔=

−+′

′′=

∑ ∑∑

εε

λλ

λλλλ

πε

mmm

ji kkij

kjiijijkk

1X

cd

cu

N2X

cd

1X

cu

N

+

1X

N

cd

cd2X

cu

1X

cd

cd

+

X fields mediate a 4-fermion interaction:

ck

cj

ci

X

ddNum2

λλ ′

This operator results in the following decays:

eeepN epepNmmm νν ++++→+> +− ,:

eeepN eNeNpmmm νν ++++→+< −+ ,:

N is stable and becomes a viable dark matter candidate if:

epNep mmmmm +≤≤−

The condition is stable against radiative corrections for:

)10( 1−≤ Oλ

Stability of DM candidate is tied to the stability of proton.

Odd & even number of DM particles produced from SM particles.

No additional symmetry, like R-parity, is invoked.

N quanta produced from/annihilate to SM particles in thermal bath:

4

5224 )|||||(|~

XmTλλλ ′+Γ:XN mTm <<<

:)(~),10(|||,| 2 TeVOmO X−≥′λλ

HmmT pN ≥Γ⇒=≥ )(DM reaches equilibrium with the thermal bath at T > O(GeV).

Thermal freeze-out overproduces DM. Lee, Weinberg PRL 39, 165 (1977)

:)(~,1 TeVOmGeVm XN ≈

Nonthermal mechanism is needed in order to obtain the correct DM relic abundance.

A natural scenario is late decay of a scalar field S that reheats the universe to a temperature . fr TT <

Such a decay can produce with branching ratios : 2,1X 2,1Br

∑ ∑∑+′

=

ji kkij

kk

X

NBr

nn

,

21

21

211

||||

||

1λλ

λ

∑ ∑∑+′

=

ji kkij

kk

X

NBr

nn

,

22

22

222

||||

||

2λλ

λ

1X

cu

N2X

cu

N

∑ ∑ ∑

→+

+′−

′′×=

kjiji k

kij

ijijkk

S

rB

mmBrm

mT

sn

,,,

21

21

22

21

212*11

21 )21(

||||)(8)Im(3λλπ

λλλλ

→+

+′×=∑ ∑

∑)21(

||||

||3

,

21

21

211

ji kkij

kk

S

rNBr

mT

sn

λλ

λ

)10(~ On

n

B

DM

For O(1) couplings and CP phases, it is easy to have:

)10(~ OmmB

DMpDM Ω

Ω⇒≈

Detection Prospects: Direct detection:

X

u

Nu

N

Spin-independent interactions:

..))((1

))((

4

4

chm

mmm

qqNNX

qqNNX

uN

+∂∂ ψγψψγψ

ψψψψ

νµνµ

8

64 )(|~|

XSI m

GeVOλσ

Spin-dependent interactions:

))((1 552 qqNNXm

ψγγψψγγψ νµ

4

44 )(|~|

XSD m

GeVOλσ

pbTeVOm SIX1610)(~ −<⇒σ

pbTeVOm SDX410)(~ −<⇒σ

COUPP PRD 86, 052001 (2012)

Indirect detection:

4

24 |||~|

Xann m

pv

λσ ><

scmvTeVOm annX /10)(~ 331−<<>⇒<σ

Too low to see any gamma-ray signal.

X

u

cuN

N

Also, no detectable galactic/extragalactic neutrino signal.

Neutrino signal from solar DM annihilation is negligible too: 1) Capture and annihilation both suppressed, 2) Evaporation efficient for O(GeV) DM.

However, possible indirect signal if two almost degenerate N exist. R.A., B. Dutta, Y. Gao arXiv:1403.5717

2,12,1Nmmmmm epNep ⇒+≤≤−

γ+→ 12 NNThe only allowed decay channel is:

4

23

4

221

16||

2X

NemN m

mm∆≈Γ απλλ

||12 NN mmm −≡∆

12, NN mm have same phase

..122 chF

mm

NNX

N +µνµνψσψ

4

5

4

221

16||

2X

emN mm∆

≈Γ απλλ

12, NN mm have opposite phase

In general, one can get a photon line at energy:

emmE 2<∆=γ

There has been claims of a 3.5 keV photon line from clusters. Boyarsky et al. arXiv:1402.4119 Bulbul et al. arXiv:1402.2301

The model can explain this line if: keVm 5.3≈∆ sN

23102≈τ

)10(||)10( 121

6 −− << OO λλ )(~ TeVOmX

This is satisfied for:

(Also, see I. Gogoladze talk in this workshop)

Collider signal:

B. Dutta, Y. Gao, T. Kamon arXiv:1401.1825

Both odd & even number of DM particles are produced from the interactions of the SM particles:

XN

cu

d

d

X

d

dd

d

cd

N

cu

d

g

X

Monojets (including monotops) & dijets plus missing energy.

d

X

X

Monojets + MET Dijets

Dijets + MET Paired dijets + MET

g

g

Resonance

λ λ

λ′ λ′

Combined collider bounds (assuming single value for and ): λ λ′

GeVm 5001 = TeVm 11 =

Also, possibilities with monotops (see the paper).

Extension to supersymmetry is straightforward:

Supersymmetric Version:

NNmXXmuXNddXW Ncii

cj

ciijnew 2

+++′= ααααααα λλ

:, αα XX Iso-singlet color triplet superfields Y =+4/3, Y=-4/3

:N Singlet superfield

Babu, Mohapatra, Nasri PRL 98, 161301 (2007) R.A., B. Dutta, K. Sinha PRD 82, 035004 (2010)

The model can lead to thermal and non-thermal baryogenesis.

It also has a real scalar DM candidate protected by R-parity. N~

The lighter of the two components of can be DM candidate.

NNN Bmmmm ±+= 222~

~

N~

Spin-independent interactions:

The prospect for direct detection of is high.

)~~)((12 NN

m qqX

ψγψ µµ∂

4

24|~|

X

pSI m

mλσ

X

u

N~u

N~

pbTeVOm SIX510)(~ −<⇒σ

N~

In order to address the coincidence puzzle, one can have:

)10(~ GeVOmN ≤

R.A., B. Dutta, R. N. Mohapatra, K. Sinha PRL 111, 051302 (2013)

The model allows for multi-component DM coming from the same superfield N.

LUX PRL 112, 001303 (2014)

pbSI510−<σ

• A minimal BSM with colored states to explain baryogenesis.

• Model can give rise to O(GeV) DM candidate.

• Nonthermal DM and baryon production needed. • Direct & indirect DM detection unlikely in the minimal model.

• Sub-GeV Photon line possible with two copies of DM.

• DM particles can be produced singly and doubly at colliders. • Distinct monojet signal is possible due to resonance.

• SUSY version allows new DM candidates.

• Direct detection signal possible, multi-component DM possible.

Outlook:

Coincidence problem (?) The DM and BAU densities are of similar order: How serious is the issue? have the same EOS, is constant in time. Different from the DE coincidence problem: EOS of DM and DE different, why today? Nevertheless, one can explore the possibility that may be related dynamically. Relation between baryogenesis and DM production mechanisms.

BDM ΩΩ 6~

BDM ΩΩ , BDM ΩΩ /

)1(~/ ODMDE ΩΩ

BDM ΩΩ ,

D. B. Kaplan PRL 68, 741 (1992) …

severely constrained by processes: 2,2 =∆=∆ SB|| 121λλ ′

1) oscillations.

2) double proton decay.

nn −++→ KKpp

:)(~,)(~ TeVOmGeVOm XN6

121 10|| −<′λλ

Successful baryogenesis then needs nontrivial flavor structure of and/or degeneracy in .

21, XX mmiji λλ ′,

Monojet and monotop signals are still possible:

1|~||,|,10|~|

1|~||,||,|

326

1

231312

λλλ

λλλ−

′′′