light nonthermal dark matter: a minimal model & detection...
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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−
′′′