Neutralino Dark Matter Mass Limits
How Heavy can Neutralino Dark
Matter be?
Hajime Fukuda (Kavli IPMU)
Based on 1812.02066
with
S. Shirai and F. Luo
Outline
•
Introduction
•
Coannihilation
•
Coannihilation through the brown muck
INTRODUCTION
TeV scale supersymmetry (SUSY)
•
Minimal SUSY SM (MSSM) at TeV scale has
many motivations
–
Naturalness (?)
–
Coupling unification
–
Dark matter
Is MSSM getting unfavored?
MSSM parameter regions
easy to see @ LHC
is getting unfavored
ATLAS Summary Plot
Is there a goal for SUSY search?
•
We can impose
an upper bound for the
lightest SUSY particle (LSP) mass
•
If
–
R-parity is conserved, so that the LSP is DM
–
LSP abundance is given by thermal freeze-out
•
Once the Universe is hot enough and the LSP is in the
thermal bath
Why does an upper bound exist?
WIMP Miracle
Ω
ℎ 2
ℎ
ℎ 2
2
ℎ 2
∼
0.1
10 −26 c m 3 /s 〈𝜎𝑣〉
10 −26
10
10 −26
−26
10 −26
c
m 3
m
m 3
3
m 3
/s
10 −26 c m 3 /s 〈𝜎𝑣〉
〈𝜎𝑣〉
10 −26 c m 3 /s 〈𝜎𝑣〉
For too large LSP mass,
〈
𝜎𝑣
〉
is too
small and
Ω
ℎ 2
ℎ
ℎ 2
2
ℎ 2
is too large
It’s quite important to clarify the
upper bound
of
〈
𝜎𝑣
〉
to get the
LSP mass upper bound
COANNIHILATION
Coannihilation
Color
Neutral
•
If
a colored sparticle “helps” LSP
annihilation, effective
〈𝜎𝑣〉
is much
enhanced
⇒
Coannihilation
Mass spectrum
Mass
LSP
How is LSP Annihilation Enhanced?
LSP
Amount
/d.o.f.
How is LSP Annihilation Enhanced?
LSP
Amount
/d.o.f.
How is LSP Annihilation Enhanced?
LSP
Amount
/d.o.f.
Mass bound by pert. coannihilation
•
Bino LSP coannihilation
–
with gluino
⇒
8 TeV
–
with squark
⇒
2 TeV
•
Can we go beyond this? – Use of brown muck
–
Assume bino LSP and degenerated right handed
squark
See e.g. Ellis, Luo, Olive 15
Ibarra et al. 15
Gross et al.
18
HF, Luo, Shirai 18
(Non-perturbative effect of QCD)
COANNIHILATION THROUGH THE
BROWN MUCK
Brown muck
•
If the squark lives after the QCD PT, the
quark/gluon cloud surrounds it (brown muck)
Kang et al. 06
Brown muck collision
Kang et al. 06
Brown muck collision
Kang et al. 06
•
Brown mucks form a bound
state with
𝜎∼𝜋
𝑅 ℎ𝑎𝑑 2
𝑅
𝑅 ℎ𝑎𝑑 2
ℎ𝑎𝑑
𝑅 ℎ𝑎𝑑 2
2
𝑅 ℎ𝑎𝑑 2
•
Thus, if the bound state
decays soon, the effective
DM annihilation cross section
is
𝜎𝑣 𝑒𝑓𝑓
𝜎𝑣
𝜎𝑣
𝜎𝑣
𝜎𝑣 𝑒𝑓𝑓
𝑒𝑓𝑓
𝜎𝑣 𝑒𝑓𝑓
∼𝜋
𝑅 ℎ𝑎𝑑 2
𝑅
𝑅 ℎ𝑎𝑑 2
ℎ𝑎𝑑
𝑅 ℎ𝑎𝑑 2
2
𝑅 ℎ𝑎𝑑 2
𝑣 𝑚𝑢𝑐𝑘
𝑣
𝑣 𝑚𝑢𝑐𝑘
𝑚𝑢𝑐𝑘
𝑣 𝑚𝑢𝑐𝑘
Large annihilation?
Bound state decay
•
Bound state doesn’t decay immediately
–
Due to the small overwrap of the wavefunctions
Kang et al. 06
Fate of the bound state
•
Eventually, it
deexcites
into the ground state
and annihilates efficiently
•
Tracking the deexcitation process is essential
to estimate
𝜎𝑣 𝑒𝑓𝑓
𝜎𝑣
𝜎𝑣
𝜎𝑣
𝜎𝑣 𝑒𝑓𝑓
𝑒𝑓𝑓
𝜎𝑣 𝑒𝑓𝑓
Deexcitation & Destruction
Deexcitation process
•
Dipole emission
•
Collision b/w pion/photon
–
Boltzmann supp. for pion
Destruction process
•
Decay (&
collisional
decay)
•
Collision
Annihilation efficiency
Chemical Equilibrium
Chemical Equilibrium
Difficult to
maintain!
Chemical Equilibrium
•
Boltzmann suppression for meson is large
•
Weak interaction is too weak
Chemical equilibrium: result
Result
For bino LSP
Detection
•
Direct detection is effective
Result
Result
Summary
•
Using QCD non-perturbative effect, the DM
mass can be as heavy as 300 TeV
•
Since the squark and bino is highly
degenerated, the direct detection is effective
for light flavor squarks
Brown muck: flavor
Result
Difference b/w Strumia’s group
•
They didn’t consider the confinement effect
–
It seems that they simply extrapolate the
perturbative treatment of the bound state
•
They didn’t consider chem. eq.
What if for other NLSP?
•
Left-handed squark NLSP
–
d.o.f is larger
–
Up and down type squarks are degenerated
•
Gluino NLSP
–
Chem. eq. is hard to maintain
•
The squark must be light
–
No Larmor radiation
What if for other LSP?
Hajime Fukuda, along with researchers Shirai and Luo, conducted a study on the maximum mass of Neutralino dark matter particles. They investigated coannihilation effects and how colored sparticles can enhance LSP annihilation. The study delves into the implications for TeV-scale supersymmetry models like MSSM and the constraints imposed by the WIMP Miracle 2.0. It also examines the upper bounds for the lightest SUSY particle (LSP) mass in the context of R-parity conservation and dark matter abundance. Through detailed analyses, the research sheds light on the range of permissible masses for Neutralino dark matter.
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Presentation Transcript
How Heavy can Neutralino Dark Matter be? Hajime Fukuda (Kavli IPMU) Based on 1812.02066 with S. Shirai and F. Luo
Outline Introduction Coannihilation Coannihilation through the brown muck
TeV scale supersymmetry (SUSY) Minimal SUSY SM (MSSM) at TeV scale has many motivations Naturalness (?) Coupling unification Dark matter
Is MSSM getting unfavored? MSSM parameter regions easy to see @ LHC is getting unfavored ATLAS Summary Plot
Is there a goal for SUSY search? We can impose an upper bound for the lightest SUSY particle (LSP) mass If R-parity is conserved, so that the LSP is DM LSP abundance is given by thermal freeze-out Once the Universe is hot enough and the LSP is in the thermal bath
Why does an upper bound exist? WIMP Miracle 2 0.110 26cm3/s ?? For too large LSP mass, ?? is too small and 2 is too large It s quite important to clarify the upper bound of ?? to get the LSP mass upper bound
Coannihilation Color Neutral LSP Candidates: ?, ?, If a colored sparticle helps LSP annihilation, effective ?? is much enhanced Coannihilation
Mass spectrum Mass ? or ? Mass difference is less than about ??????? ???? 30 LSP
How is LSP Annihilation Enhanced? Amount /d.o.f. @ ? ??????? ? or ? LSP
How is LSP Annihilation Enhanced? Amount /d.o.f. @ ? ??????? ? or ? LSP
How is LSP Annihilation Enhanced? Amount /d.o.f. @ ? ??????? Scattering with ? or ? ? or ? LSP
Mass bound by pert. coannihilation Bino LSP coannihilation with gluino 8 TeV with squark 2 TeV See e.g. Ellis, Luo, Olive 15 Ibarra et al. 15 (Non-perturbative effect of QCD) Can we go beyond this? Use of brown muck Assume bino LSP and degenerated right handed squark Gross et al. 18 HF, Luo, Shirai 18
COANNIHILATION THROUGH THE BROWN MUCK
Brown muck Kang et al. 06 If the squark lives after the QCD PT, the quark/gluon cloud surrounds it (brown muck) 1 ? ??= ??
Brown muck collision Kang et al. 06 ????? ? ????? ?/? ? 2 ? 1/? ?? ? ? ??/????? ? ? ? ?(1)????? ?????
Brown muck collision Kang et al. 06 Brown mucks form a bound state with ? ? ? ?? 2 Thus, if the bound state decays soon, the effective DM annihilation cross section is ????? ?? ?? 2 ????? Large annihilation?
Bound state decay Kang et al. 06 Bound state doesn t decay immediately Due to the small overwrap of the wavefunctions ? ? ? ?? ? ? ?? ? ? TeV ? ? ?? 10
Fate of the bound state Eventually, it deexcites into the ground state and annihilates efficiently Tracking the deexcitation process is essential to estimate ?????
Deexcitation & Destruction During deexcitation, squarkonium can also be broken by squark decay/particle collision In total, the effective annihilation cross section for the squark is ????? ?????+ ???? 2 ? ?? ??
Deexcitation process Dipole emission Collision b/w pion/photon Boltzmann supp. for pion
Destruction process Decay (& collisional decay) Collision
Annihilation efficiency ????? ?????+ ????
Chemical Equilibrium Difficult to maintain!
Chemical Equilibrium Boltzmann suppression for meson is large Weak interaction is too weak
Result For bino LSP
Detection Direct detection is effective
Summary Using QCD non-perturbative effect, the DM mass can be as heavy as 300 TeV Since the squark and bino is highly degenerated, the direct detection is effective for light flavor squarks
Difference b/w Strumias group They didn t consider the confinement effect It seems that they simply extrapolate the perturbative treatment of the bound state They didn t consider chem. eq.
What if for other NLSP? Left-handed squark NLSP d.o.f is larger Up and down type squarks are degenerated Gluino NLSP Chem. eq. is hard to maintain The squark must be light No Larmor radiation
What if for other LSP? Wino LSP d.o.f is larger Higgsino LSP d.o.f is larger Chem. eq. w/ gluino can be achieved by ?(100 TeV) squark & gluino ?
