How heavy can the weak
scale SUSY be?
Hajime Fukuda (Kavli IPMU)
In collaboration with:
N. Nagata, H. Otono, S. Shirai, 1703.09675
S. Matsumoto, S. Shirai, In preparation

Supersymmetry is Important• SUSY around the weak scale is highly motivated.
• GUT• “Hierarchy problem”• Dark matter (With R-parity)• Where’s the SUSY scale?

SUSY Scale on hep-ph in 25 Years

Code on github: https://github.com/hajifkd/susy_energy

SUSY Search with the Goal
• It is very important to clarify the upper bound on
the SUSY scale• Supersymmetric DM can set the upper bound• Assumption: R-Parity & Thermal Equilibrium

How Is the DM Scale Fixed?
• WIMP Miracle: Ω ~ ΩDM (1 pb / <σv>)• Roughly, the weaker the LSP interaction is, themore the abundance is• The heavier a particle is, the weaker the interaction is• This imposes the upper bound on the LSP scale• As long as we look for LSP, we have a definite goal!
• DM candidate: Wino, Bino or Higgsino• “How heavy?” = “How strong can they interact?”• How can we detect them?

LSP Mass Upper Bound
Mass Bound(Ordinary) SUSY

1 TeV for Higgsino
3 TeV for Wino

Assumption

Detection
Direct detection /Collider
HF, Nagata, Otono, Shirai 17

Coannihilation~ 8 TeV+ gluino - LSP
Colliderdegeneracy (< 3 %)~ 14 TeV+ heavy Higgs - LSP Direct detection
degeneracy, LSP –NLSP degeneracy(< 1 %)

Profumo et al 04, Ellis et al 15(See F. Luo’s talk)Higgs Funnel
Profumo 05, Gilmore 07,
HF Matsumoto Shirai in prep.

Brown muck
Kang et al 06

LSP Mass Upper Bound
Mass Bound(Ordinary) SUSY

1 TeV for Higgsino
3 TeV for Wino

Assumption

Detection
Direct detection /Collider
HF, Nagata, Otono, Shirai 17

Coannihilation~ 8 TeV+ gluino - LSP
Colliderdegeneracy (< 3 %)~ 14 TeV+ heavy Higgs - LSP Direct detection
degeneracy, LSP –NLSP degeneracy(< 1 %)

Profumo et al 04, Ellis et al 15(See F. Luo’s talk)Higgs Funnel
Profumo 05, Gilmore 07,
HF Matsumoto Shirai in prep.

Brown muck
Kang et al 06

1/3 TeV Goal• Roughly speaking, for DM with large mixing angle,
the direct detection worksℎ෨𝜒𝑁෨ 𝑊෩𝐵/𝜒𝑁• How is pure wino/Higgsino? – Disappearing track
HF, Nagata, Otono, Shirai, 1703.09675

Disappearing Track• A charged partner always accompanies with DM• For pure wino/Higgsino, the mass difference is only
from the radiative correction, Δ𝑚 ∼ 𝛼𝑣/4𝜋• The partner is long lived!
• Wino: ~ 7 cm
• Higgsino: ~ 0.7 cm• Tracking technology is very important• Wino/higgsino @ 33 TeV by tracking improvement
HF, Nagata, Otono, Shirai, 1703.09675

Result (Higgsino)

HF, Nagata, Otono, Shirai, 1703.09675

Higgs Funnel Scenario: Idea
• If electroweakino scattering hits the heavy Higgs
pole, the cross section gets much enhanced𝜒

𝐻, 𝐴, 𝐻 ±
𝜒′11𝐺∼∼−𝑝2 + 𝑀2 − 𝑖 𝑀Γ ΓFor 𝑚𝜒 + 𝑚𝜒′ ∼ 𝑀𝐻Profumo 05

Annihilation Process• Since the mass is 10-20 TeV, the freeze out
temperature is T ~ 300-600 GeV > v• Neutralinos don’t mix with each other• Annihilation between different neutralino iseffective
HF, Matsumoto, Shirai In prep

Mass VS Abundance• We need to calculate Ω for hW, hB, hWB system• hW system:(Similar to other)• The Goal: ~ 14 TeV

Direct Detection• Neutralino degeneracy: m / 30 ~ O(100) GeV• neutralino mixing → O(1)• Direct detection becomes effective

Around here?

Summery• Dark matter search is very important as the SUSYsearch• In the “ordinary” case, 1/3 TeV are the goal
• Direct detection / Disappearing track• In Higgs Funnel case, ~ 14 TeV is the goal
• Direct detection• We have a definite goal for SUSY searchWhat Limits the Sensitivity?
• Usual channel: Energy• σweak(1 TeV higgsino pair @ 14 TeV) >~ O(fb)• Rather, the analysis, in particular the tracking
technology, is importantImproving the Analysis• If we require shorter track, the acceptance rate
becomes greater.

ATLAS Analysis

The ATLAS collabolation, 1712.02118

Can We Do Better?
• In principle, 3 points are enough to draw a nontrivial line
• Moreover, we may use the information from theprimary vertex from other tracks• The best analysis: 2 point analysis
HF, Nagata, Otono, Shirai, 1703.09675

Result (Higgsino)

HF, Nagata, Otono, Shirai, 1703.09675

Result (Wino)

HF, Nagata, Otono, Shirai, 1703.09675

Summary• For SUSY search, the dark matter search is essential• 1/3 TeV Higgsino/wino is most important• Disappearing track search is the important strategy• Reducing the required length for the disappearing
track is the key to improve the sensitivity• We need to discuss how we reduce the backgroundBackup

Can We Avoid This Constraint?
• If the amount of the LSP is changed, we can evadethe constraint.
• Low reheating temperature• The LSP has never existed in the Universe• Inconsistent with the thermal leptogenesis• Entropy production• Dilutes LSP by energy injection from decaying heavy particle• Requires a very stable new particle• RPV

Backgrounds• Fake Track• Failure of tracking due to the points from pileup• Kink Track• Pions scattered by materials