Di-Higgs signature from R-parity violation for

neutrino mass

Eung Jin Chun

1st IBS-Honam Focus Program, Jeonju, 29-31 Aug. 2016

in collaboration with Sanjoy Biswas and Pankaj Sharma, 1604.02821

Motivation

• Supersymmetry – still a promising framework for naturalness

• R-parity violation – abandons LSP dark matter candidate but explains neutrino masses and mixing

• Higgsino LSP scenario – minimizing the fine-tuning in EWSB

• Higgsino decays thu RpV mainly to 𝜈ℎ: 𝑝𝑝 → ෩𝐻 ෩𝐻 → ℎℎ +𝑀𝐸𝑇

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Di-Higgs at the LHC

• Measurement of the Higgs self-coupling (needs 100 TeV machine).

• Search for Xhh.

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2014-019: ATLAS 𝑏𝑏𝛾𝛾 study

Bilinear RpV & Neutrino Masses

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• Bilinear RpV terms:

• Neutrino-neutralino mixing mass:

Bilinear RpV & Neutrino Masses

• Neutrino mass matrix from seesaw by neutralino

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∝ 𝐷𝑒𝑡(𝑀𝑁)

• Neutrino oscillation data determine

Mixing induced by BRpV

• 𝜈 − 𝜒0 mixing:

• 𝑙 − 𝜒− & 𝑙𝑐 − 𝜒+ mixing:

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RpV vertices for 𝜒 → 𝑙𝑊, 𝜈𝑍, 𝜈ℎ

• 𝜒 − 𝑙 −𝑊:

• 𝜒 − 𝜈 − 𝑍:

• 𝜒 − 𝜈 − ℎ:

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Branching ratio of the 𝜈ℎ channel

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Higgsino pair production & di-Higgs channels at LHC14

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Signaling the 𝛾𝛾𝑏𝑏 +𝑀𝐸𝑇 channel

• Basic cuts:

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𝑝𝑇𝛾> 10 𝐺𝑒𝑉 & 𝜂𝛾 < 2.5

pTb > 20 GeV & 𝜂𝑏 < 2.5

Δ𝑅 𝑗𝑗,𝑗𝑏,𝑏𝑏,𝛾𝑗,𝛾𝑏,𝛾𝛾 > 0.4

Photon cut: 𝑝𝑇(𝛾1,𝛾2) > 30,20 𝐺𝑒𝑉

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Invariant mass cut: 𝑀𝛾𝛾 −𝑀ℎ < 2.5𝐺𝑒𝑉, 𝑀𝑏𝑏 −𝑀ℎ < 15𝐺𝑒𝑉

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MET cut:𝑀𝐸𝑇 > 100𝐺𝑒𝑉

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Separation cut:Δ𝑅𝑏𝑏,𝛾𝛾 < 2.0

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Cut flow on the backgrounds

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Basic Photon pT Invariant mass MET Δ𝑅

Cut flow on the signals

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Basic Photon pT Invariant mass MET Δ𝑅

Signal significances

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Conclusion

• Di-Higgs search is the next step to probe the EWSB sector.

• Light Higgsino is preferred for naturalness and hard to probe at LHC.

• Higgsino LSP in RpV SUSY opens a large parameter scape to produce di-Higgs with missing energy.

• Promising is the 𝑏𝑏𝛾𝛾 +𝑀𝐸𝑇 channel: small BR but much less background.

• Missing energy is a clean discriminant and allows us to probe the Higgsino mass up to ~600 GeV at HL-LHC with 3/ab.

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