Constraining the neutralino and chargino sectors of the NMSSM at the LHC

Constraining the neutralino and chargino sectors of the NMSSM at the LHC

Pablo Mart´ın Ramiro

Instituto de F´ısica Te´orica UAM/CSIC

In collaboration with D. G. Cerde˜no, F. Domingo, V. Martin-Lozano, R. Ruiz de Austri, J. Soo Kim

Outline

1. SUSY LHC searches and electroweak SUSY

2. The Next-to-Minimal Supersymmetric Standard Model (NMSSM)

3. Scanning the parameter space of the NMSSM electroweakino sector 4. Do the SUSY limits from LHC searches apply to the NMSSM?

SUSY LHC searches

• Unsuccesful SUSY searches in Run1 LHC

• 1st & 2nd generation squarks and gluinos above 1 TeV.

• 3th generation squarks above 800 GeV.

• Limits oneχ⁰_i andeχ^±_j above EW scale.

Electroweak SUSY

• Strong production of SUSY particles (via squarks and gluinos) at the LHC has higher cross-sections than electroweak (EW) processes.

• However, direct production of electroweak particles can dominate if the masses of the gluinos and squarks are significantly higher.

• Decays of neutralinos and charginos can lead to high lepton multiplicity final states.

Spin Gauge eigenstates Mass eigenstates

Squarks 0

˜ uLu˜R˜dLd˜R

˜cLc˜R˜sL˜sR

˜tL˜tR˜bLb˜R

(same) (same)

˜t₁˜t₂b˜₁b˜₂

Sleptons 0

˜ eL ˜eR˜νe

˜ µL ˜µRν˜µ τ˜L ˜τRν˜τ

(same) (same) τ˜₁τ˜₂ν˜τ Neutralinos ¹₂ Be⁰We⁰Heu⁰He_d⁰eS eχ⁰₁eχ⁰₂eχ⁰₃eχ⁰₄eχ⁰₅

Charginos ¹₂ We^±He⁺u He⁻_d eχ^±₁ eχ^±₂ Higgs bosons 0 H⁰uH⁰_dHu⁺H_d⁻S H₁H₂H₃A₁A₂H^±

Gluinos ¹₂ g˜ (same)

Direct electroweakino/slepton production may be the dominant SUSY cross-section at the LHC!

Electroweak SUSY

Don’t panic yet!

Limits are derived assuming some simplified scenarios: m

χ⁰₂ =m

χ^±₁ and BR(→LSP+leptons) =1.

In a generic MSSM or NMSSM these limits would change due to reduced BRs and modified kinematics

→the interpretation of the SUSY LHC searches and DM phenomenology would be affected. [hep-ph/0509024, ep-ph/0505142, 1104.1754]

The Next-to-MSSM

• Addition of a new superfieldbSto the MSSM, singlet under the SM gauge group

NMSSM=MSSM +bS

(2 extra Higgs(1 CP-even,1 CP-odd) 1 additional neutralino

The Next-to-MSSM

• Addition of a new superfieldbSto the MSSM, singlet under the SM gauge group

NMSSM=MSSM +bS

(2 extra Higgs(1 CP-even,1 CP-odd) 1 additional neutralino

• In the NMSSM there is a fifth neutralino due to the mixing with thesinglino

M0=

















M₁ 0 ^−g√1vd

2 g√1vu

2 0

0 M₂ ^g√2vd

2

−g√₂vu

2 0

−g√₁vd

2 g√2vd

2 0 −µ_eff −λv_u

g√1vu

2

−g√₂vu

2 −µ_eff 0 −λv_d

0 0 −λv_u −λv_d 2κs

















The lightest neutralino has now asinglinocomponent

χ⁰₁=N₁₁Be+N₁₂We³

| {z }

Gaugino

+N₁₃He_d⁰+N₁₄He_u⁰

| {z }

Higgsino

+N₁₅S˜

| {z }

Singlino

→DM candidate!

Phenomenology of the NMSSM

• WNMSSM=WMSSM+λbSHbu·Hb_d+^κ₃bS³

• New higgsino and singlino couplings to the Higgs sector, involving singlet as well as doublet Higgs components.

• For a pure singlino state, the Higgs sector is the only point of contact with SM matter.

• Pure singlet components only interact with the Higgs and higgsino sectors.

• When the lighter neutralinos are dominated by the higgsino and singlino components, their decays and production channels in the NMSSM might occur more often through a Higgs mediator, instead of a gauge boson→suppressed leptonic signatures

χ⁰₁=N₁₁eB+N₁₂We³

| {z }

Gaugino

+N₁₃He_d⁰+N₁₄He_u⁰

| {z }

Higgsino

+N₁₅S˜

| {z }

Singlino

• In particular, singlet states typically lead tobb¯orτ⁺τ⁻signatures: their couplings to higgsino and singlino components might be larger than gauge couplings and, if light, they may easily be exchanged on-shell.

Electroweak SUSY searches

• Leptons are cleaner than jets→leptons +E/^miss_T in the final state.

• Production channels: pp→χ^±_i χ^∓_j (2 leptons) pp→χ⁰_iχ^±_j (1 or 3 leptons) pp→χ⁰_iχ⁰_j (4 leptons)

[Diagrams taken from 1501.07110, 1403.5294, 1402.7029]

Scanning procedure and scenarios

• Generic scanof the NMSSM electroweakino sector: no simplified model setup!

• {λ,κ,tanβ,µeff,M1,M2,mP}

• Decoupled squarks (2 to 15 TeV) and sleptons (1 TeV)

• Apply some basic phenomenological constraints: perturbativity, stability of the spectrum, collider (LEP, LHC, TeVatron) and B-physics limits, DM relic density.

• Define 5 scenarios:

1. MSSM-like spectra:λ,κ1→if singlino and singlet states are heavy, outcome of collider searches comparable to that of the MSSM.

2. Singlino LSP:decays toχ⁰₁mediated by the Higgs sector→supressed lepton final states.

3. Singlino NLSP:χ⁰₂ is mainly singlino and intervenes at more than 30 % in decay chains.

4. Decays into Higgs singlets: light Higgs singlets now intervene in neutralino and chargino decay chains, leading tobb¯andτ⁺τ⁻final states.

5. Higgs singlet on LSP annihilation threshold:the LSP annihilation is mediated by a Higgs singlet state.

Analysis

• Event Simulation: Pythia 8.

• Detector simulator: Delphes 3.

• Experimental analysis implemented in CheckMATE 2 with 8 TeV data.

• Exclusion if the point is excluded in one SR. We do not combine signal regions.

• CheckMATE compares the simulated signal with the actual experimental observationat and determines whether the model point is excluded at the 95%C.L.

r≡S−1.96∆S S⁹⁵_exp

• We will follow the conservative approach:

• r≥1.5: clearly excluded

• 0.67<r<1.5: potentially excluded

• r≤0.67: clearly allowed

Large uncertainties: pdf sets, choice of renormalization and factorisation scale, details of parton showering, finite MC statistics,. . .

1) MSSM-like scenario

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

excluded pot. excluded allowed

Our exclusion limits are conservative compared to the ATLAS search

• ATLAS: pure Bino LSP + pure Wino NLSP withm_χ0 2 =m_χ^±

1 →large cross sections.

• ATLAS: BR(χ^±₁ →χ⁰₁W^±) =BR(χ⁰₂→χ⁰₁Z) =1→large number of leptons.

1) MSSM-like scenario

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV]10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

100 120 140 160 180 200 220 240 260 280 300

Σiσi(BR)i

m_χ

1 +

MSSM-like scenario and m_χ

1 0 < 80 GeV

r < 0.67 0.67 < r < 1.5 r > 1.5

• 3-lepton searches have the largest sensitivity to MSSM models.

∑

i,j

σ(pp→χ⁰_iχ^±_j )·BR(χ⁰_i →χ⁰₁leptons)·BR(χ^±_j →χ⁰₁leptons)

• Exclusion coming from the 3-lepton search.

2) Singlino LSP

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 Singlino LSP scenario

• NMSSM scenarios can populate regions on them_χ0 1−m_χ^±

1 plane that will never be covered by MSSM benchmark points!

• ATLAS searches (3-lepton) still show some sensitivity, although they are optimized for MSSM benchmark points.

3) Singlino NLSP

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 Singlino NLSP scenario

• Exclusion coming from the 1-lepton search!

3) Singlino NLSP

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 Singlino NLSP scenario

• Exclusion coming from the 1-lepton search!

• Very weak experimental limits on this region→need more data.

4) Decays into Higgs singlets

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 Light singlet scenario

• Exclusion coming from the 3-lepton search.

• Very low sensitivity to ATLAS searches.

5) Higgs singlet on LSP annihilation threshold

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 MSSM-like

[GeV]

1 χ±

m 100 120 140 160 180 200 220 240 260 280 300 [GeV] 10χm

0 10 20 30 40 50 60 70 80 90

100 Higgs singlet on LSP annihilation threshold scenario

• Regions on them_χ0 1−m_χ^±

1 plane that can’t be covered by MSSM benchmarks!

• ATLAS searches (mainly 3-lepton) still show some sensitivity.

• Light Higgs sector opens up new annihilation channels.

Conclusions

• We do a generic scan of the NMSSM electroweakino sector: we are not considering a simplified model setup.

• NMSSM scenarios can populate regions on them

χ⁰₁−m_χ±

1 plane that will never be covered by MSSM benchmark points→ATLAS and CMS should also try to cover those regions.

• When the lighter neutralinos are dominated by the higgsino and singlino components, their decays and production channels in the NMSSM might occur more often through a Higgs mediator, instead of a gauge boson, leading to suppressed leptonic signatures.

• ATLAS searches (3-lepton) still show some sensitivity, although they are optimized for MSSM benchmark points

• However, for models with a singlino NLSP exclusion limits come from 1-lepton searches, which only cover a small region on them

χ⁰₁−m_χ±

1 plane→ATLAS and CMS should also try to cover those regions.

• Therefore, the MSSM and NMSSM can have very different experimental signatures. NMSSM cannot be excluded at all!