Naturalness and Light Higgsinos: a Powerful Reason to Build ILC!

Naturalness and light higgsinos: a powerful reason to build ILC!

Howard Baer (U. of Oklahoma) Jenny List (DESY) with J. Yan (KEK), S.L. Lehtinen (DESY), M. Berggren (DESY), K. Fujii (KEK) and T. Tanabe (Tokyo) SUSY Motivation: simplicity and naturalness

2 The SM is unnatural beyond a scale ⇤ 1 TEV due to well-known • quadratic divergences in scalar sector ⇠ simple extension to include larger spacetime symmetry (SUSY) renders • SM natural: MSSM! ) other attempts to gain naturalness typically involve baroque constructions- • hard to believe nature follows those routes But: LHC hasn’t found SUSY and Higgs mass m (125) seems heavy: • h Is SUSY also unnatural? Little Hierarchy problem: m(SUSY ) m • Z

3 In the past several years, the notion of electroweak naturalness in SUSY has been clariﬁed:

Most direct expression within MSSM: minimize scalar potential to determine VeVs: relate measured value of m(Z) to SUSY Lagrangian

weak scale soft term:

radiative corrections: biggest from t1,t2 no large unnatural cancellations: SUSY conserving mu term all terms on RHS are <~100-200 GeV

4 mHu : may be large ( m3/2 multi-TeV) at GUT scale but driven to natural values by radiative corrections⇠ ⇠ at weak scale: radiatively-driven naturalness) or RNS

no EWSB

natural

unnatural

u ˜ ⌃u(t1,2): small for TeV-scale highly mixed stops; m < 4 TeV (˜g beyond LHC reach?) g˜ ⇠

SUSY µ term: feeds mass to W, Z, h and higgsinos: 0 higgsinos ˜1±,˜1,2 100 200 GeV! soft decay products⇠ (due to small mass gaps) hard to see at LHC but easy to see at ILC with ps>2m(higgsino) 5 How much tuning is too much?

higgsinos should be accessible6 to ILC! Crisis averted: * naturalness: only higgsinos need lie near ~100 GeV scale stops, gluinos can safely lie ~1-4 TeV scale at little cost to naturalness: contributions suppressed by loop factors Natural SUSY Prospects at the ILC

• studied two benchmark scenarios

8 Natural SUSY Prospects at the ILC

• studied two benchmark scenarios

• : cross sections ~ few 100 fb • mass gaps ~ 10…20 GeV

• decay via virtual W*/Z*, e.g. • visible decay products soft, small missing momentum • other sparticles heavy

8 Natural SUSY Prospects at the ILC

ILC1:m0 =7025GeV,m1/2 =568.3GeV,A0 = −11426.6GeV,tanβ =10,µ =115GeV,mA =1000GeV

4 µ+µ− ˜ ˜ ˜ ˜ 10 W1 W1 Z1 Z3 ˜ ˜ ˜ ˜ • studied two benchmark scenarios W1 W2 Z1 Z4 ˜ ˜ Z1 Z1 Z˜2 Z˜3 ˜ ˜ 3 Z2 Z2 Z˜2 Z˜4 10 ˜ ˜ Z3 Z3 Z˜3 Z˜4 0 Z˜1 Z˜2 Z h

2 10

1 10 (fb)

σ 0 10

−1 10

−2 10

−3 10 200 300 400 500 600 700 800 900 1000 √s (GeV) • : cross sections ~ few 100 fb • mass gaps ~ 10…20 GeV

• decay via virtual W*/Z*, e.g. • visible decay products soft, small missing momentum • other sparticles heavy

8 ILD Simulation Study

• Event generation by Whizard 1.95 & Pythia 6.422 (hadronisation tuned to LEP) • Detailed Geant4-based ILD simulation and reconstruction (Mokka & Marlin) • Beam energy spectrum and ISR included • Studied so far: •

9 Neutralino mixed producton with leptonic decay Polarizaton (Pe-,Pe+) = (-0.8, +0.3) preliminary

79.02+/- 0.92 GeV di-muon 20.83+/- 0.27 GeV di-muon Mass and Cross Section Measurementenergy mass

• masses: • maximum invariant mass of W*/Z* gives mass splitting • then maximum energy of W*/Z* gives absolute masses since initial state is known! di-electron di-electron 75.19+/- 0.49 GeV 20.90+/- 0.29 GeV • preliminary precision for 500/fb @ GeV: energy mass δm/m ≈1% • cross sections: 2 • ﬁt overall shape to “count” events • preliminary precision for 500/fb @ GeV: δσ/σ ≈ 3% (for P(e-,e+)=(±80%,∓30%) • polarisation dependence reveals higgsino nature!

10 Neutralino mixed producton with leptonic decay Polarizaton (Pe-,Pe+) = (-0.8, +0.3) preliminary

Neutralino mixed producton with leptonic decay Polarizaton (Pe-,Pe+) = (-0.8, +0.3) preliminary 79.02+/- 0.92 GeV di-muon 20.83+/- 0.27 GeV di-muon Mass and Cross Section Measurementenergy mass

• masses: 79.02+/- 0.92 GeV di-muon 20.83+/- 0.27 GeV di-muon • maximum invariant mass of W*/Z* gives mass splitting energy mass • then maximum energy of W*/Z* gives absolute masses since initial state is known! di-electron di-electron 75.19+/- 0.49 GeV 20.90+/- 0.29 GeV • preliminary precision for 500/fb @ GeV: energy mass δm/m ≈1% • cross sections: 2 • ﬁt overall shape to “count” events di-electron di-electron 75.19+/- 0.49 GeV 20.90+/- 0.29 GeV • preliminary precision for 500/fb @ GeV: energy mass δσ/σ ≈ 3% (for P(e-,e+)=(±80%,∓30%)

• polarisation dependence reveals higgsino nature! 2

10 Neutralino mixed producton with leptonic decay Polarizaton (Pe-,Pe+) = (-0.8, +0.3) preliminary

Neutralino mixed producton with leptonic decay Polarizaton (Pe-,Pe+) = (-0.8, +0.3) preliminary 79.02+/- 0.92 GeV di-muon 20.83+/- 0.27 GeV di-muon Mass and Cross Section Measurementenergy mass

• ﬁt overallproduction shape cross to sections “count” for this wino-like events case are below 0.1 fb and do not show up in this frame. This observation will be important in Sec. 5 wherewedescribeouranalysis. di-electron di-electron • The polarization dependence of the chargino pair productioncrosssectionprovidesan 75.19+/- 0.49 GeV 20.90+/- 0.29 GeV preliminaryindependent precision handle that may enable for us 500/fb to argue the higgsino- @ GeV:like nature of the charginos energy mass of the ILC1 point. For a right-handed electron beam the amplitude for charged wino pair δσ/σ ≈ 3% (for P(e-,e+)=(±80%,2 ∓30%) production is suppressed by a factor of MW /s relative to that for charged higgsino pair production, accounting for the strong drop of the dashed curve at P (e )= 1. L − − • polarisation dependence reveals higgsino nature! ILD Preliminary 500 GeV, 500 fb-1, P 2 m =7025 GeV, A =-11426.6 GeV, tanβ =10, m =1 TeV -80,+30 0 0 A 250 10 4 ILC1: m1/2=568.3 GeV, µ=115 GeV ∼0∼0

(fb) (ILC1) χ1χ2 σ m =120 GeV, µ=473 GeV 200 1/2 SM bkg

SUSY bkg ~ ~ 150 W1W1

10 3 100 Events / 4.0 GeV

~ ~ Z Z 1 2 50

0 0 50 100 150 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 Eee [GeV] - 10 PL(e )

− + − Figure 3: Sparticle production cross sections vs. PL(e )atane e collider for the ILC1 benchmark point with √s = 250 GeV. The positrons are taken to be unpolarized. For comparison, we

show a point with a wino-like chargino of similar mass. For the wino-like case with m1/2 =120GeV, + − then the σ(e e Z1Z2) 0.1 fb, while σ(Z2Z2) is even smaller, and so is far below the cross → ! ! ∼ ! ! section values shown.

3.2 Higgsino decays

Since the inter-higgsino mass gaps are so small, for the case of RNS one expects the following three-body decays to be dominant:

W − Z ff¯′ , (3.1) "1 → !1 Z Z ff,¯ (3.2) !2 → !1

–8– And the Higgs boson?

• only light higgsinos => H(125) SM-like:

Deviation of ILC1 Higgs branching ratio from SM

% 40 ILC model-independent Higgs 20 coupling determination [arXiv:1506.05992]

0 Projected precision of Higgs coupling and width (model-independent fit) 10% ILC 500 GeV, 500 fb-1 ⊕ 350 GeV, 200 fb-1 ⊕ 250 GeV, 500 fb-1 18% 20% -20 9% ILC 500 GeV, 4000 fb-1 ⊕ 350 GeV, 200 fb-1 ⊕ 250 GeV, 2000 fb-1 ILC ⊕ HL-LHC 3000 fb-1 combination 8% - ILC 500 GeV 500 fb-1 ⊕ 250 GeV 250 fb-1 precisions, P(e ,e+)=(-0.8,+0.3) 7% -40 SM and SUSY BRs for ILC1 from FeynHiggs2.10.2 6% bb cc gg γγ ττ ZZ WW 5% 4% • here only conservative 3% precisions corresponding to 2% initial ILC dataset (red bars) 1% 0% (CL95%) κ Z κ W κ b κ g κ γ κ τ κ c κ t κ µ Γtot Γinvis

11 Parameter Determination with Fittino [arXiv:hep-ph/0412012]

calculators: Model type, Trial SUSY starting • parameters values & SUSY spectrum: step size SPheno 3.3.9beta

• Higgs properties: Calculators e.g. SPheno

n FeynHiggs 2.10.2 i

h C

experimental inputs: v o

k Masses,

r Trial

a xsxbr & M observables • δm(higgsinos) = 1% uncertainties • δσ(higgsinos) = 3% • Higgs mass & couplings ‰2 value • gluino mass to ~ 10% from LHC

12 Weak Scale Parameter Determination

• ﬁt all parameters which enter gaugino

2 10 2 10

and higgsino sector at tree-level χ ILC1 χ ILC1

∆ SUSY+h from ILC ∆ SUSY+h from ILC ~ ~ 8 g from LHC 8 g from LHC • other SUSY parameters ﬁxed µ=115.0+0.7-0.7 GeV tan β=10.0+0.3-0.3 • only fraction of ILC standard 6 6 running scenario assumed 4 4 [c.f. talk by J.Brau in accelerator session today, and arXiv:1506.07830] 2 2

• � determined to better than 1% 0 0 112 113 114 115 116 117 118 9 9.5 10 10.5 11 [GeV] tan • Higgs properties very important µ β

2 10 2 10 2 10

χ ILC1 χ ILC1 χ ILC1

∆ SUSY+h from ILC ∆ SUSY+h from ILC ∆ SUSY+h from ILC ~ ~ ~ 8 g from LHC 8 g from LHC 8 g from LHC

M1=252+23-23 GeV M2=467+21-21 GeV M3=1272+132-132 GeV 6 6 6

4 4 4

2 2 2

0 0 0 200 220 240 260 280 300 400 450 500 550 1000 1100 1200 1300 1400 1500 M1 [GeV] M2 [GeV] M3 [GeV]

13 Probing the GUT scale with LHC & ILC

2000 ILC1 SUSY+h from ILC at 1 TeV: ~ [GeV]

i g from LHC

M 1500 • δM1 ≈ 25 GeV

• δM2 ≈ 20 GeV

• δM3 ≈ 130 GeV 1000 M3 • run to high scale (SPheno): M2 • do gaugino masses unify? 500 • determine the GUT scale!

M1 0 104 106 108 1010 1012 1014 1016 Q [GeV]

14 Conclusions

• naturalness: need to take high-scale relations between parameters and running into account

• SUSY can still be natural if higgsinos are sufﬁciently light

• stops, gluino can safely lie in the 1…4 TeV regime => maybe discoverable at LHC - but don’t panic if not!

• if there is natural SUSY, ILC is a higgsino factory

ILD Preliminary 500 GeV, 500 fb-1, P => if no higgsinos at ILC, then need to re-think naturalness -80,+30 250

0 0 ∼χ ∼χ (ILC1) 200 1 2 SM bkg

SUSY bkg • and offers ideal environment for measuring higgsino 150 100 Events / 4.0 GeV properties at the percent-level 50 0 0 50 100 150 Eee [GeV] • together with the higgs couplings: full determination of 2000 ILC1 SUSY+h from ILC ~ [GeV]

i g from LHC electroweakino sector, including M1 and M2 M 1500

1000 M3

M2 • weak-scale parameter determination allows to test for 500

M1 0 uniﬁcation and to probe the GUT scale 104 106 108 1010 1012 1014 1016 Q [GeV]

15 BACK UP A 20 Year Strawman Running Program for the ILC

• 500 GeV: general purpose - Higgs & top physics, Higgs self-coupling, top-Yukawa, BSM • 350 GeV: top threshold scan

• Integrated250 GeV: specialLuminosities Higgs measurements [fb] (mass, CP in H->��) 4000 ILC, Scenario H-20 ECM = 250 GeV 3000 ECM = 350 GeV ECM = 500 GeV Total integrated luminosities 3.6 x1034 2000 /cm2/s √s ∫ℒ dt 1.8 x1034 250 GeV 2 ab-1 /cm2/s 1.5 x1034 3 x1034 350 GeV 200 fb-1 1000 /cm2/s /cm2/s 500 GeV 4 ab-1 refer to these as full Luminosity Upgrade ILC500 programme

integrated luminosities [fb] 0 0 5 10 15 20 years 17 A 20 Year Strawman Running Program for the ILC

• 500 GeV: general purpose - Higgs & top physics, Higgs self-coupling, top-Yukawa, BSM • 350 GeV: top threshold scan

• Integrated250 GeV: specialLuminosities Higgs measurements [fb] (mass, CP in H->��) 4000 ILC, Scenario H-20 NEW in 2015 ECM = 250 GeV arXiv:1506.07830 3000 ECM = 350 GeV ECM = 500 GeV Total integrated luminosities 3.6 x1034 2000 /cm2/s √s ∫ℒ dt 1.8 x1034 250 GeV 2 ab-1 /cm2/s 1.5 x1034 3 x1034 350 GeV 200 fb-1 1000 /cm2/s /cm2/s 500 GeV 4 ab-1 refer to these as full Luminosity Upgrade ILC500 programme

integrated luminosities [fb] 0 0 5 10 15 20 years 17 The candidate site: Kitakami scientiﬁc Earthquake-proof, stable bed rock decision of granite, no faults across site

Highway

Oshu

Shinkansen Ofunato Sendai Ichinoseki Kesen-numa IP Region

18 The candidate site: Kitakami scientiﬁc Earthquake-proof, stable bed rock decision of granite, no faults across site

Highway

Oshu

Shinkansen Ofunato Sendai Ichinoseki 67 km (500 GeV = 34 km) Kesen-numa IP Region

18 Review by Japanese Science Ministry (MEXT)

Science Council of Japan

after Higgs discovery: community decision for ILC

19 Review by Japanese Science Ministry (MEXT)