DM & SUSY Direct Search at ILC. Tomohiko Tanabe (U. Tokyo) December 8, 2015 Tokusui Workshop 2015, KEK

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1 & SUSY Direct Search at ILC Tomohiko Tanabe (U. Tokyo) December 8, 2015 Tokusui Workshop 2015, KEK

2 Contents The ILC has access to new physics via: Precision Higgs measurements Precision top measurements Direct searches Search for Search for SUSY particles (incl. ) Other precision probes of indirect search for new particles I will cover the last two topics. 2

3 Mass Mass Spectra for Other NPs (heavy) If is the only particle that is kinematically accessible: At LHC: Discovery possible At ILC: Discovery possible Reach depends on type of à complementarity between LHC/ILC LHC and ILC have complementary capabilities in searches. 3

4 Dark Matter Searches Indirect Detection Direct Detection Colliders Complementary ways to search for 4

5 Dark Matter Searches q LHC q e + ILC e- different initial state à complementary sensitivity to 5

6 Dark Matter Searches g q LHC q mono-jets also, mono-photons mono-z/w/h γ e + ILC mono-photons e- different initial state à complementary sensitivity to 6

7 e.g.) Leptophilic e + ILC e- q, N l LHC, Direct Detection q, N γ à loop suppression l ILC has unique sensitivity to electron- coupling 7

8 ILC 500 GeV [Chae, Perelstein, ] LEP limits [Fox, Harnik, Kopp, Tsai, ] 8

9 Mono-photon Status (1) Signal: WIMP pair production with ISR photon e+ e- à γ Initial state radiation (ISR) photon Missing energy + missing momentum Observables: E γ, θ γ mass reach ~ s/2 Backgrounds: Radiative neutrino production e+ e- à ν ν γ à ν ν γ γ Contribution will be known / can be calibrated. Bhabha scattering e+ e- à e+ e- γ where the electrons go down the beam pipe undetected. Coverage of forward detectors crucial. [C.Bartels, Ph.D. Thesis at DESY] 9

10 Mono-photon Status (2) Geant4-based full simulation study Publication: C. Bartels, M. Berggren, J. List, EPJC 72:2213 [arxiv: ] s = 500 GeV 1 GeV < M WIMP < 250 GeV WHIZARD 1.96 ilcsoft v01-06 Beam parameters: RDR Detector models: LDC_PrimeSc_02, ILD_00 Update plan: Other s, WHIZARD 2, latest software tools, TDR parameters, ILD_v1_o5 model 10

11 11 Mass What if? Other NPs 250 GeV Indirect searches can exceed reach of direct search

12 Effective Field Theory New physics interaction mediated by a heavy particle can be integrated out to give a four-point contact interaction: g mediator g effective operator g f g q 2 M 2 (f µ f)( µ ) 1 2 (f µf)( µ ) EFT is valid for M med >> 2M ; identify: = M/ g f g *Outside the domain of validity, must take into account effects of on-shell resonance enhancement and off-shell production. 12

13 Effective Field Theory New physics interaction mediated by a heavy particle can be integrated out to give a four-point contact interaction: g mediator g effective operator g mediator g effective operator *In general, t-channel diagrams also exist 13

14 e+e- à 2 fermion process e+e- à ff with f = u/d/s, c, b, t, e, µ, τ e+e- à WW, ZZ may also be useful e + f Observables: Polarized cross sections Forward backward asymmetries (or equivalently differential cross section) _ e- f The large cross section of these events implies measurements will quickly become systematically limited. Need to demonstrate control of all the relevant systematics; it will immediately pay off! Z study [TDR] Baseline [Snowmass] LumiUp [Snowmass] Luminosity 0.2% 0.1% 0.05% Polarization 0.25% 0.1% 0.05% b-tagging 0.5% 0.3% 0.15% 14

15 e+e- à 2f [SUSY example] [Harigaya, Ichikawa, Kundu, Matsumoto & Shirai ] Binned likelihood analysis of differential cross sections, comparing expected number of events in B vs. that of. Wino Mass - s/2 [GeV] Efficiencies assumed: leptons 100%, b-jet 80%, c-jet 50% e+e- à µ+µ- e+e- à bb Other assumptions P(e-,e+) = (-0.8,+0.6), Lumi = 3 ab-1 Indirect reach significantly higher than direct search if systematics is under control e.g. for s=500 GeV, e+e- àµ+µ- : Wino mass reach = 350 GeV (for total systematics 0.3%) CM Energy [GeV] 15

16 Supersymmetry (SUSY) u d c t s b ~ u ~ d ~ c ~ s ~ t ~ b ν ν ν e µ τ e µ τ ν ~ ~ ν ν ~ e µ τ ~ e µ ~ ~ τ γ Z 0 W ± ~ ~ ± W g ~ 0 0 g G ~ G ~ B W 0 h H A H 0 0 ± ~ ~ ~ ± 2 H H H ü ü ü 16

17 SUSY Electroweak Sector Bino-like LSP Wino-like LSP Higgsino-like LSP LSP/NLSP typically degenerate (depends on mixing) 17

18 Sensitivity to SUSY Gluino search at LHC Chargino/Neutralino search at ILC à Comparison assuming gaugino mass relations Bino LSP (Gravity mediation Wino LSP (Anomaly mediation LHC 8 TeV (heavy squarks) LHC 300 fb -1, s=14 TeV Preliminary LHC 3000 fb -1, s=14 TeV ILC 500 GeV ILC 1 TeV (no relation between µ and M 3) Higgsino LSP M 3 (TeV) [Gluino mass] *Assumptions: MSUGRA/GMSB relation M 1 :M 2 :M 3 = 1:2:6; AMSB relation M 1 :M 2 :M 3 = 3.3:1:

19 Natural Radiative SUSY: µ not far above 100GeV Typically Δm of 20 GeV or less Challenging for LHC 19

20 Naturalness and Light Higgsino Naturalness arguments [e.g. Baer et al, ] imply existence of light Higgsinos at O(100) GeV. Higgsino LSP scenarios typically lead to compressed spectra: à small mass gaps between LSP and NLSPs Small mass gaps (20 MeV < ΔM < 30 GeV) challenging for LHC à No problem for ILC [ ] (a) Before ATLAS Run 1 (b) After ATLAS Run 1 20

21 Power of Beam Polarization Bkg. Suppression W + W - (Largest bkg in SUSY searches) Chargino pair K. Fujii Decomposition Slepton pair WW-fusion Higgs prod. Pol(e - ) -0.8 Pol (e + ) +0.3 (σ/σ0)vvh 1.8x1.3=2.34 Signal Enhancement 21

22 Higgsinos in Natural SUSY (ΔM~1 GeV) 22 e e + ISR +1 1 W + W soft [Berggren et al ] M(C1) ~ M(N1) ~ 170 GeV, ΔM ~ 1.6 and 0.8 GeV Only very soft particles in the final states à Require a hard ISR to reduce large two-photon background. Separation of chargino and neutralino channels clearly possible: 2 Mχ 2 Mχ Production Cross section ( +0 0 ) 80 fb ( 01 02) 50 fb Precision Expected for 500 GeV, 500 fb-1 P(e-,e+)=(-0.8,+0.3) M =1.6 GeV M =0.8 GeV

23 Gaugino Mass Extraction [Baer et al ] e + e +1 1, M(C1)~118 GeV, M(N1)~103 GeV à ΔM=15GeV ILC ILC LHC 100fb -1 Preliminary [Baer, List] In this benchmark point, M 1 and M 2 are expected to be measured to few % or better. à Test of gaugino mass relation Assume: Gluino LHC Ewkino ILC à Test of gaugino mass relation by LHC/ILC synergy à Discrimination of SUSY breaking models Full simulation study is started. 23

24 Stau coannihilation (ΔM~10 GeV) Study of stau pair production at the ILC Observation of lighter and heavier stau states with decay to neutralino + hadronic tau Benchmark point: m(n1) = 98 GeV m(stau1) = 108 GeV m(stau2) = 195 GeV (e + e +1 (e + e +2 1 ) = 158 fb 2 ) = 18 fb Bechtle, Berggren, List, Schade, Stempel, arxiv: , PRD82, (2010) Signal bkg SUSY bkg s=500 GeV, Lumi=500 fb-1, P(e-,e+)=(+0.8,-0.3) Stau1 mass ~0.1%, Stau2 mass ~3% à LSP mass ~1.7% 24

25 WMAP/Planck (68% CL) Relic Abundance ESA/Planck Once a candidate is discovered, it is crucial to check the consistency with the measured relic abundance. Precise measurements of mass and couplings at the ILC relic density Baltz, Battaglia, Peskin, Wizansky PRD74 (2006) , arxiv:hep-ph/

26 Summary ILC capabilities for new physics: Higgs, top, direct searches, other indirect probes. Dark Matter: Collider search complementary to direct detection / indirect detection ILC advantages: Electron- coupling Precise measurements allow check with observed relic density SUSY: Well-motivated even after LHC data. Important parameter space remains to be explored. ILC advantages: Compressed spectra (challenging for LHC) Coupling structure determination (via beam polarization) Discrimination of SUSY breaking mechanism (gaugino mass relations) Indirect probes (e.g. e+e- à 2f): Mass reach can be higher than s/2 if systematics is under control. Dedicated studies on systematics are desired. 26