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Analyses and motivation

Analyses and motivation. CPPM February 7, 2014 Dirk Zerwas LAL Orsay. Higgs Top Supersymmetry. Higgs analyses. Inclusive measurement via Z decay to leptons use recoil technique Higgs Bremsstrahlung wins over fusion Thesis Hengne Li (LAL) 2009

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Analyses and motivation

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  1. Analyses and motivation CPPM February 7, 2014 Dirk Zerwas LAL Orsay • Higgs • Top • Supersymmetry

  2. Higgs analyses • Inclusive measurement via Z decay to leptons • use recoil technique • Higgs Bremsstrahlung wins over fusion • Thesis Hengne Li (LAL) 2009 • tracking essential (error less than beam spread 0.3%)

  3. Higgs analyses • recoil measurement with Zjets • gain in BR(leptons)≪ BR(had) • Thesis Yacine Haddad (LLR) • shown at JCL IRFU 2013 • high purity difficult • PFLOW reconstruction important • Higgs self-coupling • LPC Clermont-Ferrand • theory+exp: C. Castanier, P. Gay, P. Lutz, J. Orloff • difficult channel at any machine • translation from Xsection coupling: factor <2 • typically 20-30% • Hgg and Hcc: combined extraction (flavour)

  4. The Higgs sector: couplings • Search for deviations from the Standard Model via the precise determination of Higgs couplings Definition: ΔX deviation of XXH coupling from SM value: gXXH= gXgXSM (1+ΔX) Loop induced coupling: gXXH=gXgXSM (1+ΔXSM+ΔX) Gupta, Rzehak, Wells: Phys.Rev. D86 (2012) 095001 • Overall phase choice: HWW positive • two sets of models: • without anomalous effective couplings • with anomalous effective couplings • Essential: decay and cross section calculation As observables are in gj2 : expected ambiguity for -2 and 0! + couple the 2nd and 3rd generation quarks

  5. ILC measurements Taken from Snowmass draft • absolute coupling determination: inclusive measurement • flavour tagging: distinguish c and top • typical experimental error: % level • gain on the theory error (0.5% Xsec ZH, WWH, 1% ttH) wrt LHC • theory error at ILC dominated by the BR uncertainty

  6. The Higgs sector precision • LCC (250GeV): • great precision on ΔZ • but not an order of magnitude gain in others? • total width an issue: • σ*BR(ZZ) difficult (low BR) • width determined at 10% level via: • LHC+LCC combined analysis (…500GeV): • ILC only Gauss errors • clear improvement on Δt • some improvement on D5 couplings Δγ, Δg • LHCLCC better than each machine alone

  7. The top quark Top quark enters in RGE evolution….. • Theory side: • νNRQCD • ν: subtraction velocity linking scales • theory boundary 120MeV • Experimental side: • threshold scan • 10fb-1 per point • illustration for: ±200MeV • good knowledge of detector and selection efficiency essential

  8. The top quark: electroweak couplings • Reconstruct top decays and polarization • Large S/B • Difficulty in the control of systematic errors Theses Amjad, Rouene (LAL) https://agenda.linearcollider.org/conferenceDisplay.py?confId=6296LIA FJ-PPL followed by a European meeting, participation welcome 

  9. Supersymmetry • Good news: the LHC discovered the Higgs boson • Better news: it’s compatible with the SUSY constraints • Colored sparticles: some room left by LHC but need to contrived scenarios • Best chance for ILC: • weak/electromagnetic coupled sparticles • LSP pair production (link to cosmology) • e.g. Higgs funnel of DM annihilation not ruled out… S. Henrot-Versillé et al 1309.6958 (accepted by PRD)

  10. Supersymmetry • single photon with missing ET • Large signal • Z peak background • Translation into WIMP-nucleon: • model dependent • e.g., MSSM: • s-channel + t-channel selectron exchange • will be fun to figure out the parameters…. • and if we get lucky: • measure precisely sparticle masses • endpoints • example here: stau (100GeV) • pair production • decay to LSP (50GeV) and tau • SM and SUSY background… • tau jet energy endpoint • energy scale • also: threshold scan (eg smuons)

  11. Conclusion • ILC can do precision physics: with excellent tracking, vertexing, flavor tagging and PFLOW • Top: mass, couplings • Higgs: many channels, refinement, couplings • Don’t underestimate the resiliance of SUSY to take us to the GUT scale • SUSY (weak sector): masses, couplings….

  12. Flat theory errors SFitter-style • ILC errors dominated by branching ratio errors (2% for b-quarks, mass induced) • gain in the statistics limited couplings • Theory errors on BR are important! • non-measurement of Δt means determination via Δc, theory error 3x reflected in deterioration of precision • cascades into Δg • impacts the total width • impacts all predictions

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