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Extraction of SUSY Parameters from Collider Data

Extraction of SUSY Parameters from Collider Data. SUSY 2008 Seoul 06/17/2008 Dirk Zerwas LAL Orsay. Introduction Measurements Reconstruction of fundamental Parameters Summary. Supersymmetry. fermion boson has “no” problems with radiative corrections (quadrat. div.)

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Extraction of SUSY Parameters from Collider Data

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  1. Extraction of SUSY Parameters from Collider Data SUSY 2008 Seoul 06/17/2008 Dirk Zerwas LAL Orsay • Introduction • Measurements • Reconstruction of fundamental Parameters • Summary

  2. Supersymmetry • fermion boson • has “no” problems with radiative corrections (quadrat. div.) • has a light Higgs Boson (<150GeV) • interesting pheno at the TeV scale 3 neutral Higgs bosons: h, A, H 1 charged Higgs boson: H± and supersymmetric particles • Many different models: • MSSM (low scale many parameters) • mSUGRA (high scale few parameters) • DSS (SUSY with heavy scalars) • GMSB • AMB • NMSSM ~ ~ ~ ~ ~ • R-parity • production of SUSY particles in pairs • (Cascade-) decays to the lightest SUSY particle • LSP stable, neutral and weakly interacting: neutralino (χ1) • experimental signature: missing ET

  3. A typical (optimistic) point “Physics Interplay of the LHC and ILC” G. Weiglein et al gluinos and squarks (not too heavy) heavy and light gauginos ~ • τ1 lighter than the lightest χ± : • χ± BR 100% τν • χ2 BR 90% ττ • cascade: • qLχ2 q  ℓR ℓq  ℓℓqχ1 ~ ~ ~ ~ Higgs boson mass at the LEP limit light sleptons

  4. Edges at the LHC • hard jets with leptons • invariant mass: • jet-lepton • lepton-lepton-jet • lepton-lepton less statistics: 1-10fb-1 • Improvements over past studies: • full simulation and reconstruction • realistic detector description (with additional distorsions) • early Data: 0.5-10fb-1 SUSY08: Paul de Jong, Peter Wienemann, talks by CMS

  5. LHC and ILC measurements LHC: lepton energy scale 0.1% LHC: jet energy scale 1% luminosity 100fb-1 • Linear collider • e+e- collisions • up to 1TeV • LHC: • from edges/thresholds to masses: toy/fit • ILC: • direct measurements/threshold scans SPS1a for the following continue with SPS1a as example

  6. Determination of Supersymmetric Parameters from edges, masses (etc) to fundamental parameters: e.g.: mSUGRA m(Smuon) = f(m0, m1/2, tanβ) m(Chargino) = f(m1/2, tanβ,…) correlations exp and theoretical treatment of theory errors!  global ansatz necessary Beenakker et al See Allanach arXiv:0805.2088[hep-ph] for complete list • mass spectra and decays: SOFTSUSY, SUSPECT, FeynHiggs, ISASUSY,SPHENO, SDecay, SUSY-HIT, HDECAY, NMSSMtools,… • NLO cross sections from Prospino2.0,… • dark matter: micrOMEGAS, DarkSUSY, IsaRED,… Search for parameter point, determine errors including treatement of error correlations: Pioneers: G. Blair, W. Porod and P.M. Zerwas(Eur.Phys.J.C27:263-281,2003) / Allanach et al. hep-ph/0403133 FITTINO: P. Bechtle, K. Desch, P. Wienemann with W. Porod(Eur.Phys.J.C46:533-544,2006) SFITTER: R. Lafaye, T. Plehn, M. Rauch, D. Z.(Eur.Phys.J.C54:617-644,2008) GFITTER: M. Goebel, J. Haller, A. Hoecker, K. Moenig, J. Stelzer (EW fit) EW fits plus dark matter:Buchmueller et al, Phys.Lett.B657:87-94,2007 Super-Bayes: R.R. de Austri, R. Trotta, (MCMC, collider observables and dark matter…) CMSSM fits and weather forcasts: B. Allanach, K. Cranmer, C. Lester, A. Weber …

  7. Information Extraction from Standard Measurements alone Buchmueller et al: electroweak plus dark matter, bsγ, bμμ CMSSM χ2 slightly better than SM mh=110+8-10±3GeV SUSY08: Sven Heinemeyer Allanach et al: Predict SUSY cross sections at LHC: ~fb  μ and B (high scale parameters) Bayesian measure: same order of magnitude for all parameters (no scale imposed nor unification) slightly higher cross sections in non-Bayesian approach (Profile Likelihood ~maximum instead of measure)

  8. Lagrangian@GUT scale: mSUGRA Hypothesis: SUSY particles discovered and discrete quantum numbers (spin) measured • First question: • do we find the right point? mSUGRA advantage: few parameters, testing ground for studies of principles disadvantage: starts at GUT scale and adds RGE extrapolation, not the most general lagrangian brute force method GRID: disadvantage: NP advantage: computer industry (OECD?) brute force method MINUIT: disadvantage: starting point Sign(μ) fixed ~300 toy experiments: convergence OK with MINUIT alone for LHC (largest errors)!

  9. Lagrangian@GUT scale: mSUGRA • Fittino: • Simulated annealing • SFitter: • Markov Chains (efficient sampling in high dimensions, linear in number of parameters) • Full dimensional exclusive likelihood map with the possibility of different types of projections: • marginalisation (Bayes) introduces a measure • profile likelihood (Frequentist approach) Ranked list of minima: • secondary minima exist (LHC) • discarded by χ2 alone • interplay with top mass (parameter!)

  10. mSUGRA: Errors RFit Scheme: Höcker, Lacker, Laplace, Lediberder • No information within theory errors: flat distribution • use edges not masses (improvement: 10x)! • e-scale correlations at LHC 25-50% impact on error • remember the standard model (top quark mass 1GeV at LHC) 10%.

  11. mSUGRA: Errors LHC and ILC • ILC improves by 3-4x on LHC • LHC+ILC better than any machine alone SFitter • Fittino: • the beginning 1 fb-1 • 1 year low lumi 10 fb-1 • 3 years nominal 300 fb-1 • and then the ILC: • theory errors impact the expected precision at all machines also at LHC SPA project: precision of the theoretical calculations Eur.Phys.J.C46:43-60,2006

  12. The LHC neutralino enigma • The uniqueness problem: • LHC measures the neutralino index in SPS1a? • permute: χ4 with χ3 • Exchanging χ3 and χ4 leads to a secondary minimum • M0 and M1/2 ok, but tanβ and A0 more than 2-3σ from nominal values • so in principle need ILC to see which neutralino are present…. • the predicted mass of χ4 is about 400GeV • the predicted branching ratios would lead us to expect more χ4 thanχ3 in the measurement channel in disagrement with the observation • general rule: beware of the “hidden” measurements……

  13. MSSM 19 parametersat the EW scale no unification of the 1st and 2nd generation • mix techniques: • markov flat full Parameter space • MINUIT in 5 best points • Markov flat gaugino-higgsino space • MINUIT on 15 best points • BW pdf on remaining parameters • MINUIT on 5 best solutions (all parameters) • 3 neutralino masses at LHC • M1, M2, μ • 8 fold ambiguity in Gaugino-Higgsino subspace at the LHC! • LHC+ILC: • all parameters determined • several parameters improved

  14. MSSM Running up to the GUT scale: G. Blair, W. Porod and P.M. Zerwas (Eur.Phys.J.C27:263-281,2003) P. Bechtle, K. Desch, P. Wienemann with W. Porod (Eur.Phys.J.C46:533-544,2006) SPS1a (SPA1): dashed bands: today’s theory errors included unification measured from low energy (TeV) data from LHC+ILC remember: all results valid within a well defined model/hypothesis

  15. A difficult example: SUSY with heavy scalars Arkani-Hamed & Dimopoulos 2004 Giudice, Romanino 2004 N. Bernal, A. Djouadi, P. Slavich JHEP 0707:016,2007 E. Turlay et al. (Proceedings BSM-SUSY les Houches 2007) • Phenomenology: • scalar Mass scale 104 to 16 GeV • scalars are at MS • fermions O(TeV) • SM Higgs h • effective theory below MS • at MS matching with complete theory • and standard RGE • DSS parameters: • MS: decoupling scale, scalar masses • m1/2: gaugino mass parameter • μ: Higgs mass parameter • At: trilinear coupling at MS • tanβ: mixing angle between Higgs at MS ATLAS/CMS talks: Paul de Jong, Tapas Sarangi, Daniel Teyssier Parameter determination at LHC possible

  16. Connection Colliders-Cosmology E. Baltz,M.Battaglia, M.Peskin, T.Wizansky: Phys.Rev.D74:103521,2006 Nojiri et al/Dutta et al • SUSY breaking parameters (determined) • spectrum and couplings (deduced) • darkSUSY, isaRed or micrOMEGAs • ΩCDMh2=nLSP*mLSP (relic density) NASA/WMAP science team SPS1a’ Temperature range: ±200μK • Measurement of the fluctuations of the cosmic microwave background • WMAP • ΩCDMh2=0.127±0.01 (astro-ph/0603449) • Planck • ΩCDMh2 ~ 2% • MSUGRA SPS1a (central value irrelevant) • LHC : Ωh2 = 0.19060.0033 • LHC+ILC: Ωh2 = 0.19100.0003 • % precision at LHC, permil LHC+ILC • theory errors! Comparable precision of CMB and Collider data possible

  17. Summary • LHC alone could provide a wealth of measurements for SUSY • LHC+ILC is the dream team • will collider dark matter property predictions • be comparable to WMAP/Planck? • LHC is starting now, is SUSY just around the corner? • Hope to start testing grand unification soon! SFitter+Suspect Thank you: Klaus Desch, Remi Lafaye, Tilman Plehn, Michael Rauch, Laurent Serin, Mathias Uhlenbrock, Peter Wienemann

  18. MSSM • LHC: • can assign errors on badly measured parameters • LHC+ILC: • all parameters determined • several parameters improved

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