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A Linear Collider Run Scenario

A Linear Collider Run Scenario. Choose a physics scenario that is CONSERVATIVE in the sense that it has many particles and thresholds to explore. Assume electron, but not positron polarization … again conservative !

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A Linear Collider Run Scenario

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  1. A Linear Collider Run Scenario Choose a physics scenario that is CONSERVATIVE in the sense that it has many particles and thresholds to explore. Assume electron, but not positron polarization … again conservative ! The purpose of the exercise is to show that a good physics program is achievable in a reasonable length of time. Based upon guesses from talks of R. Brinkmann and T. Raubenheimer – we imagine the luminosity curve is: Year 1 2 3 4 5 6 7 Yrly Lum(fb^-1) 10 40 100 150 200 250 250 total program = 1000 fb^-1 at 500 Gev

  2. Susy model: Assume mSUGRA model with many sparticles accessible at 500 GeV. m_0 = 100 GeV m_1/2 = 200 GeV A_0 = 0 tan b = 3 m > 0 (This model is now ruled out from recent data, but something like it with larger tan b and finite A_0 yields a similar sparticle mass spectrum) **Note: all Susy models are idiosyncratic – cross sections, branching ratios, masses, sensitivities to Susy parameters vary strongly with specific parameter choices. Higgs: take m_Higgs = 120 GeV

  3. Sparticle masses: Selectron_R 132 GeV Selectron_L 176 Sneutrino_e 161 Smuon_R 132 Smuon_L 176 Sneutrino_mu161 Stau_1 131 Stau_2 177 Sneutrino_tau 161 Chargino_1 128 Chargino_2 346 Neutralino_1 72 Neutralino_2 130 Neutralino_3 320 Neutralino_4 348 Squarks, gluino out of reach at 500 GeV (m(stop_1) = 377 GeV

  4. Susy particle mass determinations. • Obtain masses to O(GeV) precision from end points at energy above threshold ( 2 such energies – 320 & 500 GeV) • Scan selected thresholds for improved precision (use e-e- for selectron_R) • Use Snowmass and previous studies for mass precision : • U. Nauenberg, M. Dima, J. Barron, A. Johnson, L. Hamilton, D. Staszak, T. Turner for end point precisions • G. Wilson for chargino threshold scan • H.-U. Martyn & G. Blair, hep-ph/9910416 for scans • J. Feng & M. Peskin, hep-ph/0105100 for e-e- selectron • H. Baer, A. Belyaev, J. Mizukoshi, X. Tata for sneutrino scans • (not all studies at exactly same Susy point – or with same BRs or backgrounds!) • Backgrounds, resolutions, Beamsstrahlung approximately taken into account (backgrounds vary considerably with model point!) • Scan luminosities are for all points in a scan – location of points not optimized

  5. Run Plan for 1000 inverse fb

  6. Susy particle mass precisions from end point determinations – Snowmass studies by Colorado group

  7. Estimated mass precision for Sparticles * * * * Sneutrino mass determinations are quite sensitive to specific Susy model (BR to lepton chi+), and suffer from low rates. Studies differ on sneutrino mass precision.

  8. Determination of mSUGRA parameters(estimated) m_0 = 100 +/- 0.1 GeV(largely determined by selectron_R) m_1/2 = 200 +/- 0.2 GeV(largely determined by charginos) A = 0 +/- 10 GeV (largely determined by stau_1,2) tan b = 3 +/- 0.03(largely determined by chi^+, chi^0 ) The TeV scale Susy parameters and the RGE extrapolation to the GUT scale mSUGRA parameter errors need further investigation – here scaled from TESLA TDR study of same point, assuming errors from cross sections and masses both scale statistically. It will also be useful to estimate the attainable Susy coupling relation precision, and to estimate cross section accuracies more carefully. Attention should also be given to how well the quantum numbers of the Sparticles can be determined.

  9. For the scenario chosen, the LHC will also produce most of the sparticles, and because of the favorable decay chains, can do precision mass measurements leading to good determination of mSUGRA parameters. LHC squark masses enabled by LC determination of an absolute scale will give needed information on threshold corrections for gaugino mass parameters. For less rich scenarios without most of the gauginos, limits on chargino/neutralino mixing parameters will limit mSUGRA parameter determination. (Murayama) However, this study of precision of mass determinations at the Linear Collider is illustrative that a precision program can be performed within reasonable time.

  10. Higgs measurements (number of ZH events equivalent to 650 fb^-1 at 350 GeV or 1350 fb^-1 at 500 GeV ) (scaled from Tesla TDR and LC Resource book – M. Battaglia, G. Bernardi, R. Cahn) Top quark measurements Top mass : +/- 150 MeV (limited by QCD uncertainties) Top width : 5%

  11. Conclusion A high precision program is achievable with 1000 fb^-1 (~7 years) of data, determining Susy masses, underlying Susy parameters and Higgs studies. Details of Susy results are dependent on the specific Susy parameters. For the case studied, sneutrino masses are not precisely determined.

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