Linear Collider Run Planning: E3-DQ3

Introduction

  • In discussions about the physics program at a Linear Collider, there is a need to try and understand how a rational Run Plan for initial operation of a Linear Collider might look. To this end the convenors of the Linear Collider Working Group for Snowmass 2001 have given a charge. Since there are specific working groups looking at Positron Polarisation, Giga-Z and gamma-gamma/e-e- options, we do not emphasise these (nevertheless important) issues.

    What follows is an attempt to translate the charge into some concrete approaches.

    We expect to organise four meetings, we will get 1 hour of plenary on Wednesday July 11, when we will say what we have or hope to get, and another on Wednesday July 18,when we are supposed to report on our achievements. These are shown in the E3 schedule. We will also try to organise two other meetings, likely on Friday July 13 or Saturday July 14, and one on Monday, July 16. We expect that M3 will discuss "realistic" machine operating scenarios in the Joint E3-M3 Meeting on July 4..

    If you have questions or comments, please send e-mail to mont@fnal.gov.

    Initial Running

    Approaches to running with a Linear Collider.

    • One approach is embodied in the paper from Blair and Martyn( hep-ph/9910416) from LCWS1999-Sitges. In that paper, heavy reliance is placed on careful choice of several beam energies to unravel the spectrum.
    • An alternative approach is advocated by Joel Butler in his talk in the Linedrive Series; ppt, pdf and the full streaming video versions of the talk are available.
    • The subject is also addressed in the Scenarios chapter of the US LC Resource Book.


    As with any new machine, making the machine work will be difficult, the actual first year of operation may well yield negligible luminosity. It also seems prudent to plan for a relatively modest degree of flexibility, luminosity and extra bells and whistles during the initial running after machine operations have been established. It would be interesting to understand the limitations (if any) of such an approach. The following parameters are an initial guess. A serious discussion of this and official responses, by the M3 group have been requested for the first week of Snowmass.

    Quasi-realistic Run Plan Parameters.

    • Year 1:
      • CM Energy : 360 GeV
      • Electron Polarisations: 50% at P=0.8, 50% at P=-0.8
      • Positron Polarisations: 100% at 0.0
      • Luminsity : 25 fb^-1
    • Year 2:
      • CM Energy : 360 GeV
      • Electron Polarisations: 50% at P=+0.8, 50% at P=-0.8
      • Positron Polarisations: 100% at P=0.0
      • Integrated Luminosity : 75 fb^-1
    • Year 3:
      • CM Energy : 500 GeV
      • Electron Polarisations: 50% at P=+0.8, 50% at P=-0.8
      • Positron Polarisations: 100% at P=0.0
      • Integrated Luminsity : 200 fb^-1



    Positron Polarisation

    In the paper from Blair and Martyn( hep-ph/9910416) the importance of positron polarisation was stressed, " Polarisation of both e- and e+ beams is extremely important for optimizing signal/background ratios." is a quote from the paper. After some recent work, Steve Mrenna, see his talk from the Johns-Hopkins Workshop, was much more circumspect. "We came to the conclusion that e+ polarization would be nice, but wasn't crucial, and could be replaced with more integrated luminosity in the end. A lot of nice effects come from polarizing one beam fairly well. Positron polarization can help if the electron polarization is mediocre by increasing the "effective" polarization. In the off chance that there is a scalar with significant couplings to the electron, then positron polarization can help in yielding a "background free" signal." is a quote from an e-mail from Steve. Joel Butler came to a similar conclusion. Nevertheless, the issue is not closed; Moortgat-Pick and Steiner give an extensive discussion of the advocacy position in LC-TH-2000-055, DESY 00-178 (.ps).

    Positron polarisation is not expected to be a feature of early operation of any currently proposed machine.

    These issues are discussed in the Positron Polarisation Chapter of the Resource Book

    There is a specific working group which will handle the polarisation issues in general; we do include questions about what the positron polarisation gains us where they are a natural continuation.


    Exercises


    Exercise 1. An interesting hypothetical scenario.

    • Analyse Benchmark 2; see Benchmarks assuming 200 fb^-1 with 500 GeV cms energy only, +/- 0.8 Electron Polarisation and No Positron Polarisation.

      • Which states are established?
      • What precision is obtained on the mass of states observed?
      • What precision is obtained on which Higgs branching fractions?
      • For which states does one obtain a hint that would be clarified with more running at the same energy?
      • What is the precision obtained for the top mass measurement? Compare with expectations for dedicated scan of threshold.
      • What is the precision obtained for the W mass measurement? Compare with expectations for dedicated scan of threshold.
      • What are the further machine energies and corresponding luminosities, which are needed to clarify or dramatically improve parameters?
      • What extra physics information would become available with positron polarisation?

    Exercise 2. A quasi-realistic scenario.

    • Analyse Benchmark 2; see Benchmarks assuming the "quasi-realistic" run plan detailed above with 360 GeV for 2 years and 500 GeV for 1 year.

          Part I: 360 GeV, 100 pb^-1

      • Which states can be established?
      • What precision is obtained on the mass of states observed? Compare with expectations for dedicated scan of threshold.
      • What precision is obtained on which Higgs branching fractions?
      • What is the precision obtained for the top mass measurement? Compare with expectations for dedicated scan of threshold.
      • What is the precision obtained for the W mass measurement? Compare with expectations for dedicated scan of threshold.
      • For which states does one obtain a hint that would be clarified with more running at the same energy?
      • What extra physics information would become available with positron polarisation?

          Part II: 500 GeV, 200 pb^-1

      • Which states can be established with the 500 GeV running (in addition to the 360 GeV)?
      • What precision is obtained on the mass of states observed? Compare with expectations for dedicated scan of threshold.
      • What precision is obtained on which Higgs branching fractions?
      • What is the precision obtained for the top mass measurement? Compare with expectations for dedicated scan of threshold.
      • What is the precision obtained for the W mass measurement? Compare with expectations for dedicated scan of threshold.
      • For which states does one obtain a hint that would be clarified with more running at the same energy?
      • What are the further machine energies and corresponding luminosities, which are needed to clarify or dramatically improve parameters?
      • What extra physics information would become available with positron polarisation?

    Exercise 3. Higher Energies.

  • 300 fb^-1 of luminosity and a cms energy of 800 GeV only, +/- 0.8 Electron Polarisation and No Positron Polarisation.?
    • Analyse Benchmark 3; see Benchmarks
      • Which states are established?
      • What precision is obtained on the mass of states observed?
      • For which states does one obtain a hint that would be clarified with more running at the same energy?
      • What are the further machine energies and corresponding luminosities, which are needed to clarify or dramatically improve parameters?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 4; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 5; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 6; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?
  • 300 fb^-1 of luminosity and a cms energy of 1000 GeV only, +/- 0.8 Electron Polarisation and No Positron Polarisation.
    • Analyse Benchmark 3; see Benchmarks
      • Which states are established?
      • What precision is obtained on the mass of states observed?
      • For which states does one obtain a hint that would be clarified with more running at the same energy?
      • What are the further machine energies and corresponding luminosities, which are needed to clarify or dramatically improve parameters?

    • Analyse Benchmark 4; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 5; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 6; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?
  • 300 fb^-1 of luminosity and the possible upgrade cms energy of 1500 GeV only, +/- 0.8 Electron Polarisation and No Positron Polarisation..
    • Analyse Benchmark 4; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 5; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?

    • Analyse Benchmark 6; see Benchmarks
      • What can be observed with what precision?
      • Is the luminosity a limitation, if so, what more would be required?
      • What extra physics information would become available with positron polarisation?


    Last Modified: 06/14/2001(American Notation)

  • e-mail: (mont@fnal.gov)