Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

The Case for a 500 GeV e+e- Linear Collider

J. Bagger

TL;DR

This paper argues that a high-luminosity 500 GeV e+e− linear collider is the optimal next step to illuminate the mechanism of electroweak symmetry breaking. It defends a dual strategy with the LHC, detailing how lepton collisions offer model‑independent Higgs studies, precise SUSY spectroscopy, top and gauge coupling measurements, and stringent tests of new physics scenarios. The authors outline concrete accelerator designs, physics capabilities, and upgrade paths toward multi‑TeV energies, underscoring the collider’s role in achieving a complete, precision understanding of TeV‑scale phenomena. The work emphasizes complementarity with hadron colliders and presents a long‑term vision for a scalable, high‑impact program in particle physics.

Abstract

Several proposals are being developed around the world for an e+e- linear collider with an initial center of mass energy of 500 GeV. In this paper, we will discuss why a project of this type deserves priority as the next major initiative in high energy physics.

The Case for a 500 GeV e+e- Linear Collider

TL;DR

This paper argues that a high-luminosity 500 GeV e+e− linear collider is the optimal next step to illuminate the mechanism of electroweak symmetry breaking. It defends a dual strategy with the LHC, detailing how lepton collisions offer model‑independent Higgs studies, precise SUSY spectroscopy, top and gauge coupling measurements, and stringent tests of new physics scenarios. The authors outline concrete accelerator designs, physics capabilities, and upgrade paths toward multi‑TeV energies, underscoring the collider’s role in achieving a complete, precision understanding of TeV‑scale phenomena. The work emphasizes complementarity with hadron colliders and presents a long‑term vision for a scalable, high‑impact program in particle physics.

Abstract

Several proposals are being developed around the world for an e+e- linear collider with an initial center of mass energy of 500 GeV. In this paper, we will discuss why a project of this type deserves priority as the next major initiative in high energy physics.

Paper Structure

This paper contains 34 sections, 20 equations, 17 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Lepton colliders and the long-term future of high energy physics
  3. A twenty-year goal for high energy physics
  4. A twenty-year program for accelerators
  5. Parameters of a 500 GeV linear collider
  6. Why we expect new physics below 500 GeV
  7. A fundamental versus composite Higgs boson
  8. A fundamental Higgs boson should be light
  9. The constraint on the Higgs mass from precision electroweak data
  10. The lightest supersymmetry partners are likely to appear at 500 GeV
  11. What if there is no fundamental Higgs boson?
  12. What if the LHC sees no new physics?
  13. Physics at a 500 GeV linear collider
  14. Study of the Higgs boson
  15. Discovery of the Higgs independent of its decay modes
  16. ...and 19 more sections

Figures (17)

  • Figure 1: Cross sections for a variety of physics processes at an $e^+e^-$ linear collider, from MiyamotoH.
  • Figure 2: Capability of the ATLAS experiment to study the Higgs sector of the MSSM ATLAS.
  • Figure 3: Processes for production of the Higgs boson at an $e^+e^-$ linear collider.
  • Figure 4: Higgs reconstruction in the process $e^+e^- \to Z^0 h^0$ for various Higgs boson masses, using $\ell^+\ell^-$, $\nu\overline{\nu}$, and hadronic $Z^0$ decays, for a 30 fb$^{-1}$ event sample at 300 GeV, from JLCone. The background is dominated by the process $e^+e^-\to Z^0 Z^0$, which produces the missing-mass peak at $m_Z$. The unshaded solid histogram gives the background if a $b$-tag is applied to the Higgs candidate. The dashed histograms in (a) and (b) show the background with no $b$-tag.
  • Figure 5: Determination of Higgs boson branching ratios in a variety of decay modes, from Battaglia. The error bars show the expected experimental errors for 500 fb$^{-1}$ at 350 GeV. The bands show the theoretical errors in the Standard Model predictions.
  • ...and 12 more figures