Linear Collider Physics Resource Book for Snowmass 2001 - Part 3: Studies of Exotic and Standard Model Physics

TL;DR

The paper surveys the physics program of a future e+e- linear collider at 500–1000 GeV, focusing on exotic and Standard Model phenomena. It details how precision measurements of gauge couplings, electroweak observables, top quark properties, QCD, two-photon processes, and potential new particles (Z′, W′, leptoquarks, exotic fermions) can illuminate physics beyond the Standard Model. The work highlights the collider’s complementary discovery potential with the LHC, the importance of beam polarization, and the role of two-photon and precision Z-pole studies (Giga-Z) in constraining new theories via S,T,U, and Λ scales. It argues that LC can both discover new phenomena and provide diagnostic tools to distinguish among competing models, including extra dimensions, composite Higgs scenarios, and string-inspired effects. The conclusions emphasize preparation for unexpected discoveries and the value of upgrades to higher energy to maximize physics reach.

Abstract

This Resource Book reviews the physics opportunities of a next-generation e+e- linear collider and discusses options for the experimental program. Part 3 reviews the possible experiments on that can be done at a linear collider on strongly coupled electroweak symmetry breaking, exotic particles, and extra dimensions, and on the top quark, QCD, and two-photon physics. It also discusses the improved precision electroweak measurements that this collider will make available.

Figures (33)

• Figure 5.1: Expected measurement error for the real part of four different TGCs. The numbers below the "LC" labels refer to the center-of-mass energy of the linear collider in GeV. The luminosity of the LHC is assumed to be 300 fb$^{-1}$, while the luminosities of the linear colliders are assumed to be 500, 1000, and 1000 fb$^{-1}$ for $\sqrt{s}$=500, 1000, and 1500 GeV respectively.
• Figure 5.2: Histogram of correlation coefficients for all 171 pairs of TGCs when 19 different TGCs are measured using one-parameter fits at LEP2 (unpolarized beams). The 19 TGCs are made up of the real and imaginary parts of the 8 C- and P-violating couplings along with the real parts of the three CP-conserving couplings $g^Z_1$, $\kappa_\gamma$, $\lambda_\gamma$.
• Figure 5.3: 95% C.L. contour for $F_T$ for $\sqrt{s}=500$ GeV and 500 fb$^{-1}$. Values of $F_T$ for various masses $M_\rho$ of a vector resonance in $W_{\rm L}W_{\rm L}$ scattering are also shown. The $F_T$ point "LET" refers to the case where no vector resonance exists at any mass in strong $W_{\rm L}W_{\rm L}$ scattering.
• Figure 5.4: Direct strong symmetry breaking signal significance in $\sigma$'s for various masses $M_\rho$ of a vector resonance in $W_{\rm L}W_{\rm L}$ scattering. In the first three plots the signal at the LHC is a bump in the $WW$ cross section; in the LET plot, the LHC signal is an enhancement over the SM cross section. The various LC signals are for enhancements of the amplitude for pair production of longitudinally polarized $W$ bosons. The numbers below the "LC" labels refer to the center-of-mass energy of the linear collider in GeV. The luminosity of the LHC is assumed to be 300 fb$^{-1}$, while the luminosities of the linear colliders are assumed to be 500, 1000, and 1000 fb$^{-1}$ for $\sqrt{s}$=500, 1000, and 1500 GeV respectively. The lower right hand plot "LET" refers to the case where no vector resonance exists at any mass in strong $W_{\rm L}W_{\rm L}$ scattering.
• Figure 5.5: The 95% confidence level limits for the compositeness scale $\Lambda^+_{\rm LL}$ from Møller and Bhabha scattering as a function of the $e^-e^- \,$ or $e^+e^-$ center-of-mass energy. The luminosity is given by ${\@fontswitch\mathcal{L}}=680\ {\rm pb}^{-1}\cdot s/M_Z^2$. The polarization of the electron beam(s) is indicated in the figure.