Searches for electroweak states at future plasma wakefield colliders

TL;DR

The study assesses the discovery potential of future multi-TeV plasma wakefield colliders for new electroweak multiplets by incorporating realistic beam-beam spectra across five configurations (e+e-, e-e-, round/flat beams, and gamma-gamma). It shows that beam-beam effects qualitatively reshape search strategies, with significant emphasis on the low-energy tail and secondary initial-state channels, yet key targets such as wino-like triplets and higgsino-like doublets remain accessible under plausible luminosities. The analysis covers production channels, decay modes, and a suite of signatures—disappearing tracks, WW plus MET, mono-X, HSCP, and hadronic decays—evaluating discovery reach and luminosity requirements for each collider option. It finds that e+e- and gamma-gamma configurations deliver competitive or superior reach compared with a 10 TeV muon collider, while e-e- colliders face more severe limitations unless extremely high luminosities are achieved. The results underscore the importance of tightly integrated accelerator design, beam-beam modeling, detector concepts, and theory in shaping a practical path to new electroweak physics at the energy frontier.

Abstract

We quantify the discovery potential of future multi-TeV plasma wakefield colliders for new electroweak multiplets. We include beam-beam effects through realistic luminosity spectra, comparing five collider configurations: $e^+e^-$ and $e^-e^-$ machines with round- and flat-beams, and a $γγ$ collider. The beam-beam effects qualitatively change search strategies relative to idealized mono-energetic lepton colliders, highlighting the importance of the low-energy part of the luminosity spectrum and additional beam-induced initial-state channels. Our results have implications for accelerator R&D priorities, since key electroweak targets may remain accessible even if efficient positron acceleration and flat-beam delivery prove technically challenging at the multi-TeV scale.

Figures (21)

• Figure 1: Integrated luminosity spectra $\mathrm{d}\mathscr{L}_\text{int}/\mathrm{d}M$ for four initial states (panels) of Ref. simulationpaper: $e^+e^-$, $e^-e^-$, $e^-\gamma$, and $\gamma\gamma$. Each curve represents one of the five collider configurations (colors). All collider configurations are normalized such that $\mathscr{L}_\text{geom} = 1\per a\barn$. The relative values and the hardness of the spectra reflect the beam--beam dynamics: $e^+e^-$ exhibits stronger pinch and beamstrahlung (more weight at lower $M$), while $e^-e^-$ shows anti-pinch and a more pronounced endpoint spike at $M=2E_{\rm beam}$. Finally, only the $e^-\gamma$ initial state is shown; $e^+\gamma$ is similar for the $e^+e^-$ collider configurations and is otherwise negligible since no primary positron beam exists for the $e^-e^-$ and $\gamma\gamma$ colliders.
• Figure 2: Double-differential integrated luminosity spectra $\left.\mathrm{d}^2\mathscr{L}_\text{int}/(\mathrm{d}M\,\mathrm{d}Y)\right|_{M}$ as a function of rapidity $Y$ for representative masses $M$ (line thickness), across collider configurations (colors) as in \ref{['fig:initial_state_lumis']}. These were derived from the simulation data in simulationpaper, as explained in the text. For primary--primary channels ($e^\pm e^\mp$ and $e^-e^-$) the distributions approach the kinematic limits $Y=\pm Y_{\max}(M)$. Increasing $M$ narrows the allowed rapidity range $|Y|\le Y_{\max}(M)$ and raises the endpoint weight.
• Figure 3: $\chi^\pm$ production rates in the triplet model as a function of the COM energy $M$ of the collision. Top: Rate for Drell-Yan production for $m_\chi=1.5\TeV$ and $m_\chi=3\TeV$. Bottom: Rate for $\gamma\gamma \to \chi^+\chi^-$ for $m_\chi=1.5\TeV$ and $m_\chi=3\TeV$.
• Figure 4: Total $\chi^\pm$ production rates in the triplet model as a function of the $m_{\chi^\pm}$ for Drell-Yan (left), photon fusion (middle) and $e^\pm$ associated production (right). For most scenarios, the sum of the Drell-Yan and photon fusion rates is the most relevant figure of merit. If both the $\chi$ particles are invisible to the detector, the rate for $e^\pm$ associated production is the right figure of merit.
• Figure 5: Schematic overview of the considered decay modes.