Two-to-Two Processes at an Electron-Muon Collider

Antonio O Bouzas,F Larios,Burak Bilki

doi:10.1155/2022/3603613

Antonio O Bouzas, F Larios + Show 1 more

Open Access

https://doi.org/10.1155/2022/3603613

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Abstract

Based on a recent proposal to build an electron-muon collider, we study two-to-two production processes e − μ + ⟶ f f ¯ , γ γ that originate from dimension 6 and 8 operators. We compare the sensitivity to those effective couplings obtained at the collider with that of low energy measurements of μ ⟶ e γ , μ ⟶ e e ¯ e , and μ ⟶ e conversion that have recently been reported in the literature. Whereas for the production of first family fermions, the sensitivity of the collider processes is much weaker; for the second and third family fermions, it is similar or stronger than that of low-energy processes. In the case of e − μ + ⟶ γ γ , the sensitivity to a dimension 8 contact operator turns out to be the strongest in comparison.

Highlights

With the main objective of measuring Higgs boson properties, there has been renewed interest in muon colliders [1–3]
Based on a recent proposal to build an electron-muon collider, we study two-to-two production processes e−μ+ ⟶ f f, γγ that originate from dimension 6 and 8 operators
We compare the sensitivity to those effective couplings obtained at the collider with that of low energy measurements of μ ⟶ eγ, μ ⟶ eee, and μ ⟶ e conversion that have recently been reported in the literature

Summary

Introduction

With the main objective of measuring Higgs boson properties, there has been renewed interest in muon colliders [1–3]. LFV operators are already being strongly constrained from low energy measurements like muon decays and μ − e transitions [28–30]. For the two-photon production e−μ+ ⟶ γγ, we address the contribution from the LFV dipole operator, that is very strongly constrained by μ ⟶ eγ, and we consider as well a dimension 8 contact operator that is bound more strictly by our results than by low-energy measurements. We estimate limits on the coefficients in the same way we did, but we carry out a detailed Monte Carlo analysis of signal and background processes.

Four Fermion Operators

Helicity Amplitudes

Cross Sections and Limits on Coefficients

Monte Carlo Analysis of γγ Production and Its SM Background

Findings

Conclusions