Complementary signals of lepton flavor violation at a high-energy muon collider

Abstract

A muon collider would be a powerful probe of flavor violation in new physics. There is a strong complementary case for collider measurements and precision low-energy probes of lepton flavor violation (as well as CP violation). We illustrate this by studying the collider reach in a supersymmetric scenario with flavor-violating slepton mixing. We find that the collider could discover sleptons and measure the slepton and neutralino masses with high precision, enabling event reconstruction that could cleanly separate flavor-violating new physics signals from Standard Model backgrounds. The discovery reach of a high-energy muon collider would cover a comparably large, and overlapping, range of parameter space to future μ → e conversion and electron EDM experiments, and unlike precision experiments could immediately shed light on the nature of new physics responsible for flavor violation. This complementarity strengthens the case that a muon collider could be an ideal energy-frontier laboratory in the search for physics beyond the Standard Model.

A comparative study of Z′ mediated charged lepton flavor violation at future lepton colliders

“…In this study, we are interested in searching for CLFV at those future lepton colliders. Similar studies [26][27][28] exist in literature but either only for electron positron colliders or being performed with models (e.g., effective operators) different from this study.…”

Towards a Muon Collider

“…It should be noted that detailed muon collider sensitivity projections for the BSM candidates in Figure 3 have not been performed yet. In general, a relatively limited literature exists on direct new physics searches at the MuC [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. More studies would be desirable also to offer targets to the design of the detector.…”

“…The concept can be made concrete by considering scenarios where the sensitivity to new physics stems from colliding muons, rather than electrons or other particles. An overview of such "muonspecific" opportunities is provided in Section 5.3 based on the available literature [22,[28][29][30][31][32][33][34][35][36][37]49,[96][97][98][99][100][101][102][103][104][105][106][107][108][109][110]. A brief discussion is reported below.…”

“…HL-LHC Fig. 83 Global fit to the EFT operators in the Lagrangian (37). We show the marginalised 68% probability reach for each Wilson coefficient c i /Λ 2 in eq.…”

“…Composite Higgs is described under the assumption that the new dynamics is parameterised in terms of a single coupling, g , and mass, m . Furthermore, as in [247], we assume for definiteness that the new physics contributions to the operator Wilson coefficients in (37) follow the power-counting formula with unit numerical coefficients, namely we take…”