Exploring Anomalous Flavor-Changing Neutral tqh Transitions at Future Muon Colliders: Insights from $\mu^{+}\mu^{-}\rightarrow t\bar{q}h$ Interactions

TL;DR

This study investigates the potential of future muon colliders to detect flavor-changing neutral Higgs-top quark interactions, providing improved limits over current experiments and highlighting their role in probing new physics beyond the Standard Model.

Contribution

It offers a detailed analysis of FCNC Higgs-top interactions at 1 TeV and 3 TeV muon colliders, establishing new sensitivity limits surpassing current experimental bounds.

Findings

At 1 TeV, the limit on Br(t→qH) is 1.96×10⁻⁴, improving current limits by 1.5 times.

At 3 TeV, the limit on Br(t→qH) is 1.1×10⁻⁴, improving current limits by 3 times.

Muon colliders show strong potential for discovering rare Higgs-top FCNC interactions.

Abstract

Flavour-changing neutral current (FCNC) interactions between the Higgs boson and the top quark are subject to significant suppression within the Standard Model (SM). Consequently, these interactions can only attain an observable level through the influence of Beyond the Standard Model (BSM) physics effects. It is therefore of great importance to investigate these rare interactions, both to test the limits of the Standard Model and to reveal new physical signatures.In this context, the present study analyses the signal of the process $\mu^+\mu^- \to t\bar{q}h$ and the background processes $t\bar{t}$, $tW\bar{b}$, $WWh$ and $WW$ at both in $\sqrt{s} = 1$ TeV and $\sqrt{s} = 3$ TeV energy levels. Analyses at the $1 TeV$ energy level reveal the observability of FCNC interactions even at low energy conditions and achieve the limit $\text{Br}(t \to qH) = 1.96 \times 10^{-4}$. This result corresponds to an improvement of approximately 1.5 times compared to the current limits of the ATLAS experiment, which are $3.0 \times 10^{-4}$. On the other hand, at the 3 TeV energy level, the most stringent limit was calculated under the luminosity $\mathcal{L} = 20 ab^{-1}$ , yielding a value of $\text{Br}(t \to qH) = 1.1 \times 10^{-4}$. This result coincides an improvement of approximately 3 times with respect to the current ATLAS experimental limits. The findings of the study underscore the potential of muon colliders in the search for new physics and the pivotal role they can play in the study of rare processes such as Higgs-top quark interactions. Consequently, the results are expected to provide a crucial foundation for both experimental and theoretical studies and to make a significant contribution to the search for BSM physics.