Investigation of the FCNC couplings between the top quark and the photon in $\gamma\gamma$ and $\gamma^{*}\gamma^{*}$ collisions at the CLIC

TL;DR

This paper explores flavor-changing neutral current interactions involving the top quark and photon at the Compact Linear Collider, providing improved constraints on rare top quark decays beyond current experimental limits.

Contribution

It presents a phenomenological study of anomalous FCNC top quark couplings via effective field theory at high-energy photon collisions, with new constraints at 95% confidence level.

Findings

Constraints on BR(t→qγ) are improved by at least an order of magnitude.

Analysis covers multiple collision processes at 1.5 TeV and 3 TeV.

Provides theoretical predictions for future collider experiments.

Abstract

The investigation of flavour-changing neutral current transitions(FCNC) involving the top quark are only possible with new theoretical frameworks that extend the Standard Model(SM), given that these transitions are almost entirely suppressed within the SM. In this regard, examining these transitions with extended theories beyond the SM may provide significant insights into future experiments. To this end, we present a phenomological study about the anomalous FCNC transitions via $tq\gamma$ couplings with effective field theory. Here, ${\gamma \gamma}{\rightarrow} {\textit{l}} {\nu}_\textit{l} b \bar{q} $ , ${e^{+}} {e^{-}} {\rightarrow} {e^{+}} {\gamma}^{} {\gamma}^{} {\rightarrow} {e^{+}} \textit{l}{} {\nu_\textit{ l}} b \bar{q} {e^{-}} $, $\gamma \gamma {\rightarrow} j \bar{j} b \bar{q} $ and ${e^{+}} {e ^{-}} {\rightarrow} {e^{+}} {\gamma}^{} {\gamma}^{} {e^{-}} {\rightarrow}{e^{+}} j \bar{j} b \bar{q} {e^{-}} $ processes are investigated for the CLIC at $\sqrt{s} =1.5$TeV and 3 TeV. Thus, we have calculated the constraints at $95{\%}$ confidence level on the $BR(t\rightarrow q\gamma)$. As a result, the obtained constraints are at least one order of magnitude better than the available experimental ones.