Measuring |V_ts| directly using strange-quark tagging at the LHC

The Cabibbo–Kobayashi–Maskawa (CKM) element V_ts , representing the coupling between the top and strange quarks, is currently best determined through fits based on the unitarity of the CKM matrix, and measured indirectly through box-diagram oscillations, and loop-mediated rare decays of the B or K mesons. It has been previously proposed to use the tree level decay of the t quark to the s quark to determine |V_ts| at the LHC, which has become a top factory. In this paper, we extend the proposal by performing a detailed analysis of measuring t → sW in dileptonic tt̅ events. In particular, we perform detector response simulation, including the reconstruction of K^0_S , which are used for tagging jets produced by s quarks against the dominant t → bW decay. We show that it should be possible to exclude |V_ts|= 0 at 5.5 σ with the expected High Luminosity LHC luminosity of 3000 fb ^-1 , considering only the statistical uncertainties, and not the systematic uncertainties which will play a role in setting the final analysis limits.