Speaker
Description
We have studied the sensitivity of FCC-ee(240GeV) with an integrated luminosity of 10.8$ab^{-1}$ to the quark flavor violating (QFV) Higgs boson decay branching ratio $\mathcal{B}(H\to bs)$. We analyzed the Monte Carlo (MC) generated signal event samples for four orthogonal signal channels $e^- e^+ \to Z(e^+ e^-)H(bs), \,
Z(\mu^+ \mu^-)H(bs), \, Z(\nu \bar{\nu})H(bs), \, Z(q \bar{q})H(bs)$, where $Z(q \bar{q})H(bs)$ includes $Z(\tau^+ \tau^-)H(bs)$. The corresponding background event samples used in this analysis were produced by the FCC-ee Collaboration as apart of their Winter2023 Campaign. We analyzed these signal and background event samples using the IDEA detector concept and the fast detector simulation framework Delphes. For signal event sample and background event sample, physics-motivated pre-selection cuts and then a channel-specific XGBoost BDT classifier were applied to enhance signal to background ratio efficiently. In this BDT classifier analysis, the ParticleNET algorithm
was employed for jet-flavor tagging. The statistical analysis was performed using the CMS Combine framework when we evaluate the expected precision of $\mathcal{B}(H\to bs)$ measurement and the expected upper limit on $\mathcal{B}(H\to bs)$. As for the expected precision of $\mathcal{B}(H\to bs)$ measurement, we have found that this measurement is very powerful in testing and distinguishing models such as the SM, the MSSM with minimal flavor violation (MFV) and the MSSM with general QFV. As for the expected upper limit on $\mathcal{B}(H\to bs)$, the $Z(\nu \bar{\nu})H(bs)$ channel analysis provides the highest sensitivity giving an expected 95% CL upper limit of $2.31 \times 10^{-4}$. Combining all four channels yields an expected limit of $1.46 \times 10^{-4}$, demonstrating that the FCC-ee(240GeV) with an integrated luminosity of 10.8$ab^{-1}$ has strong sensitivity to this decay mode at the $10^{-4}$ level.
Authors: Aman Desai (Adelaide University, Australia) and Keisho Hidaka
Work in progress.