Exploring the anomalous top–Higgs FCNC couplings at the electron proton colliders

• Main Authors: Hao Sun, Xuan Luo, Jing Li
• Format: Article
• Language: English
• Published: SpringerOpen 2018-04-01
• Series: European Physical Journal C: Particles and Fields
• Online Access: http://link.springer.com/article/10.1140/epjc/s10052-018-5761-9
• ISSN: 1434-6044; 1434-6052

Abstract We perform an updated analysis on the searches for the anomalous FCNC Yukawa interactions between the top quark, the Higgs boson, and either an up or charm quark $${{tqh,\ q=u,\ c}}$$ tqh,q=u,c ). We probe the observability of the FCNC top–Higgs couplings through the processes $${e^- p\rightarrow \nu _{\mathrm{e}} }\bar{{t}} \rightarrow \nu _{\mathrm{e}} h \bar{{q}}$$ e-p→νet¯→νehq¯ signal I) and $$e^- p \rightarrow \nu _{\mathrm{e}} h b$$ e-p→νehb signal II) at the proposed electron proton ep colliders, where the Higgs boson decays to a $${b}\bar{{b}}$$ bb¯ pair. We find that at the high-luminosity ($$1\;{ab}^{-1}$$ 1ab-1 ) ep colliders where the electrons have a polarization of $$80\%$$ 80% and electron energy is typical 60 GeV, the 2$$\sigma $$ σ upper limits on $${ Br t\rightarrow uh)}$$ Brt→uh) are $$0.15\times 10^{-2}$$ 0.15×10-2 $$2.9\times 10^{-4}$$ 2.9×10-4 ) at the 7TeV@LHeC 50TeV@FCC-eh) for signal I and $$0.15\times 10^{-2}$$ 0.15×10-2 $$2.2\times 10^{-4}$$ 2.2×10-4 ) for signal II. We also give an estimate on how the sensitivity (taking signal I as example) would change when we reduce the electron beam energy from 60 to 50 GeV or even 40 GeV due to the cost. The conclusion is that the discovery potential is reduced $$8.7\%$$ 8.7% ($$29.4\%$$ 29.4% ) if the electron beam changes from 60 to 50 (40) GeV at the 7 TeV LHeC, and $$16.8\%$$ 16.8% ($$19.8\%$$ 19.8% ) at the 50 TeV FCC-eh.