Precision from the diphoton Zh channel at FCC-hh

Abstract

The future 100 TeV FCC-hh hadron collider will give access to rare but clean final states which are out of reach of the HL-LHC. One such process is the $Zh$ production channel in the $(\nu \bar{\nu }/{\ell }^{+}{\ell }^{-})\gamma \gamma$ final states. We study the sensitivity of this channel to the ${\mathcal{O}}_{\phi q}^{(1)}$, ${\mathcal{O}}_{\phi q}^{(3)}$, ${\mathcal{O}}_{\phi u}$, and ${\mathcal{O}}_{\phi d}$ SMEFT operators, which parametrize deviations of the $W$ and $Z$ couplings to quarks, or, equivalently, anomalous trilinear gauge couplings (aTGC). While our analysis shows that good sensitivity is only achievable for ${\mathcal{O}}_{\phi q}^{(3)}$, we demonstrate that binning in the $Zh$ rapidity has the potential to improve the reach on ${\mathcal{O}}_{\phi q}^{(1)}$. Our estimated bounds are one order of magnitude better than projections at HL-LHC and is better than global fits at future lepton colliders. The sensitivity to ${\mathcal{O}}_{\phi q}^{(3)}$ is competitive with other channels that could probe the same operator at FCC-hh. Therefore, combining the different diboson channels sizeably improves the bound on ${\mathcal{O}}_{\phi q}^{(3)}$, reaching a precision of $|\delta g_{1z}|\lesssim 2\times 10^{-4}$ on the deviations in the $ZWW$ interactions.

Comments: 32 pages, 6 figures, 9 tables. v2: a few small clarifications added, results and discussion unchanged, matches version published in JHEP