Searching for anomalous top quark interactions with proton tagging and timing detectors at the LHC

Abstract

We study the LHC sensitivity to new broad neutral resonances produced in two-photon fusion and decaying to a top quark pair, γγ → t t. This is probed in central exclusive t t production in proton-proton collisions, pp → pt tp. We use the tagging of the intact protons by PPS (CMS) and AFP (ATLAS) and consider the semi-leptonic t t channel. The sensitivity is also mapped onto a set of dimension-8 γγt t operators in the large mass limit. Using the kinematical correlations between the intact protons and the reconstructed t t system, we obtain a sensitivity to the couplings of the dimension-8 operators of 1.4 • 10 −11 GeV −4 at 95% CL. The sensitivity to the anomalous couplings is significantly improved down to about 7 • 10 −12 GeV −4 if the proton time-of-flight is known with a precision of 20 ps in future measurements. The 95% CL sensitivity to broad neutral resonances reaches masses of order 1500 GeV when using timing information.

The Future of US Particle Physics: The Energy Frontier Report – 2021 US Community Study on the Future of Particle Physics

“…[399,400]. In the γγ mode with tagging on two intact initial hadrons, the LHC can reach unprecedented sensitivities to quartic anomalous couplings, such as γγγγ, γγW W , γZZ, γγγZ, γγtt only to quote a few [389,[401][402][403][404][405][406][407][408]. The final states in γγ interactions at the LHC are remarkably clean (like at LEP), resulting in sensitivities to quartic anomalous couplings and to the production of axion-like particles (ALPs) at high masses that is better by 2-3 orders of magnitude than in usual LHC searches.…”