Causality-Violating Higgs Singlets at the LHC

TL;DR

This paper proposes a theoretical model where certain particles, Higgs singlets, can travel backward in time via closed timelike curves in extra dimensions, and suggests potential observable signatures at the LHC.

Contribution

It introduces a model with CTCs in extra dimensions that allows Higgs singlets to exhibit time-traveling behavior, with possible detection at the LHC.

Findings

Time-traveling Higgs singlets can be produced at the LHC.

Pre-appearing decay vertices could be observable.

The model satisfies all classical energy conditions.

Abstract

We construct a simple class of compactified five-dimensional metrics which admits closed timelike curves (CTCs), and derive the resulting CTCs as analytic solutions to the geodesic equations of motion. The associated Einstein tensor satisfies all the null, weak, strong and dominant energy conditions. In particular, no negative-energy "tachyonic" matter is required. In extra-dimensional models where gauge charges are bound to our brane, it is the Kaluza-Klein (KK) modes of gauge-singlets that may travel through the CTCs. From our brane point of view, many of these KK modes would appear to travel backward in time. We give a simple model in which time-traveling Higgs singlets can be produced by the LHC, either from decay of the Standard Model (SM) Higgs or through mixing with the SM Higgs. The signature of these time-traveling singlets is a secondary decay vertex pre-appearing before the primary vertex which produced them. The two vertices are correlated by momentum conservation. We demonstrate that pre-appearing vertices in the Higgs singlet-doublet mixing model may well be observable at the LHC.