Anomalous U(1) Gauge Bosons and String Physics at the Forward Physics Facility

TL;DR

This paper discusses how the Forward Physics Facility can detect anomalous U(1) gauge bosons predicted by Little String Theory, potentially revealing new physics at string scales between 10^5 and 10^7 TeV.

Contribution

It demonstrates the potential of FASER2 to probe string scales over two orders of magnitude through searches for anomalous U(1) gauge bosons.

Findings

FASER2 can probe string scales from 10^5 to 10^7 TeV.

Anomalous U(1) gauge bosons can be detected via kinetic mixing with the photon.

The study links experimental searches to predictions of Little String Theory.

Abstract

We show that experiments at the Forward Physics Facility, planned to operate near the ATLAS interaction point during the LHC high-luminosity era, will be able to probe predictions of Little String Theory by searching for anomalous U(1) gauge bosons living in the bulk. The interaction of the abelian broken gauge symmetry with the Standard Model is generated at the one-loop level through kinetic mixing with the photon. Gauge invariant generation of mass for the U(1) gauge boson proceeds via the Higgs mechanism in spontaneous symmetry breaking, or else through anomaly-cancellation appealing to Stueckelberg-mass terms. We demonstrate that FASER2 will be able to probe string scales over roughly two orders of magnitude: 10^5 < M_s/TeV < 10^7.