Searching for Extra Z' from Strings and Other Models at the LHC with Leptoproduction

TL;DR

This paper investigates the potential to discover extra neutral Z' bosons at the LHC through resonant leptoproduction, emphasizing a string-inspired Z' model and analyzing the impact of QCD background precision on detection prospects.

Contribution

It introduces a novel string-inspired Z' model and assesses its detectability at the LHC using high-precision NNLO QCD background calculations.

Findings

Detection of weakly coupled Z' is challenging with current background precision.

Results are insensitive to specific charge assignments in the models.

Discovery depends heavily on the size of the new gauge coupling.

Abstract

Discovery potentials for extra neutral interactions at the Large Hadron Collider in forthcoming experiments are analyzed using resonant leptoproduction. For this purpose we use high precision next-to-next-to-leading order (NNLO) determinations of the QCD background in this channel, at the tail of the Drell-Yan distributions, in the invariant mass region around $ 0.8< Q < 2.5 $ TeV. We focus our analysis primarily on a novel string-inspired $Z^\prime$, obtained in left-right symmetric free fermionic heterotic string models and whose existence at low energies is motivated by its role in suppressing proton decay mediation. We analyze the parametric dependence of the predictions and perform comparison with other models based on bottom up approaches, that are constructed by requiring anomaly cancellation and enlarged Higgs structure. We show that the results are not particularly sensitive to the specific charge assignments. This may render quite difficult the extraction of significant information from the forward-backward asymmetries on the resonance, assuming that these are possible due to a sizeable width. The challenge to discover extra (non anomalous) $Z^\prime$ in this kinematic region remains strongly dependent on the size of the new gauge coupling. Weakly coupled extra $Z^\prime$ will not be easy to identify even with a very good theoretical determination of the QCD background through NNLO.