An Anomalous Extra Z Prime from Intersecting Branes with Drell-Yan and Direct Photons at the LHC

TL;DR

This paper investigates the effects of gauge anomalies in an extended Standard Model with an extra Z' boson at the LHC, finding that anomalous contributions are negligible compared to QCD backgrounds.

Contribution

It introduces a general framework for analyzing anomalous U(1) gauge symmetries from intersecting branes and compares anomaly-induced effects with anomaly-free models at the LHC.

Findings

Anomalous effects are very small, below 1% of the total cross section.

Anomalies contribute at higher orders, but are negligible compared to NNLO QCD corrections.

The study provides a method to distinguish anomalous from anomaly-free models using LHC data.

Abstract

We quantify the impact of gauge anomalies at the Large Hadron Collider by studying the invariant mass distributions in Drell-Yan and in double prompt photon, using an extension of the Standard Model characterized by an additional anomalous U(1) derived from intersecting branes. The approach is rather general and applies to any anomalous abelian gauge current. Anomalies are cancelled using either the Wess-Zumino mechanism with suitable Peccei-Quinn-like interactions and a Stueckelberg axion, or by the Green-Schwarz mechanism. We compare predictions for the corresponding extra Z-prime to anomaly-free realizations such as those involving U(1)_{B-L}. We identify the leading anomalous corrections to both channels, which contribute at higher orders, and compare them against the next-to-next-to-leading order (NNLO) QCD background. Anomalous effects in these inclusive observables are found to be very small, far below the percent level and below the size of the typical QCD corrections quantified by NNLO K-factors.