Minimal Z' models: present bounds and early LHC reach

TL;DR

This paper analyzes minimal Z' models with three key parameters, evaluating current bounds and the early LHC's potential to discover or constrain these models at energies up to 10 TeV.

Contribution

It provides a comprehensive analysis of minimal Z' models, including effects of mixing, and estimates the early LHC's discovery reach considering existing experimental bounds.

Findings

LHC can explore Z' masses around 700 GeV at 7-10 TeV energies.

Tevatron and electroweak tests already exclude lower and higher mass regions.

Early LHC data with limited luminosity can probe new parameter space.

Abstract

We consider `minimal' Z' models, whose phenomenology is controlled by only three parameters beyond the Standard Model ones: the Z' mass and two effective coupling constants. They encompass many popular models motivated by grand unification, as well as many arising in other theoretical contexts. This parameterization takes also into account both mass and kinetic mixing effects, which we show to be sizable in some cases. After discussing the interplay between the bounds from electroweak precision tests and recent direct searches at the Tevatron, we extend our analysis to estimate the early LHC discovery potential. We consider a center-of-mass energy from 7 towards 10 TeV and an integrated luminosity from 50 to several hundred pb^-1, taking all existing bounds into account. We find that the LHC will start exploring virgin land in parameter space for M_Z' around 700 GeV, with lower masses still excluded by the Tevatron and higher masses still excluded by electroweak precision tests. Increasing the energy up to 10 TeV, the LHC will start probing a wider range of Z' masses and couplings, although several hundred pb^-1 will be needed to explore the regions of couplings favored by grand unification and to overcome the Tevatron bounds in the mass region around 250 GeV.