Z' physics with early LHC data

Accomando, Elena, Belyaev, Alexander, Fedeli, Luca, King, Stephen F. and Shepherd-Themistocleous, Claire (2011) Z' physics with early LHC data. Physical Review D, 83 (7), 075012-[23pp]. (doi:10.1103/PhysRevD.83.075012).

Abstract

We discuss the prospects for setting limits on or discovering spin-1 Z? bosons using early LHC data at 7 TeV. Our results are based on the narrow width approximation in which the leptonic Drell-Yan Z? boson production cross section only depends on the Z? boson mass together with two parameters cu and cd. We carefully discuss the experimental cuts that should be applied and tabulate the theoretical next-to-next-to-leading order corrections which must be included. Using these results the approach then provides a safe, convenient, and unbiased way of comparing experiment to theoretical models which avoids any built-in model-dependent assumptions. We apply the method to three classes of perturbative Z? boson benchmark models: E6 models, left-right symmetric models, and sequential standard models. We generalize each class of model in terms of mixing angles which continuously parametrize linear combinations of pairs of generators and lead to distinctive orbits in the cu-cd plane. We also apply this method to the strongly coupled four-site benchmark model in which two Z? bosons are predicted. By comparing the experimental limits or discovery bands to the theoretical predictions on the cu-cd plane, we show that the LHC at 7 TeV with integrated luminosity of 500??pb-1 will greatly improve on current Tevatron mass limits for the benchmark models. If a Z? is discovered our results show that measurement of the mass and cross section will provide a powerful discriminator between the benchmark models using this approach.

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Contributors

Author: Alexander Belyaev

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