Wednesday, July 10, 2013

1307.2393 (Alexey Gulov et al.)

Model-Independent Estimates for the Couplings of the Abelian Z' Boson in
the Drell-Yan Process at the LHC
   [PDF]

Alexey Gulov, Andrey Kozhushko
In the present paper we investigate the Drell-Yan process with the intermediate heavy $Z'$ boson. The $Z'$ couplings to the SM fermions are described by an effective low-energy Lagrangian. In our investigation we use a model-independent approach that utilizes the renormalization-group relations between the $Z'$ couplings and allows to reduce the number of unknown $Z'$ parameters significantly. Earlier this approach was applied to analyze the LEP data, and a maximum-likelihood value for the $Z'$ coupling to axial-vector fermion currents was derived. We use this result in a newly proposed strategy for estimating $Z'$ contributions to the Drell-Yan cross section in order to constrain the $Z'$ couplings to lepton and quark vector currents. We determine the values of the $Z'$ couplings that allow to use the Narrow-Width Approximation. Then we calculate the $Z'$-related contribution in this approximation and compare it to the experimental data from the LHC presented by the ATLAS and CMS collaborations. Our method allows to estimate the values of $Z'$ couplings to the $u$ and $d$ quarks and to final-state leptons.
View original: http://arxiv.org/abs/1307.2393

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