arXiv subjects

A. Pevzner

Publications and source records attributed to A. Pevzner.

4 recordsLinked to original sources

arXiv2018

Influence of the $Z-Z'$ mixing on the $Z'$ production cross section in the model-independent approach

The new module SMZp is developed for the Monte-Carlo generator Sherpa that extends simulations of the Standard model (SM) processes with the Abelian $Z'$ boson in the model-independent approach. The special derived earlier relations between the $Z'$ couplings to the SM fields proper to the renormalizable theories are taken into account. Using this module, dependence of the $Z'$ production cross section on the $Z-Z'$ mixing angle $θ_0$ in the Drell-Yan process is investigated within the range of 1 TeV $\leq m_{Z'} \leq$ 5 TeV. It is shown that if it is essential to keep the $Z'$ theory renormalizable, $θ_0$ cannot be neglected as it is often done, even if it is small.

hep-ph↗

arXiv2018

Model-independent constraints on the Abelian $Z'$ couplings within the ATLAS data on the dilepton production processes at $\sqrt{s} =$ 13 TeV

The study of lepton pair production is a powerful test of the Standard Model (SM) and can be used to search for phenomena beyond the SM. New heavy neutral bosons $Z'$ decaying to charged lepton pairs $l^+l^-$ ($l=e, μ$) are predicted by many scenarios of new physics, including models with extended gauge sector. We estimate the LHC $Z'$ discovery potential with Run 2 data comprised of 36.1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV and recorded by ATLAS detector at the CERN LHC. The model-independent constraints on the $Z'$ fermion couplings were obtained for the first time for a selected set of $Z'$ signal mass points of $M_{Z'}=2$, 3, and 4 TeV by using the ATLAS data collected at the LHC. The analysis is based on the derived earlier special relations between the $Z'$ couplings proper to the renormalizable theories. Taking into account the dependence of $Z-Z'$ mixing angle $θ_0$ on the $Z'$ axial-vector coupling $a$, the limits on $θ_0$ are established as $θ_0 < 10^{-4} - 10^{-3}$ in the investigated $Z'$ mass range.

hep-ph↗

arXiv2017

Estimate of the Abelian Z' boson decay width

The Abelian $Z'$ boson decay width is calculated in a model-independent approach. The analysis takes into consideration the special relations between the $Z'$ couplings to the Standard model fields proper to the renormalizable theories. The constraints on the $Z'$ couplings to the Standard model fermions corresponding to the narrow width approximation are derived. The results are compared with the benchmark $Z'$ models, such as $Z'_{χ}$ and $LR$. It is shown that the current experimental limits on the Standard model $Z$ width impose no limits on the $Z'$ width, so that the ratio $Γ_{Z'} / m_{Z'}$ is allowed to be up to 100%. This fact is connected with the smallness of the $Z-Z'$ mixing. So, the finite-width $Z'$ is admitted and cannot be excluded from consideration. Also, the new constraints on the $Z-Z'$ mixing angle are derived which agree with the corresponding earlier results of the LEP data analysis.

hep-ph↗

arXiv2016

Estimates of Z'couplings within data on the A_{FB} for Drell-Yan process at the LHC at s^(1/2) = 7 TeV and 8 TeV

Model-independent search for the Abelian Z' gauge boson in the Drell-Yan process at the LHC at s^{1/2}= 7 TeV and 8 TeV is fulfilled. Estimations of the Z' axial-vector coupling a_f^2 to the standard model fermions, the couplings of the axial-vector to lepton vector currents a_f v_l and the couplings of the axial-vector to quark vector currents a_f v_q are derived within data on the forward-backward asymmetry presented by the CMS Collaboration. The analysis takes into consideration the behaviour of the differential cross-section which exhibits itself if the derived already special relations between the couplings proper to the renormalizable theories are accounted for. In particular, they hold in all the models of Abelian Z' usually considered in the model-dependent analysis of the LHC data. The coupling values are estimated at ~ 92 % CL by means of the maximum likelihood function. They weakly depend on the Z' mass in the investigated interval 1.2 TeV < m_Z' < 5 TeV. Taking into account the dependence of Z-Z' mixing angle theta_0 on m_Z' and the LEP constraints |theta_0|~ 10^{-3}-10^{-4}, the optimistic limits on m_{Z'} are established as 3 < m_Z' < 7-8 TeV. Comparison with the results of other authors is given.

hep-ph↗