Measurement of electroweak production of two jets in association with a Z boson in proton-proton collisions at $\sqrt{s}=8\,\text {TeV}$

• Main Author: CMS collaboration (2146 authors)
• Publication Date: 2015
• Other Authors: Hollar, Jonathan, Nayak, Aruna, Bargassa, Pedrame, Beirão Da Cruz E Silva, Cristóvão, Faccioli, Pietro, Ferreira Parracho, Pedro Guilherme, Gallinaro, Michele, Nguyen, Federico, Rodrigues Antunes, Joao, Seixas, Joao, Varela, Joao, Vischia, Pietro, Lloret Iglesias, Lara, David Tinoco Mendes, Andre, Musella, Pasquale, Silva, Pedro, Pela, Joao, Leonardo, Nuno
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://dx.doi.org/10.1140/epjc/s10052-014-3232-5; http://hdl.handle.net/10400.26/26704

The purely electroweak (EW) cross section for the production of two jets in association with a Z boson, in proton–proton collisions at $\sqrt{s}=8\,\text {TeV}$ , is measured using data recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 19.7 $\,\text {fb}^\text {-1}$ . The electroweak cross section for the $\ell \ell \mathrm {jj}$ final state (with $\ell = \mathrm {e}$ or $\mu $ and j representing the quarks produced in the hard interaction) in the kinematic region defined by $M_{\ell \ell } >50$ $\,\text {GeV}$ , $M_\mathrm {jj} >120$ $\,\text {GeV}$ , transverse momentum $p_\mathrm {T j}> 25$ $\,\text {GeV}$ , and pseudorapidity $|\eta _\mathrm {j} |< 5$ , is found to be $\sigma _\mathrm {EW}(\ell \ell \mathrm {jj})=174 \pm 15\,\text {(stat)}\pm 40\,\text {(syst)}\text {\,fb}$ , in agreement with the standard model prediction. The associated jet activity of the selected events is studied, in particular in a signal-enriched region of phase space, and the measurements are found to be in agreement with QCD predictions.