ثمانية تصادمات كشفت عملية جديدة سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2602.17165

This paper presents the first evidence of the simultaneous production of two $$Z$$ bosons and one photon with the ATLAS detector at the Large Hadron Collider. The measurement is performed using the full Run-2 dataset, recorded from 2015 to 2018, of proton-proton collisions at a center-of-mass energy of $$13$$ TeV, corresponding to an integrated luminosity of $$140$$ fb$$^{-1}$$. The fully leptonic final state with four leptons and one photon is analyzed, $$pp\rightarrow ZZ\gamma\rightarrow\ell^+\ell^-\ell'^+\ell'^-\gamma$$ with $$\ell, \ell' = e$$ or $$\mu$$. This final state is measured in a fiducial region where photon final-state radiation is minimized, and the photon has a transverse momentum of $$p_{\mathrm{T}}^\gamma > 20$$ GeV. Eight events are selected, with a background estimate of $$0.92\pm0.15$$. This results in an observed (expected) significance of the $$ZZ\gamma$$ final state of $$4.4\sigma$$ ($$4.4\sigma$$). The measured cross-section for $$pp\rightarrow ZZ\gamma\rightarrow\ell^+\ell^-\ell'^+\ell'^-\gamma$$ in the fiducial region is $$\sigma_{ZZ\gamma} = 0.144 _{-0.051}^{+0.064} \text{ (stat.)} _{-0.005}^{+0.007} \text{ (syst.) fb}$$, in agreement with the predicted Standard Model one, $$\sigma_{\textrm{fid.}}^{\textrm{SM}} = 0.143 _{-0.004}^{+0.007}$$ fb.