Measurement of $Z\gamma\gamma$ production in $pp$ collisions at $\sqrt{s}= 13$ TeV with the ATLAS detector

The collaboration
CERN-EP-2022-192, 2022.

Abstract (data abstract)
CERN-LHC. Cross-sections for the production of a $Z$ boson in association with two photons are measured in proton-proton collisions at a centre-of-mass energy of $13 \, \mathrm{TeV}$. The data used correspond to an integrated luminosity of $139 \, \mathrm{fb}^{-1}$ recorded by the ATLAS experiment during Run 2 of the LHC. The measurements use the electron and muon decay channels of the $Z$ boson, and a fiducial phase-space region where the photons are not radiated from the leptons. The integrated $Z(\rightarrow\ell\ell)\gamma\gamma$ cross-section is measured with a precision of $12\%$ and differential cross-sections are measured as a function of six kinematic variables of the $Z\gamma\gamma$ system. The data are compared with predictions from MC event generators which are accurate to up to next-to-leading order in QCD. The cross-section measurements are used to set limits on the coupling strengths of dimension-8 operators in the framework of an effective field theory.

• #### Table 1

Data from Figure 4, located on page 15.

10.17182/hepdata.132903.v1/t1

Measured fiducial-level integrated cross-section. NLO predictions from Sherpa 2.2.10 and MadGraph5_aMC@NLO 2.7.3 are also shown. The uncertainty in the predictions...

• #### Table 2

Data from Figure 5(a), located on page 16.

10.17182/hepdata.132903.v1/t2

Measured unfolded differential cross-section as a function of the leading photon transverse energy $E^{\gamma1}_{\mathrm{T}}$. NLO predictions from Sherpa 2.2.10 and...

• #### Table 3

Data from Figure 5(b), located on page 16.

10.17182/hepdata.132903.v1/t3

Measured unfolded differential cross-section as a function of the subleading photon transverse energy $E^{\gamma2}_{\mathrm{T}}$. NLO predictions from Sherpa 2.2.10 and...

• #### Table 4

Data from Figure 6(a), located on page 17.

10.17182/hepdata.132903.v1/t4

Measured unfolded differential cross-section as a function of the dilepton transverse momentum $p^{ll}_{\mathrm{T}}$. NLO predictions from Sherpa 2.2.10 and MadGraph5_aMC@NLO...

• #### Table 5

Data from Figure 6(b), located on page 17.

10.17182/hepdata.132903.v1/t5

Measured unfolded differential cross-section as a function of the the four-body transverse momentum $p^{ll\gamma\gamma}_{\mathrm{T}}$. NLO predictions from Sherpa 2.2.10 and...

• #### Table 6

Data from Figure 7(a), located on page 18.

10.17182/hepdata.132903.v1/t6

Measured unfolded differential cross-section as a function of the diphoton invariant mass $m_{\gamma\gamma}$. NLO predictions from Sherpa 2.2.10 and MadGraph5_aMC@NLO...

• #### Table 7

Data from Figure 7(b), located on page 18.

10.17182/hepdata.132903.v1/t7

Measured unfolded differential cross-section as a function of the four-body invariant mass $m_{ll\gamma\gamma}$. NLO predictions from Sherpa 2.2.10 and MadGraph5_aMC@NLO...

• #### Table 8

Data from Figure 9, located on page 21.

10.17182/hepdata.132903.v1/t8

Expected and observed $95\%$ confidence intervals for the coupling parameters $f_{T,j}/\Lambda^{4}$ of transverse dimension-8 operators. All parameter values outside of...

• #### Table 9

Data from Figure 10, located on page 22.

10.17182/hepdata.132903.v1/t9

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,8}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 10

Data from aux material, Figure 4(a).

10.17182/hepdata.132903.v1/t10

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,0}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 11

Data from aux material, Figure 4(b).

10.17182/hepdata.132903.v1/t11

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,1}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 12

Data from aux material, Figure 4(c).

10.17182/hepdata.132903.v1/t12

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,2}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 13

Data from aux material, Figure 4(d).

10.17182/hepdata.132903.v1/t13

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,5}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 14

Data from aux material, Figure 5(a).

10.17182/hepdata.132903.v1/t14

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,6}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 15

Data from aux material, Figure 5(b).

10.17182/hepdata.132903.v1/t15

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,7}/\Lambda^{4}$ in the clipping energy range between 1.1 and...

• #### Table 16

Data from aux material, Figure 5(c).

10.17182/hepdata.132903.v1/t16

Expected and observed unitarised $95\%$ confidence intervals for the coupling parameter $f_{T,9}/\Lambda^{4}$ in the clipping energy range between 1.1 and...