CMS-PAS-SMP-16-004

CMS-PAS-SMP-16-004
Measurement of the production cross section for $\mathrm{pp} \rightarrow \mathrm{Z}\gamma \rightarrow \nu\overline{\nu}\gamma$ at $\sqrt{s}=$ 13 TeV at CMS
CMS Collaboration
August 2016

Abstract: A measurement of the $\mathrm{Z}\gamma \rightarrow \nu\overline{\nu}\gamma$ cross section in pp collisions at $\sqrt{s}=$ 13 TeV is presented, using data corresponding to an integrated luminosity of 2.3 fb$^{-1}$ collected with the CMS detector at the LHC. Events are selected requiring a single photon with transverse momentum above 175 GeV within the pseudorapidity range $\|\eta\| <$ 1.44 accompanied by missing transverse energy above 170 GeV. The measured ${\mathrm{Z}\gamma \rightarrow \nu\overline{\nu}\gamma}$ production cross section, 66.5 $\pm$ 13.6 (stat) $\pm$ 14.3 (syst) $\pm$ 2.2 (lumi) fb for a single photon with transverse momentum above 175 GeV within the pseudorapidity range $\|\eta\| < $ 1.44, agrees within uncertainties with the next-to-next-to-leading order standard model prediction of 65.5 $\pm$ 3.3 fb.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: The tree-level Feynman diagram for $ {\mathrm {Z}}\gamma $ production via initial state radiation in the SM.
png pdf	Figure 2-a: The $E_\mathrm {T}^{\gamma }$ (a) and ${E_{\mathrm {T}}^{\text {miss}}}$ (b) distributions in data (points with error bars) compared with the SM ${\mathrm {Z}\gamma \rightarrow \nu \overline {\nu }\gamma }$ signal and estimated contributions from backgrounds. The background uncertainty includes statistical and systematic components.
png pdf	Figure 2-b: The $E_\mathrm {T}^{\gamma }$ (a) and ${E_{\mathrm {T}}^{\text {miss}}}$ (b) distributions in data (points with error bars) compared with the SM ${\mathrm {Z}\gamma \rightarrow \nu \overline {\nu }\gamma }$ signal and estimated contributions from backgrounds. The background uncertainty includes statistical and systematic components.

Tables
png pdf	Table 1: Summary of systematic uncertainties on the cross section in %. Data/simulation scale factors include a correction for the modeling of photon identification, pixel seed and for the combination of several requirements: the PF isolation computed from the charged hadron having the largest isolation sum, the MIP tag, and the rejection of events with additional leptons.
png pdf	Table 2: Summary of estimated backgrounds and observed total number of candidates for 2.3 fb$^{-1}$ at 13 TeV. Other rare backgrounds include the contributions from the $\gamma $+jets, ${\mathrm {Z}\gamma \rightarrow \ell ^{+}\ell ^{-}\gamma } $, ${\mathrm {W}\rightarrow \mu \nu } $, ${\mathrm {W}\rightarrow \tau \nu }$ and $ {\mathrm {t\overline {t}}\gamma }$ processes.

Summary

A measurement of the $\mathrm{ Z }\gamma\to\nu\overline{\nu}\gamma$ cross section in pp collisions at $ \sqrt{s} = $ 13 TeV is presented, using data corresponding to an integrated luminosity of 2.3 fb$^{-1}$ collected with the CMS detector at the LHC. Events are selected requiring a single photon with transverse momentum above 175 GeV within the pseudorapidity range $ | \eta | <$ 1.44 accompanied by missing transverse energy above 170 GeV. The measured $\mathrm{ Z }\gamma\to\nu\overline{\nu}\gamma$ production cross section, 66.5 $\pm$ 13.6 (stat) $\pm$ 14.3 (syst) $\pm$ 2.2 (lumi) fb, agrees within uncertainties with the next-to-next-to-leading order standard model prediction of 65.5 $\pm$ 3.3 fb.

References
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