CMS-PAS-EXO-16-031

CMS-PAS-EXO-16-031
Search for a high-mass resonance decaying into a dilepton final state in 13 fb$^{-1}$ of pp collisions at $ \sqrt{s} = $ 13 TeV
CMS Collaboration
August 2016

Abstract: A search for new narrow resonances in dielectron and dimuon spectra is performed using data obtained from 2016 proton-proton collisions at 13 TeV. The integrated luminosity corresponds to 12.4 fb$^{-1}$ and 13.0 fb$^{-1}$ for the dielectron and dimuon samples, respectively. No significant deviations from the standard model expectation are observed. Upper bounds are set on the masses of hypothetical particles that arise in new-physics scenarios.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ;

Figures	Summary	References	CMS Publications

Figures
png pdf	Figure 1-a: The invariant mass spectrum of (a) $ {\mathrm {e}} {\mathrm {e}}$ and (b) $ {{\mu ^+}} {{\mu ^-}}$ events. The points with error bars represent the data. The histograms represent the expectations from SM processes: $ {\mathrm {Z}}{/}\gamma ^*$, $ {\mathrm {t}} {\overline {\mathrm {t}}}$ and other sources of prompt leptons ($ {\mathrm {t}} {\mathrm {W}}$, diboson production, $ {\mathrm {Z}}\rightarrow {\tau } {\tau }$), and the multijet backgrounds. Multijet backgrounds contain at least one jet that has been misreconstructed as an electron. The MC simulated backgrounds are normalised to the data in the region of 60 $ < m_{\ell \ell } < $ 120 GeV, with the muon channel using a prescaled lower threshold trigger for this purpose.
png pdf	Figure 1-b: The invariant mass spectrum of (a) $ {\mathrm {e}} {\mathrm {e}}$ and (b) $ {{\mu ^+}} {{\mu ^-}}$ events. The points with error bars represent the data. The histograms represent the expectations from SM processes: $ {\mathrm {Z}}{/}\gamma ^*$, $ {\mathrm {t}} {\overline {\mathrm {t}}}$ and other sources of prompt leptons ($ {\mathrm {t}} {\mathrm {W}}$, diboson production, $ {\mathrm {Z}}\rightarrow {\tau } {\tau }$), and the multijet backgrounds. Multijet backgrounds contain at least one jet that has been misreconstructed as an electron. The MC simulated backgrounds are normalised to the data in the region of 60 $ < m_{\ell \ell } < $ 120 GeV, with the muon channel using a prescaled lower threshold trigger for this purpose.
png pdf	Figure 2-a: The 95% CL upper limits on the production cross section times branching fraction for a spin-1 resonance with a width equal to 0.6% of the resonance mass, relative to the production cross section times branching fraction for a Z boson, for the (a) dielectron and (b) dimuon channel. The shaded bands correspond to the 68 and 95% quantiles for the expected limits. Theoretical predictions for the spin-1 $ { {\mathrm {Z}^\prime }_\mathrm {SSM}} $ and $ { {\mathrm {Z}^\prime }_\psi } $ resonances are shown for comparison.
png pdf	Figure 2-b: The 95% CL upper limits on the production cross section times branching fraction for a spin-1 resonance with a width equal to 0.6% of the resonance mass, relative to the production cross section times branching fraction for a Z boson, for the (a) dielectron and (b) dimuon channel. The shaded bands correspond to the 68 and 95% quantiles for the expected limits. Theoretical predictions for the spin-1 $ { {\mathrm {Z}^\prime }_\mathrm {SSM}} $ and $ { {\mathrm {Z}^\prime }_\psi } $ resonances are shown for comparison.
png pdf	Figure 3: The 95% CL upper limits on the production cross section times branching fraction for a spin-1 resonance with a width equal to 0.6% of the resonance mass, relative to the production cross section times branching fraction for a Z boson, for the combined dielectron and dimuon channels.

Summary

A search for new narrow neutral spin-1 resonances decaying to an $\mathrm{ e }\mathrm{ e }$ or $\mu^+\mu^-$ final state has been performed using 2016 proton-proton collision data collected at $ \sqrt{s} = $ 13 TeV. The data correspond to an integrated luminosity of 12.4 (13.0) fb$^{-1}$ for the dielectron (dimuon) sample. The observations are consistent with the expectations of the standard model. Upper limits at 95% CL are set on the cross section times branching fraction for new boson production relative to standard model Z boson production. For the $\mathrm{Z'_{SSM}}$ and $\mathrm{Z'_{\psi}}$ bosons, we obtain lower mass limits of 4.0 TeV and 3.5 TeV, respectively. These results extend the mass limits from previous searches.

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