CMS-PAS-EXO-14-014

CMS-PAS-EXO-14-014
Search for heavy Majorana neutrinos in $\mathrm{ e^{\pm} e^{\pm} }$ + jets and $\mathrm{ e^{\pm} \mu^{\pm} }$ + jets events in proton-proton collisions at $\sqrt{s} =$ 8 TeV
CMS Collaboration
September 2015

Abstract: We report a search for heavy Majorana neutrinos (N) decaying into a W boson and a lepton using the CMS detector at the Large Hadron Collider. We search for a signature of two same-sign electrons and two jets or a same-sign electron-muon pair and two jets using 19.7 fb $^{-1}$ of data collected during 2012 in proton-proton collisions at a center-of-mass energy of 8 TeV. We find the data to be consistent with the expected standard model background and upper limits are set on $\| V_{\ell \mathrm{N}} \|^2$ , as a function of Majorana neutrino mass from 40-500 GeV/ $c^2$ , where $V_{\ell \mathrm{N}}$ is the mixing element of the heavy neutrino with the standard model neutrino. The upper limits obtained for $\| V_{e \mathrm{N}} \|^2$ ( $\| V_{e \mathrm{N}} V_{\mu \mathrm{N}}^* \|$ ) are 0.022 (0.009) for $m_\mathrm{N} =$ 90 GeV/ $c^2$ , 0.016 (0.009) for $m_\mathrm{N} =$ 200 GeV/ $c^2$ , and 0.72 (0.47) for $m_\mathrm{N} =$ 500 GeV/ $c^2$ . These results extend considerably the regions excluded by previous direct searches.
Links: CDS record (PDF) ; inSPIRE record ; Public twiki page ; CADI line (restricted) ; These preliminary results are superseded in this paper, JHEP 04 (2016) 169. The superseded preliminary plots can be found here.

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