Search for excited electrons singly produced in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment at the LHC

The ATLAS collaboration
No Journal Information, 2019

Abstract (data abstract)
A search for excited electrons produced in $pp$ collisions at $\sqrt{s} = 13$ TeV via a contact interaction $q\bar{q} \to ee^*$ is presented. The search uses 36.1 fb$^{-1}$ of data collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider. Decays of the excited electron via a contact interaction into an electron and a pair of quarks ($eq\bar{q}$) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a $W$ boson ($\nu W$) are probed in final states with an electron, missing transverse momentum, and a large-radius jet consistent with a hadronically decaying $W$ boson. No significant excess is observed over the expected backgrounds. Upper limits are calculated for the $pp \to ee^* \to eeq\bar{q}$ and $pp \to ee^* \to e\nu W$ production cross sections as a function of the excited electron mass $m_{e^*}$ at 95% confidence level. The limits are translated into lower bounds on the compositeness scale parameter $\Lambda$ of the model as a function of $m_{e^*}$. For $m_{e^*} < 0.5$ TeV, the lower bound for $\Lambda$ is 11 TeV. In the special case of $m_{e^*} = \Lambda$, the values of $m_{e^*} < 4.8$ TeV are excluded. The presented limits on $\Lambda$ are more stringent than those obtained in previous searches.

  • Table 1

    Data from Figure 3c of paper

    10.17182/hepdata.90452.v1/t1

    The distribution of $m_{lljj}$ used to discriminate the signal from background processes in the $eejj$ channel. The distribution is shown...

  • Table 2

    Data from Figure 4b of paper

    10.17182/hepdata.90452.v1/t2

    The distribution of $m_{T}^{\nu W}$ used to discriminate the signal and background processes in the $e\nu J$ channel. The distribution...

  • Table 3

    Data from Figure 5a of paper

    10.17182/hepdata.90452.v1/t3

    Upper limits on $\sigma\times B$ as a function of $m_{e^*}$ in the $eejj$ channel. The $\pm 1(2)\sigma$ uncertainty bands around...

  • Table 4

    Data from Figure 5b of paper

    10.17182/hepdata.90452.v1/t4

    Upper limits on $\sigma\times B$ as a function of $m_{e^*}$ in the $e\nu J$ channel. The $\pm 1(2)\sigma$ uncertainty bands...

  • Table 5

    Data from Figure 6a of paper

    10.17182/hepdata.90452.v1/t5

    Lower limits on $\Lambda$ as a function of $m_{e^*}$ for the $eejj$ channel. The $\pm\ 1(2)\sigma$ uncertainty bands around the...

  • Table 6

    Data from Figure 6b of paper

    10.17182/hepdata.90452.v1/t6

    Lower limits on $\Lambda$ as a function of $m_{e^*}$ for the $e\nu J$ channel. The $\pm\ 1(2)\sigma$ uncertainty bands around...

  • Table 7

    Data from Figure 6c of paper

    10.17182/hepdata.90452.v1/t7

    Lower limits on $\Lambda$ as a function of $m_{e^*}$ combined for the $eejj$ and the $e\nu J$ channels. The $\pm\...

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