Search for Pair-Produced vectorlike lepton singlet at the ILC by the XGBoost method

We study the pair production of the vector-like lepton singlet in the W nu r channel at the International Linear Collider (ILC) given that .,/s = 500 GeV. We analyse the characters of the signal and backgrounds. Through the detailed detector simulation and the Extreme Gradient Boosting (XGBoost) method, we obtain the excluding and discovering capabilities. For comparative study, we divide the search into the leptonic channel and the hadronic channel. We find that the statistical significance in the hadronic channel is better than the leptonic channel. The model includes only one free parameter, the vector-like lepton mass mr!. Given that the polarized incident beams Pe- = 0.8, Pe+ = -0.3, the excluding and discovering capabilities can be given as follows: (1) the ILC can exclude the region mr! e [180 GeV, 240 GeV] with an integrated luminosity of [3.49x10-2, 0.167] fb-1 ([0.286, 1.58] fb-1) in the hadronic channel (leptonic channel); (2) the ILC can discover the region mr! e [180 GeV, 240 GeV] with an integrated luminosity of [0.185x10-2, 1.21] fb-1 ([1.74, 9.83] fb-1) in the hadronic channel (leptonic channel). These integrated luminosities can be achieved, which are lower than the maximum design integrated luminosity.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.