我們在此呈現一次針對激發態輕子於2e2μ末態之搜尋結果。此分析為CMS實驗在尋找激發態輕子於四輕子末態實驗之部分。此次實驗利用LHC於√s = 8 TeV撞擊之數據。數據的蒐集由CMS偵測器完成，使用數據之累積照度達到19.7 fb-1。激發態輕子(l^*)預期將透過接觸相互作用與一標準模型之輕子伴隨生成。而後，激發態輕子將以l^*→lZ→lll (l=e,μ)的機制衰變，造成四輕子之末態。這是LHC第一個針對激發態輕子於四輕子末態之搜尋。實驗結果並未超出標準模型背景的預期。激發態輕子的預期生成截面積受到T_3耦合因子f以及Y耦合因子f′的選擇影響。對於2e2μ之末態，當f/f^′=1 (f/f^′=-1)及在Λ=M_(l^*)時，激發態電子與渺子之質量上限皆設在1.60(1.85) TeV於95%的信心水準。結合4e與4μ之實驗結果，激發態電子與渺子之質量上限可分別設在1.70(1.95) TeV以及1.75(2.00) TeV。;A search of excited lepton in 2e2μ fi nal state is performed using a data sample of pp collisions at a center-of-mass energy √s = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb-1. This is a part of the excited lepton search in 4-lepton final state in CMS. Excited leptons (l^*) are assumed to be produced via contact interactions in conjunction with a standard model lepton and to decay via l^*→lZ→lll (l=e,μ), yielding a fi nal state with four leptons. We present the first study of the search for excited lepton in 4-lepton fi nal state at LHC. No signi cant excess is observed in the data above the expected standard model background. The expect cross section of l^* can be signi cantly aff ected by diff erent choice of coupling constant f and f′ to T_3 and Y. For f/f′=1(f/f′=-1), upper bounds at 95% confi dence level are set to 1.60(1.85) TeV for both e^* and μ^* in 2e2μ fi nal state with Λ=M_(l^*). Combining these results with 4e and 4μ channels, the limits can be set to 1.70(1.95) TeV and 1.75(2.00) TeV for e^* and μ^*, respectively.
