Same-sign tetralepton signature in type-Ⅱ seesaw at lepton colliders  

作　　者：Xu-Hong Bai Zhi-Long Han Yi Jin Hong-Lei Li Zhao-Xia Meng 白旭红;韩志龙;金毅;李洪蕾;孟召霞(School of Physics and Technology,University of Jinan,Jinan 250022,China)

机构地区：[1]School of Physics and Technology,University of Jinan,Jinan 250022,China

出　　处：《Chinese Physics C》2022年第1期21-30,共10页中国物理C（英文版）

基　　金：Supported by the National Natural Science Foundation of China(11605074,11805081);Natural Science Foundation of Shandong Province(ZR2019QA021,ZR2018MA047);Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U2032115)。

摘　　要：The same-sign tetralepton signature via the mixing of neutral Higgs bosons and their cascade decays to charged Higgs bosons is a unique signal in the type-Ⅱ seesaw model with the mass spectrum M_(A^(0))≈M_(H^(0))>M_(H^(+))>M_(H^(±±)).In this study,we investigate this signature at future lepton colliders,such as the ILC,CLIC,and MuC.Direct searches for doubly charged scalar H^(±±)at the LHC have excluded MHg+t<350(870) GeV in the H^(±±)+W^(±)W(±)(l^(±)^(±))decay mode.Therefore,we choose M_(A^(0))=400,600,1000,1500 GeV as our benchmark scenarios.Constrained by direct search,H^(±±)+W^(±)W(±)(l^(±)^(±))d=is the only viable decay mode for Mρ=400 GeV at the √s=1 TeV ILC.With an integrated luminosity L=8 ab^(-1),the promising region,with approximately 150 signal events,corresponds to a narrow band in the range of 10^(-4) GeV≤v△≤10^(-2)GeV.Meanwhile,for Mpo=600 GeV at the √s=1.5 TeV CLIC,approximately 10 signal events can be produced with L=2.5 ab^(-1).For heavier triplet scalars M_(A^(0))■870 GeV,although the H^(±±) decay mode is allowed,the cascade decays are suppressed.A maximum event number~16 can be obtained at approximately v△~4×10^(4)GeV and λ_(14)~0.26 for M_(A^(0))=1000 GeV with L=5 ab^(-1) at the √s=3 TeV CLIC.Finally,we find that this signature is not promising for M_(A^(0))= 1500 GeV at the √s=6 TeV MuC.Based on the benchmark scenarios,we also study the observability of this signature.In the H^(±±)+W^(±)W(±)(l^(±)^(±))d mode,one can probe MρS 800(1160) GeV at future lepton colliders.

关 键 词：same-sign tetralepton signature type-II seesaw lepton colliders 

分 类 号：O572.214[理学—粒子物理与原子核物理]