Searches for Pair Production of a Heavy Vector-Like Quarks in pp Collisions ats=13 TeV with the ATLAS Detector

ATLAS;Vector-like Quarks;Physics;Science;Physics

Marley, DanielQian, Jianming ;

University of Michigan

关键词: ATLAS;    Vector-like Quarks;    Physics;    Science;    Physics;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/138552/demarley_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A summary of two orthogonal and complementary searches for pair production of heavy vector-like quarks is presented. The first analysis considers final states with 1-lepton and hadronic jets that can be used to reconstruct the vector-like quark system after identifying the boosted decay of W bosons and building the neutrino from the missing transverse momentum. Control and signal regions constrain the uncertainties associated with top quark production that most negatively impact this analysis. The second analysis searches in the fully-hadronic final state where no leptons are considered.An explicit veto on the lepton number ensures orthogonality between the analyses. The analysis uses a deep neural network to reconstruct the decays of heavy objects and a data-driven technique to estimate the dominant multi-jet background. Data were recorded by the ATLAS experiment in sqrt(s)=13 TeV proton-proton collisions delivered by the Large Hadron Collider in 2015 and 2016.No excess above the Standard Model background is observed in either analysis.The results from the 1-lepton analysis are interpreted assuming vector-like quarks decay TT->Wb+X.The 0-lepton analysis assumes both types of pair produced vector-like quarks TT and BB that decay to T->Wb,Ht,Zt and B->Wt,Hb,Zb.The 1-lepton analysis observes a 95% CL lower limit on the T mass of 1090 (810) GeV assuming the scenario BR(T->Wb)=1 (SU(2) singlet).The strongest observed 95% CL lower limits in the 0-lepton analysis are 850 GeV and 903 GeV in the BR(T->Ht)=1 and BR(B->Hb)=1 decays, respectively.