Searches for pair production of a heavy vector-like quarks in pp collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

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 $t\bar{t}$ 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 $T\bar{T}\rightarrow Wb+X$. The 0-lepton analysis assumes both types of pair produced vector-like quarks $T\bar{T}$ and $B\bar{B}$ that decay to $T\rightarrow Wb,Ht,Zt$ and $B\rightarrow Wt,Hb,Zb$. The 1-lepton analysis observes a 95\% CL lower limit on the $T$ mass of 1090 (810) GeV assuming the scenario BR($T\rightarrow Wb)=1$ ($SU(2)$ singlet). The strongest observed 95\% CL lower limits in the 0-lepton analysis are 850 GeV and 903 GeV in the BR($T\rightarrow Ht)=1$ and BR($B\rightarrow Hb)=1$ decays, respectively.