Probing electroweak precision physics via boosted Higgs-strahlung at the LHC

We study the process pp -> Z(l(+) l(-)) in the standard model effective field theory (SMEFT) at high energies using subjet techniques to reconstruct the Higgs boson. We show that at high energies this process probes four directions in the dimension-6 EFT space, namely the operators that contribute to the four contact interactions, hZ(mu.)(f) over bar gamma(mu) where f = u(L), u(R) ,d(L) and d(R). These four directions are, however, already constrained by the Z-pole and diboson measurements at LEP. WC show that by utilizing the energy growth of this process in the SMEFT and the accuracy that can be achieved by using subjet techniques at the High Luminosity LHC, one can obtain bounds on these operators that are an order of magnitude better than existing LEP bounds.