Laboratory-frame tests of quantum entanglement in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>H</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>W</mml:mi><mml:mi>W</mml:mi></mml:math>
J. A. Aguilar–Saavedra
Abstract
Quantum entanglement between the two $W$ bosons resulting from the decay of a Higgs boson may be investigated in the dilepton channel $H\ensuremath{\rightarrow}WW\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\nu}\ensuremath{\ell}\ensuremath{\nu}$ using laboratory-frame observables that only involve the charged leptons $\ensuremath{\ell}=e$, $\ensuremath{\mu}$. The dilepton invariant mass distribution, already measured by the ATLAS and CMS Collaborations at the LHC, can be used to observe the quantum entanglement of the $WW$ pair with a statistical sensitivity of $7\ensuremath{\sigma}$ with run 2 data, and of $6\ensuremath{\sigma}$ when including theoretical systematics. As a by-product, the relation between $W$ rest frame (four-dimensional) angular distributions, $H\ensuremath{\rightarrow}WW$ decay amplitudes, and spin correlation coefficients, is written down.