Role of backflow correlations for the nonmagnetic phase of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>t</mml:mi><mml:mtext>–</mml:mtext><mml:msup><mml:mi>t</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:mrow></mml:math>Hubbard model

We introduce an efficient way to improve the accuracy of projected wave functions, widely used to study the two-dimensional Hubbard model. Taking the clue from the backflow contribution, whose relevance has been emphasized for various interacting systems on the continuum, we consider many-body correlations to construct a suitable approximation for the ground state at intermediate and strong couplings. In particular, we study the phase diagram of the frustrated $t\ensuremath{-}{t}^{\ensuremath{'}}$ Hubbard model on the square lattice and show that, thanks to backflow correlations, an insulating and nonmagnetic phase can be stabilized at strong coupling and sufficiently large frustrating ratio ${t}^{\ensuremath{'}}/t$.

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