Search for superfluidity in supercooled liquid parahydrogen

The possible superfluid transition of supercooled liquid parahydrogen is investigated by quantum Monte Carlo simulations. The cooling protocol adopted here allows for the study of a fluid phase down to a temperature $T=0.25$ K. No evidence of superfluidity is found, as exchanges of identical particles are strongly suppressed even at the lowest temperature. It is shown that, contrary to a commonly held belief, it is not the well depth of the pairwise interaction but rather its relatively large, hard-core diameter that physically hinders superfluidity in parahydrogen.