Dynamic structure factor of liquidHe4across the normal-superfluid transition

Dynamic structure factor of superfluid He4 from quantum Monte Carlo: Maximum entropy revisited

“…17 does yield a sharp peak in this case as well, of width comparable to that of the experimental image, and ∼ 30% greater height (data from Ref. 18 for this wave vector were not available). However, the position of the peak itself is off, compared to experiment, by roughly as much as that estimated by MaxEnt (in the case of GIFT the peak is detected at higher energy).…”

“…On the other hand, the spectral image obtained in Ref. 18 is much broader, with a significantly lower peak. It is interesting to compare these curves with that arising from χ 2 -fitting carried out in the context of our procedure, namely by simply setting α = 0.…”

Momentum Distribution of Liquid $$^{4}$$ 4 He Across the Normal–Superfluid Phase Transition

“…3 data obtained for the maxon and phonon energies. For the maxon excitation, the behavior is similar to the one of the roton, but in this case the strength of the peak when crossing T λ is not so drastically reduced [19]. In the case of the phonon, the influence of the temperature is much smaller than in the previous cases.…”

“…The evolution of the roton with temperature has been studied by means of the inverse Laplace transform of the intermediate scattering function [19], as commented in the previous Section. In Fig.…”

“…In this work, to obtain the dynamic structure factor, we use a stochastic optimization algorithm based on simulated annealing, as described in Ref. [19].…”