Nonuniversal critical phenomena along the lambda line of4He

We present a new calculation of the critical thermal conductivity near the lambda line of⁴He. Static and dynamic effects are properly separated and are calculated within modelF in three dimensions by means of renormalized field theory up to two-loop order. The result provides an appropriate basis for analyzing forthcoming thermal conductivity data and for determining the temperature and pressure dependence of the effective dynamic parameters of⁴He in the entire critical region. This can be used to predict other nonuniversal dynamic critical phenomena above and below the lambda line.     

Nonuniversal routes to universality: critical phenomena in colloidal dispersions

We investigate critical phenomena in colloids by means of the renormalization-group based hierarchical reference theory of fluids. We focus on three experimentally relevant model systems: namely, the Asakura-Oosawa model of a colloidal dispersion under the influence of polymer-induced attractive depletion forces; fluids with competing short-range attractive and longer-range repulsive interactions; solutions of star polymers whose pair potential presents both an attractive well and an ultrasoft repulsion at shorter distance. Our results show that the ability to tune the effective interactions between colloidal particles allows one to generate a variety of crossovers to the asymptotic critical behavior, which are not observed in atomic fluids.     

Nonuniversal properties in the dipolar critical region of uniaxial ferromagnets

The amplitude of the critical isotherm is expressed by microscopic magnetic parameters and the transition temperature. The agreement between calculated and experimental values is good for GdCl₃ and LiTbF₄, whereas for DyEs a discrepancy is observed.     

The hypernuclei (4)(lambda)He and (4)(lambda)H: challenges for modern hyperon-nucleon forces

The hypernuclei (4)(Lambda)He and (4)(Lambda)H provide important information on the hyperon-nucleon interaction. We present accurate Faddeev-Yakubovsky calculations for the Lambda separation energies of the 0(+) ground and the 1(+) excited states based on the Nijmegen SC YN interactions. We explicitly take the Sigma admixture into account. Mass differences of the baryons and the charge dependence of the interaction are considered. The results show that the Nijmegen models cannot predict all separation energies simultaneously hinting to failures of the current interaction models. It is pointed out that the differences of the Lambda separation energies of (4)(Lambda)He and (4)(Lambda)H are interesting observables to probe the YN interaction models.     

The density maximum in liquid He4 and its relationship to the lambda point

The lambda point in liquid He⁴ is a very well-established phenomenon. London, in 1938, suggested that the effect might be an example of Bose–Einstein condensation and it is this model that is generally accepted nowadays. There are, however, serious discrepancies between the theory and experimental results. Here we present an alternative model based on the existence of the density maximum in liquid He⁴ near 2.18 K, that explains the anomaly in the specific heat capacity but does not have the failings of the BEC model. In addition the theory explains the occurrence of the density maximum in liquid He⁴.