Possible Resolution of the Finite-Size Scaling Problem inHe4

We offer an explanation of the long-standing discrepancy between finite-size scaling theory and the observed temperature shift $T_{\lambda }-T_m$ of the specific-heat maximum in confined ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. On the basis of a renormalization-group calculation using Dirichlet boundary conditions we argue that a new size-dependent scaling variable should be employed. The theory agrees with the data in the regime $T_{\lambda }\gtrsim T_m$ without an adjustment of parameters and explains the gradual onset of finite-size effects far from $T_{\lambda }$.