Condensed Matter Physics, 2015, vol. 18, No. 4, 43001
DOI:10.5488/CMP.18.43001           arXiv:1512.07742

Title: First sound velocity in liquid 4He
  O.I. Hryhorchak (Department for Theoretical Physics, Ivan Franko National University of Lviv, 12 Drahomanov St., 79005 Lviv, Ukraine)

Based on the many-boson system structure factor, which takes into account three- and four-particle direct correlations, there was found the first sound velocity temperature behaviour in liquid 4He in the post-RPA approximation. The expression received for the sound velocity matches with the well-known results in both low and high temperature limits. The results of this paper can be used to analyze the contributions of three- and four-particle correlations into thermodynamic and structural features of liquid 4He .

Key words: boson systems, liquid
PACS: 05.30.Jp, 67.25.-k, 43.35.+d, 62.60.+v,67.25.dt

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