{
  "id": "2106.00821",
  "version": "v1",
  "published": "2021-06-01T22:00:06.000Z",
  "updated": "2021-06-01T22:00:06.000Z",
  "title": "Negative group velocity and Kelvin-like wake in superfluid $^{4}He$",
  "authors": [
    "Eugene B. Kolomeisky",
    "Jonathan Colen",
    "Joseph P. Straley"
  ],
  "comment": "4+ pages, 2 figures",
  "categories": [
    "cond-mat.mes-hall",
    "physics.flu-dyn"
  ],
  "abstract": "The dispersion law $\\Omega(k)$ of elementary excitations in superfluid $^{4}He$ is a non-monotonic function of the wave number $k$. After an initial increase, the function $\\Omega(k)$ reaches a maximum followed by a \"roton\" minimum at finite $k$. As a result, there is a range of $k$ between these extrema where the elementary excitations have negative group velocity. These excitations are generated when a fast heavy impurity travels through the superfluid or the latter flows past an obstacle with the speed exceeding $60~m/s$. Their interference leads to a pattern resembling the Kelvin ship wake.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-06-01T22:00:06.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "negative group velocity",
      "kelvin-like wake",
      "superfluid",
      "elementary excitations",
      "fast heavy impurity travels"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}