Jones Apparel Group has acquired Barneys, the American luxury department store operator, which operates out of 21 locations including its flagships in New York City, Beverly Hills and Chicago. Jones, a highly acquisitive group that owns Nine West Group and recently acquired also Maxwell Shoe Company, is paying about $400 million in cash and shares for Barneys, whose operating income jumped by 95.3 percent to $24.5 million in the nine months ended Oct. 30. Its sales increased by 17.0 percent to $341.7 million during the period, with a 15.9 percent increase on a comparable basis. The takeover of Barneys brings a level of competence in luxury specialty retailing to Jones, raising from 17 to 24 percent the proportion of Jones’ revenues derived from retailing. Howard Socol will continue to run Barneys as president and CEO.