The lawsuit over title to the art holdings of Armand Hammer has heated up with allegations of illicit sex between the late industrialist and the woman who is now chief fund-raiser at Los Angeles museum that bears his name. The allegations of longtime infidelity are contained in court filings made on behalf of Joan Weiss, the niece of Hammer's deceased wife, Frances.

Weiss, who is seeking to gain half ownership of Hammer's $450 million art collection, contends Frances Hammer was improperly induced to sign away her interest in the paintings, drawings and sculptures.

The allegations of an extramarital affair involve Hammer and Hilary Gibson, now chief financial officer at the Armand Hammer Museum of Art and Cultural Center. When the alleged affair began in the early 1970s, Gibson was known by another name, Martha Wade Kaufman. The Weiss documents allege that the legal name change "reflected the desire of both Martha Kaufman and Armand Hammer ... to conceal from Frances Hammer that he had selected Martha Kaufman to hold a high-ranking position at the Armand Hammer museum."

A spokeswoman for the Hammer museum said Gibson would have no comment on the charges. Sally Field Threatened Over Film Actress Sally Field has hired a bodyguard after receiving an unspecified number of threats against her since the release of her film "Not Without My Daughter." "We felt it might be wise," said her publicist, Pat Kingsley, adding that Field decided to get personal protection "because of the times we're in right now." In her latest film, based on a true story, the Oscar-winning actress plays the wife of an Iranian-born physician who convinces her and their daughter to return with him to Iran. They find themselves effectively held hostage, and search for an escape. Brian Gilbert, the British director of the film, said he hoped that there would be no problems with Moslem extremists. "Obviously, one has thought a lot about it," Gilbert said.

D.C.'s Starr-Studded Day Music producer Maurice Starr honored Washington with a visit on Thursday, and was honored in return as California Rep. Ron Dellums read into the Congressional Record that Jan. 17 was Maurice Starr Day in the District of Columbia. Starr, the Svengali responsible for New Kids on the Block and the New Edition, was on the Hill visiting Jesse Jackson and Eleanor Holmes Norton, where he announced that he was seriously considering moving his entertainment empire to Washington. He also addressed an assembly at Roosevelt High School, where he was joined by Black Entertainment Television head Alvin Jones in urging the students to stay in school. He invited them to come onstage for an impromptu singing audition, an invitation a number accepted, as did assistant principal Warren Davis, but there was no word on any imminent signings. Starr took a day off from working on the latest recordings of Lionel Richie and Frank Sinatra to make the visit. Prince Protege Arrested Guitarist Jesse Johnson of the funk band the Time has been arrested and charged with felony assault. He is accused of threatening to shoot his estranged wife, Teresa Laws, and then trying to shoot himself outside Laws's mother's home near Minneapolis. Johnson has been a member of the off-again, on-again band since Prince formed it as a side project in 1981. The band was featured in Prince's films "Purple Rain" and "Graffiti Bridge." The guitarist's lawyer said that Johnson has been under a lot of stress, and has been released and is receiving medical treatment.

Iglesias Denies Song-Stealing Julio Iglesias took the stand this week to testify in a copyright infringement suit that alleges he stole the music to his 1980 hit song "Hey." The suit, brought by Enrique Chia, claims that Chia's ballad "Es," which had been submitted to and rejected by Iglesias's label, CBS Records, had found its way to Iglesias, who then used its music without credit. Iglesias testified: "It's the main song of my life. It's a song I sing every day." The popular singer said that Italian composer Mario Balducci came up with the music, to which Iglesias then added lyrics, and he denied ever having heard Chia's composition. "Sitting here and defending myself against something I never did in my life is very difficult," Iglesias said.