One of the hottest rock groups in the world, Fleetwood Mac, will fly to Indianapolis this spring to stage of fund-raising concert for Sen. Birch Bayh (D-Ind.) who faces a tough reelection race because conservative groups have targeted him for defeat.

Bayh's Hollywood connection stems from his Young Democrats, he made friends with another Young Dem named Mickey Shapiro. Bayh, of course, grew up to be a senator, while Shapiro because a West Coast Attorney who counts Fleetwood Mac as a client. This won't be the first gig the group has played for the senator; in 1976 Fleetwood Mac raised $75,000 to help Bayh settle debts from his losing bid for the presidency.

Raising campaign cash through rock concerts became popular 10 years ago, but it's an open question how savvy show-biz types are about politics. For example, one former Capitol Hill worker, now a political science professor, recently learned how wide the gulf separating the two worlds is.

Rutgers professor Ross Baker thought the romance between politicians and Hollywood stars might be material for a book. In Los Angeles last month, Baker attended a party that friends told him would include some Hollywood political activists. This is what happened:

Introduced to a filmaker who allegedly helped make commercials for George McGovern's presidential bid "in a small state back east," Baker asked him the state. "New Zealand," replied the man. You must mean New Hampshire, Baker said. "New Hampshire?" replied the filmmaker, "No, "I'm almost certain it was New Zealand."

A woman who had once done some work for Walter Mondale asked how he was getting on in Washington. Baker thought she was inquiring about Mondale's relationship with the president but finally realized she didn't know Mondale had left the Senate to become vice president. Informed of this, the woman exclaimed, "Terrific!"

Another guest asked Baker what he did, and the professor began describing his job. But the guest interrupted to explain she was merely asking his preference in drugs.