How negative campaigning boomeranged on Jerry Brown

''Negative campaigning,'' a technique that apparently reached a peak in campaigns across the United States this fall, is cited by some observers as possibly the major factor in Democrat Jerry Brown's loss to Republican Pete Wilson in the California contest for the US Senate.

After being some 20 percentage points behind Mr. Wilson in early June, Mr. Brown narrowed the gap to a virtual tie by mid-October. But the governor, who had already been widely criticized for a TV commercial which was said to misrepresent Wilson's position on social security, allowed another ad to be televised which portrayed the San Diego mayor as irresponsible in regard to the use of nuclear weapons.

An even stronger storm of criticism was triggered, and some observers say that Wilson began to pull ahead again at this point - with the election only about two weeks away.

Conceding defeat on the morning after, Brown bore no aspect of the disconsolate loser. He indicated voters may have been tired of ''my semiannual foray into the electoral process'' and had decided ''to retire me, either temporarily or permanently.''

But he more than hinted that his political retirement is temporary: ''I'm going to be a force in the government process for a long time to come, even though I may be temporarily on sabbatical or something.''