LONDON - The United States men's archery team experienced both ends of the Olympics' emotional spectrum Saturday. First, the Americans were euphoric after scoring a convincing upset of world power South Korea in the semifinals at Lord's Cricket Ground. About an hour later, they were crushed in the gold medal match when Italy beat them by a single point on the final arrow of the competition. While a silver medal is hardly disappointing, the manner in which the United States lost was brutal. After scoring 27 points in their final end to cut their deficit to 1, the Americans watched as Italy scored 17 points on the first two arrows of its last series. If the final Italian archer, Michele Frangilli, scored 8 points, the United States would win outright; if he scored 9, the match would be tied; and if he scored 10, the Italians would win the gold medal after losing it four years ago on a similar last-arrow shot.