The U.S. EPA and the Energy Department summoned executives from the nation’s biggest oil companies to Washington, D.C., yesterday to make them explain why gas prices are rising markedly in the Midwest, all but accusing the companies of price gouging. The EPA doesn’t buy the oil industry’s excuse that prices are as high as $2 a gallon in Chicago and other cities because the agency is requiring that cleaner-burning, reformulated gasoline be sold in polluted areas. The cost of complying with the EPA standards should be about five to eight cents a gallon, said EPA Assistant Administrator Bob Perciasepe, not the increases of more than 30 cents a gallon seen in parts of the Midwest in recent weeks. Still, Perciasepe wouldn’t rule out the option of the EPA relaxing requirements for reformulated gasoline over the summer to help lower prices.