Entropy of the quantum electromagnetic field in static, spherically symmetric dilaton black holes

The quantum correction to the entropy of four-dimensional nonextreme static , spherically symmetric dilaton black holes arising from electromagnetic fi elds is investigated by 't Hooft's "brick wall" model. The Garfinkle-Horowi tz-Strominger, Gibbons-Maeda, and Garfinkle-Horne dilaton black holes are c onsidered. It is shown that the one-loop quantum correction arising from th e electromagnetic fields is exactly twice that due to a massless scalar fie ld. The result agrees with that of the Schwarzschild and Reissner-Nordstrom black holes.