Calculation of Hawking Radiation in Local Field Theory

Hawking radiation of the blackhole is calculated based on the principle of local field theory. In our approach, the radiation is a unitary process, therefore no information loss will be recorded. In fact, observers in different regions of the space communicate using the Hawking radiation, when the systems in the different regions are entangled with each other. The entanglement entropy of the blackhole is also calculated in the local field theory. We found that the entanglement entropy of the systems separated by the blackhole horizon is closely connected to the Hawking radiation in our approach. Both Hawking radiation and entanglement entropy of the four-dimensional blackholes are ultraviolet divergent quantity, but the equation relating the two quantities is free of divergences and is given simply by $S_{EE} = \frac{1}{\sqrt 2} \cal A R_H$, where $S_{EE}$ is the entanglement entropy, $\cal A$ is the area of the horizon, and $R_H$ is the Hawking radiation.