Hawking radiation from the dilaton-（anti） de Sitter black hole via covariant anomaly

Adopting the anomaly cancellation method, initiated by Robinson and Wilczek recently, this paper discusses Hawking radiation from the dilaton--(anti) de Sitter black hole. To save the underlying gauge and general covariance, it introduces covariant fluxes of gauge and energy--momentum tensor to cancel the gauge and gravitational anomalies. The result shows that the introduced compensating fluxes are equivalent to those of a 2-dimensional blackbody radiation at Hawking temperature with appropriate chemical potential.     

Higher-spin gauge and trace anomalies in two-dimensional backgrounds

Two-dimensional quantum fields in electric and gravitational backgrounds can be described by conformal field theories, and hence all the physical (covariant) quantities can be written in terms of the corresponding holomorphic quantities. In this paper, we first derive relations between covariant and holomorphic forms of higher-spin currents in these backgrounds, and then, by using these relations, obtain higher-spin generalizations of the trace and gauge (or gravitational) anomalies up to spin 4. These results are applied to derive higher-moments of Hawking fluxes in black holes in a separate paper [S. Iso, T. Morita, H. Umetsu, Hawking radiation via higher-spin gauge anomalies, arXiv: 0710.0456 [hep-th]].     

Quantum anomaly at horizon and Hawking radiation from higher dimensional Reissner–Nordström–de Sitter black hole

Based on the anomaly cancellation method, initiated by Robinson and Wilczek, we investigate Hawking radiation from the event horizon and cosmological horizon of the higher dimensional Reissner–Nordström–de Sitter black hole via covariant gauge and gravitational anomalies. Unlike in black hole space-time, to describe the observable physics, the effective field theory here is constructed between the event horizon and cosmological horizon. Our result shows that to restore the underlying gauge covariance and diffeomorphism covariance at the quantum level, the covariant compensating fluxes of gauge and energy–momentum tensor, which are shown to equal to those of Hawking radiation, should be radiated from the event horizon and absorbed from the cosmological horizon, respectively.     

Hawking radiation of dyon particles from the Einstein –Maxwell-Dilaton–Axion black hole via covariant anomaly

Hawking radiation of particles with electric and magnetic charges from the Einstein–Maxwell-Dilaton–Axion black hole is derived via the anomaly cancellation method, initiated by Robinson and Wilczek and elaborated by Banerjee and Kulkarni recently. We reconstruct the electromagnetic field tensor to redefine the gauge potential and equivalent charge corresponding to the source with electric and magnetic charges. We only adopt the covariant gauge and gravitational anomalies to discuss the near-horizon quantum anomaly in the dragging coordinate frame. Our result shows that Hawking radiation in this case also can be reproduced from the viewpoint of anomaly.     

Hawking Radiation from the Cylindrical Symmetric Black Hole via Covariant Anomaly

Hawking radiation from the cylindrical symmetric black hole, which is asymptotically anti-de Sitter not only in the transverse direction but also in the string or membrane direction, is discussed from the anomaly point of view. We implement the covariant anomaly cancellation method, the more refined formalism that was proposed by Banerjee and Kulkarni recently than the initial work of Robinson et al., to discuss the near-horizon gauge and gravitational anomalies. Our result shows that Hawking radiation from the cylindrical configurations with horizons also can be reproduced by the anomaly cancellation method.     

Hawking Radiation from NUT Kerr Newman Kusuya Black Hole via Effective Action and Covariant Anomalies

Using the theory of the anomalous (chiral) effective action and covariant anomalies method, the Hawking radiation from NUT-Kerr-Newman-Kusuya black hole is researched. In this paper, the electric charge parameter and magnetic monopole parameter are rewritten as equivalent parameter. In addition, we simplify the metric as 1+1 dimensional effective metric. Finally, with the method of anomalous effective action and covariant anomalies respectively, we calculate the chiral covariant current and covariant energy-momentum tensor.     

Gauge and gravitational anomalies and Hawking radiation of rotating BTZ black holes

In this paper we obtain the flux of Hawking radiation from rotating BTZ black holes from the gauge and gravitational anomalies point of view. Then we show that the gauge and gravitational anomaly in BTZ spacetime is cancelled by the total flux of a 2-dimensional blackbody at the Hawking temperature of the spacetime.     

Anomalies,Hawking Radiation in Taub-NUT Black Hole

In this paper, we mainly investigate the anomalous effective action of the rotating Taub-NUT black hole and show that the flux of Hawking radiation can be determined by anomaly cancellation conditions and regularity requirement at the event horizon. With the method of a dimensional reduction technique, that is, the (1+1) dimensional quantum anomalies equation, we successfully obtain the simplified metric near the horizon. In addition, the covariant energy-momentum tensor that is related with Hawking temperature are calculated in this black hole.     

Consistent and covariant anomalies in gauge and gravitational theories

The gauge structure of anomalies and the related currents is analyzed in detail. We construct the covariant forms for both the currents and the anomalies for general gauge theories in even-dimensional space-time. The results are then extended to determine the structure of gravitational anomalies. These can always be interpreted as anomalies for local Lorentz transformations.     

Hawking radiation from the charged and magnetized BTZ black hole via covariant anomaly

This paper discusses Hawking radiation from the charged and magnetized Ba?ados--Teitelboim--Zanelli (BTZ) black hole from the viewpoint of anomaly, initiated by Robinson and Wilczek recently. It reconstructs the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge and gauge potential. It employs the covariant anomaly cancellation method to determine the compensating fluxes of charge flow and energy-momentum tensor, which are shown to match with those of the 2-dimensional blackbody radiation at the Hawking temperature exactly.     

Covariant and consistent anomalies in even-dimensional chiral gauge theories

This paper is devoted to various aspects of anomalies in even-dimensional chiral gauge theories. The difference between the covariant and consistent anomalies is carefully explained in terms of their different origins. The consistent current is defined in terms of a gauge-variant effectve action constructed from the covariant current. An alternative scheme is set up where the covariant anomaly is unaltered but the consistent anomaly vanishes because the effective actions is gauge-invariant. A discussion of theories with vector and axial currents separately gauged is included: here, apart from the covariant anomalies, two different ways of constructing gauge-variant effective actions are possible, giving rise to different structures of the consistent anomalies.     

Quantum Anomaly and Hawking Radiation of Charged and Magnetized Reissner-Nordström de Sitter Black Hole

The recent work of Robinson and Wilczek that Hawking radiation can be determined by the compensating fluxes is extended to the charged and magnetized Reissner-Nordström de Sitter black hole. We reconstruct the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge and gauge potential. We construct the effect field theory between the event horizon and cosmological horizon to respectively determine the compensating fluxes from them, which are shown to exactly equal to those of Hawking radiation, by the covariant anomaly cancellation conditions.     

Anomaly analysis of Hawking radiation from Kaluza–Klein black hole with squashed horizon

Considering gravitational and gauge anomalies at the horizon, a new method to derive Hawking radiation from black holes has been developed by Wilczek et al. In this paper, we apply this method to non-rotating and rotating Kaluza–Klein black holes with squashed horizon, respectively. For the rotating case, we found that, after dimensional reduction, an effective U(1) gauge field is generated by an angular isometry. The results show that the gauge current and energy-momentum tensor fluxes are exactly equivalent to Hawking radiation from the event horizon.     

Determination of covariant Schwinger terms in anomalous gauge theories

A functional integral method is used to determine equal time commutators between the covariant currents and the covariant Gauss-law operators in theories which are affected by an anomaly. By using a differential geometrical setup we show how the derivation of consistent- and covariant Schwinger terms can be understood on an equal footing. We find a modified consistency condition for the covariant anomaly. As a by-product the Bardeen-Zumino functional, which relates consistent and covariant anomalies, can be interpreted as connection on a certain line bundle over the space of all gauge potentials. Finally the convariant commutator anomalies are calculated for the two- and four dimensional case.     

Hawking radiation,effective actions and covariant boundary conditions

From an appropriate expression for the effective action, the Hawking radiation from charged black holes is derived, using only covariant boundary conditions at the event horizon. The connection of our approach with the Unruh vacuum and the recent analysis [S.P. Robinson, F. Wilczek, Phys. Rev. Lett. 95 (2005) 011303, gr-qc/0502074; S. Iso, H. Umetsu, F. Wilczek, Phys. Rev. Lett. 96 (2006) 151302, hep-th/0602146; R. Banerjee, S. Kulkarni, arXiv: 0707.2449 [hep-th]] of Hawking radiation using anomalies is established.     

Anomalies and de Sitter radiation from the generic black holes in de Sitter spaces

Robinson–Wilczek's recent work shows that, the energy–momentum tensor flux required to cancel gravitational anomaly at the event horizon of a Schwarzschild-type black hole has an equivalent form to that of a (1+1)$(1+1)$-dimensional blackbody radiation at the Hawking temperature. Motivated by their work, Hawking radiation from the cosmological horizons of the general Schwarzschild–de Sitter and Kerr–de Sitter black holes, has been studied by the method of anomaly cancellation. The result shows that the absorbing gauge current and energy momentum tensor fluxes required to cancel gauge and gravitational anomalies at the cosmological horizon are precisely equal to those of Hawking radiation from it. It should be emphasized that the effective field theory for generic black holes in de Sitter spaces should be formulated within the region between the event horizon (EH) and the cosmological horizon (CH), to integrate out the classically irrelevant ingoing modes at the EH and the classically irrelevant outgoing modes at the CH, respectively.     

Covariant anomaly and Hawking radiation from the modified black hole in the rainbow gravity theory

Recently, Banerjee and Kulkarni (R. Banerjee, S. Kulkarni, arXiv: 0707. 2449 [hep-th]) suggested that it is conceptually clean and economical to use only the covariant anomaly to derive Hawking radiation from a black hole. Based upon this simplified formalism, we apply the covariant anomaly cancellation method to investigate Hawking radiation from a modified Schwarzschild black hole in the theory of rainbow gravity. Hawking temperature of the gravity’s rainbow black hole is derived from the energy-momentum flux by requiring it to cancel the covariant gravitational anomaly at the horizon. We stress that this temperature is exactly the same as that calculated by the method of cancelling the consistent anomaly.     

Gauge Covariant Fermion Propagator in the Presence of Arbitrary External Gauge Field and Its Schwinger--Dyson Equation

Gauge covariance for Green＇s functions of a gauge theory through a fermion propagator in the presence of arbitrary external gauge field is proven and a formalism of gauge and Lorentz covariant Schwinger-Dyson equation for the fermion propagator with external gauge field is built up within ladder approximation.     

Gauge theory of the star product

The choice of a star product realization for non-commutative field theory can be regarded as a gauge choice in the space of all equivalent star products. With the goal of having a gauge invariant treatment, we develop tools, such as integration measures and covariant derivatives on this space. The covariant derivative can be expressed in terms of connections in the usual way giving rise to new degrees of freedom for non-commutative theories.