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Register a new userSchwinger-Keldysh effective action for relativistic Brownian particle in AdS-CFT
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We compute Schwinger-Keldysh effective action for a relativistic heavy quark (with constant background velocity) in strongly coupled N = 4 supersymmetric Yang-Mills plasma. The holographic dual description involves a noisy trailing string moving in Schwarzschild-AdS5 black brane. The noise is caused by Hawking radiation emitted from string worldsheet horizon. Besides quadractic terms, the effective action contains cubic interactions, which are entirely induced by the constant background velocity. The nonlinear fluctuation-dissipation relations for three-point functions are discussed based on holographic results.
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We derive a simple formula for the action of any supersymmetric solution to minimal gauged supergravity in the AdS$_4$/CFT$_3$ correspondence. Such solutions are equipped with a supersymmetric Killing vector, and we show that the holographically renormalized action may be expressed entirely in terms of the weights of this vector field at its fixed points, together with certain topological data. In this sense, the classical gravitational partition function localizes in the bulk. We illustrate our general formula with a number of explicit examples, in which exact dual field theory computations are also available, which include supersymmetric Taub-NUT and Taub-bolt type spacetimes, as well as black hole solutions. Our simple topological formula also allows us to write down the action of any solution, provided it exists.
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Spontaneous pair production from background fields or spacetimes is one of the most prominent phenomena predicted by quantum field theory. The Schwinger mechanism of production of charged pairs by a strong electric field and the Hawking radiation of all species of particles from a black hole are the consequence of nonperturbative quantum effects. In this review article, the vacuum structure and pair production is reviewed in the in-out formalism, which provides a consistent framework for quantum field theory in the sense that the complex action explains not only the vacuum persistence but also pair production. The current technology of intense lasers is still lower by a few order than the Schwinger limit for electron-positron pair production, while magnetic fields of magnetars on the surface are higher than the Schwinger limit and even higher at the core. On the other hand, the zero effective mass of electron and hole in graphene and Dirac or Weyl semimetals will open a window for experimental test of quantum electrodynamics (QED) phenomena in strong fields.
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Some astrophysical objects are supposed to have very strong electromagnetic fields above the critical strength. Quantum fluctuations due to strong electromagnetic fields modify the Maxwell theory and particularly electric fields make the vacuum unstable against pair production of charged particles. We study the strong field effect such as the effective action and the Schwinger pair production in scalar QED.
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