118525095
Lamb shift for static atoms outside a Schwarzschild black hole
We study, by separately calculating the contributions of vacuum fluctuations and radiation reaction to the atomic energy level shift, the Lamb shift of a static two-level atom interacting with real massless scalar fields in the Boulware, Unruh, and Hartle-Hawking vacuums outside a Schwarzschild black hole. We find that in the Boulware vacuum, the Lamb shift gets a correction arising as a result of the backscattering of vacuum field modes off the space-time curvature, which is reminiscent of the correction to the Lamb shift induced by the presence of cavities. However, when the Unruh and Hartle-Hawking vacua are concerned, our results show that the Lamb shift behaves as if the atom were irradiated by a thermal radiation or immersed in a thermal bath at the Hawking temperature, depending on whether the scalar field is in the Unruh or the Hartle-Hawking vacuum. Remarkably, the thermal radiation is always backscattered by the space-time geometry.
118559190
Casimir-Polder-like force on an atom outside a Schwarzschild black hole
Abstract We calculate, in the framework of open quantum systems, the ground state energy-level shift for a static two-level atom outside a spherically symmetric black hole in interaction with fluctuating massless scalar fields in the Boulware and Unruh vacuums. We find that the energy-level shift is position dependent and thus gives rise to a force on the atom besides the classical gravitational force. For the case of the Boulware vacuum that represents a star which has not collapsed through its event horizon, this force is attractive near the horizon and is repulsive far away from the black hole with a behavior of r−3. For the case of the Unruh vacuum which represents a radiating black hole, we find that the contribution to the Casimir-Polder-like force due to the presence of Hawking radiation is always attractive and, remarkably, this attractive force diverges at the event horizon.
120750405
Mass renormalization at finite temperature and random motion of an electron driven by quantum electromagnetic fluctuations
119204385
Entanglement generation outside a Schwarzschild black hole and the Hawking effect
We examine the Hawking effect by studying the asymptotic entanglement of two mutually independent two-level atoms placed at a fixed radial distance outside a Schwarzschild black hole in the framework of open quantum systems. We treat the two-atom system as an open quantum system in a bath of fluctuating quantized massless scalar fields in vacuum and calculate the concurrence, a measurement of entanglement, of the equilibrium state of the system at large times, for the Unruh, Hartle-Hawking and Boulware vacua respectively. We find, for all three vacuum cases, that the atoms turn out to be entangled even if they are initially in a separable state as long as the system is not placed right at the even horizon. Remarkably, only in the Unruh vacuum, will the asymptotic entanglement be affected by the backscattering of the thermal radiation off the space-time curvature. The effect of the back scatterings on the asymptotic entanglement cancels in the Hartle-Hawking vacuum case.
118496881
Perturbative Correction to Transverse Ward—Takahashi Relation for the Vertor Vertex
We re-derive exactly the transverse Wark-Takahashi relation for the vector vertex in momentum space,The result shows that this transverse Ward-Takahashi relation in momentum space involves a perturbative correction term.We demonstrate explicitly that this transverse Ward-Takahashi relation is satisfied indeed at one-loop order.
118998732
Spontaneous excitation of an accelerated hydrogen atom coupled with electromagnetic vacuum fluctuations
We consider a multilevel hydrogen atom in interaction with the quantum electromagnetic field and separately calculate the contributions of the vacuum fluctuation and radiation reaction to the rate of change of the mean atomic energy of the atom for uniform acceleration. It is found that the acceleration disturbs the vacuum fluctuations in such a way that the delicate balance between the contributions of vacuum fluctuation and radiation reaction that exists for inertial atoms is broken, so that the transitions to higher-lying states from ground state are possible even in vacuum. In contrast to the case of an atom interacting with a scalar field, the contributions of both electromagnetic vacuum fluctuations and radiation reaction to the spontaneous emission rate are affected by the acceleration, and furthermore the contribution of the vacuum fluctuations contains a nonthermal acceleration-dependent correction, which is possibly observable.
125436491
Study of xi(2230) produced in J/psi radiative decay process
The processes e(+) + e(-) --> J / psi --> + X, X --> p (p) over bar are discussed using the generalized moment analysis method. The moment expressions of the above processes are given. And they are used to determine the spin of the resonance X decaying to p (p) over bar. The helicity amplitude ratios of the above processes in terms of moment expressions are also given.
120093276
CONSISTENT FACTORIZATION AND TWIST-3 CONTRIBUTIONS TO THE POLARIZED NUCLEON STRUCTURE FUNCTION g2(x,Q2)
Quark mass effects are clarified in the parton model approach to the transversely polarized nucleon structure function. The special propagator technique is employed to obtain manifestly gauge invariant results and extract the buried short-distance contributions inside the soft part after momentum factorization in the collinear expansion approach. A generalized massive special propagator for a massive quark is constructed. We identify the corresponding matrix elements of the transversely polarized structure function in deep inelastic scattering by the massive special propagator technique.
122878082
Induced Topological Terms, Hidden Local Symmetry, and Anyon Superconductivity
We show how the topological Chern-Simons term in three dimensions and the θ-term, in four dimensions can be dynamically generated due to quantum fluctuations in Nambu-Jona-Lasinio models. These results give a vivid demonstration of hidden local symmetry at work. The fluctuation-induced Chern-Simons term provides a natural way to incorporate fractional statistics and thus a more direct connection with anyon superconductivity. Possible phenomenological implications of this approach in particle physics are also discussed.
120346822
NOETHER CHARGES, BLACK HOLES AND THE IMMIRZI PARAMETER
We have shown that terms in the action which won't contribute to local equation of motions do contribute to globally conversed physical quantities in classical theories of gravity due to general coordinate covariance. This observation allows one to determining the Immirzi parameter in the Ashtekar variable formulation of gravitational theories even at classical level. Applying Wald's Noether charge approach and identifying the entropy on black hole horizon as the Noether charge for translation, one can demonstrate explicitly that the Immirzi parameter does make its contributions through the boundary term. Our results also shed lights in connecting the Immirzi paramter to quasi-normal modes of black holes.
119222434
Quantum Modifications to Gravity Waves in de Sitter Spacetime
We treat a model in which tensor perturbations of de Sitter spacetime, represented as a spatially flat model, are modified by the effects of the vacuum fluctuations of a massless conformally invariant field, such as the electromagnetic field. We use the semiclassical theory of gravity with the expectation value of the conformal field stress tensor as a source. We first study the stability of de Sitter spacetime by searching for growing, spatially homogeneous modes, and conclude that it is stable within the limits of validity of the semiclassical theory. We next examine the modification of linearized plane gravity waves by the effects of the quantum stress tensor. We find a correction term which is of the same form as the original wave, but displaced in phase by {pi}/2, and with an amplitude which depends upon an initial time. The magnitude of this effect is proportional to the change in scale factor after this time. We discuss alternative interpretations of this time, but pay particular attention to the view that this is the beginning of inflation. So long as the energy scale of inflation and the proper frequency of the mode at the beginning of inflation are well below the Planckmore » scale, the fractional correction is small. However, modes which are trans-Planckian at the onset of inflation can undergo a significant correction. The increase in amplitude can potentially have observable consequences through a modification of the power spectrum of tensor perturbations in inflationary cosmology. This enhancement of the power spectrum depends upon the initial time, and is greater for shorter wavelengths.« less