Abstract:
It is shown that the equations of relativistic Bohmian mechanics for multiple bosonic particles have a dual description in terms of a classical theory of conformally "curved" space-time. This shows that it is possible to formulate quantum mechanics as a purely classical geometrical theory. The results are further generalized to interactions with an external electromagnetic field.

Abstract:
In this paper it is shown that an equivalent to the complex Klein-Gordon equation can be obtained from the (2+3) dimensional Einstein equations coupled to a conserved energy momentum tensor. In an explicit toy model we give matching conditions for what corresponds to the phase, the amplitude, and the mass of the complex wave function.

Abstract:
In this article we show that the fundamental equations of relativistic Bohmian mechanics for a single particle can be derived from a scalar theory of curved space-time.

Abstract:
We consider the possibility that the superluminal neutrino propagation reported by the OPERA collaboration originates from a violation of CPT. On this basis we compare our actual knowledge concerning the CPT theorem to the nuclear reaction chain between CNGS and OPERA.

Abstract:
In this article it is shown that the fundamental equations of relativistic Bohmian mechanics for multiple bosonic particles have a dual description in terms of a classical theory of curved space-time. We further generalize the results to interactions with an external electromagnetic field, which corresponds to the minimally coupled Klein-Gordon equation.

Abstract:
We study the quantum modifications of classical, spherically symmetric Schwarzschild (Anti-) de Sitter black holes within Quantum Einstein Gravity. The quantum effects are incorporated through the running coupling constants $G_k$ and $\Lambda_k$, computed within the exact renormalization group approach, and a common scale-setting procedure. We find that, in contrast to common intuition, it is actually the cosmological constant that determines the short-distance structure of the RG-improved black hole: in the asymptotic UV the structure of the quantum solutions is universal and given by the classical Schwarzschild-de Sitter solution, entailing a self-similarity between the classical and quantum regime. As a consequence asymptotically safe black holes evaporate completely and no Planck-size remnants are formed. Moreover, the thermodynamic entropy of the critical Nariai-black hole is shown to agree with the microstate count based on the effective average action, suggesting that the entropy originates from quantum fluctuations around the mean-field geometry.

Abstract:
Assuming an effective gravitational action with scale dependent coupling constants, a consistency condition for the local form of the cut-off scale is derived. The approach is applied to homogeneous cosmology and running couplings with an ultraviolet fixed point. Within the given approach this allows to derive bounds on the value of the fixed point.

Abstract:
Working with the assumption of nonzero photon mass and a trajectory that is described by the nongeodesic world line of a spinning top we find, by deriving new astrophysical bounds, that this assumption is in contradiction with current experimental results. This yields the conclusion that such photons have to be exactly massless. 1. Introduction Although there are good theoretical reasons to believe that the photon mass should be exactly zero, there is no experimental proof of this belief. A long series of very different experiments lead to the current experimental upper bound on the photon mass . However, even with further improvement of the experimental technology and precision a complete exclusion of a nonzero photon mass by those techniques will never be possible. In order to improve on this situation we will work with the assumption that the photon mass is different from zero . We will not speculate on the origin of this mass and its underlying theory. In the simplest case, such a photon will be described by a wave equation of the Proca type. For waves describing massless particles with spin, it is well understood, in the eikonal approximation, how the propagating wave can be treated as geometric path that minimizes a Lagrangian described by the length where . As soon as mass and rotational degrees of freedom ( , ) are involved, it is natural to assume that, in the eikonal approximation, the resulting geometric action also involves the invariant functions of the corresponding additional degrees of freedom: This generic approach to the geometric action which includes spin and mass was developed and discussed in the context of a spinning top, a point on a world line to which a rotating frame has been attached [1–10]. The resulting equations of motion do not depend on the particular form in which the Lagrangian terms (1, 2) are combined. This formulation and the corresponding equations of motion can also be derived as consistent eikonal limit as quantum field theory in curved space-time. This has been shown independently for spin one half [11, 12], for spin one [13, 14], and for spin three half [15, 16]. Exact solutions to those equations coupled to gravity via the metric show that spinning tops without mass follow geodesics, while massive spinning tops have different trajectories. Further implications and discussions of the spinning top approach can be found in [17–22]. 2. Astrophysical Bound As master equation for the trajectory of massive particles with spin we use the solution of the spinning top equations in a Schwarzschild background [5, 6, 9,

Abstract:
Working with the assumption of non-zero photon mass and a trajectory that is described by the non geodesic world line of a spinning top we find, by deriving new astrophysical bounds, that this assumption is in contradiction with current experimental results. This yields the conclusion that such photons have to be exactly massless.

Abstract:
We calculate the inclusive cross section of double Z-boson production within large extra dimensions at the Large Hadron Collider (LHC). Using perturbatively quantized gravity in the ADD model we perform a first order calculation of the graviton mediated contribution to the pp to ZZ cross section. At low energies (e.g. Tevatron) this additional contribution is very small, making it virtually unobservable, for a fundamental mass scale above 2500 GeV. At LHC energies however, the calculation indicates that the ZZ-production rate within the ADD model should differ significantly from the Standard Model if the new fundamental mass scale would be below 15000 GeV. A comparison with the observed production rate at the LHC might therefore provide direct hints on the number and structure of the extra dimensions.