Narrow Results

The relativistic quantum interference effects in the spacetime of slowly rotating object in braneworld as the Sagnac effect and phase shift effect of interfering particle in neutron interferometer are derived in unified way. It is found that in the case of the Sagnac effect, the influence of brane parameter is becoming important due to the fact that the angular velocity of the locally non-rotating observer is increased by the brane tension. In the case of neutron interferometry, it is found that an additional term in the phase shift of interfering particle emerges due to the presence of the brane parameter Q*. From the obtained expressions of phase shift in Mach–Zehnder interferometer upper limit for brane parameter has been estimated. From the results of the recent experiments we have obtained upper limit for the tidal charge as Q* ≲ 10⁷cm². Finally, as an example, we apply the obtained results to the calculation of the (ultra-cold neutrons) energy level modification in the gravitational field of slowly rotating gravitating object in the braneworld.

We construct simple standing wave solutions in a 5D spacetime with a ghost-like scalar field. The nodes of these standing waves are "islands" of 4D anti-de Sitter spacetime. In the case of increasing (decreasing) warp factor, there are a finite (infinite) number of nodes and thus a finite (infinite) number of anti-de Sitter island-universes having different gravitational and cosmological constants. This is similar to the landscape models, which postulate a large number of universes with different parameters.

We investigate the motion of a magnetized particle orbiting around a black hole in braneworld immersed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized spinning particle around the braneworld black hole using Hamilton–Jacobi formalism is studied. It is found that circular orbits for photons and slowly moving particles may become stable near r = 3M. It was argued that the radii of the innermost stable circular orbits are sensitive on the change of brane parameter. Similar discussion without Weil parameter has been considered by de Felice et al. in Refs. 1 and 2.

As an extension of previous works on classical tests of a braneworld model which is called as the Dadhich, Maartens, Papadopoulos and Rezania (DMPR) solution, and as an attempt to find more stringent constraints on this model, we investigate its effects on physical experiments and astronomical observations conducted in the Solar System by modeling new observable effects and adopting new datasets. First, we investigate gravitational time delay at inferior conjunction (IC) caused by the braneworld model, which was not considered in previous works, because these measurements are not affected by the solar corona noise. Second, the Cassini superior conjunction (SC) experiment is, for the first time, used to test the DMPR model. Third, compared to previous works, we refine the model, which confronts the perihelion shift induced by the braneworld model with modern Solar System ephemerides INPOP10a (IMCCE, France) and EPM2011 (IAA RAS, Russia). The correction of DMPR solution to Einstein’s general relativity (GR) in the four-dimensional spacetime can be characterized by a constant bulk “tidal charge” parameter $Q$, which is confined in the present work. We find that time delay experiment at IC is independent of $Q$ and not suitable for testing the braneworld model. However, the Cassini SC experiment and modern Solar System ephemerides can give better upper bounds on $Q$: (1) $\left|Q\right|\le 1.2\times 10^7{\mathrm{\text{m}}}^2$ by Cassini, and (2) $\left|Q\right|\le 61{\mathrm{\text{m}}}^2$ based on the supplementary advances of the perihelia provided by INPOP10a and $\left|Q\right|\le 3.0\times 10^2{\mathrm{\text{m}}}^2$ based on the ones of EPM2011. The latter upper bounds are improved to be tighter than the ones of previous works by at least two orders of magnitude. Besides, the stronger constraints on the brane tension are given by the modern ephemerides, which are $\lambda \ge 3.1\times 10^5{\mathrm{\text{MeV}}}^4$ for INPOP10a and $\lambda \ge 6.2\times 10^4{\mathrm{\text{MeV}}}^4$ for EPM2011. These improved upper bounds mean that the Solar System tests can serve as a good testbed for high dimensional theories.

We discuss the specificity of the interactions of the electroweak gauge boson excitations in models with warped extra dimensions and the Standard Model fields living in the bulk. In particular, we show that the couplings of the gauge boson excitations $W^{\prime }$, $Z^{\prime }$, and ${\gamma }^{\prime }$ to the SM gauge bosons treated as the zero modes of the 5D gauge fields are either exactly equal to zero or very much suppressed. In the former case, the three-particle and four-particle interaction Lagrangians of the SM gauge bosons and their lowest excitations are found explicitly. Meanwhile, the couplings of $W^{\prime }$, $Z^{\prime }$, and ${\gamma }^{\prime }$ to the SM fermions are nonzero allowing for their production and decays. These are the characteristic features of the gauge boson excitations in models with warped extra dimensions, which distinguish them from the gauge boson excitations in other models beyond the SM.

Motivated by stringy considerations, Randall and Sundrum have proposed a model where all the fields and particles of physics, save gravity, are confined on a four-dimensional brane embedded in five-dimensional anti-de Sitter space. Their scenario features a stable bound state of bulk gravity waves and the brane that reproduces standard general relativity. We demonstrate that in addition to this zero-mode, there is also a discrete set of metastable bound states that behave like massive four-dimensional gravitons which decay by tunneling into the bulk. These are resonances of the bulk-brane system akin to black hole quasinormal modes — as such, they give rise to the dominant corrections to four-dimensional gravity. The phenomenology of braneworld perturbations is greatly simplified when these resonant modes are taken into account, which is illustrated by considering gravitational radiation emitted from nearby sources and early universe physics.

We investigate the role of the tidal charge in orbital models of high-frequency quasiperiodic oscillations (QPOs) observed in neutron star binary systems. We show how the standard relativistic precession (RP) model modified by the tidal charge fits the observational data, giving estimates of the allowed values of the tidal charge and the brane tension based on the processes going in the vicinity of neutron stars. We compare our strong field regime restrictions with those given in the weak field limit of solar system experiments.