The strong coupling effect and auxiliary fields in the DGP-model

The DGP-model with additional terms in the action is considered. These terms have a special form and include auxiliary scalar fields without kinetic terms, which are non-minimally coupled to gravity. The use of these fields allows one to exclude the mode, which corresponds to the strong coupling effect, from the theory. Effective four-dimensional theory on the brane appears to be the same, as in the original DGP-model.Comment: 9 pages, LaTe

Classical behaviour of Q-balls in the Wick-Cutkosky model

In this paper, we continue discussing Q-balls in the Wick--Cutkosky model. Despite Q-balls in this model are composed of two scalar fields, they turn out to be very useful and illustrative for examining various important properties of Q-balls. In particular, in the present paper we study in detail (analytically and numerically) the problem of classical stability of Q-balls, including the nonlinear evolution of classically unstable Q-balls, as well as the behaviour of Q-balls in external fields in the non-relativistic limit.Comment: 21 pages, 12 figures, LaTeX; v2: section 3.3 slightly enlarged, typos corrected, minor changes in the tex

Consistent ADD scenario with stabilized extra dimension

A model with one compact extra dimension and a scalar field of Brans-Dicke type in the bulk is discussed. It describes two branes with non-zero tension embedded into the space-time with flat background. This setup allows one to use a very simple method for stabilization of the size of extra dimension. It appears that the four-dimensional Planck mass is expressed only through parameters of the scalar field potentials on the branes.Comment: 11 pages, LaTeX, enlarged content, corrected typo

The specificity of searches for W′W^{\prime}, Z′Z^{\prime} and γ′\gamma^{\prime} coming from extra dimensions

We discuss the specificity of searches for hypothetical $W^{\prime}$, $Z^{\prime}$ and $\gamma^{\prime}$ bosons at hadron colliders in single top quark and $\mu^{+}\nu_{\mu}$ production and Drell-Yan processes assuming these particles to be the Kaluza-Klein excitations of the gauge bosons of the Standard Model. In this case any process mediated by $W$ is also mediated by the whole KK tower of its excitations, whereas to the processes mediated by $Z$ and $\gamma$ there is not only a contribution from their KK towers, but also from that of the graviton. The contributions of the towers above $W^{\prime}$, $Z^{\prime}$ and $\gamma^{\prime}$ and above the first excitation of the graviton are included with the help of effective four-fermion Lagrangians. We compute the cross-sections of these processes taking into account the contributions of the Standard Model gauge bosons, of their first KK modes and of the corresponding KK towers and discuss the impact of the interference between them. For pp-collisions at the LHC with the center of mass energy 14 TeV we found specific changes of the distribution tails due to the interference effects. Such a modification of distribution tails is characteristic for the processes mediated by particles coming from extra dimensions and should always be taken into account when looking for them.Comment: 14 pages, 12 figures, LaTeX. References added, figures added, text enlarge

A non-standard matter distribution in the RS1 model and the coupling constant of the radion

In the zero mode approximation we solve exactly the equations of motion for linearized gravity in the Randall-Sundrum model with a non-standard distribution of matter in the neighbourhood of the negative tension brane. It is shown that the form of this distribution can strongly affect the coupling of the radion to matter. We believe that such a situation can arise in models with a realistic mechanisms of matter localization.Comment: 12 pages, LaTe