Q-stars in scalar-tensor gravitational theories

We study q-stars in Brans-Dicke gravitational theory. We find that when the Brans-Dicke constant, $\omega_{\textrm{BD}}$, tends to infinity, the results of General Relativity are reproduced. For other values of $\omega_{\textrm{BD}}$, the particle number, mass and radius of the star and the absolute value of the matter field are a few percent larger than in the case of General Relativity. We also investigate the general scalar-tensor gravitational theory and find that the star parameters are a few percent larger than in the case of General Relativity.Comment: 14 pages, to appear in Phys. Lett.

Testing the AMSB Model via e+e−→χ~+χ~−γe^+e^- \to \tilde{\chi}^+ \tilde{\chi}^- \gamma}

The possibility of detecting the signature of a nearly invisible charged wino (\CH) decaying into a soft pion and the LSP(\LSP), predicted by the Anomaly Mediated Symmetry Breaking model, via the process $e^+e^-\r\gamma{\tilde\chi}^{+}{\tilde\chi}^{-}$ at the Next Linear Collider has been explored. Using the recently, proposed bounds on slepton and wino masses derived from the condition of stability of the electroweak symmetry breaking vacuum and employing some standared kinematical cuts to supress the background, we find that almost the whole of the allowed parameter space with the slepton mass less than 1 TeV, can be probed at $\sqrt{s}$ 500 GeV. Determination of the slepton and the chargino masses from this signal is a distinct possiblity. Any violation of the above mass bound will suggest that the standard vacuum is unstable and we are living in a false vacuum.Comment: 10pages, Latex style, 4 figs, revised versio

Q-stars and charged q-stars

We present the formalism of q-stars with local or global U(1) symmetry. The equations we formulate are solved numerically and provide the main features of the soliton star. We study its behavior when the symmetry is local in contrast to the global case. A general result is that the soliton remains stable and does not decay into free particles and the electrostatic repulsion preserves it from gravitational collapse. We also investigate the case of a q-star with non-minimal energy-momentum tensor and find that the soliton is stable even in some cases of collapse when the coupling to gravity is absent.Comment: Latex, 19pg, 12 figures. Accepted in Phys. Rev.