Yann Mambrini

Gamma-ray detection from neutralino annihilation in non-universal SUGRA scenarios

We analyze the indirect detection of neutralino dark matter in supergravity scenarios with non-universal soft scalar and gaugino masses. In particular, the gamma-ray flux arising from the galactic center due to neutralino annihilation is computed. In important regions of the parameter space it can be increased significantly (about two orders of magnitude) with respect to the universal scenario. This result is compared with the sensitivity of current and planned experiments, such as the satellite-based detectors EGRET and GLAST and the ground-based atmospheric telescope HESS. For example, for tan� < 35 the sensitivity region of GLAST and HESS can only be reached in non-universal scenarios.

A comparison between direct and indirect dark matter search

We carry out a comparison between different kinds of experiments for the detection of neutralino dark matter. In particular, we compare the theoretical predictions for the direct detection of these particles, through their elastic scattering on target nuclei through nuclear recoils, with those for their indirect detection through the gamma rays produced by their annihilation in the galactic centre. For the comparison we pay special attention to points which will be testable by very sensitive experiments, such as e.g.?EDELWEISS II and GENIUS for direct detection, and GLAST for indirect detection. We perform the analysis in the framework of a general SUGRA theory, allowing the presence of non-universal soft scalar and gaugino masses in the parameter space. As a conclusion, we find that indirect detection experiments will be able to test larger regions of the parameter space than direct detection ones.

Direct and indirect detection of dark matter in heterotic orbifold models

Abstract We study the neutralino dark matter phenomenology in the context of effective field theories derived from the weakly-coupled heterotic string. We consider in particular direct detection and indirect detection with neutrino telescopes rates. The two cases of moduli dominated and dilaton dominated SUSY breaking lead to completely different phenomenologies. Even if in both cases relic density constraints can be fulfilled, moduli domination generically leads to detection rates which are much below the present and future experimental sensitivities, whereas dilaton domination gives high detection rates accessible to the next generation of experiments. This could make dark matter searches an alternative way to constrain high energy fundamental parameters.

Annihilation radiation of dark matter in heterotic orbifold models

Abstract We investigate the prospects for indirect detection of neutralino dark matter in the context of effective supergravity theories derived from the heterotic superstring. These models provide a consistent framework linking fundamental high-energy theory with low energy physics, and a phenomenology in the gaugino and scalar sector, which is considerably different from the commonly discussed case of minimal Supergravity. We show that astrophysical observations, in particular with gamma-ray experiments like GLAST and HESS, will provide significant constraints on combinations of astrophysical and particle physics parameters, and interesting clues on the SUSY breaking mechanism.

GLAST versus PAMELA: a comparison between the detection of gamma rays and positrons from neutralino annihilation

We study the indirect detection of neutralino dark matter using positrons and gamma rays from its annihilation in the galactic halo. Considering the HESS data as the spectrum constituting the gamma ray background, we compare the prospects for the experiments GLAST and PAMELA in a general supergravity framework with non-universal scalar and gaugino masses. We show that with a boost factor of about 10, PAMELA will be competitive with GLAST for typical NFW cuspy profiles.We study the indirect detection of neutralino dark matter using positrons and gamma rays from its annihilation in the galactic halo. Considering the HESS data as the spectrum constituting the gamma--ray background, we compare the prospects for the experiments GLAST and PAMELA in a general supergravity framework with non--universal scalar and gaugino masses. We show that with a boost factor of about 10, PAMELA will be competitive with GLAST for typical NFW cuspy profiles.

Gamma-ray excess from the galactic center and supergravity models

In the light of recent and forthcoming experiments (EGRET, CANGAROO, HESS, GLAST), we analyse the effect of the compression of the dark matter due to the infall of baryons to the galactic center on the gamma-ray flux in the Supergravity framework.

Gamma‐Ray Excess from the Galactic Center and Supergravity Models

We analyse the effect of the compression of the dark matter due to the infall of baryons to the galactic center on the gamma‐ray flux. In addition, we also consider the effect of non‐universal supersymmetric soft terms. This analysis shows that neutralino dark matter annihilation can give rise to signals largely reachable by future experiments like GLAST. This is a remarkable result if we realise that direct detection experiments will only be able to cover a small region of the parameter space. Actually, in this SUGRA framework we have also been able to fit present excess from EGRET and CANGAROO using different non‐universal scenarios, and even fit the data from both experiments with only one scenario. We have also studied the recent HESS data implying a neutralino heavier than 12 TeV. Because of such a heavy neutralino, it is not natural to find solutions in the SUGRA framework. Nevertheless we have carried out a quite model‐independent analysis, and found the conditions required on the particle physics ...

PHENOMENOLOGICAL ASPECTS OF HETEROTIC ORBIFOLD MODELS AT ONE LOOP

LBNL–53419 UCB-PTH-03/17 LPT Orsay–03/54 MCTP - 03/36 hep-ph/0308047 arXiv:hep-ph/0308047 v1 5 Aug 2003 Phenomenological Aspects of Heterotic Orbifold Models at One Loop Pierre Bin´ truy a , Andreas Birkedal-Hansen b , Yann Mambrini a and e Brent D. Nelson c Laboratoire de Physique Th´ orique 1 , e Universit´ Paris-Sud, F-91405 Orsay, France e b a Department of Physics and Theoretical Physics Group, Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720, USA c Michigan Centre for Theoretical Physics, Randall Laboratory, University of Michigan, Ann Arbor MI 48109 Abstract We provide a detailed study of the phenomenology of orbifold compactifications of the het- erotic string within the context of supergravity effective theories. Our investigation focuses on those models where the soft Lagrangian is dominated by loop contributions to the various soft supersymmetry breaking parameters. Such models typically predict non-universal soft masses and are thus significantly different from minimal supergravity and other universal models. We consider the pattern of masses that are governed by these soft terms and investigate the im- plications of certain indirect constraints on supersymmetric models, such as flavor-changing neutral currents, the anomalous magnetic moment of the muon and the density of thermal relic neutralinos. These string-motivated models show novel behavior that interpolates between the phenomenology of unified supergravity models and models dominated by the superconformal anomaly. Unit´ Mixte de Recherche UMR n o 8627 - CNRS e