Astroparticle and Collider Physics as complementary sources for the study of string motivated supergravity models

We provide a study of the phenomenology of heterotic orbifold compactifications scenarii 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, giving a mixed anomaly-gravity mediation model. We consider the pattern of masses that are governed by these soft terms and investigate the implications of certain indirect constraints on supersymmetric models. In this framework, we point out how the complementarity between direct and indirect detection of a neutralino Dark Matter, and futur accelerator prospects can reduce considerably the parameter space of such modelsComment: 4 pages, 1 figure, to appear in the proceedings of International Conference on Linear Colliders (LCWS 05), Stanford, USA, 18-22 Mar 200

Quantum critical phase with infinite projected entangled paired states

A classification of SU(2)-invariant Projected Entangled Paired States (PEPS) on the square lattice, based on a unique site tensor, has been recently introduced by Mambrini et al.~\cite{Mambrini2016}. It is not clear whether such SU(2)-invariant PEPS can either i) exhibit long-range magnetic order (like in the N\'eel phase) or ii) describe a genuine quantum critical point (QCP) or quantum critical phase (QCPh) separating two ordered phases. Here, we identify a specific family of SU(2)-invariant PEPS of the classification which provides excellent variational energies for the $J_1-J_2$ frustrated Heisenberg model, especially at $J_2=0.5$, corresponding to the approximate location of the QCP or QCPh separating the N\'eel phase from a dimerized phase. The PEPS are build from virtual states belonging to the $\frac{1}{2}^{\otimes N} \oplus 0$ SU(2)-representation, i.e. with $N$ "colors" of virtual \hbox{spin-$\frac{1}{2}$}. Using a full update infinite-PEPS approach directly in the thermodynamic limit, based on the Corner Transfer Matrix renormalization algorithm supplemented by a Conjugate Gradient optimization scheme, we provide evidence of i) the absence of magnetic order and of ii) diverging correlation lengths (i.e. showing no sign of saturation with increasing environment dimension) in both the singlet and triplet channels, when the number of colors $N\ge 3$. We argue that such a PEPS gives a qualitative description of the QCP or QCPh of the $J_1-J_2$ model.Comment: 11 pages, 13 figures, supplementary material as a zip file in source package, v4: minor adds to text + Table I and Appendix D (with 1 figure) adde

X-ray lines and self-interacting dark matter

We study the correlation between a monochromatic signal from annihilating dark matter and its self-interacting cross section. We apply our argument to a complex scalar dark sector, where the pseudo-scalar plays the role of a warm dark matter candidate while the scalar mediates its interaction with the Standard Model. We combine the recent observation of the cluster Abell 3827 for self-interacting dark matter and the constraints on the annihilation cross section for monochromatic X-ray lines. We also confront our model to a set of recent experimental analyses and find that such an extension can naturally produce a monochromatic keV signal corresponding to recent observations of Perseus or Andromeda while in the meantime predicts self-interacting cross section of the order of $\sigma / m\simeq0.1-1~\mathrm{cm^2/g}$ as recently claimed in the observation of the cluster Abell 3827. We also propose a way to distinguish such models by future direct detection techniques.Comment: 11 pages, 6 figure

Higgs searches and singlet scalar dark matter: Combined constraints from XENON 100 and the LHC

XENON100 and the LHC are two of the most promising machines to test the physics beyond the Standard Model. In the meantime, indirect hints push us to believe that the dark matter and Higgs boson could be the two next fundamental particles to be discovered. Whereas ATLAS and CMS have just released their new limits on the Higgs searches, XENON100 obtained very recently strong constraints on DM-proton elastic scattering. In this work, we show that when we combined WMAP and the most recent results of XENON100, the invisible width of the Higgs to scalar dark matter is negligible($\lesssim 10$), except in a small region with very light dark matter ($\lesssim 10$ GeV) not yet excluded by XENON100 or around 60 GeV where the ratio can reach 50% to 60%. The new results released by the Higgs searches of ATLAS and CMS set very strong limits on the elastic scattering cross section, even restricting it to the region 8 \times 10^{-46} \mrm{cm^2} \lesssim \sigma_{S-p}^{SI}\lesssim 2 \times 10^{-45} \mrm{cm^{2}} in the hypothesis 135 \mrm{GeV} \lesssim M_H \lesssim 155 \mrm{GeV}.Comment: 9 pages, 8 figures, final version to appear in PR

Signals from 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. 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 side to fit the HESS data thanks to dark matter annihilation.Comment: 6 pages, 3 figures, contributed to 41st Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta Valley, Italy, 11-18 Mar 200

The Case for an EeV Gravitino

We consider the possibility that supersymmetry is broken above the inflationary mass scale and that the only "low" energy remnant of supersymmetry is the gravitino with mass of order the EeV scale. The gravitino in this class of models becomes a candidate for the dark matter of the Universe. To avoid the over-production of gravitinos from the decays of the next-to-lightest supersymmetric particle we argue that the supersymmetric spectrum must lie above the inflationary mass scale ($M_{\rm SUSY} > 10^{-5} M_{\rm P} \sim 10^{13}$ GeV). Since $m_{3/2} \simeq M_{\rm SUSY}^2/M_{\rm P}$, we expect $m_{3/2} \gtrsim 0.2$ EeV. Cosmological constraints then predict a relatively large reheating temperature between $10^{10}$ and $10^{12}$ GeV.Comment: 6 pages, 1 figure. Dedicated to the memory of Pierre Binetru

Phenomenological Aspects of Heterotic Effective Models At One Loop

We provide a study of the phenomenology of orbifold compactifications of the heterotic 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. We consider the pattern of masses that are governed by these soft terms and investigate the implications 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.Comment: 5 pages, 2 figures, To appear in the proceedings of 2nd International Conference on String Phenomenology 2003, Durham, England, 29 Jul - 4 Aug 200

SUSY Phenomenology of KKLT Flux Compactifications

We study SUSY phenomenology of the KKLT (Kachru-Kallosh-Linde-Trivedi) scenario of string theory compactifications with fluxes. This setup leads to a specific pattern of soft masses and distinct phenomenological properties. In particular, it avoids the cosmological gravitino/moduli problems. Remarkably, the model allows for the correct abundance of SUSY dark matter consistently with all experimental constraints including the bound on the Higgs mass, b-->s gamma, etc. This occurs for both small and large tan beta, and requires the SUSY spectrum above 1 TeV.Comment: 23 pages, 8 figures; v2: erratum attache

Impact of Dark Matter Direct and Indirect Detection on Simplified Dark Matter Models

We discuss simple extensions of the Standard Model featuring a (fermionic) stable DM candidate interacting with SM fermions through a $Z^{'}$ mediator. These kind of models offer a wide phenomenology but result, at the same time, particularly manageable, given the limited number of free-parameters, and offer a broad LHC phenomenology. We will discuss the impact Direct and Indirect Dark Matter searches, assuming the latter to be thermal WIMPs. We will show in particular that the combinations of the limits on the DM Spin Independent and Spin Dependent scattering cross-section on nuclei already exclude large portions of the parameter space favored by DM relic density, in particular if, in addition, a DM Indirect signal, like the Galactic Center gamma-ray excess is required.Comment: 7 pages, 2 figures. To appear as proceeding of the conference HEP-EPS 2015, Wien (Austria