Collider and Dark Matter Phenomenology of Models with Mirage Unification

TL;DR

The paper investigates collider and dark matter phenomenology in models with mixed modulus-anomaly mediated SUSY breaking (MM-AMSB), where soft terms arise from comparable moduli and anomaly contributions and gaugino masses exhibit mirage unification at $Q=\mu_{\rm mir}=M_{\rm GUT}e^{-8\pi^2/(l\alpha)}$. By scanning nine discrete Higgs/matter modular weight combinations $(n_H,n_m)$ across low and high $\tan\beta$, the authors map WMAP-compatible regions, compute neutralino relic densities, and assess LHC/ILC reach as well as direct and indirect dark matter detection prospects; they also analyze low-energy observables like $(g-2)_{\mu}$ and $BF(b\to s\gamma)$. The study finds rich DM phenomenology with coannihilation, funnel, and mixed bino-wino-higgsino regimes, many of which are accessible to ton-scale direct detection and LHC/ILC experiments, while highlighting the potential to test mirage unification especially for intermediate $\mu_{\rm mir}$ values and the challenges when $\mu_{\rm mir} \gg M_{\rm GUT}$. The work emphasizes the distinctive sparticle mass patterns in MM-AMSB that differentiate it from mSUGRA, and provides practical benchmarks for experimental searches and for probing the underlying extra-dimensional modular weights.

Abstract

We examine supersymmetric models with mixed modulus-anomaly mediated SUSY breaking (MM-AMSB) soft terms which get comparable contributions to SUSY breaking from moduli-mediation and anomaly-mediation. The apparent (mirage) unification of soft SUSY breaking terms at Q=mu_mir not associated with any physical threshold is the hallmark of this scenario. The MM-AMSB structure of soft terms arises in models of string compactification with fluxes, where the addition of an anti-brane leads to an uplifting potential and a de Sitter universe, as first constructed by Kachru {\it et al.}. The phenomenology mainly depends on the relative strength of moduli- and anomaly-mediated SUSY breaking contributions, and on the Higgs and matter field modular weights, which are determined by the location of these fields in the extra dimensions. We delineate the allowed parameter space for a low and high value of tan(beta), for a wide range of modular weight choices. We calculate the neutralino relic density and display the WMAP-allowed regions. We show the reach of the CERN LHC and of the International Linear Collider. We discuss aspects of MM-AMSB models for Tevatron, LHC and ILC searches, muon g-2 and b->s γbranching fraction. We also calculate direct and indirect dark matter detection rates, and show that almost all WMAP-allowed models should be accessible to a ton-scale noble gas detector. Finally, we comment on the potential of colliders to measure the mirage unification scale and modular weights in the difficult case where mu_mir>>M_GUT.