Baryogenesis, Electric Dipole Moments and Dark Matter in the MSSM

TL;DR

The paper investigates electroweak baryogenesis in the MSSM under current and forthcoming EDM and dark matter constraints, showing that resonant higgsino/gaugino dynamics with $| mu|$ near $|M_{1,2}|$ can generate the observed BAU while remaining consistent with two-loop electron EDM limits. It analyzes neutralino dark matter in EWB contexts, finding that thermal production can suffice in some scenarios (e.g., heavy sleptons with certain gaugino/higgsino mixtures) but non-thermal or cosmological enhancements are required in others. It demonstrates that DM detection—especially ton-scale direct detectors and neutrino telescopes like IceCube, together with SuperKamiokande limits—will probe most of the viable parameter space, while collider tests at the LHC and future ILC provide complementary avenues. Overall, the results highlight a strong interplay between CP violation, cosmology, and collider phenomenology, with upcoming experiments poised to rigorously test MSSM EWB across multiple channels.

Abstract

We study the implications for electroweak baryogenesis (EWB) within the minimal supersymmetric Standard Model (MSSM) of present and future searches for the permanent electric dipole moment (EDM) of the electron, for neutralino dark matter, and for supersymmetric particles at high energy colliders. We show that there exist regions of the MSSM parameter space that are consistent with both present two-loop EDM limits and the relic density and that allow for successful EWB through resonant chargino and neutralino processes at the electroweak phase transition. We also show that under certain conditions the lightest neutralino may be simultaneously responsible for both the baryon asymmetry and relic density. We give present constraints on chargino/neutralino-induced EWB implied by the flux of energetic neutrinos from the Sun, the prospective constraints from future neutrino telescopes and ton-sized direct detection experiments, and the possible signatures at the Large Hadron Collider and International Linear Collider.

Figures (10)

• Figure 1: Regions, on the $(M_{1,2},\mu)$ planes, producing the central value for the baryon asymmetry in the Universe deduced from the WMAP analysis Spergel:2003cb, for various values of the CP-violating phase $\phi_\mu$, at $m_A=150$ GeV. In panel (a) we assume gaugino soft breaking masses unification at the GUT scale, leading, at the EW scale, to $M_2\simeq 2M_1$, while in panel (b) we assume an anomaly-mediated inspired gaugino mass pattern, leading to $M_1\simeq 3M_2$. The red regions correspond to chargino masses below the LEP2 limit ($m_{\widetilde{\chi}^\pm}<103.5\ {\rm GeV})$.
• Figure 2: Iso-level curves of the electron electric dipole moment, on the $(M_{1,2},\mu)$ planes, at various values of $m_A$ and of the CP violating phase $\phi_\mu$, in the limit of heavy sfermions. The thick blue lines represent the current experimental upper limit Regan:2002ta. We also shade in light blue the 2-$\sigma$ regions corresponding to a WMAP BAU Spergel:2003cb. In the two upper panels we take $m_A=1$ TeV and $\sin\phi_\mu=0.5$, while in the two lower panels $m_A=150$ GeV and $\sin\phi_\mu=0.1$. In panels (a) and (c) we assume gaugino soft breaking masses unification at the GUT scale, leading, at the EW scale, to $M_2\simeq 2M_1$, while in panels (b) and (d) we assume an anomaly-mediated inspired gaugino mass pattern, leading to $M_1\simeq 3M_2$. The red (dark) regions correspond to chargino masses below the LEP2 limit ($m_{\widetilde{\chi}^\pm}<103.5\ {\rm GeV})$.
• Figure 3: The range of the one-loop electron EDM, as a function of the common slepton mass, obtained varying the gaugino soft breaking SUSY masses and the $\mu$ parameter on the planes shown in Fig. \ref{['fig:edm']}, i.e. between 0.1 and 1 TeV. We plot the quantity $d_e/\sin\phi_\mu$, and show the experimental upper limit for various values of $\sin\phi_\mu$, including those shown in Fig \ref{['fig:edm']}..
• Figure 4: A sketch of the possible spectral patterns for the parameters entering the neutralino mass matrix (the higgsino mass parameter $\mu$ and the gaugino soft breaking masses $M_{1,2}$), in the context of resonant EWB. In case $(a)$ the sector relevant for dark matter phenomenology is decoupled from the one responsible for EWB, while in case $(b)$ the two sectors are connected: the same fields which drive the resonant EWB non-trivially participate in the determination of the dark matter particle mass and composition.
• Figure 5: A close-up on the relic abundance of neutralino dark matter on the $(M_{1,2},\mu)$ planes. The red regions are excluded by the LEP2 chargino mass bound, while in the grey regions the stop becomes the LSP. The conventions for the values of $m_A$, $\sin\phi_\mu$ and for the gaugino soft breaking masses are as in the previous Fig. \ref{['fig:edm']}. We shade in light green regions of the parameter space where the neutralino thermal relic abundance falls within 2-$\sigma$ in the CDM abundance range determined by WMAP Spergel:2003cb. We indicate with black curves the contours of constant $\eta_\Omega$, the number of "extra" neutralinos needed per thermally produced neutralino to bring low thermal relic abundance models into accord with the inferred CDM density.