General Minimal Supersymmetric Standard Model Research Articles

Large lepton flavor violating signals in supersymmetric particle decays at futuree+e−colliders

We study lepton flavor violating signals at a future ${e}^{+}{e}^{\ensuremath{-}}$ linear collider within the general minimal supersymmetric standard model (MSSM), allowing for the most general flavor structure. There exists a large region in parameter space with large signals being consistent with present experimental bounds on rare lepton decays. We include all possible signals from slepton and sneutrino production and their decays as well as from neutralino and chargino decays. We also consider the background from the standard model and the MSSM. We find that in general the signature $e\ensuremath{\tau}{E}_{T}$ is the most pronounced one.

CP-violating phases in supersymmetry, electric dipole moments, and linear colliders

We reexamine large CP-violating phases in the general Minimal Supersymmetric Standard Model, as well as more restricted models. We perform a detailed scan over parameter space to find solutions which satisfy the current experimental limits on the electric dipole moments of the electron, neutron and $^{199}$Hg atom, exploring the allowed configurations of phases and masses, and we attempt to quantify the level of tuning of the parameters necessary to populate the regions of cancellations. We then consider the measurement of CP-violating phases at a future linear collider. We find that measurements of chargino and neutralino masses and production cross-sections allow for a determination of $\phi_1$(the phase of $M_1$) to a precision of $\pi/30$, while the EDM constraints require that $\theta_\mu$ be too small to be measured. Using the EDM constraints we find that the CP-even model parameters and the phase $\phi_1$ can be determined at a Linear Collider with $400 \gev$ c.m. energy. As long as some information on the size of $|\mu|$ is included in the observables, a measurement of $\phi_1$ is guaranteed for $\phi_1 > \pi/10$. To unambiguously identify CP violation, we construct CP-odd kinematical variables at a linear collider. However, the CP asymmetries are rather small, typically about $0.1-1.5%$, and it will be challenging to experimentally observe the predicted asymmetries.

CP violation as a probe of flavor origin in supersymmetry

We address the question of the relation between supersymmetry breaking and the origin of flavor in the context of CP violating phenomena. We prove that, in the absence of the Cabibbo–Kobayashi–Maskawa phase, a general Minimal Supersymmetric Standard Model with all possible phases in the soft-breaking terms, but no new flavor structure beyond the usual Yukawa matrices, can never give a sizeable contribution to ε K , ε′/ ε or hadronic B 0 CP asymmetries. Observation of supersymmetric contributions to CP asymmetries in B decays would hint at a non-flavor blind mechanism of supersymmetry breaking.

Supersymmetry and large transition magnetic moment of the neutrino.

We show that the most general minimal supersymmetric standard model with ${\mathit{l}}_{\mathit{e}}$-${\mathit{l}}_{\mathrm{\ensuremath{\mu}}}$ symmetry (${\mathit{l}}_{\mathit{i}}$=ith lepton number) and a discrete horizontal symmetry between e and \ensuremath{\mu} families can generate a large transition magnetic moment for the neutrino while leading to a naturally small mass. A magnetic moment of order ${\mathrm{\ensuremath{\mu}}}_{\ensuremath{\nu}}$\ensuremath{\approxeq}0.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ implies ${\mathit{m}}_{\ensuremath{\nu}\mathit{e}}$=${\mathit{m}}_{\ensuremath{\nu}\mathrm{\ensuremath{\mu}}}$\ensuremath{\ge}1 eV. The photino, which is expected to be the lightest supersymmetric particle, is unstable in this scheme, decaying dominantly into three-lepton final states (${\mathrm{\ensuremath{\mu}}}^{+}$\ensuremath{\nu}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}_{\mathit{e}}$${\mathrm{\ensuremath{\tau}}}^{\mathrm{\ensuremath{-}}}$, ${\mathrm{e}}^{+}$\ensuremath{\nu}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}_{\mathrm{\ensuremath{\mu}}}$${\mathrm{\ensuremath{\tau}}}^{\mathrm{\ensuremath{-}}}$+charge conjugate).