Focus Point Supersymmetry: Proton Decay, Flavor and CP Violation, and the Higgs Boson Mass

In focus point supersymmetry, all squarks and sleptons, including those of the third generation, have multi-TeV masses without sacrificing naturalness. We examine the implications of this framework for low energy constraints and the light Higgs boson mass. Undesirable contributions to proton decay and electric dipole moments, generic in many supersymmetric models, are strongly suppressed. As a result, the prediction for alpha_s in simple grand unified theories is 3 to 5 standard deviations closer to the experimental value, and the allowed CP-violating phases are larger by one to two orders of magnitude. In addition, the very heavy top and bottom squarks of focus point supersymmetry naturally produce a Higgs boson mass at or above 115 GeV without requiring heavy gauginos. We conclude with an extended discussion of issues related to the definition of naturalness and comment on several other prescriptions given in the literature.Comment: 31 pages, 10 figures, references added, version to appear in Phys. Rev.

Solar stereoscopy - where are we and what developments do we require to progress?

Observations from the two STEREO-spacecraft give us for the first time the possibility to use stereoscopic methods to reconstruct the 3D solar corona. Classical stereoscopy works best for solid objects with clear edges. Consequently an application of classical stereoscopic methods to the faint structures visible in the optically thin coronal plasma is by no means straight forward and several problems have to be treated adequately: 1.)First there is the problem of identifying one dimensional structures -e.g. active region coronal loops or polar plumes- from the two individual EUV-images observed with STEREO/EUVI. 2.) As a next step one has the association problem to find corresponding structures in both images. 3.) Within the reconstruction problem stereoscopic methods are used to compute the 3D-geometry of the identified structures. Without any prior assumptions, e.g., regarding the footpoints of coronal loops, the reconstruction problem has not one unique solution. 4.) One has to estimate the reconstruction error or accuracy of the reconstructed 3D-structure, which depends on the accuracy of the identified structures in 2D, the separation angle between the spacecraft, but also on the location, e.g., for east-west directed coronal loops the reconstruction error is highest close to the loop top. 5.) Eventually we are not only interested in the 3D-geometry of loops or plumes, but also in physical parameters like density, temperature, plasma flow, magnetic field strength etc. Helpful for treating some of these problems are coronal magnetic field models extrapolated from photospheric measurements, because observed EUV-loops outline the magnetic field. This feature has been used for a new method dubbed 'magnetic stereoscopy'. As examples we show recent application to active region loops.Comment: 12 Pages, 9 Figures, a Review articl

Supersymmetry and the Anomalous Anomalous Magnetic Moment of the Muon

The recently reported measurement of the muon's anomalous magnetic moment differs from the standard model prediction by 2.6 standard deviations. We examine the implications of this discrepancy for supersymmetry. Deviations of the reported magnitude are generic in supersymmetric theories. Based on the new result, we derive model-independent upper bounds on the masses of observable supersymmetric particles. We also examine several model frameworks. The sign of the reported deviation is as predicted in many simple models, but disfavors anomaly-mediated supersymmetry breaking.Comment: 4 pages, 4 figures, version to appear in Phys. Rev. Let

The Measurement of the Muon's Anomalous Magnetic Moment Isn't

Recent results announced as measurements of the muon's anomalous magnetic moment are in fact measurements of the muon's anomalous spin precession frequency. This precession frequency receives contributions from both the muon's anomalous magnetic and electric dipole moments. We note that all existing data cannot resolve this ambiguity, and the current deviation from standard model predictions may equally well be interpreted as evidence for new physics in the muon's anomalous magnetic moment, new physics in the muon's electric dipole moment, or both.Comment: 2 pages, 1 figure, published versio

Muon Dipole Moment Experiments: Interpretation and Prospects

We examine the prospects for discovering new physics through muon dipole moments. The current deviation in $g_{\mu}-2$ may be due entirely to the muon's {\em electric} dipole moment. We note that the precession frequency in the proposed BNL muon EDM experiment is also subject to a similar ambiguity, but this can be resolved by up-down asymmetry measurements. We then review the theoretical expectations for the muon's electric dipole moment in supersymmetric models.Comment: 5 pages, 3 figures, uses RevTeX4, contribution to Snowmass 2001, references adde

Goldilocks Supersymmetry: Simultaneous Solution to the Dark Matter and Flavor Problems of Supersymmetry

Neutralino dark matter is well motivated, but also suffers from two shortcomings: it requires gravity-mediated supersymmetry breaking, which generically violates flavor constraints, and its thermal relic density \Omega is typically too large. We propose a simple solution to both problems: neutralinos freezeout with \Omega ~10-100, but then decay to ~1 GeV gravitinos, which are simultaneously light enough to satisfy flavor constraints and heavy enough to be all of dark matter. This scenario is naturally realized in high-scale gauge-mediation models, ameliorates small scale structure problems, and implies that ``cosmologically excluded'' models may, in fact, be cosmologically preferred.Comment: 4 pages; v2: references added; v3: published versio

Naturalness Re-examined: Implications for Supersymmetry Searches

We discuss the origin of "focus points" in the scalar mass RGEs of the MSSM and their implications for collider searches. We present a new exact analytic solution to the homogeneous system of scalar mass RGEs in the MSSM for general $\tan\beta$. This is then used to prove that the focus point for $m^2_{H_u}$ depends only on the value of the top Yukawa coupling at the {\em weak} scale (not its value at the GUT scale) and is independent of the bottom Yukawa coupling.Comment: 7 pages, 2 figures, to appear in the Proceedings of PASCOS'99, Lake Tahoe, December 10-16, 199

Surface Adsorbate Fluctuations and Noise in Nanoelectromechanical Systems

Physisorption on solid surfaces is important in both fundamental studies and technology. Adsorbates can also be critical for the performance of miniature electromechanical resonators and sensors. Advances in resonant nanoelectromechanical systems (NEMS), particularly mass sensitivity attaining the single-molecule level, make it possible to probe surface physics in a new regime, where a small number of adatoms cause a detectable frequency shift in a high quality factor (Q) NEMS resonator, and adsorbate fluctuations result in resonance frequency noise. Here we report measurements and analysis of the kinetics and fluctuations of physisorbed xenon (Xe) atoms on a high-Q NEMS resonator vibrating at 190.5 MHz. The measured adsorption spectrum and frequency noise, combined with analytic modeling of surface diffusion and adsorption−desorption processes, suggest that diffusion dominates the observed excess noise. This study also reveals new power laws of frequency noise induced by diffusion, which could be important in other low-dimensional nanoscale systems