CP Violating Asymmetry in Stop Decay into Bottom and Chargino

In the MSSM with complex parameters, loop corrections to the decay of a stop into a bottom quark and a chargino can lead to a CP violating decay rate asymmetry. We calculate this asymmetry at full one-loop level and perform a detailed numerical study, analyzing the dependence on the parameters and complex phases involved. In addition, we take the Yukawa couplings of the top and bottom quark running. We account for the constraints on the parameters coming from several experimental limits. Asymmetries of several percent are obtained. We also comment on the feasibility of measuring this asymmetry at the LHC.Comment: Contributed talk given by Sebastian Frank in June 2009 at SUSY09 - 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions, Northeastern University, Boston, USA. To appear in the AIP conference proceedings, 4 pages, 7 figures (fixed links in references

Hopping conductivity in heavily doped n-type GaAs layers in the quantum Hall effect regime

We investigate the magnetoresistance of epitaxially grown, heavily doped n-type GaAs layers with thickness (40-50 nm) larger than the electronic mean free path (23 nm). The temperature dependence of the dissipative resistance R_{xx} in the quantum Hall effect regime can be well described by a hopping law (R_{xx} \propto exp{-(T_0/T)^p}) with p=0.6. We discuss this result in terms of variable range hopping in a Coulomb gap together with a dependence of the electron localization length on the energy in the gap. The value of the exponent p>0.5 shows that electron-electron interactions have to be taken into account in order to explain the occurrence of the quantum Hall effect in these samples, which have a three-dimensional single electron density of states.Comment: 5 pages, 2 figures, 1 tabl

Accelerometer-Determined Physical Behavior Metrics and their Associations with Sarcopenia among Oldest-Old Adults

INTRODUCTION: Sarcopenia is a loss of muscle function and muscle mass which frequently occurs among the oldest-old adult population (aged 85+ years). The analysis of accelerometer-determined physical behavior volumes and patterns of oldest-old adults might provide novel insights into the associations with sarcopenia and its components. METHODS: A total of 145 participants in the primary sample and 87 participants in the subsample with a mean age of 88.2 (2.5) years from the Health, Aging, and Body Composition study cohort provided cross-sectional data of handgrip strength, appendicular lean mass, gait speed, and accelerometry. Probable, confirmed, and severe sarcopenia were assessed based on the revised definition of the European Working Group on Sarcopenia in Older People 2. Binomial logistic and multivariate linear regression models as well as dose-response analyses were applied and adjusted for demographics, accelerometer wear time, lifestyle factors, and chronic health conditions. RESULTS: Oldest-old adults with higher total volumes of moderate to vigorous physical activity (MVPA) (OR=0.74, 95% CI 0.62 to 0.89) showed a lower likelihood for a probable sarcopenic condition in the primary sample. Likewise, patterns of higher accumulated time spent in MVPA bouts of less than 10 minutes (OR=0.78, 95% CI 0.64 to 0.95) and MVPA bouts of at least 10 minutes (OR=0.78, 95% CI 0.63 to 0.98) were also related with lower odds of probable sarcopenia. A 2.1 times (95% CI 1.01 to 4.35) higher likelihood for confirmed sarcopenia was observed among participants who spent 60 minutes more per day in sedentary behavior (SB). Furthermore, 2.9 times (95% CI 1.05 to 8.02) greater odds of severe sarcopenia were identified following each 0.1 higher active-to-sedentary transition probability (ASTP). Focusing on individual sarcopenic components, higher total activity counts, higher MVPA, higher light intensity physical activity (LIPA), lower SB, and lower ASTP were related with better gait speed. CONCLUSION: The total volume of MVPA, whether accumulated in short sporadic bouts or prolonged bouts, was associated with lower odds of probable sarcopenia. Higher LIPA, lower SB, and a less fragmented activity pattern might also be related with a lower likelihood of sarcopenia status and better physical performance among oldest-old adults

Electroweak radiative corrections to single Higgs-boson production in e+e- annihilation

We have calculated the complete electroweak O(alpha) radiative corrections to the single Higgs-boson production processes e+ e- --> nu_l anti-nu_l H (l=e,mu,tau) in the electroweak Standard Model. Initial-state radiation beyond O(alpha) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross section. In the G_mu scheme, the bulk of the corrections is due to initial-state radiation, which affects the cross section at the level of -7% at high energies and even more in the ZH threshold region. The remaining bosonic and fermionic corrections are at the level of a few per cent. The confusing situation in the literature regarding differing results for the fermionic corrections to this process is clarified.Comment: 11 pages, latex, 7 postscript files, some references added, final version to appear in Phys.Lett.

Kondo effect in a one-electron double quantum dot: Oscillations of the Kondo current in a weak magnetic field

We present transport measurements of the Kondo effect in a double quantum dot charged with only one or two electrons, respectively. For the one electron case we observe a surprising quasi-periodic oscillation of the Kondo conductance as a function of a small perpendicular magnetic field |B| \lesssim 50mT. We discuss possible explanations of this effect and interpret it by means of a fine tuning of the energy mismatch of the single dot levels of the two quantum dots. The observed degree of control implies important consequences for applications in quantum information processing