Hyperon forward spin polarizability gamma0 in baryon chiral perturbation theory

We present the calculation of the hyperon forward spin polarizability gamma0 using manifestly Lorentz covariant baryon chiral perturbation theory including the intermediate contribution of the spin 3/2 states. As at the considered order the extraction of gamma0 is a pure prediction of chiral perturbation theory, the obtained values are a good test for this theory. After including explicitly the decuplet states, our SU(2) results have a very good agreement with the experimental data and we extend our framework to SU(3) to give predictions to the hyperons' gamma0 values. Prominent are the Sigma^- and Xi^- baryons as their photon transition to the decuplet is forbidden in SU(3) symmetry and therefore they are not sensitive to the explicit inclusion of the decuplet in the theory

Constraints on proton structure from precision atomic physics measurements

Ground-state hyperfine splittings in hydrogen and muonium are very well measured. Their difference, after correcting for magnetic moment and reduced mass effects, is due solely to proton structure--the large QED contributions for a pointlike nucleus essentially cancel. The rescaled hyperfine difference depends on the Zemach radius, a fundamental measure of the proton, computed as an integral over a product of electric and magnetic proton form factors. The determination of the Zemach radius, (1.043 +/- 0.016) fm, from atomic physics tightly constrains fits to accelerator measurements of proton form factors. Conversely, we can use muonium data to extract an ``experimental'' value for QED corrections to hydrogenic hyperfine data; we find that measurement and theory are consistent.Comment: 4 pages, RevTeX 4; corrects errors, to be consistent with published erratu

A large Muon Electric Dipole Moment from Flavor?

We study the prospects and opportunities of a large muon electric dipole moment (EDM) of the order (10^{-24} - 10^{-22}) ecm. We investigate how natural such a value is within the general minimal supersymmetric extension of the Standard Model with CP violation from lepton flavor violation in view of the experimental constraints. In models with hybrid gauge-gravity mediated supersymmetry breaking a large muon EDM is indicative for the structure of flavor breaking at the Planck scale, and points towards a high messenger scale.Comment: 12 pages, 12 figures. v3: References and Eq 28 fixed; conclusions unchange

Risk of basal cell carcinoma after Hodgkin's disease

Background: Basal cell cancer is a common skin cancer, yet studies of second tumors after Hodgkin's disease tend to exclude basal cell cancers as second malignant tumors from analysis. Basal cell carcinomas (BCC) are possibly more common in immunosuppressed patients and were recently implicated as indicators of subsequent malignancies. Materials and Methods: Our database of 1,120 patients with Hodgkin's disease (derived from the tumor registry) was investigated for the occurrence of later BCCs. Kaplan-Meier curves were calculated. Results: A total of 9 cases of BCC were observed 0-20 years after the diagnosis of Hodgkin's disease, One case relapsed after excision. The probability of second BCC was 2.1% after 15 years of follow-up and 7.1% after 20 years. Statistically, the risk for second BCC was increased only in younger patients and with prolonged follow-up, but not in the total group of patients with Hodgkin's disease. Conclusion: BCC is not a major threat: for the survivors of Hodgkin's disease, but continued follow-up is necessary

B_s ---> \gamma \gamma decay in the model III and 3HDM(O_2) with CP violating effects

We analyse the CP asymmetry for B_{s} -->\gamma\gamma in the two Higgs doublet model with tree level flavor changing currents (model III) and three Higgs doublet model with O_2 symmetry in the Higgs sector, including O_{7} type long distance effects. Further, we study the dependencies of the branching ratio Br(B_{s} --> \gamma\gamma)$ and the ratio of CP-even and CP-odd amplitude squares, R=|A^{+}|^2/|A^{-}|^2, on the CP parameter sin \theta. We found that, there is a weak CP asymmetry, at the order of 10^{-4}. Besides, the branching ratio Br(B_{s} --> \gamma\gamma), and also R ratio, is not sensitive to the CP parameter for |\frac{\bar{\xi}^{U}_{N,tt}}{\bar{\xi}^{D}_{N,bb}}|<1.Comment: 17 pages, 11 figure

Time-delayed feedback in neurosystems

The influence of time delay in systems of two coupled excitable neurons is studied in the framework of the FitzHugh-Nagumo model. Time-delay can occur in the coupling between neurons or in a self-feedback loop. The stochastic synchronization of instantaneously coupled neurons under the influence of white noise can be deliberately controlled by local time-delayed feedback. By appropriate choice of the delay time synchronization can be either enhanced or suppressed. In delay-coupled neurons, antiphase oscillations can be induced for sufficiently large delay and coupling strength. The additional application of time-delayed self-feedback leads to complex scenarios of synchronized in-phase or antiphase oscillations, bursting patterns, or amplitude death.Comment: 13 pages, 13 figure