New Physics Effects in B→K(∗)ννB \to K^(*) \nu \nu Decays

We present a model-independent analysis of rare B decays, $B \to K^{(*)} \nu \nu$. The effect of possible new physics is written in terms of dimension-6 four-fermi interactions. The lepton number violating scalar- and tensor-type interactions are included, and they induce $B \to K^{(*)} \nu \nu ({\bar \nu} {\bar \nu})$ decays. We show systematically how the branching ratios and missing mass-squared spectrum depend on the coefficients of the four-fermi interactions.Comment: 20 pages with 7 figure

Direct CP and T Violation in Baryonic B Decays

We review the direct CP and T violation in the three-body baryonic B decays in the standard model. In particular, we emphasize that the direct CP violating asymmetry in $B^\pm\to p\bar p K^{*\pm}$ is around 22% and the direct $T$ violating asymmetry in \bar B^0 \ra \Lambda \bar p \pi^+ can be as large as 12%, which are accessible to the current B factories at KEK and SLAC as well as SuperB and LHCb.Comment: 6 pages, Talk given at 4th International Conference on Flavor Physics (ICFP 2007), Beijing, China, 24-28 Sep 200

Possible Supersymmetric Effects on Angular Distributions in B→K∗(→Kπ)ℓ+ℓ−B \to K^* (\to K \pi) \ell^+ \ell^- Decays

We investigate the angular distributions of the rare B decay, $B \to K^* (\to K \pi) \ell^+ \ell^-$, in general supersymmetric extensions of the standard model. We consider the new physics contributions from the operators $O_{7,8,9,10}$ in small invariant mass region of lepton pair. We show that the azimuthal angle distribution of the decay can tell us the new physics effects clearly from the behavior of the distribution, even if new physics does not change the decay rate substantially from the standard model prediction

Transcranial magnetic stimulation: Improved coil design for deep brain investigation

This paper reports on a design for a coil for transcranial magnetic stimulation. The design shows potential for improving the penetration depth of the magnetic field, allowing stimulation of subcortical structures within the brain. The magnetic and induced electric fields in the human head have been calculated with finite element electromagnetic modeling software and compared with empirical measurements. Results show that the coil design used gives improved penetration depth, but also indicates the likelihood of stimulation of additional tissue resulting from the spatial distribution of the magnetic field

Thermally activated decomposition of (Ga,Mn)As thin layer at medium temperature post growth annealing

The redistribution of Mn atoms in Ga1-xMnxAs layer during medium-temperature annealing, 250-450 oC, by Mn K-edge X-ray absorption fine structure (XAFS) recorded at ALBA facility, was studied. For this purpose Ga1-xMnxAs thin layer with x=0.01 was grown on AlAs buffer layer deposited on GaAs(100) substrate by molecular beam epitaxy (MBE) followed by annealing. The examined layer was detached from the substrate using a “lift-off” procedure in order to eliminate elastic scattering in XAFS spectra. Fourier transform analysis of experimentally obtained EXAFS spectra allowed to propose a model which describes a redistribution/diffusion of Mn atoms in the host matrix. Theoretical XANES spectra, simulated using multiple scattering formalism (FEFF code) with the support of density functional theory (WIEN2k code), qualitatively describe the features observed in the experimental fine structure

Temperature dependence of magnetic anisotropy of Ga-substituted cobalt ferrite

The temperature dependence of magnetization, magnetic anisotropy, and coercive field of gallium-substituted cobaltferrite was investigated for a series of compositions of CoGaxFe2−xO4 (0⩽x⩽0.8). Hysteresis loops were measured for each sample over the range of −5T⩽μ0H⩽5T for selected temperatures between 10 and 400K. The magnetization at 5T and low temperatures was found to increase for the lower Ga contents (x=0.2 and 0.4) compared to pure CoFe2O4, indicating that at least initially, Ga3+substitutes predominantly into the tetrahedral sites of the spinel structure. The high field regions of these loops were modeled using the law of approach to saturation, which represents the rotational process, together with an additional linear forced magnetization term. The first order cubic magnetocrystalline anisotropy coefficient K1 was calculated from curve fitting to these data. It was found that K1 decreased with increasing Ga content at all temperatures. Both anisotropy and coercivity increased substantially as temperature decreased. Below 150K, for certain compositions (x=0, 0.2, 0.4), the maximum applied field of μ0H=5T was less than the anisotropy field and, therefore, insufficient to saturate the magnetization. In these cases, the use of the law of approach method can lead to calculated values of K1 which are lower than the correct value