We derive the decay widths for the leptonic decays of heavy charged pseudoscalars to massive sterile neutrinos, $M^{pm} to ell^{pm} + N$, within the frameworks involving the Standard Model and two-Higgs doublets (type II). We then apply the result to
$B^pm to tau^pm +$ missing momentum of the Belle/BaBar experimental results, in order to measure directly the relevant parameter space, including the mixing parameter $U_{tau N}$.
We present a search for the rare leptonic decays $B^+ to e^+ u_e$ and $B^+ to mu^+ u_mu$, using the full $Upsilon(4S)$ data sample of $772times 10^6$ $Bbar{B}$ pairs collected with the Belle detector at the $rm {small KEKB}$ asymmetric-energy $e^+
e^-$ collider. One of the $B$ mesons from the $Upsilon(4S) to Bbar{B}$ decay is fully reconstructed in a hadronic mode, while the recoiling side is analyzed for the signal decay. We find no evidence of a signal in any of the decay modes. Upper limits of the corresponding branching fractions are determined as ${cal B}(B^+ to e^+ u_e)<3.5times 10^{-6}$ and ${cal B}(B^+ to mu^+ u_mu)<2.7 times 10^{-6}$ at 90$%$ confidence level.
Interfaces between correlated complex oxides are promising avenues to realize new forms of magnetism that arise as a result of charge transfer, proximity effects and locally broken symmetries. We report upon the discovery of a non-collinear magnetic
structure in superlattices of the ferromagnetic metallic oxide La2/3Sr1/3MnO3 (LSMO) and the correlated metal LaNiO3 (LNO). The exchange interaction between LSMO layers is mediated by the intervening LNO, such that the angle between the magnetization of neighboring LSMO layers varies in an oscillatory manner with the thickness of the LNO layer. The magnetic field, temperature, and spacer thickness dependence of the non-collinear structure are inconsistent with the bilinear and biquadratic interactions that are used to model the magnetic structure in conventional metallic multilayers. A model that couples the LSMO layers to a helical spin state within the LNO fits the observed behavior. We propose that the spin-helix results from the interaction between a spatially varying spin susceptibility within the LNO and interfacial charge transfer that creates localized Ni2+ states. This provides a new approach to engineering non-collinear spin textures in metallic oxide heterostructures that can be exploited in devices based on both spin and charge transport.
We present a search for the rare leptonic decays $B^+ to e^+ u_e$ and $B^+ to mu^+ u_mu$, using the full $Upsilon(4S)$ data sample of $772times 10^6$ $Bbar{B}$ pairs collected with the Belle detector at the $smalltextbf{KEKB}$ asymmetric-energy $e^
+ e^-$ collider. One of the $B$ mesons from the $Upsilon(4S) to Bbar{B}$ decay is fully reconstructed in a hadronic mode, while the recoiling side is analyzed for the signal decay. We find no evidence of a signal in any of the decay modes. Upper limits of the corresponding branching fractions are determined as ${cal B}(B^+ to e^+ u_e)<3.5times 10^{-6}$ and ${cal B}(B^+ to mu^+ u_mu)<2.7 times 10^{-6}$ at 90$%$ confidence level.
