Lepton flavour violation in the MSSM

We derive new constraints on the quantities delta_{XY}^{ij}, X,Y=L,R, which parametrise the flavour-off-diagonal terms of the charged slepton mass matrix in the MSSM. Considering mass and anomalous magnetic moment of the electron we obtain the bound |delta^{13}_{LL} delta^{13}_{RR}|<0.1 for tan beta=50, which involves the poorly constrained element delta^{13}_{RR}. We improve the predictions for the decays tau -> mu gamma, tau -> e gamma and mu -> e gamma by including two-loop corrections which are enhanced if tan beta is large. The finite renormalisation of the PMNS matrix from soft SUSY-breaking terms is derived and applied to the charged-Higgs-lepton vertex. We find that the experimental bound on BR(tau -> e gamma) severely limits the size of the MSSM loop correction to the PMNS element U_{e3}, which is important for the proper interpretation of a future U_{e3} measurement. Subsequently we confront our new values for delta^{ij}_{LL} with a GUT analysis. Further, we include the effects of dimension-5 Yukawa terms, which are needed to fix the Yukawa unification of the first two generations. If universal supersymmetry breaking occurs above the GUT scale, we find the flavour structure of the dimension-5 Yukawa couplings tightly constrained by mu -> e gamma.Comment: 37 pages, 15 figures; typo in Equation (35) and (49) correcte

Electromagnetically assisted densification of copper-sheathed in situ MgB2/Cu wires

peer-reviewedThis paper summarizes recent methods of improving critical current density of in situ Cu-sheathed MgB2 wires. These methods include using optimum heat treatment schedule, adding copper powder to the wire core and electromagnetic densification of wire core. The large part of work reported here focuses on the latter method applied to the relatively low-density MgB2/Cu wire core. The packing density of unreacted, monofilament wire core was increased by 8 % with oscillating magnetic pressure, reaching a peak value above 700 MPa as calculated by finite element modelling of the forming process. The higher density of the MgB2 core combined with copper powder addition resulted in a critical current density increase of more than fivefold in comparison to purely stoichiometric and cold-drawn-only wire.PUBLISHEDpeer-reviewe

Random Excitation of Bistable Harvesters

This chapter considers nonlinear piezoelastic energy harvesters driven by stationary random noise. A range of devices that exhibit nonlinear dynamics have been proposed, and their response to sinusoidal excitation is often complex, with coexisting periodic solutions or even chaotic solutions. The response of nonlinear harvesters to random noise depends on the statistics of the excitation; the maximum response can occur at particular excitation variances, and this is called stochastic resonance. The stochastic linearisation method is proposed for the optimal design of bistable harvesters subjected to random excitation