On electroweak baryogenesis in the littlest Higgs model with T parity

We study electroweak baryogenesis within the framework of the littlest Higgs model with T parity. This model has shown characteristics of a strong first-order electroweak phase transition, which is conducive to baryogenesis in the early Universe. In the T parity symmetric theory, there are two gauge sectors, viz., the T-even and the T-odd ones. We observe that the effect of the T-parity symmetric interactions between the T-odd and the T-even gauge bosons on gauge-higgs energy functional is quite small, so that these two sectors can be taken to be independent. The T-even gauge bosons behave like the Standard Model gauge bosons, whereas the T-odd ones are instrumental in stabilizing the Higgs mass. For the T-odd gauge bosons in the symmetric and asymmetric phases and for the T-even gauge bosons in the asymmetric phase, we obtain, using the formalism of Arnold and McLerran, very small values of the ratio, (Baryon number violation rate/Universe expansion rate). We observe that this result, in conjunction with the scenario of inverse phase transition in the present work and the value of the ratio obtained from the lattice result of sphaleron transition rate in the symmetric phase, can provide us with a plausible baryogenesis scenario.Comment: 13 pages, 2 figures, published version, references modifie

Jost Function for Singular Potentials

An exact method for direct calculation of the Jost function and Jost solutions for a repulsive singular potential is presented. Within this method the Schrodinger equation is replaced by an equivalent system of linear first-order differential equations, which after complex rotation, can easily be solved numerically. The Jost function can be obtained to any desired accuracy for all complex momenta of physical interest, including the spectral points corresponding to bound and resonant states. The method can also be used in the complex angular-momentum plane to calculate the Regge trajectories. The effectiveness of the method is demonstrated using the Lennard-Jones (12,6) potential. The spectral properties of the realistic inter-atomic He4-He4 potentials HFDHE2 and HFD-B of Aziz and collaborators are also investigated.Comment: 12 pages, latex, 2 eps-figures, submitted to Phys.Rev.

Suppression of Phase Separation in LiFePO4 Nanoparticles During Battery Discharge

Using a novel electrochemical phase-field model, we question the common belief that LixFePO4 nanoparticles separate into Li-rich and Li-poor phases during battery discharge. For small currents, spinodal decomposition or nucleation leads to moving phase boundaries. Above a critical current density (in the Tafel regime), the spinodal disappears, and particles fill homogeneously, which may explain the superior rate capability and long cycle life of nano-LiFePO4 cathodes.Comment: 27 pages, 8 figure

Solutions of the Faddeev-Yakubovsky equations for the four nucleons scattering states

The Faddeev-Yakubowsky equations in configuration space have been solved for the four nucleon system. The results with an S-wave interaction model in the isospin approximation are presented. They concern the bound and scattering states below the first three-body threshold. The elastic phase-shifts for the N+NNN reaction in different ($S,T$) channels are given and the corresponding low energy expansions are discussed. Particular attention is payed to the n+t elastic cross section. Its resonant structure is well described in terms of a simple NN interaction. First results concerning the S-matrix for the coupled N+NNN-NN+NN channels and the strong deuteron-deuteron scattering length are obtained.Comment: latex.tar.gz, 36 pages, 10 figures, 11 tables. To be published in Physical Review

Observation of coherent transients in ultrashort chirped excitation of an undamped two-level system

The effects of Coherent excitation of a two level system with a linearly chirped pulse are studied theoretically and experimentally (in Rb (5s - 5p)) in the low field regime. The Coherent Transients are measured directly on the excited state population on an ultrashort time scale. A sharp step corresponds to the passage through resonance. It is followed by oscillations resulting from interferences between off-resonant and resonant contributions. We finally show the equivalence between this experiment and Fresnel diffraction by a sharp edge.Comment: 4 pages, 4 figures, to appear in PR

Observation of B+ to Lambda Lambdabar K+

We report the first observation of the charmless hyperonic B decay, B^+ --> Lambda Lambdabar K^+, using a 140 fb^-1 data sample recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+e^- collider. The measured branching fraction is B(B^+ --> Lambda Lambdabar K^+) = 2.91 ^{+0.90}_{-0.70} +/- 0.38 *10^-6 . We also perform a search for the related decay mode B^+ --> Lambda Lambdabar pi^+, but do not find a significant signal. We set a 90% confidence-level upper limit of B(B^+ --> Lambda Lambdabar pi^+) < 2.8 * 10^-6.Comment: 9 pages, 3 figures, submitted to Phys. Rev. Let

Momentum distributions in ^3He-^4He liquid mixtures

We present variational calculations of the one-body density matrices and momentum distributions for ^3He-^4He mixtures in the zero temperature limit, in the framework of the correlated basis functions theory. The ground-state wave function contains two- and three-body correlations and the matrix elements are computed by (Fermi)Hypernetted Chain techniques. The dependence on the ^3He concentration (x_3) of the ^4He condensate fraction $(n_0^{(4)})$ and of the ^3He pole strength (Z_F) is studied along the P=0 isobar. At low ^3He concentration, the computed ^4He condensate fraction is not significantly affected by the ^3He statistics. Despite of the low x_3 values, Z_F is found to be quite smaller than that of the corresponding pure ^3He because of the strong ^3He-^4He correlations and of the overall, large total density \rho. A small increase of $n_0^{(4)}$ along x_3 is found, which is mainly due to the decrease of \rho respect to the pure ^4He phase.Comment: 23 pages, 7 postscript figures, Revte

Observation of X(3872)→J/ψγX(3872)\to J/\psi \gamma and search for X(3872)→ψ′γX(3872)\to\psi'\gamma in B decays

We report a study of $B\to (J/\psi \gamma) K$ and $B\to (\psi' \gamma)K$ decay modes using $772\times 10^{6}$ $B\bar{B}$ events collected at the \Upsilon(4S)$resonance with the Belle detector at the KEKB energy-asymmetric$e^+ e^-$collider. We observe$X(3872) \to J/\psi \gamma$and report the first evidence for$\chi_{c2} \to J/\psi \gamma$in$B\to (X_{c\bar{c}}\gamma) K$decays, while in a search for$X(3872) \to \psi' \gamma$no significant signal is found. We measure the branching fractions,$\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to J/\psi\gamma)$$=$$(1.78^{+0.48}_{-0.44}\pm 0.12)\times 10^{-6}$,$\mathcal{B} (B^{\pm} \to\chi_{c2} K^{\pm})$$=$$(1.11^{+0.36}_{-0.34} \pm 0.09) \times 10^{-5}$,$\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to \psi'\gamma)$$<$$3.45\times 10^{-6}$ (upper limit at 90% C.L.) and also provide upper limits for other searches.Comment: 6 pages, 3 figure

Multi-mode Flight Sliding Mode Control System for a Quadrotor

There is a wide range of applications for unmanned aerial vehicles that requires the capability of having several and robust flight controllers available. This paper presents the main framework of a multimode flight control system for a quadrotor based on the super twisting control algorithm. The design stages for the four flight control modes encompassing manual, altitude, GPS fixed and autonomous mode are presented. The stability proof for each flight mode is carried out by means of Lyapunov functions while the stability analysis for the complete system, when a transition from one mode to another occurs, is demonstrated using the switching nonlinear systems theory. The performance of the proposed framework is demonstrated in a simulation study taking into account external disturbances

Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays

We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53 events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including systematics. We also search for CP violation in the decays B+- -> K+-pi0 and B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) = 0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst), corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and -0.18<Acp(pi+-pi0)<0.14 at 90% confidence level.Comment: 9 pages, 3 figures. submitted to Physical Review Letter