Organometallic vapor phase epitaxial growth of high purity GaInAs using trimethylindium

Journal ArticleGax In1−xAs lattice matched to the InP substrate (x=0.47) has been grown by organometallic vapor phase epitaxy using trimethylindium (TMIn) and trimethylgallium (TMGa) as the group III sources and AsH3 as the As source. In a simple, horizontal, atmospheric pressure reactor, the GaInAs growth proceeds without visible evidence of parasitic prereaction problems. The process yields homogeneous, reproducible GaInAs with a high growth efficiency and a solid/vapor In distribution coefficient of nearly unity. Most importantly, several layers with room-temperature electron mobilities of approximately 10 000 cm2/Vs and carrier concentrations of approximately 1015 cm−3 have been produced. The 4-K photoluminescence shows a narrow (4-5 meV) band-edge emission peak and a low-intensity band acceptor peak at ~18 meV lower energy. Surface morphologies are routinely featureless as observed by high magnification interference contrast microscopy

3-quasi-Sasakian manifolds

In the present paper we carry on a systematic study of 3-quasi-Sasakian manifolds. In particular we prove that the three Reeb vector fields generate an involutive distribution determining a canonical totally geodesic and Riemannian foliation. Locally, the leaves of this foliation turn out to be Lie groups: either the orthogonal group or an abelian one. We show that 3-quasi-Sasakian manifolds have a well-defined rank, obtaining a rank-based classification. Furthermore, we prove a splitting theorem for these manifolds assuming the integrability of one of the almost product structures. Finally, we show that the vertical distribution is a minimum of the corrected energy.Comment: 17 pages, minor modifications, references update

Solving the Shortest Vector Problem in Lattices Faster Using Quantum Search

By applying Grover's quantum search algorithm to the lattice algorithms of Micciancio and Voulgaris, Nguyen and Vidick, Wang et al., and Pujol and Stehl\'{e}, we obtain improved asymptotic quantum results for solving the shortest vector problem. With quantum computers we can provably find a shortest vector in time $2^{1.799n + o(n)}$, improving upon the classical time complexity of $2^{2.465n + o(n)}$ of Pujol and Stehl\'{e} and the $2^{2n + o(n)}$ of Micciancio and Voulgaris, while heuristically we expect to find a shortest vector in time $2^{0.312n + o(n)}$, improving upon the classical time complexity of $2^{0.384n + o(n)}$ of Wang et al. These quantum complexities will be an important guide for the selection of parameters for post-quantum cryptosystems based on the hardness of the shortest vector problem.Comment: 19 page

Thin deformable mirrors for a reconfigurable space telescope

As part of a small satellite technology demonstration that will utilize autonomous assembly, reconfiguration, and docking technology to form the primary mirror for the mission’s telescope payload, the mirror segments are required to modify and control their shape, in order to allow for imaging in different configurations. This paper focuses on the development of 10 cm diameter active lightweight mirrors. The current mirror design, control scheme, and fabrication methods are described, as well as experimental results on initial samples. The data demonstrates that the mirrors are capable of at least 100 microns of displacement during operation, and that fabrication on polished molds can result in high quality reflective surfaces

Search for Resonant B±→K±h→K±γγB^{\pm}\to K^{\pm} h \to K^{\pm} \gamma \gamma Decays at Belle

We report measurements and searches for resonant $B^{\pm} \to K^{\pm} h \to K^{\pm} \gamma \gamma$ decays where $h$ is a $\eta,\eta^{\prime},\eta_{c},\eta_{c}(2S),\chi_{c0},\chi_{c2},J/\psi$ meson or the X(3872) particle.Comment: accepted by Physics Letters

Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S

Using 462/fb of e+e- annihilation data recorded by the Belle detector, we report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be (3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+ -> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table

Improved measurement of CP-violating parameters in rho+rho- decays

We present a measurement of the CP-violating asymmetry in rho+rho- decays using 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider. We measure CP-violating coefficients A = 0.16 +- 0.21(stat) +- 0.07 (syst) and S = 0.19 +- 0.30(stat) +- 0.07 (syst}. These values are used to determine the unitarity triangle angle phi_2 using an isospin analysis; the solution consistent with Standard Model lies in the range 53 < phi_2 < 114 deg. at 90 C.L.Comment: 6 pages, 4 figures, presented at JPS/DPF 2006 (Added KEK, BELLE preprint numbers, submitted to PRD(RC)

Search for new charmonium states in the processes e+ e- --> J/psi D(*) D(*) at sqrt{s} ~ 10.6 GeV

We present a study of the X(3940) state in the process e+e- -> J/psi D* Dbar. The X(3940) mass and width are measured to be (3942 +7 -6 +- 6)MeV/c^2 and Gamma=(37 + 26 - 15 +- 8 MeV. In the process e+e- -> J/psi D* D*bar we have observed another charmonium-like state, which we denote as X(4160), in the spectrum of invariant masses of D*+ D*- combinations. The X(4160) parameters are M= 4156 + 25 - 20 +- 15 MeV/c^2 and Gamma = 139 + 111 -61 +- 21 MeV. The analysis is based on a data sample with an integrated luminosity of 693 /fb recorded near the Upsilon(4S) resonance with the Belle detector at the KEKB e+ e- asymmetric-energy collider.Comment: 7 pages, 2 figures Contribution paper for conferences EPS2007 and Lepton Photon 2007, Belle-Conference-070

Search for \bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^- decay at Belle

We search for the doubly charmed baryonic decay $\bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^-$, in a data sample of $520\times10^6$ $B{\bar B}$ events accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric e^+e^- collider. We find no significant signal and set an upper limit of ${\cal B}(\bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^-)<6.2\times10^{-5}$ at 90% confidence level. The result is significantly below a naive extrapolation from ${\cal B}(B^-\to\Xi_c^0\bar{\Lambda}_c^)$ assuming a simple Cabibbo-suppression factor of $|V_{cd}/V_{cs}|^2$. The small branching fraction could be attributed to a suppression due to the large momentum of the baryonic decay products, which has been observed in other charmed baryonic two-body B decays. trend observed in other charmed baryonic two-body B decays.Comment: 12 page, 5 figures. Contribution paper for conferences EPS2007 and Lepton Photon 2007, Belle-Conference-070

Search for B -> h(*) nu nubar Decays at Belle

We present a search for the rare decays B -> h(*) nu nubar, where h(*) stands for a light meson. A data sample of 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider is used. Signal candidates are required to have an accompanying B meson fully reconstructed in a hadronic mode and signal-side particles consistent with a single h(*) meson. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The limits on B0 -> K*0 nu nubar and B+ -> K+ nu nubar decays are more stringent than the previous constraints, while the first searches for B0 -> K0 nu nubar, pi0 nu nubar, rho0 nu nubar, phi nu nubar and B+ -> K*+ nu nubar, rho+ nu nubar are reported.Comment: 6 pages, 2 figures, submit to PR