Updated measurements of hadronic B decays at CDF

The CDF experiment at the Tevatron $p\bar{p}$ collider established that extensive and detailed exploration of the $b$--quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from $e^+e^-$ colliders. This provides a rich, and highly rewarding program that has currently reached full maturity. In the following I report some recent results on hadronic decays: the evidence for the charmless annihilation decay mode $B^0_s \to pi^+\pi^-$, and the first reconstruction in hadron collisions of the suppressed decays $B^- \to D(\to K^+\pi^-)K^-$ and $B^- \to D(\to K^+\pi^-)\pi^-$.Comment: 5 pages,2 figures, proceedings for EPS-HEP 2011. To be published in the on-line journal Proceedings of Scienc

B Physics at the Tevatron

The Fermilab Tevatron offers unique opportunities to perform measurements of the heavier b-hadrons that are not accessible at the Y(4S) resonance. In this summary, we describe most important heavy flavor results from DO and CDF collaborations and we discuss prospects for future measurements, that could reveal New Physics before the start-up of the Large Hadron Collider (LHC)

Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin--lattice relaxation in a single crystal of the single-molecule magnet Mn$_{12}$-ac, at $T \approx 30$ mK in perpendicular fields $B_{\perp}$ up to 9 T. Although the molecular spin is in its ground state, we observe an increase of the nuclear relaxation rates by several orders of magnitude up to the highest $B_{\perp}$. This unique finding is a consequence of the zero-point quantum fluctuations of the Mn$_{12}$-ac spin, which allow it to efficiently transfer energy from the excited nuclear spin bath to the lattice. Our experiment highlights the importance of quantum fluctuations in the interaction between an `effective two-level system' and its surrounding spin bath.Comment: 5 pages, 4 figure

Charmless b-hadrons decays at CDF

We present CDF results on the branching fractions and time-integrated direct CP asymmetries for Bd, Bs and Lb decay modes into pairs of charmless charged hadrons (pions, kaons and protons). The data-set for these measurements amounts to 1fb^{-1} of pbar-p collisions at a center of mass energy 1.96TeV. We report on the first observation of the Bs->Kpi, Lb-ppi and Lb->pK decay modes and on the measurement of their branching fractions and direct CP asymmetries.Comment: 4 pages, 1 figure, 2 tables, proceedings of ICHEP200

Review of operational aspects of initial experiments utilizing the U.S. MLS

An exercise to support the Federal Aviation Administration in demonstrating the U.S. candidate for an international microwave landing system (MLS) was conducted by NASA. During this demonstration the MLS was utilized to provide the TCV Boeing 737 research airplane with guidance for automatic control during transition from conventional RNAV to MLS RNAV in curved, descending flight; flare; touchdown; and roll-out. Flight profiles, system configuration, displays, and operating procedures used in the demonstration are described, and preliminary results of flight data analysis are discussed. Recent experiences with manually controlled flight in the NAFEC MLS environment are also discussed. The demonstration shows that in automatic three-dimensional flight, the volumetric signal coverage of the MLS can be exploited to enable a commercial carrier class airplane to perform complex curved, descending paths with precision turns into short final approaches terminating in landing and roll-out, even when subjected to strong and gusty tail and cross wind components and severe wind shear

Lantana L.

https://thekeep.eiu.edu/herbarium_specimens_byname/18914/thumbnail.jp

Arrival direction distribution of cosmic rays of energy 10 (18) eV

The Haverah Park air-shower experiment recorded over 8500 events with primary energy 10 to the 18th power eV between 1963 and 1983. An analysis of these events for anisotropies in celestial and galactic coordinates is reported. No very striking anisotropies are observed

Exploring quantum chaos with a single nuclear spin

Most classical dynamical systems are chaotic. The trajectories of two identical systems prepared in infinitesimally different initial conditions diverge exponentially with time. Quantum systems, instead, exhibit quasi-periodicity due to their discrete spectrum. Nonetheless, the dynamics of quantum systems whose classical counterparts are chaotic are expected to show some features that resemble chaotic motion. Among the many controversial aspects of the quantum-classical boundary, the emergence of chaos remains among the least experimentally verified. Time-resolved observations of quantum chaotic dynamics are particularly rare, and as yet unachieved in a single particle, where the subtle interplay between chaos and quantum measurement could be explored at its deepest levels. We present here a realistic proposal to construct a chaotic driven top from the nuclear spin of a single donor atom in silicon, in the presence of a nuclear quadrupole interaction. This system is exquisitely measurable and controllable, and possesses extremely long intrinsic quantum coherence times, allowing for the observation of subtle dynamical behavior over extended periods. We show that signatures of chaos are expected to arise for experimentally realizable parameters of the system, allowing the study of the relation between quantum decoherence and classical chaos, and the observation of dynamical tunneling.Comment: revised and published versio

A Flight Evaluation of a VTOL Jet Transport Under Visual and Simulated Instrument Conditions

Transition, approach, and vertical landing tests for VTOL transport in terminal are

Magnetic dipolar ordering and relaxation in the high-spin molecular cluster compound Mn6

Few examples of magnetic systems displaying a transition to pure dipolar magnetic order are known to date, and single-molecule magnets can provide an interesting example. The molecular cluster spins and thus their dipolar interaction energy can be quite high, leading to reasonably accessible ordering temperatures, provided the crystal field anisotropy is sufficiently small. This condition can be met for molecular clusters of sufficiently high symmetry, as for the Mn6 compound studied here. Magnetic specific heat and susceptibility experiments show a transition to ferromagnetic dipolar order at T_{c} = 0.16 K. Classical Monte-Carlo calculations indeed predict ferromagnetic ordering and account for the correct value of T_{c}. In high magnetic fields we detected the contribution of the ^{55}Mn nuclei to the specific heat, and the characteristic timescale of nuclear relaxation. This was compared with results obtained directly from pulse-NMR experiments. The data are in good mutual agreement and can be well described by the theory for magnetic relaxation in highly polarized paramagnetic crystals and for dynamic nuclear polarization, which we extensively review. The experiments provide an interesting comparison with the recently investigated nuclear spin dynamics in the anisotropic single molecule magnet Mn12-ac.Comment: 19 pages, 11 eps figures. Contains extensive discussions on dipolar ordering, specific heat and nuclear relaxation in molecular magnet