Sea quark polarization and semi-inclusive DIS data

We investigate the potential impact of forthcoming Jefferson Lab semi-inclusive polarized deep inelastic scattering proton measurements in the determination of the sea quark polarization in the nucleon by means of a next to leading order global QCD analysis. Specifically, we estimate the resulting improvement in the constraints on polarized parton densities for the different flavors, which is found to be significant for up and strange quarks, and the correlation between remaining uncertainty ranges for each of the parton species.Comment: 7 pages, 4 figures. Version to be published in the European Physical Journal

Spatially Dependent Quantum Interference Effects in the Detection Probability of Charged Leptons Produced in Neutrino Interactions or Weak Decay Processes

Feynman's path amplitude formulation of quantum mechanics is used to analyse the production of charged leptons from charged current weak interaction processes. For neutrino induced reactions the interference effects predicted are usually called `neutrino oscillations'. Similar effects in the detection of muons from pion decay are here termed `muon oscillations'. Processes considered include pion decay (at rest and in flight), and muon decay and nuclear $\beta$-decay at rest. In all cases studied, a neutrino oscillation phase different from the conventionally used one is found. A concise critical review is made of previous treatments of the quantum mechanics of neutrino and muon oscillations.Comment: 45 pages, 1 table, 3 figures. Supersedes hep-ph/0110064. Consistent use of MRS matrix to describe charged lepton-neutrino couplings. Unphysical `lepton flavour eigenstates' removed from the formalis

Exotic Baryons and Monopole Excitations in a Chiral Soliton Model

We compute the spectra of exotic pentaquarks and monopole excitations of the low--lying ${1/2}^+$ and ${3/2}^+$ baryons in a chiral soliton model. Once the low--lying baryon properties are fit, the other states are predicted without any more adjustable parameters. This approach naturally leads to a scenario in which the mass spectrum of the next to lowest--lying $J^\pi={1/2}^+$ states is fairly well approximated by the ideal mixing pattern of the $\mathbf{8}\oplus\bar{\mathbf{10}}$ representation of flavor SU(3). We compare our results to predictions obtained in other pictures for pentaquarks and speculate about the spin--parity assignment for $\Xi(1690)$ and $\Xi(1950)$Comment: 16 pages, 2 figures, 6 table

A search for the fourth SM family quarks at Tevatron

It is shown that the fourth standard model (SM) family quarks can be observed at the Fermilab Tevatron if their anomalous interactions with known quarks have sufficient strength.Comment: 7 pages, 2 tables, 4 figure

A Covariant Path Amplitude Description of Flavour Oscillations: The Gribov-Pontecorvo Phase for Neutrino Vacuum Propagation is Right

An extended study is performed of geometrical and kinematical assumptions used in calculations of the neutrino oscillation phase. The almost universally employed `equal velocity' assumption, in which all neutrino mass eigenstates are produced at the same time, is shown to underestimate, by a factor of two, the neutrino propagation contribution to the phase. Taking properly into account, in a covariant path amplitude calculation, the incoherent nature of neutrino production as predicted by the Standard Model, results in an important source propagator contribution to the phase. It is argued that the commonly discussed Gaussian `wave packets' have no basis within quantum mechanics and are the result of a confused amalgam of quantum and classical wave concepts.Comment: 39 pages, 1 table, 1 figure. Subject matter similar to hep-ph/0110064, hep-ph/0110066. More pedagogical presentation addressing referee criticism of earlier paper

The pion-nucleon scattering lengths from pionic deuterium

We use the framework of effective field theories to discuss the determination of the S-wave \pi N scattering lengths from the recent high-precision measurements of pionic deuterium observables. The theoretical analysis proceeds in several steps. Initially, the precise value of the pion-deuteron scattering length a_{\pi d} is extracted from the data. Next, a_{\pi d} is related to the S-wave \pi N scattering lengths a_+ and a_-. We discuss the use of this information for constraining the values of these scattering lengths in the full analysis, which also includes the input from the pionic hydrogen energy shift and width measurements, and throughly investigate the accuracy limits for this procedure. In this paper, we also give a detailed comparison to other effective field theory approaches, as well as with the earlier work on the subject, carried out within the potential model and multiple scattering framework.Comment: The replacement includes an erratum, which is published in Eur. Phys. J.

Selection of earthquake ground motions for multiple objectives using genetic algorithms

Existing earthquake ground motion (GM) selection methods for the seismic assessment of structural systems focus on spectral compatibility in terms of either only central values or both central values and variability. In this way, important selection criteria related to the seismology of the region, local soil conditions, strong GM intensity and duration as well as the magnitude of scale factors are considered only indirectly by setting them as constraints in the pre-processing phase in the form of permissible ranges. In this study, a novel framework for the optimum selection of earthquake GMs is presented, where the aforementioned criteria are treated explicitly as selection objectives. The framework is based on the principles of multi-objective optimization that is addressed with the aid of the Weighted Sum Method, which supports decision making both in the pre-processing and post-processing phase of the GM selection procedure. The solution of the derived equivalent single-objective optimization problem is performed by the application of a mixed-integer Genetic Algorithm and the effects of its parameters on the efficiency of the selection procedure are investigated. Application of the proposed framework shows that it is able to track GM sets that not only provide excellent spectral matching but they are also able to simultaneously consider more explicitly a set of additional criteria

Creating Ioffe-Pritchard micro-traps from permanent magnetic film with in-plane magnetization

We present designs for Ioffe-Pritchard type magnetic traps using planar patterns of hard magnetic material. Two samples with different pattern designs were produced by spark erosion of 40 $\mu$m thick FePt foil. The pattern on the first sample yields calculated axial and radial trap frequencies of 51 Hz and 6.8 kHz, respectively. For the second sample the calculated frequencies are 34 Hz and 11 kHz. The structures were used successfully as a magneto-optical trap for $^{87}$Rb and loaded as a magnetic trap. A third design, based on lithographically patterned 250 nm thick FePt film on a Si substrate, yields an array of 19 traps with calculated axial and radial trap frequencies of 1.5 kHz and 110 kHz, respectively.Comment: 8 pages, 5 figures Revised and accepted for EPJD, improved picture

Near-threshold production of omega mesons in the pn -> d omega reaction

The first measurement of the p n -> d omega total cross section has been achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from the p d -> p(sp) d omega reaction in a silicon telescope placed close to the target. The cross sections lie above those measured for p p -> p p omega but seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has been added; results changed insignificantly, EPJ in pres

Measurement of the LT-asymmetry in \pi^0 electroproduction at the energy of the \Delta (1232) resonance

The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region of W=1232 MeV. From measurements left and right of q, cross section asymmetries \rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) = (-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics \rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined in the framework of the MAID2003 model. The results are in agreement with older data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring also the result of Kalleicher et al. in accordance with the rest of the data is almost excluded.Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for publication in EPJ