Search for evidence of two photon contribution in elastic electron proton data

We reanalyze the most recent data on elastic electron proton scattering. We look for a deviation from linearity of the Rosenbluth fit to the differential cross section, which would be the signature of the presence of two photon exchange. The two photon contribution is parametrized by a one parameter formula, based on symmetry arguments. The present data do not show evidence for such deviation.Comment: 15 pages 3 figures More details on the fitting procedure, more explicit explanation

K^- ^3He and K^+K^- interactions in the pd -> ^3He K^+K^- reaction

We investigate the K^- ^3He and K^+ K^- interactions in the reaction pd -> ^3He K^+ K^- near threshold and compare our model calculations with data from the MOMO experiment at COSY-Juelich. A large attractive effective K^- p amplitude would give a significant K^- ^3He final-state interaction effect which is not supported by the experimental data. We also estimate upper limits for the a_0(980) and f_0(980) contributions to the produced K^+ K^- pairs.Comment: 5 pages, 2 figures, accepted for publication in PR

Undersøkelser av hydrokarboner i sedimenter fra MAREANO-området 2006-2009

Institute of Marine Research has analysed approximately 1600 samples from sediment cores from 63 places in the MAREANO area, sampled in south-western Barents Sea and off the coast of Lofoten islands in 2006-2009. Sedimentological data obtained by Norwegian Geological Survey for sediments from the same area was combined with the measurements of hydrocarbons (PAH and total hydrocarbon content, THC). Low levels of hydrocarbons are found at all the locations, corresponding to KLIF classes I and II for PAH16, witb an increase in combustion-related PAH in modern sediment layers at coastal and southernmost locations. An increase in oilrelated PAH in deep sediments found a few places near known oil- and gas-fields is attributed to natural sources

Two-Photon Exchange and Electromagnetic Proton Form Factors

The presence of $2\gamma$-exchange in electron proton elastic scattering is discussed. From C-invariance and crossing symmetry, $2\gamma$ contribution induces a specific dependence of the reduced cross section on the variable $\epsilon$. No evidence of such dependence exists in the available experimental data.Comment: 4 pages, Contributed papers to Baryon 0

The elastic electron-deuteron scattering beyond one-photon exchange

We discuss the elastic ed scattering beyond Born approximation. It is shown that the reaction amplitude contains six generalized form factors, but only three linearly independent combinations of them (we call them generalized charge, quadrupole and magnetic form factors) contribute to the reaction cross section in the second order perturbation theory. We examine two-photon exchange and find that it includes two types of diagrams, when two virtual photons interact with the same nucleon and when the photons interact with different nucleons. Estimations based on nonrelativistic calculations with the deuteron wave function for realistic NN potential show that the main contribution to the generalized charge, quadrupole and magnetic form factors comes from diagrams of the first type.Comment: v2, published version in PR

Polarization effects in the reaction e++e−→ρ++ρ−e^++e^-\to \rho^+ +\rho^- and determination of the ρ−\rho - meson form factors in the time--like region

The electron positron annihilation reaction into four pion production has been studied, through the channel $e^++e^-\to \bar \rho+\rho$. The differential (and total) cross sections and various polarization observables for this reaction have been calculated in terms of the electromagnetic form factors of the corresponding $\gamma^*\rho\rho$ current. The elements of the spin--density matrix of the $\rho -$meson were also calculated. Numerical estimations have been done, with the help of phenomenological form factors obtained in the space--like region of the momentum transfer squared and analytically extended to the time-like region.Comment: 19 pages, 2 figures, to appear in Phys Rev

Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea

Subsurface sediments from a pockmark area in South-Western Barents Sea have been earlier found to contain elevated levels of petroleum-related polycyclic aromatic hydrocarbons. This work describes a comprehensive analysis of various biomarkers, including the highly source-specific hopanes, in a 4.5 m long gravity core from the same area, together with subsurface sediment samples from other areas in the region without pockmarks present (“background samples”). A clear difference between the pockmark gravity core and the background sediment cores was found, both with regard to genesis and the level of transformation of organic matter. A number of indicator parameters, such as methylphenanthrene index (MPI-1), point towards a significantly higher maturity of hydrocarbons in the pockmark core throughout its length as compared to the other sampled locations. Higher contents of microbial hopanoids (hopenes) may indicate the former presence of petroleum. These findings confirm the hypothesis of a natural hydrocarbon source in the deeper strata present in the studied location with pockmarks

Model independent analysis of polarization effects in elastic electron deuteron scattering in presence of two--photon exchange

The general spin structure of the matrix element, taking into account the two--photon exchange contribution, for the elastic electron (positron) --deuteron scattering has been derived using general symmetry properties of the hadron electromagnetic interaction, such as P--, C-- and T--invariances as well as lepton helicity conservation in QED at high energy. Taking into account also crossing symmetry, the amplitudes of $e^{\mp}d-$scattering can be parametrized in terms of fifteen real functions. The expressions for the differential cross section and for all polarization observables are given in terms of these functions. We consider the case of an arbitrary polarized deuteron target and polarized electron beam (both longitudinal and transverse). The transverse polarization of the electron beam induces a single--spin asymmetry which is non--zero in presence of two--photon exchange. It is shown that elastic deuteron electromagnetic form factors can still be extracted in presence of two photon exchange, from the measurements of the differential cross section and of one polarization observable (for example, the tensor asymmetry) for electron and positron deuteron elastic scattering, in the same kinematical conditions.Comment: 28 page

Intercalibration of the analytical method for alkylphenols in produced water

Fire laboratorier fra Norge og USA deltok i ringtest-undersøkelse av kjemisk analytisk metode for bestemmelse av alkylfenoler i produsert vann. Det var bra samsvar mellom resultatene fra to av laboratoraiene mens metodiske forskjell har ført til noe dårligere overenstemmelse med de to andre. Det anbefales derfor at prosedyren følges nøyaktig for å få sammenlignbare resultater. Det var imidlertid ikke nok deltakere i ringtesten for å kunne dra definitive konklusjoner