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The cross sections of high-energy μ + μ − pair production and paradimuonium production by a relativistic electron in the atomic field are discussed. The calculation is performed exactly in the parameters of the atomic field. Though the Coulomb corrections to the cross sections, related to the multiple Coulomb exchange of μ + , μ − and an atom, are negligible, the Coulomb corrections to the differential cross sections, related to the electron interaction with an atom, are large. However, the latter Coulomb corrections to the cross sections integrated over the final electron momentum are small. Apparently, this effect can easily be observed experimentally. Furthermore, it is shown that the asymmetry of the cross section with respect to the permutation of the momenta of μ − and μ + is large. [ABSTRACT FROM AUTHOR]

Abstract: Professor Osamu Hashimoto of Tohoku University passed away on February 3, 2012. As well as leading the nuclear physics laboratory of Tohoku University, Prof. Hashimoto contributed much to hypernuclear and strangeness nuclear physics community for years. In this decade, he devoted himself to establish the hypernuclear spectroscopy. I will review progresses of Λ hypernuclear spectroscopy with a memory of this decade which I was privileged to share with Prof. Hashimoto. [Copyright &y& Elsevier]

Abstract: Isobar models for the electromagnetic production of kaons are discussed with emphasis on the K+ photoproduction at very small kaon angles and K0 photoproduction on deuteron. Distorted-wave impuls approximation calculations of the cross sections for the electroproduction of hypernuclei are presented on the case of the 12 ΛB production. [Copyright &y& Elsevier]

Abstract: Developments in strangeness photo- and electro- production off the proton, as investigated using the CLAS system in Hall B at Jefferson Lab, are discussed in this paper. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the Λ(1405), which shows signs of being a composite meson-baryon object of mixed isospin. The work on other hyperons such as the Ξ resonances will be mentioned, and future prospects outlined. [Copyright &y& Elsevier]

Abstract: In a framework for non-perturbative QCD calculation of high energy processes, the amplitudes for photo- and electroproduction of vector mesons are written as integrals of the overlap product of photon and vector meson wave functions, multiplied by the amplitude for the scattering of dipole pairs off the proton. For sizes of the overlap functions that are smaller than the typical ranges of the interaction of the dipoles with the proton, the amplitudes factorize in the form of integrals, here called overlap strengths, formed only with the overlap of the wave functions times the square of the dipole separation. The integration is extended over the light front coordinates describing the dipoles. With this result, the overlap strengths contain all dependence of the observables. We show the importance of this factorization in the description of the experimental data for all S-wave vector mesons. [Copyright &y& Elsevier]

A parameter-free, nonperturbative calculation of the ΔNγ electromagnetic transition amplitudes GM*(q2), GE*(q2), and the resonant multipole ratio REM(q2)≡E1+3/2(q2)/M1+3/2(q2) is performed in terms of the well-known nucleon isovector Sachs form factor GMV. Our methods are fully relativistic with conservation of the electromagnetic current guaranteed. We find that GM*(q2) decreases more rapidly than the nucleon dipole form factor when -q2≳1 GeV2/c2 and that REM(q2) remains small even for very high four-momentum transfer implying that the perturbative QCD prediction REM(q2)→1 is purely asymptotic and is valid only for extremely high &z.sfnc;q2&z.sfnc;. [Copyright &y& Elsevier]

Eta photo- and electroproduction on the nucleon is studied using an isobar model. The model contains Born terms, and contributions from vector-meson exchanges and nucleon resonances. Our results are compared with recent eta-photoproduction data for differential and total cross sections, beam asymmetry, and target asymmetry, as well as electroproduction data. Besides the dominant S11(1535) resonance, we show that the second S11 resonance, S11(1650), is also necessary to be included in order to extract S11(1535) resonance parameters properly. In addition, the beam asymmetry data allow us to extract very small (<0.1%) N&ast;→ηN decay branching ratios of the D13(1520) and F15(1680) resonances because of the overwhelming s-wave dominance. This model (ETA-MAID) is implemented as a part of the MAID program (the MAID program can be accessed from the webpage: http://www.kph.uni-mainz.de/MAID/maid.html). [Copyright &y& Elsevier]