On kaonic hydrogen. Phenomenological quantum field theoretic model revisited

We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a ⁰ ₀ and a ¹ ₀ of ˉN scattering with isospin I = 0 and I = 1 satisfy the low-energy theorem a ⁰ ₀ +3a ¹ ₀ = 0 valid to leading order in chiral expansion. In the model of strong low-energy ˉN interactions at threshold (Eur. Phys. J. A 21, 11 (2004)) we revisit the contribution of the Σ(1750) resonance, which does not saturate the low-energy theorem a ⁰ ₀ +3a ¹ ₀ = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K^-N and K^-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and deuterium. The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the cross-sections for elastic and inelastic K^-p scattering for laboratory momenta 70MeV/c < p _K < 150MeV/c of the incident K^--meson. The theoretical results agree with the available experimental data within two standard deviations.     

Energy level displacement of the excited $n\ell$ state of pionic hydrogen

The energy level displacements of the excited states of pionic hydrogen and the contribution of the transitions and the transitions of the pair, coupled by the attractive Coulomb field in the S-wave state with a continuous energy spectrum, to the shift of the energy level of the ground state of pionic hydrogen, caused by strong low-energy interactions, are calculated within a quantum field theoretic, relativistic covariant and model-independent approach.Received: 19 November 2003, Revised: 25 November 2003, Published online: 5 February 2004PACS: 13.75.Gx Pion-baryon interactions - 11.10.St Bound and unstable states; Bethe-Salpeter equations - 21.30.Fe Forces in hadronic systems and effective interactions - 31.15.Ar Ab initio calculationsPermanent address A.N. Ivanov: State Polytechnical University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation;Permanent address N.I. Troitskaya: State Polytechnical University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation.     

Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

Several novel aromatic ketone‐based two‐photon initiators containing triple bonds and dialkylamino groups were synthesized and the structure‐activity relationships were evaluated. Branched alkyl chains were used at the terminal donor groups to improve the solubility in the multifunctional monomers. Because of the long conjugation length and good coplanarity, the evaluated initiators showed large two‐photon cross section values, while their fluorescence lifetimes and quantum yields strongly depend on the solvent polarity. All novel initiators exhibited high activity in terms of two‐photon‐induced microfabrication. This is especially true for fluorenone‐based derivatives, which displayed much broader processing windows than well‐known highly active initiators from the literature and commercially available initiators. While the new photoinitiators gave high reactivity in two‐photon‐induced photopolymerization at concentration as low as 0.1% wt, these compounds are surprisingly stable under one photon condition and nearly no photo initiation activity was found in classical photo DSC experiment. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Untersuchungen von Formaldehydeiweiß

Ohne Zusammenfassung     

High precision study of muon catalyzed fusion in D2 and HD gas

Muon catalyzed dd fusion in D₂ and HD gases in the temperature range from 28 to 350 K was investigated in a series of experiments based on a time-projection ionization chamber operating with pure hydrogen. All main observables in this reaction chain were measured with high absolute precision including the resonant and non-resonant ddμ formation rates, the rate for hyperfine transitions in dμ atoms, the branching ratio of the two charge symmetric fusion channels ³He + n and t + p and the muon sticking probability. The report presents the final analysis of the data together with a comprehensive comparison with calculations based on recent μCF theories. The energy of the loosely bound ddμ state with quantum numbers J = 1, ν = 1, which is central to the mechanism of resonant molecule formation, is extracted with precision ?₁₁(fit) = ?1.9651(7) eV. in impressive agreement with the latest theoretical results ?₁₁(theory) = ?1.9646 eV.     

Low-Energy Kaon�CNucleon/Nuclei Interaction Studies at DA��NE (SIDDHARTA and AMADEUS Experiments)

The DA??NE electron?Cpositron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negative kaons ??beam??. The SIDDHARTA experiment used this beam to perform unprecedented precision measurements on kaonic atoms, while the AMADEUS experiment plans to perform in the coming years precision measurements on kaon?Cnuclei interactions at low-energies, in particular to study the kaonic nuclei. The two experiments are briefly presented in this paper.     

Green light radiation effects on free radicals inhibition in cellular and chemical systems

Free radicals generation is inhibited through green light (GL) irradiation in cellular systems and in chemical reactions. Standard melanocyte cultures were UV-irradiated and the induced cellular reactive oxygen species (ROS) were quantified by the fluorescence technique. The same cell cultures, previously protected by a 24h GL exposure, displayed a significantly lower ROS production. A simple chemical reaction is subsequently chosen, in which the production of free radicals is well defined. Paraffin wax and mineral oil were GL irradiated during thermal degradation and the oxidation products checked by chemiluminescence [CL] and Fourier transform infrared spectra [FT-IR]. The same clear inhibition of the radical oxidation of alkanes is recorded. A quantum chemistry modeling of these results is performed and a mechanism involving a new type of Rydberg macromolecular systems with implications for biology and medicine is suggested.