Modelling climate change impacts on crop production for food security

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The kinetic studies of the solvent-promoted aggregation of a steroid-porphyrin derivative

The study of the aggregation of a steroid-functionalised porphyrin derivative shows the formation of chiral suprastuctures. Kinetic studies indicate that the mechanism of the aggregation strongly depends on both the nature of the media and on the concentration of the tetrapyrrolic macrocycle

Study of in-medium ω\omega meson properties in Ap, pA and AA collisions

We propose to investigate the in-medium properties of vector $\omega$ mesons at the normal nuclear density in Ap(pA) collisions and at higher density in AA collisions at the ITEP accelerator facility TWAC. Using of the inverse Ap kinematics will permit us to study the $\omega$ meson production in a wide momentum interval included the not yet explored range of small meson momenta relative to the projectile nuclei where the mass modification effect in nuclear matter is expected to be the strongest. Momentum dependence of the in-medium $\omega$ meson width will be studied in the traditional pA kinematics. We intend to use the electromagnetic calorimeter for reconstruction of the $\omega$ meson invariant mass by detecting photons from the $\omega \to \pi^{0}\gamma \to 3\gamma$ decay. The model calculations and simulations with RQMD generator show feasibility of the proposed experiment. Available now intensity of the ion beams provides a possibility to collect large statistics and make decisive conclusion about the $\omega$ meson properties at density of normal nuclei. At the second stage of the investigation the $\omega$ meson properties will be studied in AA collisions at higher density. Interpretation of these measurements will be based on the results obtained in Ap(pA) interactions. Further investigation of the in-medium properties of light unflavored and charmed mesons can be performed at ITEP and at GSI(FAIR) where higher ion energies will be accessible in near future.Comment: 26 pages, 10 figures, 2 table

On different lagrangian formalisms for vector resonances within chiral perturbation theory

We study the relation of vector Proca field formalism and antisymmetric tensor field formalism for spin-one resonances in the context of the large N_C inspired chiral resonance Lagrangian systematically up to the order O(p6) and give a transparent prescription for the transition from vector to antisymmetric tensor Lagrangian and vice versa. We also discuss the possibility to describe the spin-one resonances using an alternative "mixed" first order formalism, which includes both types of fields simultaneously, and compare this one with the former two. We also briefly comment on the compatibility of the above lagrangian formalisms with the high-energy constraints for concrete VVP correlator.Comment: 34 pages, 3 figure

On the background in the γp→ω(π0γ)p\gamma p \to \omega(\pi^0\gamma) p reaction and mixed event simulation

In this paper we evaluate sources of background for the $\gamma p \to \omega p$, with the $\omega$ detected through its $\pi^0 \gamma$ decay channel, to compare with the experiment carried out at ELSA. We find background from $\gamma p \to \pi^0 \pi^0 p$ followed by decay of a $\pi^0$ into two $\gamma$, recombining one $\pi^0$ and one $\gamma$, and from the $\gamma p \to \pi^0 \eta p$ reaction with subsequent decay of the $\eta$ into two photons. This background accounts for the data at $\pi^0 \gamma$ invariant masses beyond 700 MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once this is done, we perform an event mixing simulation to reproduce the calculated background and we find that the method provides a good description of the background at low $\pi^0 \gamma$ invariant masses but fakes the background at high invariant masses, making background events at low invariant masses, which are due to $\gamma$ misidentification events, responsible for the background at high invariant masses which is due to the $\gamma p \to \pi^0 \pi^0 p$ and $\gamma p \to \pi^0 \eta p$ reactions.Comment: 10 pages, 5 figure

Recent growth coherence in long-term oak (Quercus spp.) ring width chronologies in the Czech Republic

Oak ring width measurements compiled from 44 sampling sites throughout the territory of the Czech Republic are analysed for the 1655-2013 period. Measurements taken at all these sites are sorted into 10 sub-chronologies on the basis of 5 environmental factors: soil moisture (dry/wet), elevation (low/high), age (young/old), species (Quercus robur or Q. petraea), and geographical position (east/west). Several statistical tests are applied to investigate existing significant differences between chronologies during 1920-2013. Further, the sensitivities of individual sub-chronologies to precipitation are compared. Three tests indicate 5 pairs of very similar sub-chronologies. Moreover, the growth-response to May-July precipitation totals is very much the same in these sub-chronologies. This analysis demonstrates that, even in the absence of certainty about age structure, species composition and some environmental factors in the earlier parts of oak ring width chronologies, the internal homogeneity of the chronology remains essentially unaffected, and the lack of such information does not preclude their use in dendroclimatology

Generic multiloop methods and application to N=4 super-Yang-Mills

We review some recent additions to the tool-chest of techniques for finding compact integrand representations of multiloop gauge-theory amplitudes - including non-planar contributions - applicable for N=4 super-Yang-Mills in four and higher dimensions, as well as for theories with less supersymmetry. We discuss a general organization of amplitudes in terms of purely cubic graphs, review the method of maximal cuts, as well as some special D-dimensional recursive cuts, and conclude by describing the efficient organization of amplitudes resulting from the conjectured duality between color and kinematic structures on constituent graphs.Comment: 42 pages, 18 figures, invited review for a special issue of Journal of Physics A devoted to "Scattering Amplitudes in Gauge Theories", v2 minor corrections, v3 added reference

Photoproduction of {\omega} Mesons off the Proton

The differential cross sections and unpolarized spin-density matrix elements for the reaction $\gamma p\to p\omega$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV. These observables were measured from the radiative decay of the $\omega$ meson, $\omega\to\pi^0\gamma$. The cross sections cover the full angular range and show the full extent of the $t$-channel forward rise. The overall shape of the angular distributions in the differential cross sections and unpolarized spin-density matrix elements are in fair agreement with previous data. In addition, for the first time, a beam of linearly-polarized tagged photons in the energy range from 1150 MeV to 1650 MeV was used to extract polarized spin-density matrix elements. These data were included in the Bonn-Gatchina partial wave analysis (PWA). The dominant contribution to $\omega$ photoproduction near threshold was found to be the $3/2^+$ partial wave, which is primarily due to the sub-threshold $N(1720)\,3/2^+$ resonance. At higher energies, pomeron-exchange was found to dominate whereas $\pi$-exchange remained small. These $t$-channel contributions as well as further contributions from nucleon resonances were necessary to describe the entire dataset: the $1/2^-$, $3/2^-$, and $5/2^+$ partial waves were also found to contribute significantly.Comment: 8 pages, 5 figures, accepted for publication in Physics Letters