Dispersion analysis of the nucleon form factors including meson continua

Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon for all momentum transfers. Constraints from meson-nucleon scattering data, unitarity, and perturbative QCD can be included in a straightforward way. In particular, we include the 2pi, rho-pi, and KKbar continua as independent input in our analysis and provide an error band for our results. Moreover, we discuss two different methods to include the asymptotic constraints from perturbative QCD. We simultaneously analyze the world data for all four form factors in both the space-like and time-like regions and generally find good agreement with the data. We also extract the nucleon radii and the omega-NN coupling constants. For the radii, we generally find good agreement with other determinations with the exception of the electric charge radius of the proton which comes out smaller. The omega-NN vector coupling constant is determined relatively well by the fits, but for the tensor coupling constant even the sign can not be determined.Comment: 24 pages, 9 figure

Role of the total isospin 3/2 component in three-nucleon reactions

We discuss the role of the three-nucleon isospin T=3/2 amplitude in elastic neutron-deuteron scattering and in the deuteron breakup reaction. The contribution of this amplitude originates from charge-independence breaking of the nucleon-nucleon potential and is driven by the difference between neutron-neutron (proton-proton) and neutron-proton forces. We study the magnitude of that contribution to the elastic scattering and breakup observables, taking the locally regularized chiral N4LO nucleon-nucleon potential supplemented by the chiral N2LO three-nucleon force. For comparison we employ also the Av18 nucleon-nucleon potential combined with the Urbana IX three-nucleon force. We find that the isospin T=3/2 component is important for the breakup reaction and the proper treatment of charge-independence breaking in this case requires the inclusion of the 1S0 state with isospin T=3/2. For neutron-deuteron elastic scattering the T=3/2 contributions are insignificant and charge-independence breaking can be accounted for by using the effective t-matrix generated with the so-called "2/3-1/3" rule.Comment: 24 pages, 8 figures, 3 Table

The Nambu-Jona-Lasinio Chiral Soliton with Constrained Baryon Number

A regularization for the baryon number consistent with the energy in the Nambu-Jona-Lasinio model is introduced. The soliton solution is constructed with the regularized baryon number constrained to unity. It is furthermore demonstrated that this constraint prevents the soliton from collapsing when scalar fields are allowed to be space dependent. In this scheme the scalar fields actually vanish at the origin reflecting a partial restoration of chiral symmetry. Also the influence of this constraint on some static properties of baryons is discussed.Comment: 10 LaTeX pages 4 figures, report no UNITU-THEP-7/199

On radiative np -> 1s + gamma transitions, induced by strong low-energy interactions,in kaonic atoms

We calculate the rates of the radiative transitions np -> 1s + gamma in kaonic hydrogen and kaonic deuterium, induced by strong low-energy interactions and enhanced by Coulomb interactions. The obtained results should be taken into account for the theoretical analysis of the experimental data on the X-ray spectra and yields in kaonic atoms.Comment: 10 pages, 1 figur

TOWARDS STANDARDIZED EVALUATION OF IMAGE QUALITY FOR AIRBORNE CAMERA SYSTEMS

Digital airborne camera systems and their high geometric resolution demand for new algorithms and procedures of image data analysis and interpretation. Parameters describing image quality are necessary for various fields of application (e.g. sensor and mission design, sensor comparison, algorithm development, in-orbit-behaviour of instruments). The effective sensor resolution is one important parameter which comprehensively estimates the optical quality of a given imaging sensor-lens combination. Although determination of resolving power is a well-studied field of research, there are still some scientific questions to be answered when it comes to a standardized (eventually absolute) determination. This is also research object of a committee of the “German Institute for Standardization” and the given contribution outlines the current state of investigation concerning effective resolving power for airborne camera systems. Therefore an approach using signal processing techniques to calculate the effective image resolution will be described. The open scientific issues will be introduced, explained and answered to some extend

Beziehungen zwischen dem pflanzenverfügbaren Phosphor im Boden und dem Auswaschungspotenzial - neue Erkenntnisse aus Lang-Zeit-Lysimeteruntersuchungen

Die Ertragswirksamkeit der Phosphor(P)-düngung nimmt mit steigenden P-Gehalten im Boden ab. Gleichzeitig steigt aber das Risiko von P-Verlusten durch Auswaschung. Ein umfassendes kausales Verständnis dieser Wirkbeziehungen kann dazu beitragen, Empfehlungen für eine P-Düngung bzw. für P-Gehalte im Boden abzuleiten, die den Ansprüchen der Kulturpflanzen entsprechen und Austragsverluste in die Gewässersysteme vermeiden. Die hierfür benötigen Daten stehen bisher nur in begrenztem Umfang zur Verfügung. Die relevanten Stofftransport- und Transformationsprozesse wurden durch mathematische Modelle für repräsentative Bodentypen Deutschlands noch nicht ausreichend beschrieben. Die Ziele dieser Untersuchungen bestehen daher darin, den Einfluss von Landbewirtschaftungssystemen und verschiedenen Düngungsstufen hinsichtlich der P-Bodengehalte und der Auswaschungsverluste zu bewerten und die kürzlich überarbeiteten Orientierungswerte für P-Versorgungsstufen des Bodens vor dem Hintergrund möglicher Folgewirkungen auf die Gewässerqualität zu diskutieren. Zur Realisierung der Aufgabenstellung wurden vorliegende Lang-Zeit-Lysimeterversuchsergebnisse mit variierter mineralischer Zusatzdüngung bei verschiedener Landbewirtschaftung (Ackerland, Grünland, Brache), unterschiedlicher Bodentextur (lehmiger Sand, Sand, Lehm und Schluff) und verschiedenen Anbausystemen und Fruchtfolgerotationen ausgewertet. Der P- Status des Bodens (pflanzenverfügbarer P, bestimmt nach der Doppellaktatmethode) und die P- Konzentration im Sickerwasser (bestimmt als Gesamtphosphor) wurden dabei als wesentliche Prüfkriterien verwendet. Die Untersuchungen wurden an 83 nichtwägbaren Gravitationslysimetern mit einer Oberfläche von 1m2 und einer nutzbaren Tiefe von 1,25 m in den Jahren 1991 bis 2015 durchgeführt. Im Ergebnis der Lysimeteruntersuchungen konnte anhand der Beziehungen zwischen den P- Bodengehalten und den dazugehörigen Auswaschungsraten gezeigt werden, dass das empfohlene P-Düngungsniveau die Einhaltung der in der EU-Wasserrahmenrichtlinie festgelegten P-Konzentrationswerte zur Gewährleistung eines guten ökologischen und chemischen Zustands für Fließgewässer gewährleistet. Im Gegensatz dazu besteht für stehende Gewässer (u.a. Seen) ein erhöhtes Eutrophierungsrisiko durch unerwünschte P-Auswaschungsverluste

Consistency between renormalization group running of chiral operator and counting rule -- Case of chiral pion production operator --

In nuclear chiral perturbation theory (ChPT), an operator is defined in a space with a cutoff which may be varied within a certain range. The operator runs as a result of the variation of the cutoff [renormalization group (RG) running]. In order for ChPT to be useful, the operator should run in a way consistent with the counting rule; that is, the running of chiral counter terms have to be of natural size. We vary the cutoff using the Wilsonian renormalization group (WRG) equation, and examine this consistency. As an example, we study the s-wave pion production operator for NN\to d pi, derived in ChPT. We demonstrate that the WRG running does not generate any chiral-symmetry-violating (CSV) interaction, provided that we start with an operator which does not contain a CSV term. We analytically show how the counter terms are generated in the WRG running in case of the infinitesimal cutoff reduction. Based on the analytic result, we argue a range of the cutoff variation for which the running of the counter terms is of natural size. Then, we numerically confirm this.Comment: 28 pages, 5 figures, significantly changed, published versio

Few-nucleon systems with state-of-the-art chiral nucleon-nucleon forces

We apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors, to study nucleon-deuteron (Nd) scattering and selected low-energy observables in 3H, 4He, and 6Li. Calculations beyond second order differ from experiment well outside the range of quantified uncertainties, providing truly unambiguous evidence for missing three-nucleon forces within the employed framework. The sizes of the required three-nucleon force contributions agree well with expectations based on Weinberg's power counting. We identify the energy range in elastic Nd scattering best suited to study three-nucleon force effects and estimate the achievable accuracy of theoretical predictions for various observables.Comment: 5 pages, 5 figure

Strange chiral nucleon form factors

We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron scattering experiments performed by the SAMPLE and the HAPPEX collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, $= (0.05 \pm 0.09) fm^2$. We also deduce the consequences for the upcoming MAMI A4 experiment.Comment: 7 pp, REVTeX, uses epsf, minor correction