arXiv subjects

I. I. Strakovsky

Publications and source records attributed to I. I. Strakovsky.

137 records · Page 8Linked to original sources

arXiv1997

Analysis of Pion Photoproduction over the Delta Resonance Region

A number of recent multipole analyses from Mainz, RPI, BNL and Virginia Tech (VPI) have focused on the first resonance region. One goal common to these studies was an improved set of Delta(1232) photo-decay amplitudes. There has been considerable debate over the differing results found for A(1/2), A(3/2) and the E2/M1 ratio. We show that a much more consistent set of values is possible if differences in the database are considered.

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arXiv1997

Nucleon-nucleon elastic scattering analysis to 2.5 GeV

A partial-wave analysis of NN elastic scattering data has been completed. This analysis covers an expanded energy range, from threshold to a laboratory kinetic energy of 2.5 GeV, in order to include recent elastic pp scattering data from the EDDA collaboration. The results of both single-energy and energy-dependent analyses are described.

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arXiv1997

Pion photoproduction in the delta resonance region

We have updated our multipole analyses to incorporate new data from the low-energy and delta resonance regions. We note a slight decrease in our estimate of the delta photo-decay amplitudes. This agrees with results found in Compton scattering. Our values are also in good agreement with a previous RPI determination. We have reexamined our determinations of the E2/M1 ratio at the resonance energy and at the pole. We find an E2/M1 ratio (at the pole) which is in good agreement with recent the Mainz value.

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arXiv1997

Comment on `Measurement of the $π^+ \vec p$ analyzing power at 68.3 MeV'

We comment on a recent paper by Weiser et al. [Phys. Rev. C {\bf 54}, 1930 (1996)]. The authors have performed a single-energy analysis of $π^+ p$ scattering data at 68.3 MeV, finding a value for the $S_{31}$ phase shift about 1^o smaller than found in the Karlsruhe-Helsinki (KH) partial-wave analysis. The authors use this result to argue for a dispersion relation analysis using recently measured data, so that their effect on the $πNN$ coupling constant (f^2) and $Σ$ amplitude can be determined. We note that these tasks were accomplished prior to the submission of the above paper. We clarify the effect of this new analyzing power data on f^2 and the $Σ$ amplitude.

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arXiv1997

Combined analysis of the reactions $pp \to pp$, $πd\to πd$, and $πd\to pp$

Results are presented for a combined analysis of the reactions $pp\to pp$, $πd\to πd$ and $πd\to pp$ over the $\sqrt{s}$ interval from pion threshold to approximately 2.4 GeV. These results for $πd\to pp$ and $πd$ elastic scattering are superior to our previous analyses of these reactions. In particular, the overall phase in $πd\to pp$ has now been determined. Comparisons are made with previous (separate and combined) analyses of this two-nucleon system.

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arXiv1996

pi+ + d --> p + p reaction between 18 and 44 MeV

A study of the reaction pi+ + d --> p + p has been performed in the energy range of 18 - 44 MeV. Total cross sections and differential cross sections at six angles have been measured at 15 energies with an energy increment of 1 - 2 MeV. This is the most systematic data set in this energy range. No structure in the energy dependence of the cross section has been observed within the accuracy of this experiment.

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arXiv1996

Influence of spin-rotation measurements on partial-wave analyses of elastic pion-nucleon scattering

Recent measurements of spin-rotation parameters in elastic $π^+ p$ scattering are in marked disagreement with predictions of the Carnegie-Mellon$-$Berkeley and Karlsruhe-Helsinki analyses. Using the method of Barrelet, we show how this discrepancy can be removed. We then show how this Barrelet transformation alters the partial-wave amplitudes. The effect of unitarity and analyticity constraints is also considered.

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arXiv1995

Nucleon Helicity in Pion Photoproduction

Pion-photoproduction data is examined to check for the nucleon-helicity conservation predicted by asymptotic QCD. The differential cross section shows agreement with constituent-counting rules, and polarization data is not in disagreement with conservation of nucleon helicity. However large uncertainties in the polarization measurements do not allow a conclusive statement. The helicity amplitudes from a partial-wave analysis are also examined for helicity conservation. While the amplitudes become small as $s$ increases, the $s$ dependence of the helicity-conserving amplitudes is similar to the dependence of the non-conserving amplitudes.

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arXiv1995

Updated resonance photo-decay amplitudes to 2 GeV

We present the results of an energy-dependent and set of single-energy partial-wave analyses of single-pion photoproduction data. These analyses extend from threshold to 2 GeV in the laboratory photon energy, and update our previous analyses to 1.8 GeV. Photo-decay amplitudes are extracted for the baryon resonances within this energy range. We consider two photoproduction sum rules and the contributions of two additional resonance candidates found in our most recent analysis of $πN$ elastic scattering data. Comparisons are made with previous analyses.

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arXiv1995

Extraction of the $πNN$ coupling constant from NN scattering data

We reexamine Chew's method for extracting the $πNN$ coupling constant from np differential cross section measurements. Values for this coupling are extracted below 350 MeV, in the potential model region, and up to 1 GeV. The analyses to 1~GeV have utilized 55 data sets. We compare these results to those obtained via $χ^2$ mapping techniques. We find that these two methods give consistent results which are in agreement with previous Nijmegen determinations.

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arXiv1995

Updated analysis of $π$N elastic scattering data to 2.1~GeV: The Baryon Spectrum

We present the results of energy-dependent and single-energy partial-wave analyses of $π$N elastic scattering data with laboratory kinetic energies below 2.1~GeV. Resonance structures have been extracted using Breit-Wigner fits, speed plots, and a complex plane mapping of the associated poles and zeroes. This is the first set of resonance parameters from a VPI analysis constrained by fixed-t dispersion relations. We have searched our solutions for structures which may have been missed in our previous analyses, finding candidates in the $S_{11}$ and $F_{15}$ partial-wave amplitudes. Our results are compared with those found by the Karlsruhe, Carnegie-Mellon$-$Berkeley, and Kent State groups.

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