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SFB-S3 Collaboration meeting - Mainz 2019 Program


SFB-S3 Collaboration meeting
Partial Wave Analysis with Analytical Constraints
Mainz, 18-21 February 2019

Talks can be downloaded from our GitHub Page

Monday, 18 February, 10:00-12:00, A2 meeting room, Neubau, 1OG, 01-122

Jugoslav Stahov/Hedim Osmanovic: Preliminary results on single-energy PWA for $\gamma,\pi$
Rifat Omerovic:  Data binning for PWA of pion photoproduction

Monday, 18 February, 14:00-17:00, A2 meeting room, Neubau, 1OG
Discussions

Tuesday, 19 February, 10:00-12:00, KPH Seminar Room, Foyer

Michael Ostrick: Opening
Andrey Sarantsev: Eta Photoproduction in the Bonn-Gatchina model
Deborah Rönchen: Eta Photoproduction in the Jülich-Bonn model

Tuesday, 19 February, 14:00-17:00, KPH, Seminar Room


R.Beck, F.Afzal : New experimental results from ELSA and MAMI
Lothar Tiator: Eta Photoproduction in the MAID model
Alfred Svarc: Phase Ambiguities in Eta Photoproduction
Discussions

Tuesday, 19 February, 17:30 dinner in "Plaka"

Wednesday, 20 February, 10:00-12:00, A2 meeting room, Neubau, 1OG, 01-122

Kirill Nikonov: Dispersion Relations for Eta Photoproduction
Misha Gorchtein: Behaviour of Regge background under DR
Victor Kashevarov: Results on DR for high energies and proton and neutron

Wednesday, 20 February, 14:00-17:00, A2 meeting room, Neubau, 1OG
Discussions

Thursday, 21 February, 10:00-12:00, A2 meeting room, Neubau, 1OG, 01-122
Discussions
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Eta and etaprime photoproduction on the nucleon with the isobar model EtaMAID2018

L. Tiator, M. Gorchtein, V. L. Kashevarov, K. Nikonov, M. Ostrick, M. Hadžimehmedović, R. Omerović, H. Osmanović, J. Stahov, A. Švarc
The European Physical Journal A

Received 13 July 2018,  Accepted 20 October 2018.  First Online 06 December 2018
DOI https://doi.org/10.1140/epja/i2018-12643-x 
Publisher Name Springer Berlin Heidelberg
Print ISSN 1434-6001 Online ISSN 1434-601X

The isobar model EtaMAID has been updated with new and high precision data for 𝜂 and 𝜂′ photoproduction on protons and neutrons from MAMI, ELSA, GRAAL and CLAS. The background is described in a recently developed Regge cut model, and for the resonance part the whole list of nucleon resonances has been investigated with 21 𝑁∗ states contributing to 𝜂 photoproduction and 12 𝑁∗ states contributing to 𝜂′ photoproduction. A new approach is discussed to avoid double counting in the overlap region of Regge and resonances. A comparison is done among four newly updated partial waves analyses for observables and partial waves. Finally, the possibility of a narrow resonance near 𝑊=1900 MeV is discussed, that would be able to explain unexpected energy and angular dependence of observables in 𝑝(𝛾,𝜂′)𝑝 near 𝜂′ threshold.
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Role of angle-dependent phase rotations of reaction amplitudes in η photoproduction on protons


A. Švarc, H. Osmanović, M. Hadžimehmedović, R. Omerović, J. Stahov, M. Gorchteyn, V. Kashevarov, K. Nikonov, M. Ostrick, and L. Tiator
Phys. Rev. C 98, 045206 – Published 19 October 2018

Received 20 July 2018
DOI: https://doi.org/10.1103/PhysRevC.98.045206 

It was recently proved that the invariance of observables with respect to angle-dependent phase rotations of reaction amplitudes mixes multipoles, changing also their relative strength [A. Švarc et al., Phys. Rev. C 97, 054611 (2018)]. Modern partial wave analyses (PWAs) in η photoproduction on protons in the center-of-mass energy range 1.5≤W≤2.0 GeV, either energy-dependent (ED) or single-energy (SE) ones, do not take this effect into consideration. It is commonly accepted that all PWAs give very similar results for the E0+ multipole, but notable differences in this and all other partial waves still remain. In this paper we demonstrate that once these phase rotations are properly taken into account, all ED and SE partial wave analysis in η photoproduction become almost identical for the dominant E0+ multipole, and the agreement among all other multipoles becomes much better. We also show that measured observables are almost equally well reproduced in all PWAs, and the remaining differences among multipoles can be attributed solely to the difference in predictions for unmeasured observables. So, new measurements are needed.

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PWA 10 - ATHOS 5 Workshop 2018

PWA10/ATHOS4 Workshop, Beijing 2018
The International Workshop on Partial Wave Analyses and Advanced Tools for Hadron Spectroscopy, PWA10/ATHOS5, is a combination of the 10th International Workshop on Pion-Nucleon Partial Wave Analysis and the Interpretation of Baryon Resonances and the 5th Workshop on Partial Wave Analysis Tools for Hadron Spectroscopy. It took place at the Institute of High Energy Physics, Chinese Academy of Sciences in Beijing, China. Previous editions of this workshop include PWA9/ATHOS4 (U. Bonn, 2017) and PWA8/ATHOS3 (GWU, 2015). 

The aim of the workshop is to bring together experimental and theoretical groups working in hadron spectroscopy for constructive discussions of recent results, open issues and future perspectives of the field. Common issues in meson and baryon spectroscopy related to partial wave analyses and the interpretation of data will be emphasized.

In behalf of PWA Tuzla group, Hedim Osmanović and Mirza Hadžimehmedović attended the PWA10/ATHOS4 Workshop. Victor Kashevarov talk from University of Mainz,  a member of Maniz-Tuzla-Zagreb collaboration gave his talk too.  Presentation from their talks can be found on official page of Workshop, or on links below:

Hedim Osmanović - Model Independent Partial Wave Analysis for $π^0$ Photoproduction
Mirza Hadžimehmedović - Pole parameters from etaphotoproduction data using L+P method
Viktor Kashevarov - EtaMAID-2018 for η and η' photoproduction on nucleons

PWA10/ATHOS5 Workshop, Beijing, China, July 16 - 20, 2018.





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FBS: From Experimental Data to Pole Parameters in a Direct Way (Angle Dependent Continuum Ambiguity and Laurent + Pietarinen Expansion)

Paper published in Few-Body Syst (2018) 59: 96. , 

From Experimental Data to Pole Parameters in a Direct Way (Angle Dependent Continuum Ambiguity and Laurent + Pietarinen Expansion)

A. Švarc, Y. Wunderlich, H. Osmanović, M. Hadžimehmedović, R. Omerović, J. Stahov, V. Kashevarov, K. Nikonov, M. Ostrick, L. Tiator, R. Workman

Few-Body Syst (2018) 59: 96.
DOI: https://doi.org/10.1007/s00601-018-1410-y

This article belongs to the Topical Collection “NSTAR 2017—The International Workshop on the Physics of Excited Nucleons”.

Unconstrained partial-wave amplitudes obtained at discrete energies from fits to complete sets of eight independent observables which are required to uniquely reconstruct reaction amplitudes do not vary smoothly with energy, and are in principle non-unique. We demonstrate how this behavior can be ascribed to the continuum ambiguity. Starting from the spinless scattering case, we demonstrate how an unknown overall phase depending on energy and angle mixes the structures seen in the associated partial-wave amplitudes making the partial wave decomposition non-unique, and illustrate it on a simple toy model. We then apply these principles to pseudo-scalar meson photoproduction and show that the non-uniqueness effect can be removed through a phase rotation generating “up-to-a-phase” unique set of SE partial wave amplitudes. Extracting pole positions from partial wave amplitudes is the next step. Up to now, there was no reliable way to extract pole parameters from SE partial waves, but a new and simple single-channel method (Laurent + Pietarinen expansion) applicable for continuous and discrete data has been recently developed. It is based on applying the Laurent decomposition of partial wave amplitude, and expanding the non-resonant background into a power series of a conformal-mapping, quickly converging power series obtaining the simplest analytic function with well-defined partial wave analytic properties which fits the input. The generalization of this method to multi- channel case is also developed and presented. Unifying both methods in succession, one constructs a model independent procedure to extract pole parameters directly from experimental data without referring to any theoretical model.


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About PWA TUZLA

We are theoretical physicists at Faculty of Natural Sciences and Mathematics - University of Tuzla. Our group is a part of the Mainz - Tuzla - Zagreb Partial Wave Analysis collaboration.

As a part of the MTZ PWA, our results are "above the line" in PDG library.

Related sites

Physics Department >>
University of Tuzla >>
PMF Tuzla >>
Mainz-Tuzla-Zagreb PWA >>
PDG - Particle Data Group >>
MAID Mainz >>
GWU/SAID Washington >>
Bonn-Gatchina PWA >>
JPac Center Indiana Uni. >>
CLAS Phy. Database >>
JPac Center Indiana Uni. >>
ETA MAID 2018 >>

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