EPJa: N* resonances from KΛ amplitudes in sliced bins in energy

Paper published in The European Physical Journal A - Published 22 December 2017 

N* resonances from K ΛΛ amplitudes in sliced bins in energy 

A. V. Anisovich, V. Burkert, M. Hadžimehmedović, D. G. Ireland, E. Klempt, V. A. Nikonov, R. Omerović, A. V. Sarantsev, J. Stahov, A. Švarc, U. Thoma 

DOI: https://doi.org/10.1140/epja/i2017-12443-x

The two reactions $\gamma p \rightarrow K^{+} \Lambda$ and $\pi^{-}p \rightarrow K^{0}\Lambda$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann sheet close to the physical axes. The results from the L+P fit are compared with the results of an energy-dependent fit based on the Bonn-Gatchina (BnGa) approach. The study confirms the existence of several poles due to nucleon resonances in the region at about 1.9 GeV with quantum numbers $J^P=1/2+,3/2+,1/2−,3/2−,5/2−$ .

Read More

PRL: Strong evidence for nucleon resonances near 1900 MeV

Paper published in Phys. Rev. Lett. 119, 062004 – Published 11 August 2017
Accepted paper in Physical Review Letters - 10 July 2017.

https://journals.aps.org/prl/accepted/db072Yc4O111a856188a77c50a1ae4f7572e4182f

Strong evidence for nucleon resonances near 1900 MeV - A. V. Anisovich, V. Burkert, M. Hadžimehmedović, D. G. Ireland, E. Klempt, V. A. Nikonov, R. Omerović, H. Osmanović, A. V. Sarantsev, J. Stahov, A. Švarc, and U. Thoma 

Abstract:

Data on the reaction $\gamma p \to K^+\Lambda$ from the CLAS experiments are used to derive the leading multipoles, E0+, M1-, E1+, and M1+, from the production threshold to 2180\,MeV in 24 slices of the invariant mass. The four multipoles are determined without any constraints. The multipoles are fitted using a multichannel L+P model which allows us to search for singularities and to extract the positions of poles on the complex energy plane in an almost model-independent method. The multipoles are also used as additional constraints in an energy-dependent analysis of a large body of pion and photo-induced reactions within the Bonn-Gatchina (BnGa) partial wave analysis. The study confirms the existence of poles due to nucleon resonances with spin-parity J^P = 1/2^-; 1/2^+, and 3/2^+ in the region at about 1.9\,GeV.

Read More

Bled 2017: Advances in hadronic resonances

Two members of our group were participants of Mini Workshop in Bled, Slovenia (July 2 - 9, 2017). The purpose of this workshop is to give the participants an opportunity to concentrate on problems of common interest and to enable focused, intense discussions on individual topics. Typically, every day three participants present their subjects in 40-minutes talks and are encouraged to propose specific problems to be worked out in detail during the Workshop, either jointly or in smaller groups. The number of participants is typically limited to about 20.

Bled 2017 Proceedings PDF 

Organiser of Mini Workshop in Bled are  Society of Mathematicians, Physicists and Astronomers of Slovenia, Jozef Stefan Institute and Deptartment of Physics and University of Ljubljana.

Hedim Osmanovic: Single energy partial wave analysis on eta photoproduction - pseudo data --> PRESENTATION

Jugoslav Stahov : Single energy partial wave analysis on eta photoproduction - real data --> PRESENTATION

Read More

PWA 9 - ATHOS 4 Workshop 2017

The International Workshop on Partial Wave Analyses and Advanced Tools for Hadron Spectroscopy (PWA9/ATHOS4) took place in Bad Honnef near Bonn (Germany) from March 13 to 17, 2017. Members of our group participated on this Workshop.

• Hedim Osmanović - "Constraining single energy partial wave analysis"
  

  
  We perform partial wave analysis of the eta photo production data. In an iterative procedure, fixed-t amplitude analysis (FT AA) and conventional single energy partial wave analysis (SE PWA) are coupled in such a way that output from one analysis is used as an constraint in another. The fixed-t analyticity in the fixed-t amplitude analysis is imposed by using Pietarinen's expansion method known from Karlsruhe-Helsinki analysis of pion-nucleon scattering data. As a result, multipoles are consistent with fixed-t analyticity and with fixed-s analyticity as well. By construction, invariant amplitudes fulfill required crossing symmetry.

  Presentation link in .pdf
   
•  Mirza Hadžimehmedović  -  "Laurent+Pietarinen method in baryon spectroscopy "
  

  
  Fundamentals of the new, robust, pole extraction method based on representing the regular part of Laurent expansion of partial wave amplitude with quickly converging Pietarinen series are repeated. An overview of all recent applications of this method with summary of obtained results is made. Preliminary results in extracting baryon transition form factors at the pole and analysis of lowest Kaon photoproduction multipoles are also discussed. New possibilities are presented.

  Presentation link in .PDF
  
  
  

  

Read More