BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Helicity dependent cross sections for the photoproduction of π0π ± pairs from quasi-free nucleons DTSTART;VALUE=DATE-TIME:20220712T155000Z DTEND;VALUE=DATE-TIME:20220712T161000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-680@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Debdeep Ghosal\; University of Basel\, Switzerland ( )\nPhoton induced π0π±-pairs production from quasi-free nucleons bound in the deuteron has been investigated in view of the helicity dependence o f those two reactions. Measurements with a liquid deuterium target were us ed to extract the unpolarized cross sections for protons and neutrons. A d euterated\, longitudinally polarized butanol target together with a circul arly polarized photon beam was also used to measure the double polarizatio n observable E. Antiparallel and parallel spin configurations of the beam photon and target nucleon correspond to the spin-dependent cross sections σ1/2 and σ3/2 respectively\, which have been derived from E. The measure ments were done at the Mainz MAMI accelerator with tagged photon beams pro duced via bremsstrahlung from longitudinally polarized electron beams. The reaction products from the two target types were detected with an almost 4π solid-angle covering calorimeter composed of the Crystal Ball\, TAPS d etectors and particle identification detectors. The results are sensitive to sequential decays of nucleon resonances via intermediate states and als o by emission of charged ρ mesons. Furthermore\, the results have been co mpared to the recent available model calculation.\n\nhttps://indico.koza.i f.uj.edu.pl/event/7/contributions/680/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/680/ END:VEVENT BEGIN:VEVENT SUMMARY:Polarisation observables Sigma\, T\, P and H in pi0 and eta photop roduction off quasifree nucleons DTSTART;VALUE=DATE-TIME:20220712T153000Z DTEND;VALUE=DATE-TIME:20220712T155000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-679@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Nicolas Jermann\; University of Basel\, Switzerland ()\nThe excitation spectrum of the nucleon is an important testing ground for quantum chromodynamics in the regime where it cannot be treated pertur batively. During the last two decades much progress has been made on the t heory side\, e.g. lattice gauge methods and in experiments\, particularly using energy tagged photon beams at electron accelerators\, which has now reached a state where not only differential cross sections but also asymme tries measured with polarised photons\nand polarised targets allow for det ailed partial wave analyses. This provides much more stringent information about the involved reaction multipoles and thus the contributing nucleon resonances. The present experiment was done at the ELSA accelerator in Bon n with the Crystal Ball/TAPS detector setup. The incident electron beam of 3.2 GeV impinged on a diamond radiator where it produced coherent bremsst rahlung photons with linear polarisation\, which again impinged\non a tran sversely polarised\, deuterated butanol target. This allows the simultaneo us measurement of the polarisation observables Σ\, T\, P and H. Analysed were the final states Nπ0 and Nη with the almost 4π covering electromag netic calorimeter Crystal Ball/TAPS.\nOne of the main motivations of this experiment was a more detailed investigation of the not yet understood nar row structure in the excitation function of the γn→nη reaction at appr oximately 1 GeV.\nPreliminary results will be discussed.\n\nhttps://indico .koza.if.uj.edu.pl/event/7/contributions/679/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/679/ END:VEVENT BEGIN:VEVENT SUMMARY:Invited talk: Exotic properties of N*(1895) and its impact on phot ophroduction of light hyperons DTSTART;VALUE=DATE-TIME:20220712T151000Z DTEND;VALUE=DATE-TIME:20220712T153000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-678@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Kanchan Khemchandani\; Federal University of Sao Pau lo\, Brasil ()\nIn a recent work\, we have studied the decay properties of N(1895)\, which was found to arise from meson-baryon interactions in an e arlier work. We investigate the decays to different meson-baryon systems a nd to final states involving \\Lambda(1405) and a proposed \\Sigma(1400). In this talk\, I will show that the width of N^(1895) can get an important contributions from the decay to light hyperon resonances and such finding s can be relevant for processes like the photoproduction of \\Lambda(1405) .\n\nhttps://indico.koza.if.uj.edu.pl/event/7/contributions/678/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/678/ END:VEVENT BEGIN:VEVENT SUMMARY:Invited talk: Studying the process γd→π0ηd DTSTART;VALUE=DATE-TIME:20220712T145000Z DTEND;VALUE=DATE-TIME:20220712T151000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-677@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Alberto Martinez Torres\; University of Sao Paulo\, Brasil ()\nIn this talk I will present a theoretical study of the γd→π 0ηd reaction and show that the observed shift of the peaks of the π0d\, ηd invariant mass distributions with respect to the phase space distribut ions are related to the dynamics of the γp→π0ηp.\n\nhttps://indico.ko za.if.uj.edu.pl/event/7/contributions/677/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/677/ END:VEVENT BEGIN:VEVENT SUMMARY:Invited talk: Mass modifications of vector mesons in a finite dens ity matter DTSTART;VALUE=DATE-TIME:20220712T143000Z DTEND;VALUE=DATE-TIME:20220712T145000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-676@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Kyoichiro Ozawa\; Institute of Particle and Nuclear Studies\, KEK\, Japan ()\nOrigin of hadron masses have wide interests in t he field of nuclear physics. Light quarks\, such as up and down quarks\, o nly have “bare” mass of a few MeV/c^2. A proton and a neutron\, which contains only three quarks\, have mass of ~1 GeV/c^2. This difference betw een quark mass and hadron mass can be theoretically explained as dynamical generations of hadron mass by a spontaneous breaking of a symmetry in a “QCD vacuum”. In this point of view\, hadron masses are not a stable a nd it can be changed in a finite temperature and/or density medium. Severa l experimental efforts are performed to measure mass modifications of hadr ons in a finite temperature and/or density medium. In high temperature reg ion\, high energy heavy ion experiments\, such as SPS\, RHIC\, LHC\, are p erformed. Experiments at KEK-PS\, CLAS\, CBELSA/TAPS are also performed to study hadron masses in a nucleus\, as a finite density matter.\nWe are ca rrying out a new experiment to measure mass spectra of vector mesons in nu clei at J-PARC in Japan. The experiment is a successor to the experiment a t KEK-PS. In the experiment\, we measure electron-positron decays of vecto r mesons\, since mass spectra of the vector mesons have strong relations w ith an order parameter of the symmetry breaking in the medium. We focus on electron-positron decays to avoid final state interactions between medium and daughter particles. We constructed new spectrometer which consists of four layers of tracking detectors and two kinds of electron identificatio n counters. Tracking detectors are one layer of Silicon Strip Detector and three layers of Gas Electron Multiplier (GEM) Trackers. For electron iden tifications\, GEM-based gas Cherenkov counters\, so called Hadron Blind De tector\, and Lead Glass EM calorimeters are used.\nWe started construction s of a beam line and detectors in 2012. We had the first beam in 2020 and started beam study and detector shake down. We collected pilot data in 202 0 and 2021 to evaluate detector performances. We are planning to have the first physics data-taking period in early 2023. We will introduce recent a ctivities of related studies and show status of our experiment.\nAlso\, fu ture plans to measure mass modification in a high-density matter which can be created using heavy ion collisions will be discussed.\n\nhttps://indic o.koza.if.uj.edu.pl/event/7/contributions/676/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/676/ END:VEVENT BEGIN:VEVENT SUMMARY:Invited talk: Study of the eta-prime meson in nuclei in the LEPS2/ BGOegg experiment DTSTART;VALUE=DATE-TIME:20220712T141000Z DTEND;VALUE=DATE-TIME:20220712T143000Z DTSTAMP;VALUE=DATE-TIME:20260720T185847Z UID:indico-contribution-45-675@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Natsuki Tomida\; Kyoto University\, Japan ()\nA larg e mass reduction of the η′(958) in nuclei is expected in several theore tical models. If there is large mass reduction\, an η′ meson and a nucl eus can form a bound state. We investigated the η′-nucleus system in th e LEPS2/BGOegg experiment. To search for the η′-nucleus bound state\, w e carried out the missing mass spectroscopy of the 12C(γ\,p) reaction. To suppress background events from mult-meson productions\, the one nucleon absorption decay products were simultaneously measured for the first time. In addition\, we also carried out the simultaneous measurement of escapin g η′ mesons from nuclei. We will report the η′-nucleus optical poten tial evaluated by using both data. We will also show the preliminary resul ts of the direct measurement of η′ mass spectra from the η′→γγ d ecay in nuclei.\n\nhttps://indico.koza.if.uj.edu.pl/event/7/contributions/ 675/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/675/ END:VEVENT END:VCALENDAR