32 research outputs found
Detektor crystal ball u MAMI C: ishodi i izgledi
The Crystal Ball/TAPS detector setup provides a hermetic photon and hadron calorimeter for the tagged photon facility at the Mainz Microtron accelerator MAMI. High intensity, polarised photon beams of up to 1.5 GeV are used to study photoinduced reactions on nucleons and nuclei. In this article, an overview of the apparatus and selected recent results is given.Sustav detektora Crystal Ball/TAPS Äini zatvoren fotonski i hadronski kalorimetar za istraĆŸivanja s oznaÄenim fotonima mikrotronskog ubrzivaÄa MAMI u Mainzu. ProuÄavaju se reakcije izazvane jakim snopovima polariziranih fotona energije do 1.5 GeV na nukleonima i atomskim jezgrama. U radu se opisuje oprema i izbor nedavnih ishoda mjerenja
The Role of Meson Retardation in the NN Interaction above Pion Threshold
A model is developed for the hadronic interaction in the two-nucleon system
above pion threshold which is based on meson, nucleon and degrees of
freedom and which includes full meson retardation in the exchange operators.
For technical reasons, the model allows maximal one meson to be present
explicitly. Thus the Hilbert space contains besides and also
configurations consisting of two nucleons and one meson. For this reason, only
two- and three-body unitarity is obeyed, and the model is suited for reactions
in the two nucleon sector only, where one pion is produced or absorbed.
Starting from a realistic pure nucleonic retarded potential, which had to be
renormalized because of the additional and degrees of freedom, a
reasonable fit to experimental -scattering data could be achieved.Comment: 30 pages revtex including 17 figures, outline of model and discussion
shortened, typos correcte
Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons
Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015
Photoproduction of η and ηâČ mesons with EtaMAID
The unitary isobar model EtaMAID has been updated with an extended list of nucleon resonances, fitted to recent and new data for differential cross sections and polarization observables. The nonresonant background is described by Regge trajectories of Ï,Ï and a1, b1 mesons and in addition Regge cuts, where vector and axial vector mesons are exchanged together with Pomeron and f2 mesons
Photoproduction of
The unitary isobar model EtaMAID has been updated with an extended list of nucleon resonances, fitted to recent and new data for differential cross sections and polarization observables. The nonresonant background is described by Regge trajectories of Ï,Ï and a1, b1 mesons and in addition Regge cuts, where vector and axial vector mesons are exchanged together with Pomeron and f2 mesons
Measurement of the cross section for hard exclusive Ï0 muoproduction on the proton
202We report on a measurement of hard exclusive Ï0 muoproduction on the proton by COMPASS using 160 GeV/c polarised ÎŒ+ and ÎŒâ beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured ÎŒ+ and ÎŒâ cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)2<|t|<0.64(GeV/c)2. The average kinematics of the measurement are ăQ2ă=2.0(GeV/c)2, ăÎœă=12.8GeV, ăxBjă=0.093 and ăâtă=0.256(GeV/c)2. Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2±0.9statâ1.2+1.2|sys)nb/(GeV/c)2, as well as transverse-transverse and longitudinal-transverse interference contributions of (â6.1±1.3statâ0.7+0.7|sys)nb/(GeV/c)2 and (1.5±0.5statâ0.2+0.3|sys)nb/(GeV/c)2, respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transverse-transverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD EâŸT.openopenAlexeev M.G.; Alexeev G.D.; Amoroso A.; Andrieux V.; Anfimov N.V.; Anosov V.; Antoshkin A.; Augsten K.; Augustyniak W.; Azevedo C.D.R.; Badelek B.; Balestra F.; Ball M.; Barth J.; Beck R.; Bedfer Y.; Bernhard J.; Bodlak M.; Bordalo P.; Bradamante F.; Bressan A.; Buchele M.; Burtsev V.E.; Chang W.-C.; Chatterjee C.; Chiosso M.; Chumakov A.G.; Chung S.-U.; Cicuttin A.; Crespo M.L.; Dalla Torre S.; Dasgupta S.S.; Dasgupta S.; Denisov O.Y.; Dhara L.; Donskov S.V.; Doshita N.; Dreisbach C.; Dunnweber W.; Dusaev R.R.; Efremov A.; Eversheim P.D.; Faessler M.; Ferrero A.; Finger M.; Fischer H.; Franco C.; du Fresne von Hohenesche N.; Friedrich J.M.; Frolov V.; Fuchey E.; Gautheron F.; Gavrichtchouk O.P.; Gerassimov S.; Giarra J.; Gnesi I.; Gorzellik M.; Grasso A.; Gridin A.; Grosse Perdekamp M.; Grube B.; Guskov A.; Hahne D.; Hamar G.; von Harrach D.; Heitz R.; Herrmann F.; Horikawa N.; d'Hose N.; Hsieh C.-Y.; Huber S.; Ishimoto S.; Ivanov A.; Iwata T.; Jandek M.; Jary V.; Joosten R.; Jorg P.; Juraskova K.; Kabuss E.; Kaspar F.; Kerbizi A.; Ketzer B.; Khaustov G.V.; Khokhlov Y.A.; Kisselev Y.; Klein F.; Koivuniemi J.H.; Kolosov V.N.; Kondo Horikawa K.; Konorov I.; Konstantinov V.F.; Kotzinian A.M.; Kouznetsov O.M.; Kral Z.; Kramer M.; Krinner F.; Kroumchtein Z.V.; Kulinich Y.; Kunne F.; Kurek K.; Kurjata R.P.; Kveton A.; Levorato S.; Lian Y.-S.; Lichtenstadt J.; Lin P.-J.; Longo R.; Lyubovitskij V.E.; Maggiora A.; Magnon A.; Makins N.; Makke N.; Mallot G.K.; Mamon S.A.; Marianski B.; Martin A.; Marzec J.; Matousek J.; Matsuda T.; Meshcheryakov G.V.; Meyer M.; Meyer W.; Mikhailov Y.V.; Mikhasenko M.; Mitrofanov E.; Mitrofanov N.; Miyachi Y.; Moretti A.; Naim C.; Nagaytsev A.; Neyret D.; Novy J.; Nowak W.-D.; Nukazuka G.; Nunes A.S.; Olshevsky A.G.; Ostrick M.; Panzieri D.; Parsamyan B.; Paul S.; Peng J.-C.; Pereira F.; Pesek M.; Peshekhonov D.V.; Peskova M.; Pierre N.; Platchkov S.; Pochodzalla J.; Polyakov V.A.; Pretz J.; Quaresma M.; Quintans C.; Ramos S.; Regali C.; Reicherz G.; Riedl C.; Ryabchikov D.I.; Rybnikov A.; Rychter A.; Samoylenko V.D.; Sandacz A.; Sarkar S.; Savin I.A.; Sbrizzai G.; Schmieden H.; Selyunin A.; Silva L.; Sinha L.; Slunecka M.; Smolik J.; Srnka A.; Steffen D.; Stolarski M.; Subrt O.; Sulc M.; Suzuki H.; Szabelski A.; Szameitat T.; Sznajder P.; Tessaro S.; Tessarotto F.; Thiel A.; Tomsa J.; Tosello F.; Tskhay V.; Uhl S.; Vasilishin B.I.; Vauth A.; Veit B.M.; Veloso J.; Vidon A.; Virius M.; Wagner M.; Wallner S.; Wilfert M.; Zaremba K.; Zavada P.; Zavertyaev M.; Zemlyanichkina E.; Zhao Y.; Ziembicki M.Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Antoshkin, A.; Augsten, K.; Augustyniak, W.; Azevedo, C. D. R.; Badelek, B.; Balestra, F.; Ball, M.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bodlak, M.; Bordalo, P.; Bradamante, F.; Bressan, A.; Buchele, M.; Burtsev, V. E.; Chang, W. -C.; Chatterjee, C.; Chiosso, M.; Chumakov, A. G.; Chung, S. -U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Y.; Dhara, L.; Donskov, S. V.; Doshita, N.; Dreisbach, C.; Dunnweber, W.; Dusaev, R. R.; Efremov, A.; Eversheim, P. D.; Faessler, M.; Ferrero, A.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giarra, J.; Gnesi, I.; Gorzellik, M.; Grasso, A.; Gridin, A.; Grosse Perdekamp, M.; Grube, B.; Guskov, A.; Hahne, D.; Hamar, G.; von Harrach, D.; Heitz, R.; Herrmann, F.; Horikawa, N.; D'Hose, N.; Hsieh, C. -Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Iwata, T.; Jandek, M.; Jary, V.; Joosten, R.; Jorg, P.; Juraskova, K.; Kabuss, E.; Kaspar, F.; Kerbizi, A.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Y. A.; Kisselev, Y.; Klein, F.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo Horikawa, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O. M.; Kral, Z.; Kramer, M.; Krinner, F.; Kroumchtein, Z. V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Kveton, A.; Levorato, S.; Lian, Y. -S.; Lichtenstadt, J.; Lin, P. -J.; Longo, R.; Lyubovitskij, V. E.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Mamon, S. A.; Marianski, B.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, T.; Meshcheryakov, G. V.; Meyer, M.; Meyer, W.; Mikhailov, Y. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Moretti, A.; Naim, C.; Nagaytsev, A.; Neyret, D.; Novy, J.; Nowak, W. -D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J. -C.; Pereira, F.; Pesek, M.; Peshekhonov, D. V.; Peskova, M.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Ryabchikov, D. I.; Rybnikov, A.; Rychter, A.; Samoylenko, V. D.; Sandacz, A.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schmieden, H.; Selyunin, A.; Silva, L.; Sinha, L.; Slunecka, M.; Smolik, J.; Srnka, A.; Steffen, D.; Stolarski, M.; Subrt, O.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Tessaro, S.; Tessarotto, F.; Thiel, A.; Tomsa, J.; Tosello, F.; Tskhay, V.; Uhl, S.; Vasilishin, B. I.; Vauth, A.; Veit, B. M.; Veloso, J.; Vidon, A.; Virius, M.; Wagner, M.; Wallner, S.; Wilfert, M.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhao, Y.; Ziembicki, M