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15 results on '"STASSEN, R"'

1. Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHOUKAZ, A, KHREPTAK, O, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, PAROL, W, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
NUCLEON-NUCLEON COLLISIONS, 2-PION PRODUCTION, PION PRODUCTION, PROTON-PROTON COLLISIONS, PI(0)PI(0) PRODUCTION, SINGLE-PION, ISOSPIN DECOMPOSITION, SCATTERING, RESONANCE, CROSS-SECTIONS
Abstract

Exclusive measurements of the quasifree pp -> pp pi(+)pi(-) reaction have been carried out at WASA@ COSY by means of pd collisions at T-p = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region T-p = 1.08-1.36 GeV, which is the region of N* (1440) and Delta(123)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+)) produced associatedly with a pion is able to overcome these deficiencies.

Published
2018

2. Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY

Author

ADLARSON, R, COLLABORATION, WAC, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BONDAR, A, BUESCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, R, FOEHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUESKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHATRI, G, KHOUKAZ, A, KHREPTAK, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, R, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, R, MARIANSKI, B, MORSCH, HP, MOSKAL, R, OHM, H, PAROL, W, RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROEHER, H, SZCZUREK, A, TRZCINSKI, A, WOLKE, M, WRONSKA, A, WUESTNER, R, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, R, ZUREK, M, and WIRZBA, A

Subjects
CONSERVING DECAY, UPPER LIMIT
Abstract

We report on the search for the rare decay eta -> pi(0)e(+)e(-) which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 x 10(7) events of the reaction pd -> He-3 eta have been recorded at an excess energy of Q = 59.8MeV. Based on this data set the C parity violating decay eta -> pi(0)gamma* -> pi(0)e(+)e(-) via a single-photon intermediate state has been searched for, resulting in new upper limits of Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> pi(+) pi(-) pi(0)) < 3.28 x 10(-5) and Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> all)< 7.5 x 10(-6) (CL=90%), respectively. (c) 2018 The Author. Published by Elsevier B.V.

Published
2018
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3. Total and differential cross sections of eta-production in proton-deuteron fusion for excess energies between Q(eta)=13 MeV and Q(eta)=81 MeV

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVENO, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHATRI, G, KHOUKAZ, A, KHREPTAK, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, PAROL, W, DEL RIO, EP, PISKUNOVU, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, ZUREK, M, and WILKIN, C

Subjects
REACTION NEAR-THRESHOLD, QUASI-FREE, eta meson, SMALL ANGLES, ELASTIC-SCATTERING, Proton-deuteron interactions, PD SCATTERING, Meson production, TENSOR ANALYZING POWER, MESONS, HE-3
Abstract

New data on both total and differential cross sections of the production of eta mesons in proton-deuteron fusion to He-3 eta in the excess energy region 13.6 MeV

Published
2018
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4. Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi(0)

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HANHART, C, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHATRI, G, KHOUKAZ, A, KHREPTAK, O, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, PAROL, W, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, WOLKE, M, WRONSKA, A, WUNSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
COLLISIONS, Deuteron deuteron interactions, Charge symmetry breaking, MESON PRODUCTION, Pion production, NEAR-THRESHOLD, COSY, QUARK MASSES
Abstract

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd -> He-4 pi(0) using the WASA-at-COSY detector setup at an excess energy of Q = 60 MeV. The determined differential cross section can be parametrized as d sigma/d Omega = a + b cos(2) theta*, where theta* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 +/- 0.46(stat)(-0.8)(+0.32)(syst)) pb/sr and b = (13.1 +/- 2.1(stat)(-2.7)(+1.0)(syst)) pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the A isobar to the dd -> He-4 pi(0) reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions. (C) 2018 The Author(s). Published by Elsevier B.V.

Published
2018

5. Measurement of the omega -> pi(+)pi(-)pi(0) Dalitz plot distribution The WASA-at-COSY Collaboration

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHATRI, G, KHOUKAZ, A, KHREPTAK, O, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDYC, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, VARMA, R, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, ZUREK, M, KUBIS, B, and LEUPOLD, S

Subjects
Na60, Parity, Light Vector-Mesons, Meson-Meson Interactions, Pi-Pi-Scattering, Detector, Decays Of Other Mesons, Transition Form-Factors, Decays, Light Mesons, Eta, Dispersive Analysis, Mu(+)Mu(-)Gamma
Abstract

Using the production reactions pd -> He-3 omega and pp -> pp omega, the Dalitz plot distribution for the omega -> pi(+)pi(-)pi(0)decay is studied with the WASA detector at COSY, based on a combined data sample of (4.408 +/- 0.042) x 10(4) events. The Dalitz plot density is parametrised by a product of the P-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables Z and phi. For the first time, a deviation from pure P-wave phase space is observed with a significance of 4.1 sigma. The deviation is parametrised by a linear term 1+2 alpha Z, with alpha determined to be +0.147 +/- 0.036, consistent with the expectations of rho-meson-type final-state interactions of the P-wave pion pairs. (C) 2017 The Author. Published by Elsevier B.V.

Published
2017

6. Search for eta-mesic He-4 in the dd -> (3)Hen pi(0) and dd -> (3)Hep pi(-) reactions with the WASA-at-COSY facility

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, E, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KELKAR, NG, KEMMERLING, G, KHATRI, G, KHOUKAZ, A, KHREPTAK, O, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERAE, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TRZCINSKI, A, VARMA, R, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Scattering, Eta-Mesic Nuclei, Eta Meson, Near-Threshold, Systems, Detector, Nuclei, Quasi-Bound States
Abstract

The search for He-4-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd -> (3)Hen pi(0) and dd -> (3)Hep pi(-) processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd -> He-4 eta reaction ranging from Q = 70 MeV to Q = 30 MeV. The luminosity was determined based on the dd -> (3)Hen reaction and the quasi-free proton proton scattering via dd -> ppn(spectator)n(spectator) reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd -> (4He-eta)(bound) -> (3)Hen pi(0) and dd -> (He-4-eta)(bound) -> (3)Hep pi(-) processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N* (1535) momentum distribution in the anticipated mesic-He-4. Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in He-4, we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for n pi(0) and p pi(-) channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N*-He-3 nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for n pi(0) and p pi(-) channels respectively. (C) 2017 Elsevier B.V. All rights reserved.

Published
2017

7. Measurement of the (n)over-right-arrowp -> d pi(0) pi(0) reaction with polarized beam in the region of the d(*)(2380) resonance

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEEN, H, CIEPA, I, CLEMENT, H, CZERWINSKI, E, DEMMICH, K, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEJNY, V, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHATRI, G, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MORSCH, HP, MOSKAL, P, OHM, H, DEL RIO, EP, PISKUNOV, NM, PRASUHN, D, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, RUNDEL, O, SAWANT, S, SCHADMAND, S, SCHATTI-OZERIANSKA, I, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SITTERBERG, K, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TRZCINSKI, A, VARMA, R, WOLKE, M, WRONSKA, A, WUSTNER, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZINK, A, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Proton-Proton Collisions, Threshold, Nucleon-Nucleon Collisions, Pp, Double-Pionic Fusion, Isospin Decomposition, 2-Pion Production, Excitation
Abstract

We report on a high-statistics measurement of the most basic double-pionic fusion reaction over the energy region of the d (*)(2380) resonance by use of a polarized deuteron beam and observing the double fusion reaction in the quasifree scattering mode. The measurements were performed with the WASA detector setup at COSY. The data reveal substantial analyzing powers and confirm conclusions about the d(*) resonance obtained from unpolarized measurements. We also confirm the previous unpolarized data obtained under complementary kinematic conditions.

Published
2016
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8. ABC effect and resonance structure in the double-pionic fusion to He-3

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HOISTAD, B, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TRZCINSKI, A, VARMA, R, WAGNER, GJ, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUREV, L, ZABIEROWSKI, J, ZIELINSKI, MJ, ZINK, A, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Gev-C, Near-Threshold, Enhancement, Dibaryons, Proton-Proton Collisions, Pi-Pi Interaction, Pi(0)Pi(0) Production, Meson Production, Isospin Decomposition, Nuclear-Matter
Abstract

Exclusive and kinematically complete measurements of the double pionic fusion to He-3 have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the pi pi-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Julich). Similar to the observations in the basic pn -> d pi(0)pi(0) reaction and in the dd -> He-4 pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of d* resonance formation during the reaction process in addition to the conventional t-channel Delta Delta mechanism. The deduced d* resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.

Published
2015

9. Measurement of the eta -> pi(+)pi(-)pi(0) Dalitz plot distribution

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HODANA, M, HOISTAD, B, HUSKEN, N, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MARTEMYANOV, BV, MEISSNER, UG, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TRZCINSKI, A, VARMA, R, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZINK, A, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Parameter Alpha, Ratios, Electromagnetic Corrections, Current Algebra, 3-Pi(0), Pi, Decays, Wasa Detector, Kloe Detector, Dynamics
Abstract

The Dalitz plot distribution of the eta -> pi(+)pi(-)pi(0) decay is determined by using a data sample of 1.2 x 10(7) eta mesons from the pd -> He-3 eta reaction at 1 GeV collected by the WASA detector at COSY.

Published
2014
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10. Search for a dark photon in the pi(0) -> e(+)e(-)gamma decay

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, E, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEINN, F, HEIJKENSKJOLD, L, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KIRILLOV, DA, KLOS, B, KRAPP, M, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LI, L, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MEISSNER, UG, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PLUCINSKI, P, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SHWARTZ, B, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TOLBA, T, TRZCINSKI, A, VARMA, R, WAGNER, GJ, WEGLORZ, W, WIRZBA, A, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, ZABIEROWSKI, J, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Gauge Vector Boson, Dark Forces, Phi-Meson Decays, Vector Gauge Boson, Kloe Detector, Energies
Abstract

The presently world largest data sample for pi(0) -> gamma e(+)e(-) decays studies containing nearly 5 x 10(5) events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi(0) -> gamma U -> gamma e(+)e(-) decay from the pp -> pp pi(0) reaction was carried out. An upper limit on the square of the U -> gamma mixing strength parameter epsilon(2) of 5 x 10(-6) at 90% CL was obtained for the mass range 20 MeV < M-U < 100 MeV. This result together with other recent experimental limits significantly reduces the M-U vs. epsilon(2) parameter space which could explain the presently seen deviation between the Standard Model prediction and the direct measurement of the anomalous magnetic moment of the muon. (C) 2013 Elsevier B.V. All rights reserved.

Published
2013
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11. Investigation of the dd -> (3)Hen pi(0) reaction with the FZ Julich WASA-at-COSY facility

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HANHART, C, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KRAPP, M, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LERSCH, D, LI, L, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PLUCINSKI, P, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHMIDT, A, SCHADMAND, S, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TOLBA, T, TRZCINSKI, A, VARMA, R, WAGNER, GJ, WEGLORZ, W, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUAN, X, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Threshold, Quark Masses
Abstract

An exclusive measurement of the dd -> (3)Hen pi(0) reaction was carried out at a beam momentum of p(d) = 1.2 GeV/c using the WASA-at-COSY facility. Information on the total cross section as well as differential distributions was obtained. The data are described by a phenomenological approach based on a combination of a quasifree model and a partial wave expansion for the three-body reaction. The total cross section is found to be sigma(tot) = ( 2.89 +/- 0.01(stat) +/- 0.06(sys) +/- 0.29(norm)) mu b. The contribution of the quasifree processes ( with the beam or target neutron being a spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of phase space. The remaining part of the cross section can be described by a partial wave decomposition indicating the significance of p-wave contributions in the final state.

Published
2013
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12. Search for eta-mesic He-4 with the WASA-at-COSY detector

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BEDNARSKI, T, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BUSCHER, M, CALEN, H, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KRAPP, M, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LERSCH, D, LI, L, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, NIEDZWIECKI, S, OHM, H, OZERIANSKA, I, DEL RIO, EP, PLUCINSKI, P, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TOLBA, T, TRZCINSKI, A, VARMA, R, VLASOV, P, WAGNER, GJ, WEGLORZ, W, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Photoproduction, Mesons, Bound-States, Nuclei
Abstract

An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively. DOI: 10.1103/PhysRevC.87.035204

Published
2013

13. Measurement of the pn -> pp pi(0)pi(-) reaction in search for the recently observed resonance structure in d pi(0)pi(0) and d pi(+)pi(-) systems

Author

ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KRAPP, M, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LERSCH, D, LI, L, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PLUCINSKI, P, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHMIDT, A, SCHADMAND, S, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TOLBA, T, TRZCINSKI, A, VARMA, R, WAGNER, GJ, EGLORZ, WW, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUAN, X, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M

Subjects
Roper Resonance, Proton-Proton Collisions, Gev/C, Nucleon-Nucleon Collisions, Pi(0)Pi(0) Production, Meson Production, Double-Pion Production, Cross-Sections, Isospin Decomposition, Excitation
Abstract

Exclusive measurements of the quasifree pn -> pp pi(0)pi(-) reaction have been performed by means of pd collisions at T-p = 1.2 GeV using the wide angle shower apparatus (WASA) detector setup at the cooler synchrotron COSY (Institut fur Kernphysik, Julich). Total and differential cross sections have been obtained covering the energy region root s = (2.35-2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. NoABCeffect, i.e., low-mass enhancement is found in the pi(0)pi(-) -invariant mass spectrum, in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s wave. At the upper end of the covered energy region t-channel processes for Roper, Delta(1600) and Delta Delta excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at m = 2.37 GeV with Gamma = 70 MeV and I (J(P)) = 0(3(+)) observed recently in pn -> d pi(0)pi(0) and pn -> d pi(+)pi(-) reactions leads to an agreement with the data also at low energies.

Published
2013
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14. Exclusive measurement of the eta -> pi(+) pi(-) gamma decay

Author

ADLARSON, P, ADOLPH, C, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BEDNARSKI, T, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BRINKMANN, KT, BUSCHER, M, CALEN, H, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GRIGORYEV, K, GULLSTROM, CO, HANHART, C, HEIJKENSKJOLD, L, HEIMLICH, J, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JACEWICZ, M, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAKIMOVA, O, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KREN, F, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LEUPOLD, S, LORENTZ, B, MAGIERA, A, MAIER, R, MARIANSKI, B, MARCINIEWSKI, P, MEISSNER, UG, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, NIEDZWIECKI, S, OHM, H, PASSFELD, A, PAULY, C, DEL RIO, EP, PETRI, T, PETUKHOV, Y, PISKUNOV, N, PLUCINSKI, P, PODKOPAL, P, POVTOREYKO, A, PRASUHN, D, PRICKING, A, PYSZ, K, PYSZNIAK, A, RAUSMANN, T, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STERZENBACH, G, STOCKHORST, H, STOLLENWERK, F, STROHER, H, SZCZUREK, A, TASCHNER, A, TERSCHLUSEN, C, TOLBA, T, TRZCINSKI, A, VARMA, R, VLASOV, P, WAGNER, GJ, WEGLORZ, W, WINNEMOLLER, A, WIRZBA, A, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, and ZUPRANSKI, P

Subjects
Exclusive Measurement, Eta Meson, Box Anomaly
Abstract

An exclusive measurement of the decay eta -> pi(+) pi(-) gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd -> He-3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13 960 +/- 140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta -> pi(+) pi(-) gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi(+) pi(-) system. (C) 2011 Elsevier B.V All rights reserved.

Published
2012
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15. pi(0)pi(0) Production in proton-proton collisions at T-p=1.4 GeV The WASA-at-COSY Collaboration

Author

ADLARSON, P, ADOLPH, C, AUGUSTYNIAK, W, BASHKANOV, M, BEDNARSKI, T, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BRINKMANN, KT, BUSCHER, M, CALEN, H, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEIMLICH, J, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JACEWICZ, M, JANUSZ, M, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAKIMOVA, O, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KREN, F, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LORENTZ, B, MAGIERA, A, MAIER, R, MARIANSKI, B, MARCINIEWSKI, P, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, NIEDZWIECKI, S, OHM, H, PASSFELD, A, PAULY, C, DEL RIO, EP, PETUKHOV, Y, PISKUNOV, N, PLUCINSKI, P, PODKOPAL, P, POVTOREYKO, A, PRASUHN, D, PRICKING, A, PYSZ, K, RAUSMANN, T, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TOLBA, T, TRZCINSKI, A, VARMA, R, VLASOV, P, WAGNER, GJ, WEGLORZ, W, WIEDNER, U, WINNEMOLLER, A, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, and ZUPRANSKI, P

Subjects
Roper Resonance, Pion Production, Pp, Cross-Sections, 2-Pion Production, Excitation, Model
Abstract

The reaction pp -> pp pi(0)pi(0) has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 +/- 21(systematic) +/- 58(normalization)) mu b. In order to study the production mechanism, differential kinematic distributions have been evaluated. The differential distributions indicate that both initial state protons are excited into intermediate Delta(1232) resonances, each decaying into a proton and a single pion, thereby producing the pion pair in the final state. No significant contribution of the Roper resonance N*(1440) via its decay into a proton and two pions is found. (C) 2011 Elsevier B.V. All rights reserved.

Published
2012

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