Search

Your search keyword '"Gullstr��m, C. -O."' showing total 18 results
Start Over Author "Gullstr��m, C. -O."
18 results on '"Gullstr��m, C. -O."'

1. Search for $C$ violation in the decay $��\rightarrow��^0+e^++e^-$ with WASA-at-COSY

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-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., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., and Wirzba, A.

Subjects
High Energy Physics - Experiment (hep-ex), High Energy Physics::Phenomenology, Mathematics::Analysis of PDEs, FOS: Physical sciences
Abstract

We report on the investigation of the rare decay $��\rightarrow��^0+\text{e}^++\text{e}^-$ which is of interest to study both $C$ violation in the electromagnetic interaction and to search for 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 J��lich, Germany. In total $3\times10^7$ events of the reaction $\text{p}+\text{d}\rightarrow{^3\text{He}}+��$ have been recorded at an excess energy of $Q = 59.8\,\textrm{MeV}$. Based on this data set the $C$ parity violating decay $��\rightarrow��^0+��^*\rightarrow��^0+\textrm{e}^++\textrm{e}^-$ via a single-photon intermediate state has been searched for, resulting in new upper limits of $��\left(��\rightarrow��^0+\textrm{e}^++\textrm{e}^-\right)/ ��\left(��\rightarrow��^++��^-+��^0\right) < 3.28\times10^{-5}$ and $��\left(��\rightarrow��^0+\textrm{e}^++\textrm{e}^-\right)/ ��\left(��\rightarrow\textrm{all}\right) < 7.5\times10^{-6}\ (\textrm{CL} = 90\,\%)$, respectively., 7 pages, 8 figures, submitted to PLB

Published
2018
Full Text
View/download PDF

2. Backward single-pion production in the $\boldsymbol{pd\rightarrow {}^3\textrm{He}\,��^0}$ reaction with WASA-at-COSY

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. --P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-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., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., and Wilkin, C.

Subjects
Nuclear Theory (nucl-th), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

New data on the production of single neutral pions in the $pd\rightarrow{}^3\textrm{He}\,��^0$ reaction are presented. For fifteen proton beam momenta between $p_p=1.60\;\textrm{GeV}/c$ and $p_p=1.74\;\textrm{GeV}/c$, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum., 9 pages, 5 figures, 3 tables submitted to EPJA

Published
2018
Full Text
View/download PDF

3. Total and differential cross sections of $��$-production in proton-deuteron fusion for excess energies between $Q_��=13\;\text{MeV}$ and $Q_��=81\;\text{MeV}$

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawanta, S., Schadmand, S., Sch��tti-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., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., and Wilkin, C.

Subjects
Nuclear Theory (nucl-th), Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

New data on both total and differential cross sections of the production of $��$ mesons in proton-deuteron fusion to ${}^3\text{He}\,��$ in the excess energy region $13.6\;\text{MeV}\leq Q_��\leq 80.9\;\text{MeV}$ are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum J��lich, using a proton beam at 15 different beam momenta between $p_p = 1.60\;\text{GeV}/c$ and $p_p = 1.74\;\text{GeV}/c$. While significant structure of the total cross section is observed in the energy region $20\;\text{MeV}\lesssim Q_��\lesssim 60\;\text{MeV}$, a previously reported sharp variation around $Q_��\approx 50\;\text{MeV}$ cannot be confirmed. Angular distributions show the typical forward-peaking that was reported elsewhere. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a large interval., 8 pages, 7 figures, preprint submitted to Physics Letters B

Published
2018
Full Text
View/download PDF

4. Importance of d-wave contributions in the charge symmetry breaking reaction $dd \to {}^4\text{He}��^0$

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-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., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction $dd \to {}^4\text{He}��^0$ using the WASA-at-COSY detector setup at an excess energy of $Q = 60$ MeV. The determined differential cross section can be parametrized as $\text{d}��/\text{d}��= a + b\cos^{2}��^*$, where $��^*$ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are $a = \left(1.55 \pm 0.46 (\text{stat}) ^{+0.32}_{-0.8} (\text{syst}) \right)$ pb/sr and $b = \left(13.1 \pm 2.1 (\text{stat}) ^{+1.0}_{-2.7} (\text{syst})\right)$ 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 $��$ isobar to the $dd \to {}^4\text{He}��^0$ reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions., 5 figures

Published
2017
Full Text
View/download PDF

5. Measurement of the $\vec{n}p \to d��^0��^0$ Reaction with Polarized Beam in the Region of the $d^*(2380)$ Resonance

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Calen, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lawani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, . P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., del Rio, E. Perez, Piskunov, N. M., Prashun, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti--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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

We report on a high-statistics measurement of the most basic double pionic fusion reaction $\vec{n}p \to d��^0��^0$ 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
Full Text
View/download PDF

6. Measurement of the $��\to ��^+ ��^- ��^0$ Dalitz plot distribution

Author

COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-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., Str��her, H., Szczurek, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., Kubis, B., and Leupold, S.

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Using the production reactions $pd\to {}^3\mbox{He}\,��$ and $pp\to pp��$, the Dalitz plot distribution for the $��\to ��^+ ��^- ��^0$ decay is studied with the WASA detector at COSY, based on a combined data sample of $ (4.408\pm 0.042) \times 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 $��$. For the first time, a deviation from pure $P$-wave phase space is observed with a significance of $4.1��$. The deviation is parametrised by a linear term $1+2��Z$, with $��$ determined to be $+0.147\pm0.036$, consistent with the expectations of $��$-meson-type final-state interactions of the $P$-wave pion pairs., 8 pages, 7 figures

Published
2016
Full Text
View/download PDF

7. Measurements of Branching Ratios for $��$ Decays into Charged Particles

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., 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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wiedner, U., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The WASA-at-COSY experiment has collected $3\times10^{7}$ events with $��$-mesons produced via the reaction $pd\rightarrow{^{3}\textrm{He}}��$ at $\textrm{T} = 1.0 \textrm{GeV}$. Using this data set, we evaluate the branching ratios of the decays $��\to��^{+}��^{-}��$, $��\to e^{+}e^{-}��$, $��\to��^{+}��^{-}e^{+}e^{-}$ and $��\to e^{+}e^{-}e^{+}e^{-}$. The branching ratios are normalized to the $��\rightarrow��^{+}��^{-}��^{0}$ decay. In addition an upper limit on a $CP$-violating asymmetry in $��\rightarrow ��^{+}��^{-}e^{+}e^{-}$ is extracted.

Published
2015
Full Text
View/download PDF

8. ABC effect and resonance structure in the double-pionic fusion to $^{3}He$

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, 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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, High Energy Physics - Experiment
Abstract

Exclusive and kinematically complete measurements of the double pionic fusion to $^{3}He$ 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 Jülich). Similar to the observations in the basic $pn \rightarrow d \pi^{0} \pi^{0}$ reaction and in the $dd \rightarrow ^{4} He \pi^{0} \pi^{0}$ 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 $d^{\ast}$ resonance formation during the reaction process in addition to the conventional t-channel $\Delta \Delta$ mechanism. The deduced $d^{\ast}$ 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 $np \to np��^0��^0$ Reaction in Search for the Recently Observed $d^*(2380)$ Resonance

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, 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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

Exclusive measurements of the quasi-free $np \to np��^0��^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated $d^*(2380)$ resonance. Adding the $d^*$ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of F��ldt and Wilkin as well Albadajedo and Oset. The ABC effect, {\it i.e.} the low-mass enhancement in the $��^0��^0$-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.

Published
2014
Full Text
View/download PDF

10. Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hodana, M., H��istad, B., H��sken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., K��os, B., Kleines, H., Krapp, M., Krzemie��, W., Kulessa, P., Kup����, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., Passfeld, A., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

We present new data for angular distributions and on the cross section ratio of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q = 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum J��lich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between Q = 20 MeV and Q = 60 MeV, which might indicate the variation of the production mechanism within this energy interval., 9 pages, 9 figures

Published
2014
Full Text
View/download PDF

11. Charge Symmetry Breaking in dd->4He��0 with WASA-at-COSY

Author

COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., 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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He��0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production., 14 pages, 5 figures

Published
2014
Full Text
View/download PDF

12. Measurement of the $��\to��^+��^-��^0$ Dalitz plot distribution

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hodana, M., H��istad, B., H��sken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Martemyanov, B. V., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., 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., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Dalitz plot distribution of the $��\to��^+��^-��^0$ decay is determined using a data sample of $1.2\cdot 10^7$ $��$ mesons from $pd\to ^3\textrm{He}��$ reaction at 1 GeV collected by the WASA detector at COSY., 13 pages, 6 figures

Published
2014
Full Text
View/download PDF

13. Measurement of the $pn \to pp��^0��^-$ Reaction in Search for the Recently Observed Resonance Structure in $d��^0��^0$ and $d��^+��^-$ systems

Author

Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup����, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., 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., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Exclusive measurements of the quasi-free $pn \to pp��^0��^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, {\it i.e.} low-mass enhancement is found in the $��^0��^-$-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, $��(1600)$ and $����$ 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 $��$ =~70 MeV and $I(J^P)=~0(3^+)$ observed recently in $pn \to d��^0��^0$ and $pn \to d��^+��^-$ reactions leads to an agreement with the data also at low energies.

Published
2013
Full Text
View/download PDF

14. Investigation of the dd -> 3He n ��0 reaction with the FZ J��lich WASA-at-COSY facility

Author

COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup����, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., 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., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

An exclusive measurement of the dd -> 3He n ��0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. The data are described with a phenomenological approach based on a combination of a quasi-free model and a partial wave expansion for three-body reaction. The total cross section is found to be ��(tot) = (2.89 +- 0.01(stat) +- 0.06(sys) +- 0.29(norm)) ��b. The contribution of the quasi-free processes (with the neutron being target or beam spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of the phase space. The remaining part of the cross section can be described within a partial wave decomposition indicating the significance of p-wave contributions in the final state., 9 pages, 7 figures

Published
2013
Full Text
View/download PDF

15. Search for a dark photon in the $��^0 \to e^+e^-��$ decay

Author

COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup����, A., Kuzmin, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., 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., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wirzba, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.

Subjects
High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The presently world largest data sample of pi0 --> gamma e+e- decays containing nearly 5E5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay from the pp-->pp��^0 reaction was carried out. An upper limit on the square of the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained for the mass range 20 MeV, 16 pages, 8 figures; improved analysis extending the exclusion region to 20 MeV

Published
2013
Full Text
View/download PDF

16. ��^0 ��^0 Production in Proton-Proton Collisions at Tp=1.4 GeV

Author

Adlarson, P., Adolph, C., Augustyniak, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Ber��owski, M., Bhatt, H., Brinkmann, K. --T., B��scher, M., Cal��n, H., Clement, H., Coderre, D., Czerwi��ski, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryevj, K., Gullstr��m, C. --O., Heijkenskj��ld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jacewicz, M., Janusz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Kren, F., Krzemie��, W., Kulessa, P., Kup����, A., Lalwani, K., Lorentz, B., Machner, H., Magiera, A., Maier, R., Maria��ski, B., Marciniewski, P., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Nied��wiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petukhov, Y., Piskunov, N., Pluci��ski, P., Podkopa��, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., 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., Szczurek, A., T��schner, A., Tolba, T., Trzci��ski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Wiedner, U., Winnem��ller, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., and Zupra��ski, P.

Subjects
High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The reaction pp->pppi0pi0 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) mub. In order to to study the production mechanism, differential kinematical 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, Submitted to PLB

Published
2011
Full Text
View/download PDF

17. Exclusive Measurement of the eta --> pi+ pi- gamma Decay

Author

Adlarson, P., Adolph, C., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Ber��owski, M., Bhatt, H., Brinkmann, K. -T., B��scher, M., Cal��n, H., Clement, H., Coderre, D., Czerwi��ski, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jacewicz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Kren, F., Krzemie��, W., Kulessa, P., Kup����, A., Lalwani, K., Leupold, S., Lorentz, B., Magiera, A., Maier, R., Maria��ski, B., Marciniewski, P., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Nied��wiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petri, T., Petukhov, Y., Piskunov, N., Pluci��ski, P., Podkopa��, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Rausmann, T., Redmer, C. F., 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., Szczurek, A., T��schner, A., Terschl��sen, C., Tolba, T., Trzci��ski, A., Varma, R., Vlasov, P., Wagner, G. J., W��glorz, W., Winnem��ller, A., Wirzba, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., and ��upra��ski, P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
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 --> 3He X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13340\pm140 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., 7 pages, 10 figures, submitted to Phys.Lett.B

Published
2011
Full Text
View/download PDF

18. Predictions for the cusp in eta->3pi0 decay

Author

Gullstr��m, C. -O., Kup����, A., and Rusetsky, A.

Subjects
High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences
Abstract

A realistic estimate of the cusp effect in the eta->3pi0 decay is required for the forthcoming high precision experiments. The predictions for the size of this effect are given within the framework of nonrelativistic effective field theory., 4 pages, 4 figures

Published
2008
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results