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Start Over Author "K��mpfer, B." Topic fos: physical sciences
22 results on '"K��mpfer, B."'

1. Directed, elliptic and higher order flow harmonics of protons, deuterons and tritons in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV

Author

HADES Collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., B��hmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepal, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Golosov, O., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mamaev, M., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Nowakowski, K., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Str��bele, H., Stroth, J., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., W��jcik, D., Zanevsky, Y., and Zumbruch, P.

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

Flow coefficients $v_{n}$ of the orders $n = 1 - 6$ are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a multi-differential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation-of-state of dense baryonic matter., 6 pages, 5 figures; Figs. 2, 3 and 5 updated from re-analysis of data including UrQMD model predictions. Plotting error in Fig. 4 corrected; Accepted for publication in Phys. Rev. Lett

Published
2020

2. Charged pion production in $\mathbf{Au+Au}$ collisions at $\mathbf{\sqrt{s_{NN}}}$ = 2.4$\mathbf{GeV}$

Author

Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Boehmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepal, I., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Glaessel, S., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Muentz, C., Muenzer, R., Naumann, L., Nowakowski, K., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rathod, N., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Stroebele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wojcik, D., Zanevsky, Y., and Zumbruch, P.

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

We present high-statistic data on charged pion emission from Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 2.4 GeV (corresponding to $E_{beam}$ = 1.23 A GeV) in four centrality classes in the range 0 - 40$\%$ of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the world data, but undershoot by $2.5 \sigma$ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations., Comment: 17 pages, 19 figures, 4 tables

Published
2020

3. Two-Pion production in the second resonance region in $��^- p$ collisions with HADES

Author

Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., B��hmer, M., Chernenko, S., Chlad, L., Chudoba, P., Ciepa��, I., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kubo��, J., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Nowakowski, K., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Prozorov, A. P., Przygoda, W., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sing, U., Smyrski, J., Spataro, S., Spies, S., Str��bele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Ungeth��m, C., Vazquez-Doce, O., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., W��jcik, D., Zanevsky, Y., and Zumbruch, P.

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

Pion induced reactions provide unique opportunities for an unambiguous description of baryonic resonances and their coupling channels by means of a partial wave analysis. Using the secondary pion beam at SIS18, the two pion production in the second resonance region has been investigated to unravel the role of the $N(1520) \frac{3}{2}^-$ resonance in the intermediate $��$ production. Results on exclusive channels with one pion ($��^{-}p$) and two pions ($��^{+}��^{-}n$, $��^{0}��^{-}p$) in the final state measured in the $��^{-}-p$ reaction at four different pion beam momenta (0.650, 0.685, 0.733, and 0.786 GeV/c) are presented. The excitation function of the different partial waves and $����$, $N��$ and $N��$ isobar configurations is obtained, using the Bonn-Gatchina partial wave analysis. The $N(1520) \frac{3}{2}^-$ resonance is found to dominate the $N��$ final state with the branching ratio $BR=12.2 \pm 1.9\%$.

Published
2020
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4. Pseudo-scalar {\boldm $ q\bar q $} bound states at finite temperatures within a Dyson-Schwinger--Bethe-Salpeter approach

Author

Dorkin, S. M., Kaptari, L. P., and K��mpfer, B.

Subjects
Nuclear Theory (nucl-th), Nuclear Theory, High Energy Physics::Lattice, High Energy Physics::Phenomenology, FOS: Physical sciences
Abstract

The combined Dyson-Schwinger--Bethe-Salpeter equations are employed at non-zero temperature. The truncations refer to a rainbow-ladder approximation augmented with an interaction kernel which facilitates a special temperature dependence. At low temperatures, $T \to 0$, we recover a quark propagator from the Dyson-Schwinger (gap) equation which delivers, e.g. mass functions $B$, quark renormalization wave function $A$, and two-quark condensate $\la q \bar q \ra$ smoothly interpolating to the $T = 0$ results, despite the broken O(4) symmetry in the heat bath and discrete Matsubara frequencies. Besides the Matsubara frequency difference entering the interaction kernel, often a Debye screening mass term is introduced when extending the $T = 0$ kernel to non-zero temperatures. At larger temperatures, however, we are forced to drop this Debye mass in the infra-red part of the longitudinal interaction kernel to keep the melting of the two-quark condensate in a range consistent with lattice QCD results. Utilizing that quark propagator for the first few hundred fermion Matsubara frequencies we evaluate the Bethe-Salpeter vertex function in the pseudo-scalar $ q \bar q$ channel for the lowest boson Matsubara frequencies and find a competition of $ q \bar q$ bound states and quasi-free two-quark states at $T = {\cal O}$ (100 MeV). This indication of pseudo-scalar meson dissociation below the anticipated QCD deconfinement temperature calls for an improvement of the approach, which is based on an interaction adjusted to the meson spectrum at $T = 0$., 39 pages, 6 figures

Published
2018

5. Sub-threshold production of K^{0}_{s} mesons and �� hyperons in Au(1.23A GeV)+Au

Author

HADES Collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., B��hmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garzon, J. A., Gernh��user, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Str��bele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., and Leifels, Y.

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

We present first data on sub-threshold production of K0 s mesons and �� hyperons in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We observe an universal scaling of hadrons containing strangeness, independent of their corresponding production thresholds. Comparing the yields, their scaling, and the shapes of the rapidity and the pt spectra to state-of-the-art transport model (UrQMD, HSD, IQMD) predictions, we find that none of the latter can simultaneously describe all observables with reasonable \c{hi}2 values., 8 pages, 10 figures

Published
2018
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6. Deep sub-threshold �� production and implications for the K+/K- freeze-out in Au+Au collisions

Author

Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., B��hmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garzon, J. A., Gernh��user, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcy, G., Kornakov, G., Kotte, R., K��hn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Str��bele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., and Zumbruch, P.

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

We present data on charged kaons (K+-) and �� mesons in Au(1.23A GeV)+Au collisions. It is the first simultaneous measurement of K and �� mesons in central heavy-ion collisions below a kinetic beam energy of 10A GeV. The ��/K- multiplicity ratio is found to be surprisingly high with a value of 0.52 +- 0.16 and shows no dependence on the centrality of the collision. Consequently, the different slopes of the K+ and K- transverse-mass spectra can be explained solely by feed- down, which substantially softens the spectra of K- mesons. Hence, in contrast to the commonly adapted argumentation in literature, the different slopes do not necessarily imply diverging freeze- out temperatures of K+ and K- mesons caused by different couplings to baryons., Corrected and updated version, 28 November 2017

Published
2017
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7. $��$(1232) Dalitz decay in proton-proton collisions at T=1.25 GeV measured with HADES

Author

Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., B��hmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Finocchiaro, P., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., K��hn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Morini��re, E., Mihaylov, D. M., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Str��bele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., and Sarantsev, A. V.

Subjects
J.2, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

We report on the investigation of $��$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $ppe^{+}e^{-}$ and $ppe^{+}e^{-}��$ have been studied and compared with the partial wave analysis of the hadronic $pp��^{0}$ channel. They allow to access both $��^+ \to p��^0(e^+e^-��)$ and $��^+ \to pe^+e^-$ Dalitz decay channels. The perfect reconstruction of the well known $��^0$ Dalitz decay serves as a proof of the consistency of the analysis. The $��$ Dalitz decay is identified for the first time and the sensitivity to N-$��$ transition form factors is tested. The $��$(1232) Dalitz decay branching ratio is also determined for the first time; our result is (4.19 $\pm$ 0.62 syst. $\pm$ 0.34 stat.) $\times $ 10$^{-5}$, albeit with some model dependence., 13 pages, 7 figures

Published
2017
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8. Inclusive �� production in proton-proton collisions at 3.5 GeV

Author

Adamczewski-Musch, J., Agakishiev, G., Arnold, O., Atomssa, E. T., Behnke, C., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., B��hmer, M., Bordalo, P., Chernenko, S., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gill, K., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Hennino, T., Hlavac, S., H��hne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kr��sa, A., Krebs, E., Kuc, H., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Maurus, S., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Morozov, S., M��ntz, C., M��nzer, R., Naumann, L., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petousis, V., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Rehnisch, L., Reshetin, A., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataroe, S., Str��bele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Wendisch, C., Wirth, J., Zanevsky, Y., and Zumbruch, P.

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

The inclusive production of �� hyperons in proton-proton collisions at $\sqrt{s}$ = 3.18 GeV was measured with HADES at the GSI Helmholtzzentrum f��r Schwerionenforschung in Darmstadt. The experimental data are compared to a data-based model for individual exclusive �� production channels in the same reaction. The contributions of intermediate resonances such as ��(1385), ��++ or N* are considered in detail. In particular, the result of a partial wave analysis is accounted for the abundant pK$^+$�� final state. Model and data show a reasonable agreement at mid rapidities, while a difference is found for larger rapidities. A total �� production cross section in p+p collisions at $\sqrt{s}$ = 3.18 GeV of ��(pp $\to$ �� + X) = 207.3 $\pm$ 1.3 +6.0 -7.3 (stat.) $\pm$ 8.4 (syst.) +0.4 -0.5 (model) ��b is found., 12 pages, 6 figures

Published
2016
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9. Statistical model analysis of hadron yields in proton-nucleus and heavy-ion collisions at SIS 18 energies

Author

Agakishiev, G., Arnold, O., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., B��hmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garzon, J. A., Gernh��user, R., Gilardi, C., G��bel, K., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Kr��cken, R., Kuc, H., K��hn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lange, J. S., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., M��ntz, C., M��nzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Rehnisch, L., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmah, A., Schuldes, H., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., W��stenfeld, J., Yurevich, S., and Zanevsky, Y.

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

The HADES data from p+Nb collisions at center of mass energy of $\sqrt{s_{NN}}$= 3.2 GeV are analyzed by employing a statistical model. Accounting for the identified hadrons $\pi^0$, $\eta$, $\Lambda$, $K^{0}_{s}$, $\omega$ allows a surprisingly good description of their abundances with parameters $T_{chem}=(99\pm11)$ MeV and $\mu_{b}=(619\pm34)$ MeV, which fits well in the chemical freeze-out systematics found in heavy-ion collisions. In supplement we reanalyze our previous HADES data from Ar+KCl collisions at $\sqrt{s_{NN}}$= 2.6 GeV with an updated version of the statistical model. We address equilibration in heavy-ion collisions by testing two aspects: the description of yields and the regularity of freeze-out parameters from a statistical model fit. Special emphasis is put on feed-down contributions from higher-lying resonance states which have been proposed to explain the experimentally observed $\Xi^-$ excess present in both data samples.

Published
2015

10. Study of the quasi-free $np \to np ��^+��^-$ reaction with a deuterium beam at 1.25 GeV/nucleon

Author

Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., B��hmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., D��az, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Gil, A., Gilardi, C., G��bel, K., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kr��cken, R., K��hn, W., Kugler, A., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morini��re, E., Mousa, J., M��ntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Vasiliev, T., Weber, M., Wisniowski, M., Wojcik, T., W��stenfeld, J., Yurevich, S., Zanevsky, Y., and Zhou, P.

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

The tagged quasi-free $np \to np��^+��^-$ reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon ($\sqrt s \sim$ 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions for $��^{+}��^{-}$ production in $np$ collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the $np\rightarrow np��^{+}��^{-}$ reaction are compared with different models. This comparison confirms the dominance of the $t$-channel with $����$ contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the $��^{+}��^{-}$ invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M$\sim$ 2.38 GeV and with width $��\sim$ 70 MeV.

Published
2015
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11. Partial Wave Analysis of the Reaction $p(3.5 GeV)+p \to pK^+��$ to Search for the '$ppK^-$' Bound State

Author

Agakishiev, G., Arnold, O., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., B��hmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., G��bel, K., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Kr��cken, R., Kuc, H., K��hn, W., Kugler, A., Kunz, T., Kurepin, A., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michel, J., M��ntz, C., M��nzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., W��stenfeld, J., Yurevich, S., Zanevsky, Y., and Sarantsev, A. V.

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

Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction $p(3.5GeV)+p\to pK^{+}��$. This reaction might contain information about the kaonic cluster "$ppK^-$" via its decay into $p��$. Due to interference effects in our coherent description of the data, a hypothetical $\overline{K}NN$ (or, specifically "$ppK^-$") cluster signal must not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectra like $p��$. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a $\overline{K}NN$ cluster. At a confidence level of CL$_{s}$=95\% such a cluster can not contribute more than 2-12\% to the total cross section with a $pK^{+}��$ final state, which translates into a production cross-section between 0.7 $��b$ and 4.2 $��b$, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process., 7 Pages, 5 Figures

Published
2014
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12. pK+��final state: towards the extraction of the ppK- contribution

Author

Fabbietti, L., Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Berger-Chen, J-C, Blanco, A., B��hmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Eberl, T., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garzon, J. A., Gernh��user, R., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krasa, A., Krizek, F., Kr��cken, R., Kuc, H., K��hn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., M��ntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, A. Solaguren-Beascoa Negre S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., W��stenfel, J., Yurevich, S., and Zanevsky, Y. V.

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

The reaction p(@3.5\,GeV)+p -> p+��+ K^+ can be studied to search for the existence of kaonic bound states like ppK^- leading to this final state. This effort has been motivated by the assumption that in p+p collisions the ��(1405) resonance can act as a doorway to the formation of the kaonic bound states. The status of this analysis within the HADES collaboration, with particular emphasis on the comparison to simulations, is shown in this work and the deviation method utilized by the DISTO collaboration in a similar analysis is discussed. The outcome suggests the employment of a partial wave analysis to disentangle the different contributions to the measured pK^+��final state., 9 pages, 6 figures, proceeding of the HYP2012 conference Nucl. Phys. A (2013)

Published
2013
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13. Determination of the $\mathbf{��(1385)^{0}/��(1405)}$ ratio in p+p collisions at 3.5 GeV

Author

Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., B��hmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chen, J. C., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Gilardi, C., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kr��sa, A., Krizek, F., Kr��cken, R., Kuc, H., K��hn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morini��re, E., Mousa, J., M��ntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., W��stenfeld, J., Yurevich, S., and Zanevsky, Y. V.

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

The aim of the present analysis is to determine the relative production cross sections of the $��$(1405) and $��(1385)^{0}$ resonances in p+p collisions at E$_{kin}$=3.5 GeV measured with HADES. Upper and lower limits have been determined for the ratio $��_{(��(1385)^{0}+p+K^{+})}/��_{(��(1405)+p+K^{+})}=0.76_{-0.26}^{+0.54}$. The knowledge of this ratio is an essential input for the analysis of the decay $��(1405)\rightarrow��^{\pm}��^{\mp}$, where an unambiguous separation of the $��$(1405) and $��(1385)^{0}$ signals is not possible.

Published
2012
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14. Single and double pion production in np collisions at 1.25 GeV with HADES

Author

The HADES Collaboration, Kurilkin, A. K., Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Blanco, A., B��hmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., D��az, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gil, A., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Hennino, T., Holzmann, R., Huck, P., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kopp, A., Korcyl, G., Kornakov, GK., Kotte, R., Kozuch, A., Kr��sa, A., Krizek, F., Kr��cken, R., Kuc, H., K��hn, W., Kugler, A., Kurepin, A., Kurilkin, P., Khlitz, P., Ladygin, V., Lamas-Valverde, J., Lang, S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., M��ntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roskoss, J., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Siebenson, J., Sobolev, Yu. G., Spataro, S., Str��bele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., W��stenfeld, J., Yurevich, S., Zanevsky, Y., Heurteau, Sophie, Institut de Physique Nucléaire d'Orsay (IPNO), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The preliminary results on charged pion production in np collisions at an incident beam energy of 1.25 GeV measured with HADES are presented. The np reactions were isolated in dp collisions at 1.25 GeV/u using the Forward Wall hodoscope, which allowed to register spectator protons. The results for np -> pppi-, np -> nppi+pi- and np -> dpi+pi- channels are compared with OPE calculations. A reasonable agreement between experimental results and the predictions of the OPE+OBE model is observed., 6 pages, 6 figures, conference proceeding: The XX International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", JINR, Dubna, Russia, October 4-9, 2010

Published
2011

15. Lambda-p femtoscopy in collisions of Ar+KCl at 1.76 AGeV

Author

Agakishiev, G., Balanda, A., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., B��hmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., D��az, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Gil, A., Gilardi, C., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kr��cken, R., K��hn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Morini��re, E., Mousa, J., M��ntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wojcik, T., W��stenfeld, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

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

Results on $\Lambda$p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76A~GeV, the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of $\Lambda$ p correlations at small relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the $\Lambda$p emission source. The $\Lambda$p source radius is found slightly smaller than the pp correlation radius for a similar collis ion system. The present $\Lambda$p radius is significantly smaller than that found for Au+Au/Pb+Pb collisio ns in the AGS, SPS and RHIC energy domains, but larger than that observed for electroproduction from He. Taking into account all available data, we find the $\Lambda$p source radius to increase almost linearly with the number of participants to the power of one-third., Comment: 5 pages, 3 figures, submitted to Phys. Rev. C

Published
2010

16. Deep sub-threshold $��^-$ production in Ar+KCl reactions at 1.76A GeV

Author

Agakishiev, G., Balanda, A., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., B��hmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., D��az, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Gil, A., Gilardi, C., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kr��cken, R., K��hn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Morini��re, E., Mousa, J., M��ntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Str��bele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., W��stenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

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

We report first results on a deep sub-threshold production of the doubly strange hyperon $��^-$ in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $��$ sample was collected, allowing for the investigation of the decay channel $��^- \to ����^-$. The deduced $��^-/(��+��^0)$ production ratio of $(5.6 \pm 1.2 ^{+1.8}_{-1.7})\cdot 10^{-3}$ is significantly larger than available model predictions., 4 pages, including 4 figures

Published
2009
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17. Theta+ formation in inclusive gamma D -> pK- X

Author

Titov, A. I., K��mpfer, B., Dat��, S., and Ohashi, Y.

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

We analyze the possibility to produce an intermediate Theta^+ via a KN->��+ formation process in gamma D-> pK^- X (X=nK^+,pK^0) reactions at some specific kinematical conditions, in which a pK^- pair is knocked out in the forward direction and its invariant mass is close to the mass of Lambda(1520). The ��^+ signal may appear in the [��D,pK^-] missing mass distribution. The ratio of the signal (cross section at the ��^+ peak position) to the smooth background processes varies from 0.7 to 2.5 depending on the spin and parity of Theta+, and it decreases correspondingly if the pK^- invariant mass is outside of the Lambda(1520)-resonance region. We analyze the recent CLAS search for the Theta+ in the gamma D ->pK^-nK^+ reaction and show that the conditions of this experiment greatly reduce the Theta+ formation process making it difficult to extract a Theta+ peak from the data., 40 pageg, 26 figures

Published
2006
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18. Production of ��Mesons in Near-Threshold ��N and N N Reactions

Author

Titov, A. I., K��mpfer, B., and Reznik, B. L.

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

We analyze the production of $��$ mesons in $��N$ and NN reactions in the near-threshold region, using throughout the conventional ``non-strange'' dynamics based on such processes which are allowed by the non-ideal $��-��$ mixing. We show that the occurrence of the direct $��NN$ interaction may show up in different unpolarized and polarization observables in $��N\to N��$ reactions. We find a strong non-trivial difference between observables in the reactions $pp\to pp��$ and $pn\to pn��$ caused by the different role of the spin singlet and triplet states in the entrance channel. A series of predictions for the experimental study of this effect is presented., 35 pages including 18 figures

Published
2000
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19. Is there a unique thermal dilepton source in the reactions Pb(158 AGeV) + Au, Pb?

Author

Gallmeister, K., K��mpfer, B., and Pavlenko, O. P.

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

An analysis of the dilepton measurements of the reactions Pb(158 A$\cdot$GeV) + Au, Pb by the CERES and NA50 collaborations points to a unique thermal source contributing to the invariant mass and transverse momentum spectra., 7 LaTeX pages including eps figures

Published
1999

20. Thermodynamics of the ��^4 theory in tadpole approximation

Author

Peshier, A., K��mpfer, B., Pavlenko, O. P., and Soff, G.

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

Relying on the Luttinger-Ward theorem we derive a thermodynamically selfconsistent and scale independent approximation of the thermodynamic potential for the scalar $��^4$ theory in the tadpole approximation. The resulting thermodynamic potential as a function of the temperature is similar to the one of the recently proposed screened perturbation theory., 6 pages, including 1 eps figure

Published
1998
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21. The reaction NN \to NN ��near threshold

Author

Titov, A. I., K��mpfer, B., and Shklyar, V. V.

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

The sensitivity of polarization observables in the reaction $NN \to NN ��$ slightly above the threshold is studied with respect to the details of the one-boson exchange model and a possible admixture of hidden strangeness in the nucleon. It is shown that the finite-energy predictions differ strongly from the threshold predictions. A measurement of the beam - target asymmetry and the $��$ decay anisotropy can help to disentangle the role of various reaction mechanisms., 19 LaTeX pages including eps figures

Published
1998
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22. Polarization observables in the reaction $NN \to NN ��$

Author

Titov, A. I., K��mpfer, B., and Shklyar, V. V.

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

We study the reaction $NN \to NN ��$ slightly above the threshold within an extended one-boson exchange model which also accounts for $uud$ knock-out. It is shown that polarization observables, like the beam-target asymmetry, are sensible quantities for identifying a $s \bar s$ admixture in the nucleon wave function on the few per cent level., 11 LaTeX pages including 4 ps figures

Published
1997
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