1. Analysis of the exclusive final state npe$^+$e$^-$ in quasi-free np reaction
- Author
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HADES Collaboration, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, Amel, Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, 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., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kühn, 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., Mihaylov, D. M., Morinière, E., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Palka, M., Parpottas, Yiannis, Pechenov, V., Pechenova, O., Petousis, Vlassis, 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, Y. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tlusty, P., Traxler, M., Tsertos, Haralambos, Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., Sarantsev, A. V., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HADES, Institut de Physique Nucléaire d'Orsay ( IPNO ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), and Tsertos, Haralambos [0000-0001-5966-343X]
- Subjects
rho(770): production ,J.2 ,Proton ,Nuclear Theory ,01 natural sciences ,tagged beam ,pi: charged particle ,electron: pair production ,25.40.Ep ,excited state ,Invariant mass ,angular distribution ,Nuclear Experiment (nucl-ex) ,[ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex] ,Nuclear Experiment ,Monte Carlo ,Physics ,Bremsstrahlung ,pi: exchange ,deuteron: beam ,p n ,differential cross section ,Production (computer science) ,electron electron ,Nucleon ,inclusive production ,Nuclear and High Energy Physics ,p p: scattering ,13.40.Hq ,electron positron: mass spectrum ,FOS: Physical sciences ,final state ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,Kinetic energy ,bremsstrahlung ,Nuclear physics ,pi0: mass ,hydrogen: liquid: target ,Pion ,0103 physical sciences ,13.75.Cs ,010306 general physics ,numerical calculations ,energy: kinetic ,010308 nuclear & particles physics ,HADES ,particle identification ,Energy (signal processing) ,photon: virtual - Abstract
We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25 GeV/u inpinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of $e^+e^-$ pairs above the $\pi^{0}$ mass in the exclusive channel $dp \to npe^{+}e^{-}(p_{spect})$ as compared to the exclusive channel $ppe^{+}e^{-}$ measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double-$\Delta$ excitation combined with intermediate $\rho$-meson production. Differential cross sections as a function of the $e^+e^-$ invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical side., Comment: 12 pages, 7 figures
- Published
- 2017