M. Thiel - A2 Collaboration at MAMI

M. Thiel
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M. Thiel
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A2 Collaboration at MAMI
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Nuclear Experiment (34)
 
High Energy Physics - Experiment (16)
 
Mathematics - Combinatorics (9)
 
Physics - Instrumentation and Detectors (4)
 
High Energy Physics - Phenomenology (4)
 
Physics - Materials Science (1)
 
Instrumentation and Methods for Astrophysics (1)
 
Nuclear Theory (1)
 
Quantitative Biology - Subcellular Processes (1)
 
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Publications Authored By M. Thiel

Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. Read More

The double polarization observable $E$ and the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost $4\pi$ detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0$. Read More

The reactions $\gamma p\to \eta p$ and $\gamma p\to \eta' p$ have been measured from their thresholds up to the center-of-mass energy $W=1.96$GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections were obtained with unprecedented accuracy, providing fine energy binning and full production-angle coverage. Read More

We report on a new experimental method based on initial-state radiation (ISR) in e-p scattering, in which the radiative tail of the elastic e-p peak contains information on the proton charge form factor ($G_E^p$) at extremely small $Q^2$. The ISR technique was validated in a dedicated experiment using the spectrometers of the A1-Collaboration at the Mainz Microtron (MAMI). This provided first measurements of $G_E^p$ for $0. Read More

For the first time a vertically polarized electron beam has been used for physics experiments at MAMI in the energy range between 180 and 855 MeV. The beam-normal single-spin asymmetry $A_{\mathrm{n}}$, which is a direct probe of higher-order photon exchange beyond the first Born approximation, has been measured in the reaction $^{12}\mathrm C(\vec e,e')^{12}\mathrm C$. Vertical polarization orientation was necessary to measure this asymmetry with the existing experimental setup. Read More

The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the pi^0 electromagnetic transition form factor, a_pi = 0.030+/-0. Read More

The scalar dipole polarizabilities, $\alpha_{E1}$ and $\beta_{M1}$, are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry $\Sigma_{3}$ in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. Read More

2016Oct
Authors: PANDA Collaboration, B. Singh, W. Erni, B. Krusche, M. Steinacher, N. Walford, H. Liu, Z. Liu, B. Liu, X. Shen, C. Wang, J. Zhao, M. Albrecht, T. Erlen, M. Fink, F. H. Heinsius, T. Held, T. Holtmann, S. Jasper, I. Keshk, H. Koch, B. Kopf, M. Kuhlmann, M. Kümmel, S. Leiber, M. Mikirtychyants, P. Musiol, A. Mustafa, M. Pelizäus, J. Pychy, M. Richter, C. Schnier, T. Schröder, C. Sowa, M. Steinke, T. Triffterer, U. Wiedner, M. Ball, R. Beck, C. Hammann, B. Ketzer, M. Kube, P. Mahlberg, M. Rossbach, C. Schmidt, R. Schmitz, U. Thoma, M. Urban, D. Walther, C. Wendel, A. Wilson, A. Bianconi, M. Bragadireanu, M. Caprini, D. Pantea, B. Patel, W. Czyzycki, M. Domagala, G. Filo, J. Jaworowski, M. Krawczyk, E. Lisowski, F. Lisowski, M. Michałek, P. Poznański, J. Płażek, K. Korcyl, A. Kozela, P. Kulessa, P. Lebiedowicz, K. Pysz, W. Schäfer, A. Szczurek, T. Fiutowski, M. Idzik, B. Mindur, D. Przyborowski, K. Swientek, J. Biernat, B. Kamys, S. Kistryn, G. Korcyl, W. Krzemien, A. Magiera, P. Moskal, A. Pyszniak, Z. Rudy, P. Salabura, J. Smyrski, P. Strzempek, A. Wronska, I. Augustin, R. Böhm, I. Lehmann, D. Nicmorus Marinescu, L. Schmitt, V. Varentsov, M. Al-Turany, A. Belias, H. Deppe, N. Divani Veis, R. Dzhygadlo, A. Ehret, H. Flemming, A. Gerhardt, K. Götzen, A. Gromliuk, L. Gruber, R. Karabowicz, R. Kliemt, M. Krebs, U. Kurilla, D. Lehmann, S. Löchner, J. Lühning, U. Lynen, H. Orth, M. Patsyuk, K. Peters, T. Saito, G. Schepers, C. J. Schmidt, C. Schwarz, J. Schwiening, A. Täschner, M. Traxler, C. Ugur, B. Voss, P. Wieczorek, A. Wilms, M. Zühlsdorf, V. Abazov, G. Alexeev, V. A. Arefiev, V. Astakhov, M. Yu. Barabanov, B. V. Batyunya, Y. Davydov, V. Kh. Dodokhov, A. Efremov, A. Fechtchenko, A. G. Fedunov, A. Galoyan, S. Grigoryan, E. K. Koshurnikov, Y. Yu. Lobanov, V. I. Lobanov, A. F. Makarov, L. V. Malinina, V. Malyshev, A. G. Olshevskiy, E. Perevalova, A. A. Piskun, T. Pocheptsov, G. Pontecorvo, V. Rodionov, Y. Rogov, R. Salmin, A. Samartsev, M. G. Sapozhnikov, G. Shabratova, N. B. Skachkov, A. N. Skachkova, E. A. Strokovsky, M. Suleimanov, R. Teshev, V. Tokmenin, V. Uzhinsky, A. Vodopianov, S. A. Zaporozhets, N. I. Zhuravlev, A. Zinchenko, A. G. Zorin, D. Branford, D. Glazier, D. Watts, M. Böhm, A. Britting, W. Eyrich, A. Lehmann, M. Pfaffinger, F. Uhlig, S. Dobbs, K. Seth, A. Tomaradze, T. Xiao, D. Bettoni, V. Carassiti, A. Cotta Ramusino, P. Dalpiaz, A. Drago, E. Fioravanti, I. Garzia, M. Savrie, V. Akishina, I. Kisel, G. Kozlov, M. Pugach, M. Zyzak, P. Gianotti, C. Guaraldo, V. Lucherini, A. Bersani, G. Bracco, M. Macri, R. F. Parodi, K. Biguenko, K. T. Brinkmann, V. Di Pietro, S. Diehl, V. Dormenev, P. Drexler, M. Düren, E. Etzelmüller, M. Galuska, E. Gutz, C. Hahn, A. Hayrapetyan, M. Kesselkaul, W. Kühn, T. Kuske, J. S. Lange, Y. Liang, V. Metag, M. Moritz, M. Nanova, S. Nazarenko, R. Novotny, T. Quagli, S. Reiter, A. Riccardi, J. Rieke, C. Rosenbaum, M. Schmidt, R. Schnell, H. Stenzel, U. Thöring, T. Ullrich, M. N. Wagner, T. Wasem, B. Wohlfahrt, H. G. Zaunick, E. Tomasi-Gustafsson, D. Ireland, G. Rosner, B. Seitz, P. N. Deepak, A. Kulkarni, A. Apostolou, M. Babai, M. Kavatsyuk, P. J. Lemmens, M. Lindemulder, H. Loehner, J. Messchendorp, P. Schakel, H. Smit, M. Tiemens, J. C. van der Weele, R. Veenstra, S. Vejdani, K. Dutta, K. Kalita, A. Kumar, A. Roy, H. Sohlbach, M. Bai, L. Bianchi, M. Büscher, L. Cao, A. Cebulla, R. Dosdall, A. Gillitzer, F. Goldenbaum, D. Grunwald, A. Herten, Q. Hu, G. Kemmerling, H. Kleines, A. Lai, A. Lehrach, R. Nellen, H. Ohm, S. Orfanitski, D. Prasuhn, E. Prencipe, J. Pütz, J. Ritman, S. Schadmand, T. Sefzick, V. Serdyuk, G. Sterzenbach, T. Stockmanns, P. Wintz, P. Wüstner, H. Xu, A. Zambanini, S. Li, Z. Li, Z. Sun, H. Xu, V. Rigato, L. Isaksson, P. Achenbach, O. Corell, A. Denig, M. Distler, M. Hoek, A. Karavdina, W. Lauth, Z. Liu, H. Merkel, U. Müller, J. Pochodzalla, S. Sanchez, S. Schlimme, C. Sfienti, M. Thiel, H. Ahmadi, S. Ahmed, S. Bleser, L. Capozza, M. Cardinali, A. Dbeyssi, M. Deiseroth, F. Feldbauer, M. Fritsch, B. Fröhlich, D. Kang, D. Khaneft, R. Klasen, H. H. Leithoff, D. Lin, F. Maas, S. Maldaner, M. Martínez, M. Michel, M. C. Mora Espí, C. Morales Morales, C. Motzko, F. Nerling, O. Noll, S. Pflüger, A. Pitka, D. Rodríguez Piñeiro, A. Sanchez-Lorente, M. Steinen, R. Valente, T. Weber, M. Zambrana, I. Zimmermann, A. Fedorov, M. Korjik, O. Missevitch, A. Boukharov, O. Malyshev, I. Marishev, V. Balanutsa, P. Balanutsa, V. Chernetsky, A. Demekhin, A. Dolgolenko, P. Fedorets, A. Gerasimov, V. Goryachev, V. Chandratre, V. Datar, D. Dutta, V. Jha, H. Kumawat, A. K. Mohanty, A. Parmar, B. Roy, G. Sonika, C. Fritzsch, S. Grieser, A. K. Hergemöller, B. Hetz, N. Hüsken, A. Khoukaz, J. P. Wessels, K. Khosonthongkee, C. Kobdaj, A. Limphirat, P. Srisawad, Y. Yan, A. Yu. Barnyakov, M. Barnyakov, K. Beloborodov, V. E. Blinov, V. S. Bobrovnikov, I. A. Kuyanov, K. Martin, A. P. Onuchin, S. Serednyakov, A. Sokolov, Y. Tikhonov, A. E. Blinov, S. Kononov, E. A. Kravchenko, E. Atomssa, R. Kunne, B. Ma, D. Marchand, B. Ramstein, J. van de Wiele, Y. Wang, G. Boca, S. Costanza, P. Genova, P. Montagna, A. Rotondi, V. Abramov, N. Belikov, S. Bukreeva, A. Davidenko, A. Derevschikov, Y. Goncharenko, V. Grishin, V. Kachanov, V. Kormilitsin, A. Levin, Y. Melnik, N. Minaev, V. Mochalov, D. Morozov, L. Nogach, S. Poslavskiy, A. Ryazantsev, S. Ryzhikov, P. Semenov, I. Shein, A. Uzunian, A. Vasiliev, A. Yakutin, U. Roy, B. Yabsley, S. Belostotski, G. Gavrilov, A. Izotov, S. Manaenkov, O. Miklukho, D. Veretennikov, A. Zhdanov, T. Bäck, B. Cederwall, K. Makonyi, M. Preston, P. E. Tegner, D. Wölbing, A. K. Rai, S. Godre, D. Calvo, S. Coli, P. De Remigis, A. Filippi, G. Giraudo, S. Lusso, G. Mazza, M. Mignone, A. Rivetti, R. Wheadon, A. Amoroso, M. P. Bussa, L. Busso, F. De Mori, M. Destefanis, L. Fava, L. Ferrero, M. Greco, J. Hu, L. Lavezzi, M. Maggiora, G. Maniscalco, S. Marcello, S. Sosio, S. Spataro, F. Balestra, F. Iazzi, R. Introzzi, A. Lavagno, J. Olave, R. Birsa, F. Bradamante, A. Bressan, A. Martin, H. Calen, W. Ikegami Andersson, T. Johansson, A. Kupsc, P. Marciniewski, M. Papenbrock, J. Pettersson, K. Schönning, M. Wolke, B. Galnander, J. Diaz, V. Pothodi Chackara, A. Chlopik, G. Kesik, D. Melnychuk, B. Slowinski, A. Trzcinski, M. Wojciechowski, S. Wronka, B. Zwieglinski, P. Bühler, J. Marton, D. Steinschaden, K. Suzuki, E. Widmann, J. Zmeskal, K. M. Semenov-Tian-Shansky

The exclusive charmonium production process in $\bar{p}p$ annihilation with an associated $\pi^0$ meson $\bar{p}p\to J/\psi\pi^0$ is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the $J/\psi\to e^+e^-$ decay channel with the PANDA (AntiProton ANnihilation at DArmstadt) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the $\bar{p}p\to\pi^+\pi^-\pi^0$ and $\bar{p}p\to J/\psi\pi^0\pi^0$ reactions are performed with PandaRoot, the simulation and analysis software framework of the PANDA experiment. Read More

The Dalitz decays eta -> e^+e^-g and omega -> pi^0 e^+e^- have been measured in the g p -> eta p and g p -> omega p reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the electromagnetic transition form factor of eta, Lambda^{-2}_eta=(1.97+/-0. Read More

Let $\Phi$ be an irreducible crystallographic root system with Weyl group $W$, coroot lattice $\check{Q}$ and Coxeter number $h$. Recently the second named author defined a uniform $W$-isomorphism $\zeta$ between the finite torus $\check{Q}/(mh+1)\check{Q}$ and the set of non-nesting parking fuctions $\operatorname{Park}^{(m)}(\Phi)$. If $\Phi$ is of type $A_{n-1}$ and $m=1$ this map is equivalent to a map defined on labelled Dyck paths that arises in the study of the Hilbert series of the space of diagonal harmonics. Read More

High statistics measurements of the photon asymmetry $\mathrm{\Sigma}$ for the $\overrightarrow{\gamma}$p$\rightarrow\pi^{0}$p reaction have been made in the center of mass energy range W=1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. Read More

The cross section of the $p(e,e'\pi^+)n$ reaction has been measured for five kinematic settings at an invariant mass of $W = 1094$ MeV and for a four-momentum transfer of $Q^2 = 0.078$ (GeV/$c$)$^2$. The measurement has been performed at MAMI using a new short-orbit spectrometer (SOS) of the A1 collaboration, intended for detection of low-energy pions. Read More

2016Jun
Authors: PANDA Collaboration, B. Singh, W. Erni, B. Krusche, M. Steinacher, N. Walford, B. Liu, H. Liu, Z. Liu, X. Shen, C. Wang, J. Zhao, M. Albrecht, T. Erlen, M. Fink, F. Heinsius, T. Held, T. Holtmann, S. Jasper, I. Keshk, H. Koch, B. Kopf, M. Kuhlmann, M. Kümmel, S. Leiber, M. Mikirtychyants, P. Musiol, A. Mustafa, M. Pelizäus, J. Pychy, M. Richter, C. Schnier, T. Schröder, C. Sowa, M. Steinke, T. Triffterer, U. Wiedner, M. Ball, R. Beck, C. Hammann, B. Ketzer, M. Kube, P. Mahlberg, M. Rossbach, C. Schmidt, R. Schmitz, U. Thoma, M. Urban, D. Walther, C. Wendel, A. Wilson, A. Bianconi, M. Bragadireanu, M. Caprini, D. Pantea, B. Patel, W. Czyzycki, M. Domagala, G. Filo, J. Jaworowski, M. Krawczyk, F. Lisowski, E. Lisowski, M. Michałek, P. Poznański, J. Płażek, K. Korcyl, A. Kozela, P. Kulessa, P. Lebiedowicz, K. Pysz, W. Schäfer, A. Szczurek, T. Fiutowski, M. Idzik, B. Mindur, D. Przyborowski, K. Swientek, J. Biernat, B. Kamys, S. Kistryn, G. Korcyl, W. Krzemien, A. Magiera, P. Moskal, A. Pyszniak, Z. Rudy, P. Salabura, J. Smyrski, P. Strzempek, A. Wronska, I. Augustin, R. Böhm, I. Lehmann, D. Nicmorus Marinescu, L. Schmitt, V. Varentsov, M. Al-Turany, A. Belias, H. Deppe, R. Dzhygadlo, A. Ehret, H. Flemming, A. Gerhardt, K. Götzen, A. Gromliuk, L. Gruber, R. Karabowicz, R. Kliemt, M. Krebs, U. Kurilla, D. Lehmann, S. Löchner, J. Lühning, U. Lynen, H. Orth, M. Patsyuk, K. Peters, T. Saito, G. Schepers, C. J. Schmidt, C. Schwarz, J. Schwiening, A. Täschner, M. Traxler, C. Ugur, B. Voss, P. Wieczorek, A. Wilms, M. Zühlsdorf, V. Abazov, G. Alexeev, V. A. Arefiev, V. Astakhov, M. Yu. Barabanov, B. V. Batyunya, Y. Davydov, V. Kh. Dodokhov, A. Efremov, A. Fechtchenko, A. G. Fedunov, A. Galoyan, S. Grigoryan, E. K. Koshurnikov, Y. Yu. Lobanov, V. I. Lobanov, A. F. Makarov, L. V. Malinina, V. Malyshev, A. G. Olshevskiy, E. Perevalova, A. A. Piskun, T. Pocheptsov, G. Pontecorvo, V. Rodionov, Y. Rogov, R. Salmin, A. Samartsev, M. G. Sapozhnikov, G. Shabratova, N. B. Skachkov, A. N. Skachkova, E. A. Strokovsky, M. Suleimanov, R. Teshev, V. Tokmenin, V. Uzhinsky, A. Vodopianov, S. A. Zaporozhets, N. I. Zhuravlev, A. G. Zorin, D. Branford, D. Glazier, D. Watts, M. Böhm, A. Britting, W. Eyrich, A. Lehmann, M. Pfaffinger, F. Uhlig, S. Dobbs, K. Seth, A. Tomaradze, T. Xiao, D. Bettoni, V. Carassiti, A. Cotta Ramusino, P. Dalpiaz, A. Drago, E. Fioravanti, I. Garzia, M. Savrie, V. Akishina, I. Kisel, G. Kozlov, M. Pugach, M. Zyzak, P. Gianotti, C. Guaraldo, V. Lucherini, A. Bersani, G. Bracco, M. Macri, R. F. Parodi, K. Biguenko, K. Brinkmann, V. Di Pietro, S. Diehl, V. Dormenev, P. Drexler, M. Düren, E. Etzelmüller, M. Galuska, E. Gutz, C. Hahn, A. Hayrapetyan, M. Kesselkaul, W. Kühn, T. Kuske, J. S. Lange, Y. Liang, V. Metag, M. Nanova, S. Nazarenko, R. Novotny, T. Quagli, S. Reiter, J. Rieke, C. Rosenbaum, M. Schmidt, R. Schnell, H. Stenzel, U. Thöring, M. Ullrich, M. N. Wagner, T. Wasem, B. Wohlfahrt, H. Zaunick, D. Ireland, G. Rosner, B. Seitz, P. N. Deepak, A. Kulkarni, A. Apostolou, M. Babai, M. Kavatsyuk, P. J. Lemmens, M. Lindemulder, H. Loehner, J. Messchendorp, P. Schakel, H. Smit, M. Tiemens, J. C. van der Weele, R. Veenstra, S. Vejdani, K. Dutta, K. Kalita, A. Kumar, A. Roy, H. Sohlbach, M. Bai, L. Bianchi, M. Büscher, L. Cao, A. Cebulla, R. Dosdall, A. Gillitzer, F. Goldenbaum, D. Grunwald, A. Herten, Q. Hu, G. Kemmerling, H. Kleines, A. Lehrach, R. Nellen, H. Ohm, S. Orfanitski, D. Prasuhn, E. Prencipe, J. Pütz, J. Ritman, S. Schadmand, T. Sefzick, V. Serdyuk, G. Sterzenbach, T. Stockmanns, P. Wintz, P. Wüstner, H. Xu, A. Zambanini, S. Li, Z. Li, Z. Sun, H. Xu, V. Rigato, L. Isaksson, P. Achenbach, O. Corell, A. Denig, M. Distler, M. Hoek, A. Karavdina, W. Lauth, Z. Liu, H. Merkel, U. Müller, J. Pochodzalla, S. Sanchez, S. Schlimme, C. Sfienti, M. Thiel, H. Ahmadi, S. Ahmed, S. Bleser, L. Capozza, M. Cardinali, A. Dbeyssi, M. Deiseroth, F. Feldbauer, M. Fritsch, B. Fröhlich, P. Jasinski, D. Kang, D. Khaneft, R. Klasen, H. H. Leithoff, D. Lin, F. Maas, S. Maldaner, M. Marta, M. Michel, M. C. Mora Espí, C. Morales Morales, C. Motzko, F. Nerling, O. Noll, S. Pflüger, A. Pitka, D. Rodríguez Piñeiro, A. Sanchez-Lorente, M. Steinen, R. Valente, T. Weber, M. Zambrana, I. Zimmermann, A. Fedorov, M. Korjik, O. Missevitch, A. Boukharov, O. Malyshev, I. Marishev, V. Balanutsa, P. Balanutsa, V. Chernetsky, A. Demekhin, A. Dolgolenko, P. Fedorets, A. Gerasimov, V. Goryachev, V. Chandratre, V. Datar, D. Dutta, V. Jha, H. Kumawat, A. K. Mohanty, A. Parmar, B. Roy, G. Sonika, C. Fritzsch, S. Grieser, A. Hergemöller, B. Hetz, N. Hüsken, A. Khoukaz, J. P. Wessels, K. Khosonthongkee, C. Kobdaj, A. Limphirat, P. Srisawad, Y. Yan, M. Barnyakov, A. Yu. Barnyakov, K. Beloborodov, A. E. Blinov, V. E. Blinov, V. S. Bobrovnikov, S. Kononov, E. A. Kravchenko, I. A. Kuyanov, K. Martin, A. P. Onuchin, S. Serednyakov, A. Sokolov, Y. Tikhonov, E. Atomssa, R. Kunne, D. Marchand, B. Ramstein, J. van de Wiele, Y. Wang, G. Boca, S. Costanza, P. Genova, P. Montagna, A. Rotondi, V. Abramov, N. Belikov, S. Bukreeva, A. Davidenko, A. Derevschikov, Y. Goncharenko, V. Grishin, V. Kachanov, V. Kormilitsin, A. Levin, Y. Melnik, N. Minaev, V. Mochalov, D. Morozov, L. Nogach, S. Poslavskiy, A. Ryazantsev, S. Ryzhikov, P. Semenov, I. Shein, A. Uzunian, A. Vasiliev, A. Yakutin, E. Tomasi-Gustafsson, U. Roy, B. Yabsley, S. Belostotski, G. Gavrilov, A. Izotov, S. Manaenkov, O. Miklukho, D. Veretennikov, A. Zhdanov, K. Makonyi, M. Preston, P. Tegner, D. Wölbing, T. Bäck, B. Cederwall, A. K. Rai, S. Godre, D. Calvo, S. Coli, P. De Remigis, A. Filippi, G. Giraudo, S. Lusso, G. Mazza, M. Mignone, A. Rivetti, R. Wheadon, F. Balestra, F. Iazzi, R. Introzzi, A. Lavagno, J. Olave, A. Amoroso, M. P. Bussa, L. Busso, F. De Mori, M. Destefanis, L. Fava, L. Ferrero, M. Greco, J. Hu, L. Lavezzi, M. Maggiora, G. Maniscalco, S. Marcello, S. Sosio, S. Spataro, R. Birsa, F. Bradamante, A. Bressan, A. Martin, H. Calen, W. Ikegami Andersson, T. Johansson, A. Kupsc, P. Marciniewski, M. Papenbrock, J. Pettersson, K. Schönning, M. Wolke, B. Galnander, J. Diaz, V. Pothodi Chackara, A. Chlopik, G. Kesik, D. Melnychuk, B. Slowinski, A. Trzcinski, M. Wojciechowski, S. Wronka, B. Zwieglinski, P. Bühler, J. Marton, D. Steinschaden, K. Suzuki, E. Widmann, J. Zmeskal

Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel $\bar p p \to e^+ e^-$ is studied on the basis of two different but consistent procedures. Read More

Recurrence in the phase space of complex systems is a well-studied phenomenon, which has provided deep insights into the nonlinear dynamics of such systems. For dissipative systems, characteristics based on recurrence plots have recently attracted much interest for discriminating qualitatively different types of dynamics in terms of measures of complexity, dynamical invariants, or even structural characteristics of the underlying attractor's geometry in phase space. Here, we demonstrate that the latter approach also provides a corresponding distinction between different co-existing dynamical regimes of the standard map, a paradigmatic example of a low-dimensional conservative system. Read More

Chapoton has observed a simple product formula for the number of reflections in a finite Coxeter group that have full support. We give a uniform proof of his formula for Weyl groups. We furthermore refine his formula by the length of the roots. Read More

2016Feb
Affiliations: 1School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, 2School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, 3Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 4Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 5Jožef Stefan Institute, 1000 Ljubljana, Slovenia, 6Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 7Department of Physics, University of Zagreb, HR-10002 Zagreb, Croatia, 8Jožef Stefan Institute, 1000 Ljubljana, Slovenia, 9Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 10Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 11Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 12Department of Physics, University of Zagreb, HR-10002 Zagreb, Croatia, 13Rutgers, The State University of New Jersey, Piscataway, NJ 08855, USA, 14School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, 15School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, 16Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 17Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 18Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 19Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 20School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, 21Jožef Stefan Institute, 1000 Ljubljana, Slovenia, 22University of South Carolina, Columbia, South Carolina 29208, USA, 23Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 24Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel, 25Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 26Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 27Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 28Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 29Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 30Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 31Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany, 32Institut für Kernphysik, Johannes Gutenberg-Universität, 55099 Mainz, Germany

Possible differences between free and bound protons may be observed in the ratio of polarization-transfer components, $P'_x/P'_z$. We report the measurement of $P'_x/P'_z$, in the $^2\textrm{H}(\vec{e},e^{\prime}\vec{p})n$ reaction at low and high missing momenta. Observed increasing deviation of $P'_x/P'_z$ from that of a free proton as a function of the virtuality, similar to that observed in \hefour, indicates that the effect in nuclei is due to the virtuality of the knock-out proton and not due to the average nuclear density. Read More

Based on computational experiments, Jim Propp and Vic Reiner suspected that there might exist a sequence of combinatorial objects $X_n$, each carrying a natural action of the cyclic group $C_{n-1}$ of order $n-1$ such that the triple $\left(X_n,C_{n-1},\frac{1}{[n+1]_q}{2n \brack n}_q\right)$ exhibits the cyclic sieving phenomenon. We prove their suspicion right. Read More

Deprivation of essential nutrients can have stark consequences for many processes in a cell. We consider amino acid starvation, which can result in bottlenecks in mRNA translation when ribosomes stall due to lack of resources, i.e. Read More

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $\pi^0\pi^0$ pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. Read More

Photoproduction of $\pi\eta$-pairs from nucleons has been investigated from threshold up to incident photon energies of $\approx$~1.4~GeV. The quasi-free reactions $\gamma p\rightarrow p\pi^0\eta$, $\gamma n\rightarrow n\pi^0\eta$, $\gamma p\rightarrow n\pi^+\eta$, and $\gamma n\rightarrow p\pi^-\eta$ were for the first time measured from nucleons bound in the deuteron. Read More

Differential cross sections for the gamma p -> pi^0 p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of pi^0 photoproduction data by ~47%. Read More

For an irreducible crystallographic root system $\Phi$ and a positive integer $p$ relatively prime to the Coxeter number $h$ of $\Phi$, we give a natural bijection $\mathcal{A}$ from the set $\widetilde{W}^p$ of affine Weyl group elements with no inversions of height $p$ to the finite torus $\check{Q}/p\check{Q}$. Here $\check{Q}$ is the coroot lattice of $\Phi$. This bijection is defined uniformly for all irreducible crystallographic root systems $\Phi$ and is equivalent to the Anderson map $\mathcal{A}_{GMV}$ defined by Gorsky, Mazin and Vazirani when $\Phi$ is of type $A_{n-1}$. Read More

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single p0 photoproduction on deuterium using the tagged photon beam at the Mainz Microtron. The results were obtained up to a neutron energy of 400 MeV. They are compared to previous measurements made more than 15 years ago at the pion beam at the BNL AGS. Read More

Future experiments of nuclear and particle physics are moving towards the high luminosity regime, in order to access suppressed processes like rare B decays or exotic charmonium resonances. In this scenario, high rate capability is a key requirement for electronics instrumentation, together with excellent timing resolution for precise event reconstruction. The development of dedicated FrontEnd Electronics (FEE) for detectors has become increasingly challenging. Read More

At the Mainz Microtron MAMI, the first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a Be-9 target in order to study the ground-state masses of Lambda-hypernuclei. Positively charged kaons were detected by a short-orbit spectrometer with a broad momentum acceptance at zero degree forward angles with respect to the beam, efficiently tagging the production of strangeness in the target nucleus. In coincidence, negatively charged decay-pions were detected by two independent high-resolution spectrometers. Read More

We introduce type C parking functions, encoded as vertically labelled lattice paths and endowed with a statistic dinv'. We define a bijection from type C parking functions to regions of the Shi arrangement of type C, encoded as diagonally labelled ballot paths and endowed with a natural statistic area'. This bijection is a natural analogue of the zeta map of Haglund and Loehr and maps dinv' to area'. Read More

2014Sep
Authors: PANDA Collaboration, B. P. Singh, W. Erni, I. Keshelashvili, B. Krusche, M. Steinacher %, B. Liu, H. Liu, Z. Liu, X. Shen, C. Wang, J. Zhao %, M. Albrecht, M. Fink, F. H. Heinsius, T. Held, T. Holtmann, H. Koch, B. Kopf, M. Kümmel, G. Kuhl, M. Kuhlmann, M. Leyhe, M. Mikirtychyants, P. Musiol, A. Mustafa, M. Pelizäus, J. Pychy, M. Richter, C. Schnier, T. Schröder, C. Sowa, M. Steinke, T. Triffterer, U. Wiedner, R. Beck, C. Hammann, D. Kaiser, B. Ketzer, M. Kube, P. Mahlberg, M. Rossbach, C. Schmidt, R. Schmitz, U. Thoma, D. Walther, C. Wendel, A. Wilson, A. Bianconi, M. Bragadireanu, M. Caprini, D. Pantea, D. Pietreanu, M. E. Vasile, B. Patel, D. Kaplan, P. Brandys, T. Czyzewski, W. Czyzycki, M. Domagala, M. Hawryluk, G. Filo, M. Krawczyk, D. Kwiatkowski, E. Lisowski, F. Lisowski, T. Fiutowski, M. Idzik, B. Mindur, D. Przyborowski, K. Swientek, B. Czech, S. Kliczewski, K. Korcyl, A. Kozela, P. Kulessa, P. Lebiedowicz, K. Malgorzata, K. Pysz, W. Schäfer, R. Siudak, A. Szczurek, J. Biernat, S. Jowzaee, B. Kamys, S. Kistryn, G. Korcyl, W. Krzemien, A. Magiera, P. Moskal, M. Palka, A. Psyzniak, Z. Rudy, P. Salabura, J. Smyrski, P. Strzempek, A. Wrońska, I. Augustin, I. Lehmann, D. Nicmorus, G. Schepers, L. Schmitt, M. Al-Turany, U. Cahit, L. Capozza, A. Dbeyssi, H. Deppe, R. Dzhygadlo, A. Ehret, H. Flemming, A. Gerhardt, K. Götzen, R. Karabowicz, R. Kliemt, J. Kunkel, U. Kurilla, D. Lehmann, J. Lühning, F. Maas, C. Morales Morales, M. C. Mora Espí, F. Nerling, H. Orth, K. Peters, D. Rodríguez Pineiro, N. Saito, T. Saito, A. Sánchez Lorente, C. J. Schmidt, C. Schwarz, J. Schwiening, M. Traxler, R. Valente, B. Voss, P. Wieczorek, A. Wilms, M. Zühlsdorf, V. M. Abazov, G. Alexeev, A. Arefiev, V. I. Astakhov, M. Yu. Barabanov, B. V. Batyunya, Yu. I. Davydov, V. Kh. Dodokhov, A. A. Efremov, A. G. Fedunov, A. A. Festchenko, A. S. Galoyan, S. Grigoryan, A. Karmokov, E. K. Koshurnikov, V. I. Lobanov, Yu. Yu. Lobanov, A. F. Makarov, L. V. Malinina, V. L. Malyshev, G. A. Mustafaev, A. Olshevskiy, M. A. Pasyuk, E. A. Perevalova, A. A. Piskun, T. A. Pocheptsov, G. Pontecorvo, V. K. Rodionov, Yu. N. Rogov, R. A. Salmin, A. G. Samartsev, M. G. Sapozhnikov, G. S. Shabratova, N. B. Skachkov, A. N. Skachkova, E. A. Strokovsky, M. K. Suleimanov, R. Sh. Teshev, V. V. Tokmenin, V. V. Uzhinsky, A. S. Vodopyanov, S. A. Zaporozhets, N. I. Zhuravlev, A. G. Zorin, D. Branford, D. Glazier, D. Watts, P. Woods, A. Britting, W. Eyrich, A. Lehmann, F. Uhlig, S. Dobbs, K. Seth, A. Tomaradze, T. Xiao, D. Bettoni, V. Carassiti, A. Cotta Ramusino, P. Dalpiaz, A. Drago, E. Fioravanti, I. Garzia, M. Savriè, G. Stancari, V. Akishina, I. Kisel, I. Kulakov, M. Zyzak, R. Arora, T. Bel, A. Gromliuk, G. Kalicy, M. Krebs, M. Patsyuk, M. Zuehlsdorf, N. Bianchi, P. Gianotti, C. Guaraldo, V. Lucherini, E. Pace, A. Bersani, G. Bracco, M. Macri, R. F. Parodi, S. Bianco, D. Bremer, K. T. Brinkmann, S. Diehl, V. Dormenev, P. Drexler, M. Düren, T. Eissner, E. Etzelmüller, K. Föhl, M. Galuska, T. Gessler, E. Gutz, A. Hayrapetyan, J. Hu, B. Kröck, W. Kühn, T. Kuske, S. Lange, Y. Liang, O. Merle, V. Metag, D. Mülhheim, D. Münchow, M. Nanova, R. Novotny, A. Pitka, T. Quagli, J. Rieke, C. Rosenbaum, R. Schnell, B. Spruck, H. Stenzel, U. Thöring, M. Ullrich, T. Wasem, M. Werner, H. G. Zaunick, D. Ireland, G. Rosner, B. Seitz, P. N. Deepak, A. V. Kulkarni, A. Apostolou, M. Babai, M. Kavatsyuk, P. Lemmens, M. Lindemulder, H. Löhner, J. Messchendorp, P. Schakel, H. Smit, J. C. van der Weele, M. Tiemens, R. Veenstra, S. Vejdani, K. Kalita, D. P. Mohanta, A. Kumar, A. Roy, R. Sahoo, H. Sohlbach, M. Büscher, L. Cao, A. Cebulla, D. Deermann, R. Dosdall, S. Esch, I. Georgadze, A. Gillitzer, A. Goerres, F. Goldenbaum, D. Grunwald, A. Herten, Q. Hu, G. Kemmerling, H. Kleines, V. Kozlov, A. Lehrach, S. Leiber, R. Maier, R. Nellen, H. Ohm, S. Orfanitski, D. Prasuhn, E. Prencipe, J. Ritman, S. Schadmand, J. Schumann, T. Sefzick, V. Serdyuk, G. Sterzenbach, T. Stockmanns, P. Wintz, P. Wüstner, H. Xu, S. Li, Z. Li, Z. Sun, H. Xu, V. Rigato, S. Fissum, K. Hansen, L. Isaksson, M. Lundin, B. Schröder, P. Achenbach, S. Bleser, M. Cardinali, O. Corell, M. Deiseroth, A. Denig, M. Distler, F. Feldbauer, M. Fritsch, P. Jasinski, M. Hoek, D. Kangh, A. Karavdina, W. Lauth, H. Leithoff, H. Merkel, M. Michel, C. Motzko, U. Müller, O. Noll, S. Plueger, J. Pochodzalla, S. Sanchez, S. Schlimme, C. Sfienti, M. Steinen, M. Thiel, T. Weber, M. Zambrana, V. I. Dormenev, A. A. Fedorov, M. V. Korzihik, O. V. Missevitch, P. Balanutsa, V. Balanutsa, V. Chernetsky, A. Demekhin, A. Dolgolenko, P. Fedorets, A. Gerasimov, V. Goryachev, V. Varentsov, A. Boukharov, O. Malyshev, I. Marishev, A. Semenov, I. Konorov, S. Paul, S. Grieser, A. K. Hergemöller, A. Khoukaz, E. Köhler, A. Täschner, J. Wessels, S. Dash, M. Jadhav, S. Kumar, P. Sarin, R. Varma, V. B. Chandratre, V. Datar, D. Dutta, V. Jha, H. Kumawat, A. K. Mohanty, B. Roy, Y. Yan, K. Chinorat, K. Khanchai, L. Ayut, S. Pornrad, A. Y. Barnyakov, A. E. Blinov, V. E. Blinov, V. S. Bobrovnikov, S. A. Kononov, E. A. Kravchenko, I. A. Kuyanov, A. P. Onuchin, A. A. Sokolov, Y. A. Tikhonov, E. Atomssa, T. Hennino, M. Imre, R. Kunne, C. Le Galliard, B. Ma, D. Marchand, S. Ong, B. Ramstein, P. Rosier, E. Tomasi-Gustafsson, J. Van de Wiele, G. Boca, S. Costanza, P. Genova, L. Lavezzi, P. Montagna, A. Rotondi, V. Abramov, N. Belikov, S. Bukreeva, A. Davidenko, A. Derevschikov, Y. Goncharenko, V. Grishin, V. Kachanov, V. Kormilitsin, Y. Melnik, A. Levin, N. Minaev, V. Mochalov, D. Morozov, L. Nogach, S. Poslavskiy, A. Ryazantsev, S. Ryzhikov, P. Semenov, I. Shein, A. Uzunian, A. Vasiliev, A. Yakutin, B. Yabsley, T. Bäck, B. Cederwall, K. Makónyi, P. E. Tegnér, K. M. von Würtemberg, S. Belostotski, G. Gavrilov, A. Izotov, A. Kashchuk, O. Levitskaya, S. Manaenkov, O. Miklukho, Y. Naryshkin, K. Suvorov, D. Veretennikov, A. Zhadanov, A. K. Rai, S. S. Godre, R. Duchat, A. Amoroso, M. P. Bussa, L. Busso, F. De Mori, M. Destefanis, L. Fava, L. Ferrero, M. Greco, M. Maggiora, G. Maniscalco, S. Marcello, S. Sosio, S. Spataro, L. Zotti, D. Calvo, S. Coli, P. De Remigis, A. Filippi, G. Giraudo, S. Lusso, G. Mazza, M. Mingnore, A. Rivetti, R. Wheadon, F. Balestra, F. Iazzi, R. Introzzi, A. Lavagno, H. Younis, R. Birsa, F. Bradamante, A. Bressan, A. Martin, H. Clement, B. Gålnander, L. Caldeira Balkeståhl, H. Calén, K. Fransson, T. Johansson, A. Kupsc, P. Marciniewski, J. Pettersson, K. Schönning, M. Wolke, J. Zlomanczuk, J. Díaz, A. Ortiz, P. C. Vinodkumar, A. Parmar, A. Chlopik, D. Melnychuk, B. Slowinski, A. Trzcinski, M. Wojciechowski, S. Wronka, B. Zwieglinski, P. Bühler, J. Marton, K. Suzuki, E. Widmann, J. Zmeskal, B. Fröhlich, D. Khaneft, D. Lin, I. Zimmermann, K. Semenov-Tian-Shansky

Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion ($\pi N$) TDAs from $\bar{p}p \to e^+e^- \pi^0$ reaction with the future \={P}ANDA detector at the FAIR facility. At high center of mass energy and high invariant mass squared of the lepton pair $q^2$, the amplitude of the signal channel $\bar{p}p \to e^+e^- \pi^0$ admits a QCD factorized description in terms of $\pi N$ TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Read More

The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the $\Delta(1232)$ region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Read More

Differential and total cross sections for the quasifree reactions $\gamma p\rightarrow\eta p$ and $\gamma n\rightarrow\eta n$ have been determined at the MAMI-C electron accelerator using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy-tagged with the Glasgow photon tagger. Read More

An experimental study of $\omega$ photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The $\gamma p\to\omega p$ differential cross sections are measured from threshold to the incident-photon energy $E_\gamma=1.40$ GeV ($W=1. Read More

In this paper we study the diffractive $Z$ boson pair production mediated by the Kaluza-Klein graviton in the large extra dimensions scenario at the CERN Large Hadron Collider energies. Considering the Durham model we estimate the total cross section for the central inclusive and exclusive diffractive production of a $Z$ boson pair in $pp/pPb/PbPb$ collisions. Our results indicate that the experimental analysis of the central inclusive production in $pp$ collisions is feasible at CERN LHC. Read More

2014May
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI, 79A2 Collaboration at MAMI

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0. Read More

A massive, but light abelian U(1) gauge boson is a well motivated possible signature of physics beyond the Standard Model of particle physics. In this paper, the search for the signal of such a U(1) gauge boson in electron-positron pair-production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron (MAMI) is described. Exclusion limits in the mass range of 40 MeV up to 300 MeV with a sensitivity in the mixing parameter of down to $\epsilon^2 = 8\times 10^{-7}$ are presented. Read More

Precise angular distributions have been measured for the first time for the photoproduction of $\pi^{0}$-mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasi-free protons bound in the deuteron to the results for free protons and then applied as a correction to the quasi-free neutron data. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions $\boldsymbol{\gamma}p\rightarrow n\pi^0\pi^+$ off free protons and $\boldsymbol{\gamma}d\rightarrow (p)p\pi^0\pi^-$ and $\boldsymbol{\gamma}d\rightarrow (n)n\pi^0\pi^+$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. Read More

The set of dominant regions of the $k$-Catalan arrangement of a crystallographic root system $\Phi$ is a well-studied object enumerated by the Fu{\ss}-Catalan number $Cat^{(k)}(\Phi)$. It is natural to refine this enumeration by considering floors and ceilings of dominant regions. A conjecture of Armstrong states that counting dominant regions by their number of floors of a certain height gives the same distribution as counting dominant regions by their number of ceilings of the same height. Read More

Dilational materials are stable three-dimensional isotropic auxetics with an ultimate Poisson's ratio of -1. We design, evaluate, fabricate, and characterize crystalline metamaterials approaching this ideal. To reveal all modes, we calculate the phonon band structures. Read More

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon, pioneering a novel polarimetry technique with wide application to future nuclear and hadronic physics experiments. The commissioning measurement of polarization transfer in the $^{1}H$($\vec{\gamma}$,$\vec{p}$)$\pi^{0}$ reaction in the range $0.4Read More

2013Sep
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI

The Dalitz decay eta -> e^+ e^- gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon tagging facility at the Mainz Microtron MAMI. The experimental statistic used in this work is one order of magnitude greater than in any previous measurement of eta -> e^+ e^- gamma. The value obtained for the slope parameter 1/Lambda^2 of the eta transition form factor, 1/Lambda^2 = (1. Read More

Measurements of $\gamma p \rightarrow K^{+} \Lambda$ and $\gamma p \rightarrow K^{+} \Sigma^0$ cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel $K^+$ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy ($W$) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. Read More

2013Jun
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. Read More

To a crystallographic root system \Phi, and a positive integer k, there are associated two Fuss-Catalan objects, the set of nonnesting partitions NN^(k)(\Phi), and the cluster complex \Delta^(k)(\Phi). These posess a number of enumerative coincidences, many of which are captured in a surprising identity, first conjectured by Chapoton for k=1 and later generalized to k>1 by Armstrong. We prove this conjecture, obtaining some structural and enumerative results on NN^(k)(\Phi) along the way, including an earlier conjecture by Fomin and Reading giving a refined enumeration by Fu{\ss}-Narayana numbers. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions $\vec{\gamma}p\rightarrow p\pi^0\pi^0$ and $\vec{\gamma}d\rightarrow (n)p\pi^0\pi^0$, $\vec{\gamma}d\rightarrow (p)n\pi^0\pi^0$ off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Read More

In a recent paper, Baxter and Zeilberger show that the two most important Mahonian statistics, the inversion number and the major index, are asymptotically independently normally distributed on permutations. In another recent paper, Canfield, Janson and Zeilberger prove the result, already known to statisticians, that the Mahonian distribution is asymptotically normal on words. This leaves one question unanswered: What, asymptotically, is the joint distribution of the inversion number and the major index on words? We answer this question by establishing convergence to a bivariate normal distribution. Read More

A precision measurement of the differential cross sections $d\sigma/d\Omega$ and the linearly polarized photon asymmetry $\Sigma \equiv (d\sigma_\perp - d\sigma_\parallel) \slash (d\sigma_\perp + d\sigma_\parallel)$ for the $\vec{\gamma} p \rightarrow \pi^0p$ reaction in the near-threshold region has been performed with a tagged photon beam and almost $4\pi$ detector at the Mainz Microtron. The Glasgow-Mainz photon tagging facility along with the Crystal Ball/TAPS multi-photon detector system and a cryogenic liquid hydrogen target were used. These data allowed for a precise determination of the energy dependence of the real parts of the $S$- and all three $P$-wave amplitudes for the first time and provide the most stringent test to date of the predictions of Chiral Perturbation Theory and its energy region of agreement with experiment. Read More

GRAVITY is a second generation VLTI instrument, combining the light of four telescopes and two objects simultaneously. The main goal is to obtain astrometrically accurate information. Besides correctly measured stellar phases this requires the knowledge of the instrumental differential phase, which has to be measured optically during the astronomical observations. Read More