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  1. Article: New precise measurement of the pion weak form factors in pi+-->e+ nugamma decay.

    Bychkov, M / Pocanić, D / Vandevender, B A / Baranov, V A / Bertl, W / Bystritsky, Yu M / Frlez, E / Kalinnikov, V A / Khomutov, N V / Korenchenko, A S / Korenchenko, S M / Korolija, M / Kozlowski, T / Kravchuk, N P / Kuchinsky, N A / Li, W / Mekterović, D / Mzhavia, D / Ritt, S /
    Robmann, P / Rondon-Aramayo, O A / Rozhdestvensky, A M / Sakhelashvili, T / Scheu, S / Straumann, U / Supek, I / Tsamalaidze, Z / van der Schaaf, A / Velicheva, E P / Volnykh, V P / Wang, Y / Wirtz, H-P

    Physical review letters

    2009  Volume 103, Issue 5, Page(s) 51802

    Abstract: We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-chi2 fits to the measured (E(e+), E(gamma) energy distributions result in the weak form ...

    Abstract We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-chi2 fits to the measured (E(e+), E(gamma) energy distributions result in the weak form factor value of F(A)=0.0119(1) with a fixed value of F(V)=0.0259. An unconstrained fit yields F(V)=0.0258(17) and F(A)=0.0117(17). In addition, we have measured a=0.10(6) for the dependence of F(V) on q2, the e+ nu pair invariant mass squared, parametrized as F(V)(q2)=F(V)(0)(1+aq(2)). The branching ratio for the kinematic region E(gamma)>10 MeV and theta(e(+)gamma)>40 degrees is measured to be B(expt)=73.86(54)x10(-8). Earlier deviations we reported in the high-E(gamma)-low-E(e+) kinematic region are resolved without a tensor term. We also derive new values for the pion polarizability alpha(E)=2.78(10)x10(-4) fm3 and neutral pion lifetime tau(pi0)=(8.5+/-1.1)x10(-17) s.
    Language English
    Publishing date 2009-07-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.103.051802
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Book ; Online: New studies of allowed pion and muon decays

    Pocanic, D. / Palladino, A. / Alonzi, L. P. / Baranov, V. A. / Bertl, W. / Bychkov, M. / Bystritsky, Yu. M. / Frlez, E. / Kalinnikov, V. A. / Khomutov, N. V. / Korenchenko, A. S. / Korenchenko, S. M. / Korolija, M. / Kozlowski, T. / Kravchuk, N. P. / Kuchinsky, N. A. / Lehman, M. C. / Mekterovic, D. / Munyangabe, E. /
    Mzhavia, D. / Robmann, P. / Rozhdestvensky, A. M. / Shkarovskiy, S. N. / Straumann, U. / Supek, I. / Truöl, P. / Tsamalaidze, Z. / van der Schaaf, A. / Velicheva, E. P. / Volnykh, V. P.

    2012  

    Abstract: Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer Institute, to ... ...

    Abstract Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer Institute, to reduce the present 40\times experimental precision lag behind theory to ~ 6-7\times. Because of large helicity suppression, R^\pi_{e/\mu} is uniquely sensitive to contributions from non-(V-A) physics, making this decay a particularly suitable subject of study. Even at current precision, the experimental value of B_{\pi e2} provides the most accurate test of lepton universality available. During runs in 2008-10, PEN has accumulated over 2\times 10^7 \pi_{e2} events; a comprehensive maximum-likelihood analysis is currently under way. The new data will also lead to improved precision of the earlier PIBETA results on radiative \pi and \mu decays.

    Comment: 3 pages, 3 figures, to appear in Proceedings, 11th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2012), held at St. Petersburg, Florida, 29 May - 3 June 2012
    Keywords High Energy Physics - Experiment ; Nuclear Experiment
    Subject code 612
    Publishing date 2012-10-18
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Precise measurement of the pi+-->pi0 e+nu branching ratio.

    Pocanić, D / Frlez, E / Baranov, V A / Bertl, W / Brönnimann, Ch / Bychkov, M / Crawford, J F / Daum, M / Khomutov, N V / Korenchenko, A S / Korenchenko, S M / Kozlowski, T / Kravchuk, N P / Kuchinsky, N A / Li, W / Minehart, R C / Mzhavia, D / Ritchie, B G / Ritt, S /
    Rozhdestvensky, A M / Sidorkin, V V / Smith, L C / Supek, I / Tsamalaidze, Z / VanDevender, B A / Wang, Y / Wirtz, H-P / Ziock, K O H

    Physical review letters

    2004  Volume 93, Issue 18, Page(s) 181803

    Abstract: Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare pi(+)-->pi(0)e(+)nu (pi(beta)) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi(beta) decays ... ...

    Abstract Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare pi(+)-->pi(0)e(+)nu (pi(beta)) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi(beta) decays to the number of observed pi(+)-->e(+)nu (pi(e2)) decays. We find the value of Gamma(pi(+)-->pi(0)e(+)nu)/Gamma(total)=[1.036+/-0.004(stat)+/-0.004(syst)+/-0.003(pi(e2))]x10(-8), where the first uncertainty is statistical, the second systematic, and the third is the pi(e2) branching ratio uncertainty. Our result agrees well with the standard model prediction.
    Language English
    Publishing date 2004-10-29
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.93.181803
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Precise measurement of the pion axial form factor in the pi+-->e+nugamma decay.

    Frlez, E / Pocanić, D / Baranov, V A / Bertl, W / Bychkov, M / Khomutov, N V / Korenchenko, A S / Korenchenko, S M / Kozlowski, T / Kravchuk, N P / Kuchinsky, N A / Li, W / Minehart, R C / Mzhavia, D / Ritchie, B G / Ritt, S / Rozhdestvensky, A M / Sidorkin, V V / Smith, L C /
    Supek, I / Tsamalaidze, Z / VanDevender, B A / Velicheva, E P / Wang, Y / Wirtz, H-P / Ziock, K O H

    Physical review letters

    2004  Volume 93, Issue 18, Page(s) 181804

    Abstract: We have studied radiative pion decays pi(+)-->e(+)nugamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 41 601 events we have evaluated absolute pi-->enugamma branching ratios in the ... ...

    Abstract We have studied radiative pion decays pi(+)-->e(+)nugamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 41 601 events we have evaluated absolute pi-->enugamma branching ratios in the three regions. Minimum chi(2) fits to the integral and differential (E(e(+)),E(gamma)) distributions result in the axial-to-vector weak form factor ratio of gamma identical with F(A)/F(V)=0.443(15), or F(A)=0.0115(4) with F(V)=0.0259. However, deviations from standard model predictions in the high-E(gamma)-low-E(e(+)) kinematic region indicate the need for further theoretical and experimental work.
    Language English
    Publishing date 2004-10-29
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.93.181804
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  5. Book ; Online: New Precise Measurement of the Pion Weak Form Factors in the Pi+ -> e+ nu gamma Decay

    Bychkov, M. / Počanić, D. / VanDevender, B. A. / Baranov, V. A. / Bertl, W. / Bystritsky, Yu. M. / Frlež, E. / Kalinnikov, V. A. / Khomutov, N. V. / Korenchenko, A. S. / Korenchenko, S. M. / Korolija, M. / Kozlowski, T. / Kravchuk, N. P. / Kuchinsky, N. A. / Li, W. / Mekterović, D. / Mzhavia, D. / Ritt, S. /
    Robmann, P. / Rondon-Aramayo, O. A. / Rozhdestvensky, A. M. / Sakhelashvili, T. / Scheu, S. / Straumann, U. / Supek, I. / Tsamalaidze, Z. / van der Schaaf, A. / Velicheva, E. P. / Volnykh, V. P. / Wang, Y. / Wirtz, H. -P.

    2008  

    Abstract: We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy distributions ... ...

    Abstract We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy distributions result in the weak form factor value of $F_A=0.0119(1)$ with a fixed value of $F_V=0.0259$. An unconstrained fit yields $F_V=0.0258(17)$ and $F_A=0.0117(17)$. In addition, we have measured $a=0.10(6)$ for the dependence of $F_V$ on $q^2$, the ${\rm e}^{+}\nu$ pair invariant mass squared, parametrized as $F_V(q^2)=F_V(0)(1+a\cdot q^2)$. The branching ratio for the kinematic region $E_\gamma > 10 $MeV and $\theta_{{\rm e^+}\gamma} > 40^\circ $ is measured to be $B^{\rm exp}=73.86(54) \times 10^{-8}$. Earlier deviations we reported in the high-$E_\gamma$/low-$E_{{\rm e}^+}$ kinematic region are resolved, and we find full compatibility with CVC and standard $V$$-$$A$ calculations without a tensor term. We also derive new values for the pion polarizability, $\alpha_E = \rm 2.78(10) \times 10^{-4} fm^3$, and neutral pion lifetime, $\tau_{\pi 0} = (8.5 \pm 1.1) \times 10^{-17} $s.

    Comment: 4 pages, 2 PDF figures
    Keywords High Energy Physics - Experiment ; High Energy Physics - Phenomenology ; Nuclear Experiment
    Subject code 612
    Publishing date 2008-04-11
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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  6. Article: First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering.

    Alexakhin, V Yu / Alexandrov, Yu / Alexeev, G D / Amoroso, A / Badełek, B / Balestra, F / Ball, J / Baum, G / Bedfer, Y / Berglund, P / Bernet, C / Bertini, R / Birsa, R / Bisplinghoff, J / Bradamante, F / Bravar, A / Bressan, A / Burtin, E / Bussa, M P /
    Cerini, L / Chapiro, A / Cicuttin, A / Colantoni, M / Colavita, A A / Costa, S / Crespo, M L / d'Hose, N / Dalla Torre, S / Dasgupta, S S / De Masi, R / Dedek, N / Denisov, O Yu / Dhara, L / Diaz Kavka, V / Dolgopolov, A V / Donskov, S V / Dorofeev, V A / Doshita, N / Duic, V / Dünnweber, W / Efremov, A / Ehlers, J / Eversheim, P D / Eyrich, W / Fabro, M / Faessler, M / Fauland, P / Ferrero, A / Ferrero, L / Finger, M / Fischer, H / Franz, J / Friedrich, J M / Frolov, V / Fuchs, U / Garfagnini, R / Gautheron, F / Gavrichtchouk, O P / Gerassimov, S / Geyer, R / Giorgi, M / Gobbo, B / Goertz, S / Grajek, O A / Grasso, A / Grube, B / Grünemaier, A / Gustafsson, K / Hannappel, J / von Harrach, D / Hasegawa, T / Hedicke, S / Heinsius, F H / Hinterberger, F / von Hodenberg, M / Horikawa, N / Horikawa, S / Ijaduola, R B / Ilgner, C / Ishimoto, S / Iwata, T / Jahn, R / Janata, A / Joosten, R / Jouravlev, N I / Kabuss, E / Kalinnikov, V / Kang, D / Karstens, F / Kastaun, W / Ketzer, B / Khaustov, G V / Khokhlov, Yu A / Kisselev, Yu / Klein, F / Koivuniemi, J H / Kolosov, V N / Komissarov, E V / Kondo, K / Königsmann, K / Konoplyannikov, A K / Konorov, I / Konstantinov, V F / Korentchenko, A S / Korzenev, A / Kotzinian, A M / Koutchinski, N A / Kowalik, K / Kravchuk, N P / Krivokhizhin, G V / Kroumchtein, Z V / Kuhn, R / Kunne, F / Kurek, K / Lamanna, M / Le Goff, J M / Leberig, M / Lichtenstadt, J / Maggiora, A / Maggiora, M / Magnon, A / Mallot, G K / Manuilov, I V / Marchand, C / Marroncle, J / Martin, A / Marzec, J / Matsuda, T / Maximov, A N / Medved, K S / Meyer, W / Mielech, A / Mikhailov, Yu V / Moinester, M A / Nähle, O / Nassalski, J / Neyret, D P / Nikolaenko, V I / Nozdrin, A A / Obraztsov, V F / Olshevsky, A G / Ostrick, M / Padee, A / Pagano, P / Panebianco, S / Panzieri, D / Paul, S / Pereira, H D / Peshekhonov, D V / Peshekhonov, V D / Piragino, G / Platchkov, S / Platzer, K / Pochodzalla, J / Polyakov, V A / Popov, A A / Pretz, J / Rebourgeard, P C / Reicherz, G / Reymann, J / Rozhdestvensky, A M / Rondio, E / Sadovski, A B / Saller, E / Samoylenko, V D / Sandacz, A / Sans, M / Sapozhnikov, M G / Savin, I A / Schiavon, P / Schmidt, T / Schmitt, H / Schmitt, L / Shishkin, A A / Siebert, H / Sinha, L / Sissakian, A N / Skachkova, A / Slunecka, M / Smirnov, G I / Sugonyaev, V P / Stinzing, F / Sulej, R / Takabayashi, N / Tchalishev, V V / Tessarotto, F / Teufel, A / Thers, D / Tkatchev, L G / Toeda, T / Tretyak, V I / Trousov, S / Vlassov, N V / Webb, R / Weise, E / Wiesmann, M / Windmolders, R / Wirth, S / Wiślicki, W / Zanetti, A M / Zaremba, K / Zhao, J / Ziegler, R / Zvyagin, A

    Physical review letters

    2005  Volume 94, Issue 20, Page(s) 202002

    Abstract: First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon ... ...

    Abstract First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.
    Language English
    Publishing date 2005-05-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.94.202002
    Database MEDical Literature Analysis and Retrieval System OnLINE

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