Data di Pubblicazione:
2005
Abstract:
We present the first measurement of the angular distribution for the exclusive process p ¯ p → ψ ( 2 S ) → e + e − based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the angular distribution is well described by the expected functional form d N d cos θ ∗ ∝ 1 + λ cos 2 θ ∗ , where θ ∗ is the angle between the antiproton and the electron in the center of mass frame, with λ = 0.67 ± 0.15 ( stat ) ± 0.04 ( sys ) . The measured value for λ implies a small but non-zero ψ ( 2 S ) helicity 0 formation amplitude in p ¯ p , comparable to what is observed in J / ψ decays to baryon pairs.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
M. Ambrogiani;M. Andreotti;S. Argiro;S. Bagnasco;W. Baldini;D. Bettoni;G. Borreani;A. Buzzo;R. Calabrese;R. Cester;G. Cibinetto;P. Dalpiaz;X. Fan;G. Garzoglio;K. Gollwitzer;M. Graham;A. Hahn;M. Hu;S. Jin;D. Joffe;J. Kasper;G. Lasio;M. L. Vetere;E. Luppi;P. Maas;M. Macrí;M. Mandelkern;F. Marchetto;M. Marinelli;W. Marsh;M. Martini;E. Menichetti;Z. Metreveli;R. Mussa;M. Negrini;M. Obertino;M. Pallavicini;N. Pastrone;C. Patrignani;T. Pedlar;S. Pordes;E. Robutti;W. Roethel;J. Rosen;P. Rumerio;R. Rusack;A. Santroni;J. Schultz;S. Seo;K. Seth;G. Stancari;M. Stancari;J. Streets;A. Tomaradze;I. Uman;T. V. III;S. Werkema;G. Zioulas;P. Zweber
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