Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

Fermilab E835 Collaboration; Andreotti, M.; Bagnasco, S.; Baldini, W.; Bettoni, D.; Borreani, G.; Buzzo, A.; Calabrese, R.; Cester, R.; Cibinetto, G.; Dalpiaz, P.; Garzoglio, G.; Gollwitzer, K. E.; Graham, M.; Hu, M.; Joffe, D.; Kasper, J.; Lasio, G.; Vetere, M. Lo; Luppi, E.; Macrì, M.; Mandelkern, M.; Marchetto, F.; Marinelli, M.; Menichetti, E.; Metreveli, Z.; Mussa, R.; Negrini, M.; Obertino, M. M.; Pallavicini, M.; Pastrone, N.; Patrignani, C.; Pordes, S.; Robutti, E.; Roethel, W.; Rosen, J.; Rumerio, P.; Rusack, R. W.; Santroni, A.; Schultz, J.; Seo, S. H.; Seth, K. K.; Stancari, G.; Stancari, M.; Tomaradze, A.; Uman, I.; Vidnovic, T.; Werkema, S.; Zweber, P.

Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

Authors

Fermilab E835 Collaboration

Description

We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.
17 pages, 3 figures, 3 tables. Final manuscript accepted for publication in Phys. Lett. B. Parts of the text slightly expanded or rearranged; results are unchanged