Naslov
New Precise Measurement of the Pion Weak Form Factors in the Pi+ -> e+ nu gamma Decay

Autori
Bychkov, M. ; Počanić, Dinko ; VanDevender, B.A. ; Baranov, V.A. ; Bertl, W. ; Bystritsky, Yu. M. ; Frlež, Emil ; Kalinnikov, V.A. ; Khomutov, N.V. ; Korenchenko, N.S. ; Korenchenko, S.M. ; Korolija, Milorad ; Kozlowski, T. ; Kravchuk, N.P. ; Kuchinsky, N.A. ; Li, W. ; Mekterović, Darko ; Mzhavia, D. ; Ritt, S. ; Robmann, P. ; Rondon-Aramayo, O.A. ; Rozhdestvensky, A.M. ; Sakhelashvili, T. ; Scheu, S. ; Straumann, U. ; Supek, Ivan ; Tsamalaidze, Z. ; van der Schaaf, A. ; Velicheva, E.P. ; et al.

Izvornik
ArXiv: 0804.1815v1

Vrsta, podvrsta
Ostale vrste radova, rukopis

Godina
2008

Ključne riječi
New Precise Measurement

Sažetak
We have measured the + ! e+ branching ratio over a wide region of phase space, based on a total of 65, 460 events acquired using the PIBETA detector. Minimum-2 ts to the measured (Ee+ ; E) energy distributions result in the weak form factor value of FA = 0:0119(1) with a xed value of FV = 0:0259. An unconstrained t yields FV = 0:0258(17) and FA = 0:0117(17). In addition, we have measured a = 0:095  0:058 for the dependence of FV on the e+ pair invariant mass q2, parametrized as FV (q2) = FV (0)(1 + a
q2). The branching ratio for the kinematic region E > 10MeV and e+ > 40 is measured to be Bexp = 73:86(54)  10

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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