Naslov
Measurement of charge asymmetry braking by the comparison of pi+d --> pp eta with pi-d --> nn eta

Autori
Abaev, V. ; Batinić, Mijo ; Bekrenev, V. ; Briscoe, W.J. ; Chrien, R.E. ; Clajus, M. ; Isenhower, D. ; Kozlenko, N. ; Kruglov, S. ; Leitch, M.J. ; Marušić, Aljoša ; Moriwaki, T. ; Morrison, T. ; Nefkens, B. M. K. ; Peng, J. C. ; Pile, P. H. ; Price, J. W. ; Rigsby, D. ; Sadler, M. E. ; Sawafta, R. ; Šlaus, Ivo ; Seyfarth, H. ; Starostin, A. ; Supek, Ivan ; Sutter, R.J. ; Švarc, Alfred ; White, D.B.

Izvornik
Physical Review D (0556-2821) 63 (2001); 052001-052017

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
pion-deuteron interactions; eta mesons; meson production; C invariance; spontaneous symmetry breaking; isotopic spin

Sažetak
We report a measurement of charge symmetry breaking in the NNeta system. We have measured the ratio of the differential cross sections of the charge-symmetric reactions pi+d-->ppeta and pi–d-->nneta in the energy region of the eta threshold. Our result is R[equivalent]dsigma(pi+d-->ppeta)/dsigma(pi–d-->nneta) = 0.938ą0.009 after a phase-space correction is made for the difference in the threshold energies of the two reactions. The deviation of R from unity is an indication of charge symmetry breaking, which is mostly due to pi0-eta mixing. A theoretical model for eta production which includes pi0-eta mixing was used to fit the data and yields a mixing angle of (1.5ą0.4)°. Our result is consistent with the mixing angle determined in particle decay and isospin-forbidden processes as well as predictions by several theoretical analyses which yield [approximate]1° and another which yields [approximate]2°.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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