Determination of the parity of the neutral pion via its four-electron decay.
We present a new determination of the parity of the neutral pion via the double Dalitz decay pi0-->e+e-e+e-. Our sample, which consists of 30,511 candidate decays, was collected from KL-->pi0pi0pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi0 parity and place a limit on scalar contributions to the pi0-->e+e-e+e- decay amplitude of less than 3.3% assuming CPT conservation. The pi0gamma*gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase-space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi0-->e+e-e+e-)=(3.26+/-0.18)x10(-5).
The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637, USA.
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Abouzaid
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Arenton
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Barker
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Bellantoni
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Blucher
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Bock
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Cheu
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Coleman
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Corcoran
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Cox
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Erwin
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Escobar
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Glazov
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Golossanov
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Gomes
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Gouffon
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Hsiung
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Jensen
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Kessler
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Kotera
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Ledovskoy
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McBride
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Monnier
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Nguyen
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Niclasen
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Phillips
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Ramberg
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Ray
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Ronquest
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Santos
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Slater
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Smith
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Solomey
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Swallow
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Toale
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Tschirhart
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Wah
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Wang
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White
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Whitmore
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Wilking
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Winstein
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Winston
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Worcester
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Yamanaka
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Zimmerman
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Zukanovich