通过中性π介子的四电子衰变确定其宇称。
Determination of the parity of the neutral pion via its four-electron decay.
作者信息
Abouzaid E, Arenton M, Barker A R, Bellantoni L, Blucher E, Bock G J, Cheu E, Coleman R, Corcoran M D, Cox B, Erwin A R, Escobar C O, Glazov A, Golossanov A, Gomes R A, Gouffon P, Hsiung Y B, Jensen D A, Kessler R, Kotera K, Ledovskoy A, McBride P L, Monnier E, Nguyen H, Niclasen R, Phillips D G, Ramberg E J, Ray R E, Ronquest M, Santos E, Slater W, Smith D, Solomey N, Swallow E C, Toale P A, Tschirhart R, Wah Y W, Wang J, White H B, Whitmore J, Wilking M J, Winstein B, Winston R, Worcester E T, Yamanaka T, Zimmerman E D, Zukanovich R F
机构信息
The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637, USA.
出版信息
Phys Rev Lett. 2008 May 9;100(18):182001. doi: 10.1103/PhysRevLett.100.182001. Epub 2008 May 6.
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 pi0gammagamma 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).
我们通过双Dalitz衰变π0→e+e−e+e−给出了一种确定中性π介子宇称的新方法。我们的样本包含30511个候选衰变事例，是在费米国家加速器实验室的KTeV - E799实验中，从飞行中的KL→π0π0π0衰变收集而来。我们确认了π0宇称为负，并在假设CPT守恒的情况下，对标量对π0→e+e−e+e−衰变振幅的贡献设定了小于3.3%的限制。π0γγ形状因子可以用一个与动量相关的模型很好地描述，该模型的斜率参数拟合到末态相空间分布。此外，我们测量了该模式的分支比为B(π0→e+e−e+e−) = (3.26±0.18)×10−5。
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