Measurement of the K0 Charge Radius and a CP-Violating Asymmetry and a Search for CP-Violating E1 Direct Photon Emission in the Rare Decay KLπ+πe+e

E. Abouzaid et al. (KTeV Collaboration)
Phys. Rev. Lett. 96, 101801 – Published 17 March 2006

Abstract

Using the complete KTeV data set of 5241 candidate KLπ+πe+e decays (including an estimated background of 204±14 events), we have measured the coupling gCR=0.163±0.014(stat)±0.023(syst) of the CP conserving charge radius process and from it determined a K0 charge radius of rK02=[0.077±0.007(stat)±0.011(syst)]fm2. We have determined a first experimental upper limit of 0.04 (90% C.L.) for the ratio |gE1||gM1| of the couplings for the E1 and M1 direct photon emission processes. We also report the measurement of |gM1| including a vector form factor |g˜M1|(1+a1/a2(Mρ2MK2)+2MKEγ*), where |g˜M1|=1.11±0.12(stat)±0.08(syst) and a1/a2=[0.744±0.027(stat)±0.032(syst)]GeV2/c2. Finally, a CP-violating asymmetry of [13.6±1.4(stat)±1.5(syst)]% in the CP and T odd angle ϕ between the decay planes of the e+e and π+π pairs in the KL center of mass is reported.

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  • Received 3 August 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.101801

©2006 American Physical Society

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Vol. 96, Iss. 10 — 17 March 2006

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