Using the complete KTeV data set of 5241 candidate KL→π+π-e+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(Mρ2- MK2)+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 between the decay planes of the e+e- and π+π- pairs in the KL center of mass is reported.
ASJC Scopus subject areas
- Physics and Astronomy(all)