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 KL→π+π-e+e-

E. Abouzaid, M. Arenton, A. R. Barker, L. Bellantoni, A. Bellavance, E. Blucher, G. J. Bock, E. Cheu, R. Coleman, M. D. Corcoran, G. Corti, B. Cox, A. R. Erwin, C. O. Escobar, A. Glazov, A. Golossanov, R. A. Gomes, P. Gouffon, K. Hanagaki, Y. B. HsiungH. Huang, D. A. Jensen, R. Kessler, K. Kotera, A. Ledovskoy, P. L. McBride, E. Monnier, K. S. Nelson, H. Nguyen, R. Niclasen, H. Ping, X. R. Qi, E. J. Ramberg, R. E. Ray, M. Ronquest, E. Santos, J. Shields, W. Slater, D. Smith, N. Solomey, E. C. Swallow, P. A. Toale, R. Tschirhart, C. Velissaris, Y. W. Wah, J. Wang, H. B. White, J. Whitmore, M. Wilking, B. Winstein, R. Winston, E. T. Worchester, M. Worchester, T. Yamanaka, E. D. Zimmerman, R. F. Zukanovich

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24 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article number101801
JournalPhysical review letters
Volume96
Issue number10
DOIs
StatePublished - 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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