Measurement of Direct Emission in the KL->pi+pi-gamma Decay Mode

Abstract

In this paper the KTeV collaboration reports the analysis of 112.1*10^3 candidate KL->pi+pi-gamma decays including a background of 671+/-41 events with the objective of determining the photon production mechanisms intrinsic to the decay process. These decays have been analyzed to extract the relative contributions of the CP violating bremsstrahlung process and the CP conserving M1 and CP violating E1 direct photon emission processes. The M1 direct photon emission amplitude and its associated vector form factor parameterized as |g_M1|(1+ (a_1/a_2)/(M(rho)^2-M(K)^2+2M(K)*E(gamma)) have been measured to be |g_M1|=1.198 +/- 0.035(stat) +/- 0.086(syst) and a_1/a_2 = -0.738 +/- 0.007(stat) +/- 0.018 (syst) GeV^2/c^2 respectively. An upper limit for the CP violating E1 direct emission amplitude |g_E1| < 0.21 (90% CL) has been found. The overall ratio of direct photon emission (DE) to total photon emission including the bremsstrahlung process (IB) has been determined to be DE/(DE +IB) = 0.689 +/- 0.021 for E(gamma) > 20 MeV.

REVTeX 3.1, 4 pages, 4 figures submitted to Physical Review Letters

References in corpus (4)

• ππscattering
• A new measurement of K+(e4) decay and the s-wave pi-pi-scattering length a00
• Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System
• A Measurement of the K0 Charge Radius and a CP Violating Asymmetry Together with a Search for CP Violating E1 Direct Photon Emission in the Rare Decay KL->pi+pi-e+e-

Cited by in corpus (4)

• Kaon Decays in the Standard Model
• An evaluation of |Vus| and precise tests of the Standard Model from world data on leptonic and semileptonic kaon decays
• Measurement of the Ratio Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu) and Extraction of the CP Violation Parameter |eta+-|
• Form factor in K+ --> pi+ pi0 gamma: interference versus direct emission