The decay rate of K-L --> pi(o)gammagamma has been measured with the NA48 detector at the CERN SPS. A total of 2558 K-L --> pi(o)gammagamma candidates have been observed with a residual background of 3.2%. The branching ratio is determined to be (1.36 +/- 0.03((stat)) +/- 0.03((syst)) +/- 0.03((norm))) x 10(-6) and the vector coupling constant a(v) = -0.46 +/- 0.03((stat)) +/- 0.04((syst)). This result suggests that the CP-violation effects are dominating in the K-L --> pi(o)e(+)e(-) decay. An upper limit for the K-L --> pi(o)gammagamma decay rate in the two photon mass region m(gammagamma) < m(π)o is also given. (C) 2002 Published by Elsevier Science B.V.
Precise measurement of the decay K-L ->pi(0)gamma gamma
COSTANTINI, FLAVIO;GIUDICI, SERGIO;SOZZI, MARCO STANISLAO;
2002-01-01
Abstract
The decay rate of K-L --> pi(o)gammagamma has been measured with the NA48 detector at the CERN SPS. A total of 2558 K-L --> pi(o)gammagamma candidates have been observed with a residual background of 3.2%. The branching ratio is determined to be (1.36 +/- 0.03((stat)) +/- 0.03((syst)) +/- 0.03((norm))) x 10(-6) and the vector coupling constant a(v) = -0.46 +/- 0.03((stat)) +/- 0.04((syst)). This result suggests that the CP-violation effects are dominating in the K-L --> pi(o)e(+)e(-) decay. An upper limit for the K-L --> pi(o)gammagamma decay rate in the two photon mass region m(gammagamma) < m(π)o is also given. (C) 2002 Published by Elsevier Science B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
