We have carried out a new direct search for the CP violating decay K-S-> 3 pi(0) with 1.7 fb(-1) of e(+)e(-) collisions collected by the KLOEdetector at the Phi-factory DA Phi NE. We have searched for this decayin a sample of about 5.9 x 10(8) KSKL events tagging the K-S by means ofthe K-L interaction in the calorimeter and requiring six prompt photons.With respect to our previous search, the analysis has been improved byincreasing of a factor four the tagged sample and by a more effectivebackground rejection of fake K-S tags and spurious clusters. We find nocandidates in data and simulated background samples, while we expect0.12 standard model events. Normalizing to the number of K-S -> 2 pi(0)events in the same sample, we set the upper limit on BR(K-S -> 3 pi(0))<= 2.6 x 10(-8) at 90\% C.L., five times lower than the previous limit.We also set the upper limit on the eta(000) parameter, vertical bareta(000)vertical bar <= 0.0088 at 90\% C.L., improving by a factor twothe latest direct measurement. (c) 2013 Elsevier B.V. All rightsreserved.
A new limit on the CP violating decay KS → 3π0 with the KLOE experiment
Martini M.;
2013-01-01
Abstract
We have carried out a new direct search for the CP violating decay K-S-> 3 pi(0) with 1.7 fb(-1) of e(+)e(-) collisions collected by the KLOEdetector at the Phi-factory DA Phi NE. We have searched for this decayin a sample of about 5.9 x 10(8) KSKL events tagging the K-S by means ofthe K-L interaction in the calorimeter and requiring six prompt photons.With respect to our previous search, the analysis has been improved byincreasing of a factor four the tagged sample and by a more effectivebackground rejection of fake K-S tags and spurious clusters. We find nocandidates in data and simulated background samples, while we expect0.12 standard model events. Normalizing to the number of K-S -> 2 pi(0)events in the same sample, we set the upper limit on BR(K-S -> 3 pi(0))<= 2.6 x 10(-8) at 90\% C.L., five times lower than the previous limit.We also set the upper limit on the eta(000) parameter, vertical bareta(000)vertical bar <= 0.0088 at 90\% C.L., improving by a factor twothe latest direct measurement. (c) 2013 Elsevier B.V. All rightsreserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
