charged Kaon group meeting update K vertex efficiency

charged Kaon group meeting ü update: K vertex efficiency measurement patrizia ü update: absolute BR(K 0) measurement analysis erika ü update: absolute BR(Kmn) measurement analysis roberto ü update: selection of Ke 3 signal barbara K charged meeting - 24 february 2004 – P. de Simone

Small upgrade on vertex efficiency evaluation Fabio Ambrosino, Patrizia de Simone, Paolo Massarotti, Vincenzo Patera • found a nasty bug in the code that looks for the “ K neutral vertex” • the “pezzetto” code has been added in our KPM library concerning the m clusters we found out that a good event timing is obtained adding Tshift 330 ps ( Tshift has been monitored run by run for all the 2001 -2002 data set ) the “ K neutral vertex” are found with a resolution of 1 cm !! K charged meeting - 24 february 2004 – P. de Simone

vertex resolution K charged meeting - 24 february 2004 – P. de Simone

K coarse selection … looking to the p* of the 0 mass is constrained (Golden. Section procedure) E , x , t tm Kmn tag p. K x. K l. K t 0 p K ± 0 Eg, tg, xg K charged meeting - 24 february 2004 – P. de Simone

vertex efficiency vs K decay lenght Vtx global e 73. 86% Vtx global e 71. 25% data MC cm K selected events Vtx global e 76. 98% Vtx global e 73. 89% data MC cm K charged meeting - 2 february 2004 – P. de Simone

vertex efficiency vs charged momentum Vtx global e 73. 86% Vtx global e 71. 25% data MC Me. V K selected events Vtx global e 76. 98% Vtx global e 73. 89% data MC Me. V K charged meeting - 2 february 2004 – P. de Simone

kinematical fit the goals are measure the K decay vertex measure the p momentum measure the K momentum to distinguish the 3 body decay Paolo is hardly working and dl. K 0. 7 cm dp 2. 5 Me. V dp. K 1. Me. V has been obtained … stay tuned !!!! K charged meeting - 24 february 2004 – P. de Simone