The first observation of the K± → π±π0e+e− rare decay by the NA48/2 experiment at CERN SPS is reported, based on ∼ 2 ×1011 K± decays recorded in 2003-2004. From a sample of 4919 candidates with 4.9% background the branching ratio in the full kinematic region is measured to be BR(K± → π±π0e+e−) = (4.24 ±0.14) ×10−6. The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on Chiral Perturbation Theory. The CP-violating asymmetry between K+ → π+π0e+e− and K− → π−π0e+e− decay rates has been measured, providing an upper limit |ACP| < 4.82 ×10−2 at 90% CL. The NA48/2 combined measurement of the charged kaon semileptonic form factors, based on 4.4 million K± → π0e±νe and 2.3 million K± → π0µ±νµ events collected in 2004, is presented. This result represents the most precise form factor measurement from a combined Kl±3 analysis.
Recent results on Kaon decays from NA48/2 / Bizzeti A.; Anzivino G.; Arcidiacono R.; Baldini W.; Balev S.; Batley J.R.; Behler M.; Bi-Fani S.; Biino C.; Bizzeti A.; Bloch-Devaux B.; Bocquet G.; Cabibbo N.; Calvetti M.; Cartiglia N.; Ceccucci A.; Cenci P.; Cerri C.; Cheshkov C.; Cheze J.B.; Clemencic M.; Collazuol G.; Costantini F.; Cotta Ramusino A.; Coward D.; Cundy D.; Dabrowski A.; Dalpiaz P.; Damiani C.; De Beer M.; Derre J.; Dibon H.; DiLella L.; Doble N.; Eppard K.; Falaleev V.; Fantechi R.; Fidecaro M.; Fiorini L.; Fiorini M.; Fonseca Martin T.; Frabetti P.L.; Gatignon L.; Gersabeck E.; Gianoli A.; Giudici S.; Gonidec A.; Goudzovski E.; Goy Lopez S.; Hita-Hochgesand M.; Holder M.; Hristov P.; Iacopini E.; Imbergamo E.; Jeitler M.; Kalmus G.; Kekelidze V.; Kleinknecht K.; Kozhuharov V.; Kubischta W.; Lamanna G.; Lazzeroni C.; Lenti M.; Litov L.; Madigozhin D.; Maier A.; Mannelli I.; Marchetto F.; Marchevski R.; Marel G.; Markytan M.; Marouelli P.; Martini M.; Masetti L.; Mazzucato E.; Michetti A.; Mikulec I.; Misheva M.; Molokanova N.; Monnier E.; Moosbrugger U.; Morales Morales C.; Munday D.J.; Nappi A.; Neuhofer G.; Norton A.; Patel M.; Pepe M.; Peters A.; Petrucci F.; Petrucci M.C.; Peyaud B.; Piccini M.; Pierazzini G.; Polenkevich I.; Potrebenikov Yu.; Raggi M.; Renk B.; Rubin P.; Ruggiero G.; Savrie M.; Scarpa M.; Shieh M.; Slater M.W.; Sozzi M.; Stoynev S.; Swallow E.; Szleper M.; Valdata-Nappi M.; Vallage B.; Velasco M.; Veltri M.; Venditti S.; Wache M.; Wahl H.; Walker A.; Wanke R.; Widhalm L.; Winhart A.; Winston R.; Wood M.D.; Wotton S.A.; Zinchenko A.; Ziolkowski M.. - In: POS PROCEEDINGS OF SCIENCE. - ISSN 1824-8039. - ELETTRONICO. - 352:(2019), pp. 1-1.
Recent results on Kaon decays from NA48/2
Bizzeti A.
;Calvetti M.
;Collazuol G.
;Lenti M.
;Ruggiero G.
;
2019
Abstract
The first observation of the K± → π±π0e+e− rare decay by the NA48/2 experiment at CERN SPS is reported, based on ∼ 2 ×1011 K± decays recorded in 2003-2004. From a sample of 4919 candidates with 4.9% background the branching ratio in the full kinematic region is measured to be BR(K± → π±π0e+e−) = (4.24 ±0.14) ×10−6. The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on Chiral Perturbation Theory. The CP-violating asymmetry between K+ → π+π0e+e− and K− → π−π0e+e− decay rates has been measured, providing an upper limit |ACP| < 4.82 ×10−2 at 90% CL. The NA48/2 combined measurement of the charged kaon semileptonic form factors, based on 4.4 million K± → π0e±νe and 2.3 million K± → π0µ±νµ events collected in 2004, is presented. This result represents the most precise form factor measurement from a combined Kl±3 analysis.
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