Among some 400 million KSKL pairs produced in e(+)e(-) annihilations at DA Phi DNE, similar to 6500 each of K-S -> pi(+)e(-)(v) over bar and K-S -> pi(-)e(+)v decays have been observed with the KLOE detector. From these, the ratio Gamma(K-S -> pi ev)/Gamma(K-S -> pi(+)pi(-)) = (10.19 +/- 0.13) x 10(-4) is obtained, improving the accuracy on BR(K-S -> pi ev) by a factor of four and providing the most precise test of the Delta S = Delta Q rule. From the partial width F(K-S -> pi ev), a value for f(+)(K0) (0) x V-us is obtained that is in agreement with unitarity of the quark-mixing matrix. The lepton charge asymmetry A(S) = (1.5 +/- 9.6(stat) 2.9(syst)) x 10(-3) is compatible with the requirements of CPT invariance. The form-factor slope agrees with recent results from semileptonic K-L and K+ decays. These are the first measurements of the charge asymmetry and form-factor slope for semileptonic K-S decays. (c) 2006 Elsevier B.V. All rights reserved.
Ambrosino, F., Antonelli, A., Antonelli, M., Bacci, C., Beltrame, P., Bencivenni, G., et al. (2006). Study of the branching ratio and charge asymmetry for the decay K-S -> pi e nu with the KLOE detector. PHYSICS LETTERS. SECTION B, 636, 173-182 [10.1016/j.physletb.2006.03.047].
Study of the branching ratio and charge asymmetry for the decay K-S -> pi e nu with the KLOE detector
SANTOVETTI, EMANUELE;
2006-01-01
Abstract
Among some 400 million KSKL pairs produced in e(+)e(-) annihilations at DA Phi DNE, similar to 6500 each of K-S -> pi(+)e(-)(v) over bar and K-S -> pi(-)e(+)v decays have been observed with the KLOE detector. From these, the ratio Gamma(K-S -> pi ev)/Gamma(K-S -> pi(+)pi(-)) = (10.19 +/- 0.13) x 10(-4) is obtained, improving the accuracy on BR(K-S -> pi ev) by a factor of four and providing the most precise test of the Delta S = Delta Q rule. From the partial width F(K-S -> pi ev), a value for f(+)(K0) (0) x V-us is obtained that is in agreement with unitarity of the quark-mixing matrix. The lepton charge asymmetry A(S) = (1.5 +/- 9.6(stat) 2.9(syst)) x 10(-3) is compatible with the requirements of CPT invariance. The form-factor slope agrees with recent results from semileptonic K-L and K+ decays. These are the first measurements of the charge asymmetry and form-factor slope for semileptonic K-S decays. (c) 2006 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.