We present evidence for the flavor-changing neutral current decay B-->K-*.(+).(-) and a measurement of the branching fraction for the related process B-->K.(+).(-), where .(+).(-) is either an e(+)e(-) or a mu(+)mu(-) pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the SLAC PEP-II e(+)e(-) storage ring. Averaging over K-(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl(+)l(-))=(0.65(-0.13)(+0.14)+/-0.04)x10(-6) and B(B-->K(*)l(+)l(-))=(0.88(-0.29)(+0.33)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl(+)l(-) signal is over 8sigma, while for B-->K(*)l(+)l(-) it is 3.3sigma.

Evidence for the rare decay B -> K(*)l(+)l(-) and measurement of the B -> Kl(+)l(-) branching fraction RID C-2728-2008 RID C-5223-2009 RID C-5719-2008 RID D-1055-2009 RID A-2675-2009

ANGELINI, CARLO;BATIGNANI, GIOVANNI;BETTARINI, STEFANO;CALDERINI, GIOVANNI;FORTI, FRANCESCO;GIORGI, MARCELLO;PAOLONI, EUGENIO;RIZZO, GIULIANA;
2003-01-01

Abstract

We present evidence for the flavor-changing neutral current decay B-->K-*.(+).(-) and a measurement of the branching fraction for the related process B-->K.(+).(-), where .(+).(-) is either an e(+)e(-) or a mu(+)mu(-) pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the SLAC PEP-II e(+)e(-) storage ring. Averaging over K-(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl(+)l(-))=(0.65(-0.13)(+0.14)+/-0.04)x10(-6) and B(B-->K(*)l(+)l(-))=(0.88(-0.29)(+0.33)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl(+)l(-) signal is over 8sigma, while for B-->K(*)l(+)l(-) it is 3.3sigma.
2003
Aubert, B; Barate, R; Boutigny, D; Gaillard, Jm; Hicheur, A; Karyotakis, Y; Lees, Jp; Robbe, P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen,...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/184349
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