We report the first measurement of the branching fraction for the inclusive decay B-->X(s)l(+)l(-), where l is either an electron or a muon, and X(s) is a hadronic recoil system that contains an s ...quark. We analyzed a data sample of 65.4 x 10(6) B meson pairs collected with the Belle detector at the KEKB e(+)e(-) asymmetric-energy collider. We find B(B-->X(s)l(+)l(-))=6.1 +/-1.4(stat) +1.4-1.1(syst) x 10(-6) for dilepton masses greater than 0.2 GeV/c(2).
We report the first measurements of the doubly charmed baryonic B decays B --> Lambda c+ Lambda c- K. The B+ --> Lambda c+ Lambda c- K+ decay is observed with a branching fraction of ...(6.5(-0.9)(+1.0)+/-1.1+/-3.4)x10(-4) and a statistical significance of 15.4sigma. The B0 --> Lambda c+ Lambda c- K0 decay is observed with a branching fraction of (7.9(-2.3)(+2.9)+/-1.2+/-4.1)x10(-4) and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of the Lambda c+ --> pK- pi+ decay branching fraction. The analysis is based on 357 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.
Using kaon secondary interactions in the material of the Belle detector, we search for both inclusive and exclusive production of the Θ(1540)+. We set an upper limit of 2.5% at the 90% C.L. on the ...ratio of the Θ(1540)+ to Λ(1520) inclusive production cross sections. We also search for the Θ(1540)+ as an intermediate resonance in the charge exchange reaction K+n→pKS0. We set an upper limit of ΓΘ+<0.64 MeV at the 90% C.L. for mΘ+=1.539 MeV/c2. These results are obtained from a 397 fb−1 data sample collected with the Belle detector near the ϒ(4S) resonance, at the KEKB asymmetric energy e+e− collider.
Using a 282 fb{sup -1} data sample collected by the Belle experiment at the KEKB e{sup +}e{sup -} collider, we study D{sup 0} decays to K{sup -}l{sup +}{nu} and {pi}{sup -}l{sup +}{nu} final states. ...The D{sup 0} flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q{sup 2}=(p{sub l}+p{sub {nu}}){sup 2}. Normalizing to the total number of D{sup 0} tags, we measure the absolute branching fractions to be B(D{sup 0}{yields}Kl{nu})=(3.45{+-}0.07{sub stat}{+-}0.20{sub syst})% and B(D{sup 0}{yields}{pi}l{nu})=(0.255{+-}0.019{sub stat}{+-}0.016{sub syst})% and the semileptonic form factors (within the modified pole model) f{sub +}{sup K}(0)=0.695{+-}0.007{sub stat}{+-}0.022{sub syst} and f{sub +}{sup {pi}}(0)=0.624{+-}0.020{sub stat}{+-}0.030{sub syst}.
The form factor of A(o)(b) baryons is estimated using 3.46 x 10(6) hadronic Z decays collected by the DELPM experiment between 1992 and 1995. Charmed A(c)(+) baryons fully reconstructed in the ...pK(-)pi(+), pK(o)(s), and Api(+)pi(+)pi(-) modes, are associated to a c S lepton with opposite charge in order to select A(o)(b) --> A(c)(+)l(-)v(l) decays. From a combined likelihood and event rate fit to the b C distribution of the Isgur-Wise variable w, and using the Heavy Quark Effective Theory (HQET), the slope of the b-baryon form factor is measured to be p(2)=2.03+/-0.46(stat)(-1.00)(+0.72)(syst). The exclusive semileptonic branching fraction Br(A(b)(o) --> A(c)(+)l(-)v(l)) can be derived from p(2) and is found to be (5.0(-0.8)(+1.1)(stat)(-1.2)(+1.6) (syst))%. Limits on other branching fractions are also obtained. (C) 2004 Published by Elsevier B.V.
K + K- production in two-photon collisions has been studied using a large data sample of 67 fb-1 accumulated with the Belle detector at the KEKB asymmetric e + e- collider. We have measured the cross ...section for the process \(\gamma\gamma\to K^ + K^-\) for center-of-mass energies between 1.4 and 2.4 GeV, and found three new resonant structures in the energy region between 1.6 and 2.4 GeV. The angular differential cross sections have also been measured.
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