Abstract
The first observation of the B0->J/\psi K+K- decay is presented with a data sample corresponding to an integrated luminosity of 1.0/fb of pp collisions at a center-of-mass energy of 7 TeV collected with the LHCb detector. The branching fraction is measured to be B(B0->J/\psi K+K-) = (2.53 +/- 0.31 +/- 0.19)x10^{-6}, where the first uncertainty is statistical and the second is systematic. An amplitude analysis of the final state in the B0->J/\psi K+K- decay is performed to separate resonant and nonresonant contributions in the K+K- spectrum. Evidence of the a0(980) resonance is reported with statistical significance of 3.9 standard deviations. The corresponding product branching fraction is measured to be B(B0->J/\psi a0(980), a0(980)->K+K-)=(4.70 +/- 3.31 +/- 0.72)x10^{-7}, yielding an upper limit of B(B0->J/\psi a0(980), a0(980)->K+K-)<9.0x10^{-7} at 90% confidence level. No evidence of the resonant decay B0->J/\psi\phi\; is found, and an upper limit on its branching fraction is set to be B(B0->J/\psi\phi)< 1.9x10^{-7} at 90% confidence level.
Highlights
The decays of neutral B mesons to a charmonium state and a hþhÀ pair, where h is either a pion or kaon, play an important role in the study of CP violation and mixing.1 To fully exploit these decays for measurements of CP violation, a better understanding of their final state composition is necessary
We report on a measurement of the branching fraction of the decay B"0 ! J=c KþKÀ
We identify the hadron species of each track from the difference DLLðh1 À h2Þ between logarithms of the likelihoods associated with the two hypotheses h1 and h2, as provided by the ring-imaging Cherenkov detectors (RICH) detector
Summary
The decays of neutral B mesons to a charmonium state and a hþhÀ pair, where h is either a pion or kaon, play an important role in the study of CP violation and mixing. To fully exploit these decays for measurements of CP violation, a better understanding of their final state composition is necessary. The decays of neutral B mesons to a charmonium state and a hþhÀ pair, where h is either a pion or kaon, play an important role in the study of CP violation and mixing.. Dalitz plot analysis of the final state is performed to study the resonant and nonresonant structures in the KþKÀ mass spectrum using the J=c Kþ and KþKÀ mass spectra and decay angular distributions. This differs from a classical Dalitz plot analysis [5] because the J=c meson has spin one, so its three helicity amplitudes must be considered. A search for the decay B"0 ! J=c is performed
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