Home OALib Journal OALib PrePrints Submit Ranking News My Lib FAQ About Us Follow Us+
 Title Keywords Abstract Author All
Search Results: 1 - 10 of 100 matches for " "
 Physics , 1994, DOI: 10.1016/0370-2693(94)01624-L Abstract: We parametrize phenomenologically possible new physics effects and calculate their influence on the invariant dilepton mass spectrum and the Dalitz plot for the decays $B \to K \ell^+ \ell^-$ and $B \to K^\ast \ell^+ \ell^-$. Especially the decay into $K^*$ yields a wealth of new information on the form of the new interactions since the Dalitz plot is sensitive to subtle interference effects. We also show how transversely polarized $K^*$-mesons give additional information.
 Gustavo Burdman Physics , 1995, DOI: 10.1103/PhysRevD.52.6400 Abstract: We study the potential of $B\to K^{(*)} \ell^+\ell^-$ decays as tests of the standard model. After discussing the reliability of theoretical predictions for the hadronic matrix elements involved, we examine the impact of different new physics scenarios on various observables. We show that the angular information in \bks together with the dilepton mass distribution can highly constrain new physics. This is particularly true in the large dilepton mass region, where reliable predictions for the hadronic matrix elements can be made with presently available data. We compare the Standard Model predictions with those of a Two-Higgs doublet model as well as TopColor models, all of which give distinct signals in this region.
 Physics , 2002, DOI: 10.1103/PhysRevD.66.094018 Abstract: We study the exclusive decays of $B\to K^{(*)}\ell^+ \ell^-$ by the results in the perturbative QCD with the heavy quark effective theory and lattice calculations. We obtain the form factors for the $B\to K^{(*)}$ transitions in the whole allowed region. Our predictions on the branching ratios of $B\to K \ell^{+} \ell^{-}$, $B\to K^{*} e^{+}e^{-}$, and $B\to K^{*} \mu^{+} \mu^{-}$ are $0.53\pm 0.05 ^{+0.10}_{-0.07}$, $1.68\pm 0.17^{+0.14}_{-0.09}$, and $1.34\pm 0.13 ^{+0.11}_{-0.06}\times 10^{-6}$, where the errors are from the quark mixing elements and hadronic effects, respectively. We also find that our definitions of the T-odd observable and the up-down asymmetry of the $K$ meson in $B\to K^*\ell^+ \ell^-\to K\pi\ell^+ \ell^-$ can be used to probe new physics.
 High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.77.014016 Abstract: The forward-backward asymmetry ${\cal A}_{\rm FB}$ in $B\to K^*\ell^+\ell^-$ decay is a sensitive probe of New Physics. Previous studies have focused on the sensitivity in the position of the zero. However, the short distance effective couplings are in principle complex, as illustrated by $B\to \rho\ell^+\ell^-$ decay within the Standard Model. Allowing the effective couplings to be complex, but keeping the $B\to K^*\gamma$ and $K^*\ell^+\ell^-$ rate constraints, we find the landscape for ${\cal A}_{\rm FB}(B\to K^*\ell^+\ell^-)$ to be far richer than from entertaining just sign flips, which can be explored by future high statistics experiments.
 Physics , 2012, DOI: 10.1016/j.nuclphysb.2012.11.016 Abstract: We discuss the uncertainty related to the amount of unwanted $B\to K_0^\ast (K\pi)\ell^+\ell^-$ events in the sample of $B\to K^\ast (K\pi)\ell^+\ell^-$. Those events can increase the measured differential decay rate by up to 10% in the low $q^2$ region, and can be a source of non-negligible uncertainty in the full angular distribution of the $B\to K^\ast (K\pi)\ell^+\ell^-$ decay. Although the transverse asymmetries should be unaffected by the presence of the $S$-wave $K\pi$ pairs, coming from the scalar $K_0^\ast$ meson, we show that in practice their normalization might be sensitive to those events and could entail a sizable uncertainty in transverse asymmetries around $q^2=2 GeV^2$. For other $q^2$'s that error is under about 10%.
 Physics , 2000, DOI: 10.1103/PhysRevD.62.034013 Abstract: We present the angular distribution of the rare B decay, $B \to K^* (\to K \pi) \ell^+ \ell^-$. By studying the azimuthal angle distribution in the low invariant mass region of dileptons, we can probe new physics effects efficiently. In particular, this distribution is found to be quite sensitive to the ratio of the contributions from two independent magnetic moment operators, which also contribute to $B \to K^* \gamma$. Therefore, our method can be very useful when new physics is introduced without changing the total decay rate of the $b \to s \gamma$. The angular distributions are compared with the predictions of the standard model, and are shown for the cases when the afore-mentioned ratio is different from the standard model prediction.
 Physics , 2012, DOI: 10.1007/JHEP02(2013)010 Abstract: We predict the amplitude of the $B\to K \ell^+\ell^-$ decay in the region of the dilepton invariant mass squared $0  A. Ishikawa Physics , 2003, DOI: 10.1103/PhysRevLett.91.261601 Abstract: We report the first observation of the flavor-changing neutral current decay$B \to K^* \ell^+ \ell^-$and an improved measurement of the decay$B \to K \ell^+ \ell^-$, where$\ell$represents an electron or a muon, with a data sample of 140 fb${}^{-1}$accumulated at the$\Upsilon(4S)$resonance with the Belle detector at KEKB. The results for the branching fractions are${\cal B}(B \to K^* \ell^+ \ell^-)=(11.5^{+2.6}_{-2.4} \pm 0.8 \pm 0.2) \times 10^{-7}$and${\cal B}(B \to K \ell^+ \ell^-)=(4.8^{+1.0}_{-0.9} \pm 0.3 \pm 0.1) \times 10^{-7}$, where the first error is statistical, the second is systematic and the third is from model dependence.  Physics , 2001, DOI: 10.1103/PhysRevD.64.094014 Abstract: We investigate the angular distributions of the rare B decay,$B \to K^* (\to K \pi) \ell^+ \ell^-$, in general supersymmetric extensions of the standard model. We consider the new physics contributions from the operators$O_{7,8,9,10}\$ in small invariant mass region of lepton pair. We show that the azimuthal angle distribution of the decay can tell us the new physics effects clearly from the behavior of the distribution, even if new physics does not change the decay rate substantially from the standard model prediction.