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Register a new userResonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays
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We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective Lagrangian developed previously to describe the decays D -> P l nu(l) and D -> V l nu(l). Light vector mesons are included in the model which combines the heavy quark effective Lagrangian and chiral perturbation theory approach. The nonresonant and resonant contributions are compared. With no new parameters the model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We also present useful nonresonant decay distributions. Finally, a similar model, but with a modified current which satisfies the soft pion theorems at the expense of introducing another parameter, is analyzed and the results of the models are compared.
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We present a new calculation of the $Dtopi$ and $D to K$ form factors from QCD light-cone sum rules. The $overline{MS}$ scheme for the $c$-quark mass is used and the input parameters are updated. The results are $f^+_{Dpi}(0)= 0.67^{+0.10}_{-0.07}$, $f^+_{DK}(0)=0.75^{+0.11}_{-0.08}$ and $f^+_{Dpi}(0)/f^+_{DK}(0)=0.88 pm 0.05$. Combining the calculated form factors with the latest CLEO data, we obtain $|V_{cd}|=0.225pm 0.005 pm 0.003 ^{+0.016}_{-0.012}$ and $|V_{cd}|/|V_{cs}|= 0.236pm 0.006pm 0.003pm 0.013$ where the first and second errors are of experimental origin and the third error is due to the estimated uncertainties of our calculation. We also evaluate the form factors $f^-_{Dpi}$ and $f^-_{DK}$ and predict the slope parameters at $q^2=0$. Furthermore, calculating the form factors from the sum rules at $q^2<0$, we fit them to various parameterizations. After analytic continuation, the shape of the $Dto pi,K $ form factors in the whole semileptonic region is reproduced, in a good agreement with experiment.
We evaluate the form factors describing the semileptonic decays $bar{B^0}to J/psi (eta_c) D^+ ell^- bar u_ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $bar{B^0}to J/psi (eta_c) D^+ pi^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $mathcal{BR}(bar{B^0} to J/psi (eta_c) D^+ ell u_ell) simeq 10^{-13}$, $mathcal{BR}(bar{B^0} to J/psi D^+ pi^-) = 3.1 times 10^{-8}$ and $mathcal{BR}(bar{B^0} to eta_c D^+ pi^-) = 3.5 times 10^{-8}$.
We report on a measurement of the branching fractions for B- --> D(*)+ pi- l- nu-bar and B0bar --> D(*)0 pi+ l- nu-bar with 275 million BBbar events collected at the Upsilon(4S) resonance with the Belle detector at KEKB. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We obtain Br(B- --> D+ pi- l- nu-bar) = (0.54 +/- 0.07(stat) +/- 0.07(syst) +/- 0.06(BR)) x 10^-2, Br(B- --> D*+ pi- l- nu-bar) = (0.67 +/- 0.11(stat) +/- 0.09(syst) +/- 0.03(BR)) x 10^-2, Br(B0bar --> D0 pi+ l- nu-bar) = (0.33 +/- 0.06(stat) +/- 0.06(syst) +/- 0.03(BR)) x 10^-2, Br(B0bar --> D*0 pi+ l- nu-bar) = (0.65 +/- 0.12(stat) +/- 0.08(syst) +/- 0.05(BR)) x 10^-2, where the third error comes from the error on Bbar --> D(*) l- nu-bar decays. Contributions from B0bar --> D*+ l- nu-bar decays are excluded in the measurement of B0bar --> D0 pi+ l- nu-bar.
The decay bar B -> bar K* (-> bar K pi) l+ l- offers great opportunities to explore the physics at and above the electroweak scale by means of an angular analysis. We investigate the physics potential of the seven CP asymmetries plus the asymmetry in the rate, working at low dilepton mass using QCD factorization at next-to leading order (NLO). The b ->s CP asymmetries are doubly Cabibbo-suppressed lesssim 1 % in the Standard Model and its extensions where the CKM matrix is the only source of CP violation. Three CP asymmetries are T-odd, and can be O(1) in the presence of non-standard CP violation. The T-even asymmetries can reach O(0.1), limited by the small strong phases in the large recoil region. We furthermore point out an easy way to measure CP phases from time-integrated, untagged bar B_d, B_d -> K* (-> K0 pi0) l+ l- and bar B_s,B_s -> phi (-> K+ K-) l+ l- decays. Analyses of these CP asymmetries can rule out, or further support the minimal description of CP violation through the CKM mechanism. Experimental studies are promising for (super) flavor factories and at hadron colliders.
We compute the rates of semileptonic B_A to B_Bl^-l^- (l=e or mu) hyperon transitions in a model where intermediate states involve loops of baryons and a Majorana neutrino. These rates turn out to be well below present experimental bounds and other theoretical estimates. From the experimental upper limit on the Xi^- to pmu^-mu^- decay, we derive the bound <m_{mu mu}> < 22 TeV for the effective Majorana mass of the muon neutrino. Also, an estimate of background contributions for these decays due to the allowed B_A to B_Bl^-l^-bar{ u}bar{ u} decays are provided.
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