Predicted Branching Ratios Research Articles

Erratum: Charmful baryonicBdecaysB0→Λcp¯andB¯→Λcp¯π(ρ)[Phys. Rev. D65, 054028 (2002)

We study the two-body and three-body charmful baryonic B decays: $\bar B^0\to \Lambda_c\bar p$ and $\bar B\to \Lambda_c \bar p\pi(\rho)$. The factorizable W-exchange contribution to $\bar B^0\to\Lambda_c\bar p$ is negligible. Applying the bag model to evaluate the baryon-to-baryon weak transition matrix element, we find $B(\bar B^0\to\Lambda_c\bar p)\leq 1.1\times 10^{-5}|g_{B^0p\Sigma_b^+}/6|^2$ with $g_{B^0p\Sigma_b^+}$ being a strong coupling for the decay $\Sigma_b^+\to \bar B^0 p$ and hence the predicted branching ratio is well below the current experimental limit. The factorizable contributions to $B^-\to\Lambda_c\bar p\pi^-$ can account for the observed branching ratio of order $6\times 10^{-4}$. The branching ratio of order $2\times 10^{-3}$ for $B^-\to\Lambda_c\bar p\rho^-$ is larger than that of $B^-\to\Lambda_c\bar p\pi^-$ by a factor of about 2.6. We explain why the three-body charmful baryonic B decay has a larger rate than the two-body one, contrary to the case of mesonic B decays.

Lepton flavor violating process in degenerate and inverse-hierarchical neutrino models

We have investigated the lepton flavor violation in the supersymmetric framework assuming the large mixing angle MSW solution with the quasi-degenerate and the inverse-hierarchical neutrino masses. In the case of the quasi-degenerate neutrinos, the predicted branching ratio BR$(\mu \to e \gamma)$ strongly depends on $m_\nu$ and $U_{e3}$. For $U_{e3}\simeq 0.05$ with $m_\nu \simeq 0.3 \eV$, the prediction is close to the present experimental upper bound if the right-handed Majorana neutrino masses are degenerate. On the other hand, the prediction is larger than the experimental upper bound for $U_{e3}\geq 0.05$ in the case of the inverse-hierarchical neutrino masses.

Analysis ofB→φKdecays in QCD factorization

We analyze the decay $B\to \phi K$ within the framework of QCD-improved factorization. We found that although the twist-3 kaon distribution amplitude dominates the spectator interactions, it will suppress the decay rates slightly. The weak annihilation diagrams induced by $(S-P)(S+P)$ penguin operators, which are formally power-suppressed by order $(\Lambda/m_b)^2$, are chirally and logarithmically enhanced. Therefore, these annihilation contributions are not subject to helicity suppression and can be sizable. The predicted branching ratio of $B^-\to\phi K^-$ is $(3.8\pm0.6)\times 10^{-6}$ in the absence of annihilation contributions and it becomes $(4.3^{+3.0}_{-1.4})\times 10^{-6}$ when annihilation effects are taken into account. The prediction is consistent with CLEO and BaBar data but smaller than the BELLE result.

Theoretical and Experimental Investigation of the Dynamics of the Production of CO from the CH3 + O and CD3 + O Reactions

Combined experimental and theoretical investigations of the title reactions are presented. Time-resolved Fourier transform infrared (FTIR) emission studies of CO (v = 1) produced from the CH{sub 3} + O and CD{sub 3} + O reactions show that there is approximately a one-third reduction in the branching to the CO channel upon deuteration of the methyl radical. Direct dynamics, classical trajectory calculations using a B3LYP potential surface, confirm the existence of the CO producing channel. The calculations show that the CO comes from the decomposition of HCO produced by the elimination of H{sub 2} from highly vibrationally excited methoxy radicals. Scans of the potential surface reveal no saddle point for the direct elimination of H{sub 2} from methoxy. The minimum-energy path for this elimination is a stepwise process involving first a CH bond cleavage, forming H + H{sub 2}CO, followed by an abstraction, forming H{sub 2} + HCO. However, at the high internal energies produced in the initial O + CH{sub 3} addition, trajectories for the direct elimination of H{sub 2} from methoxy are observed. The predicted branching ratio between the CO and H{sub 2}CO channels is in good agreement with previous room-temperature measurements, and there is predicted to bemore » little temperature dependence to it. The observed reduction in the branching to the CO channel upon deuteration is also well reproduced in the calculations.« less

Testing neutrino mixing at future collider experiments

Low energy supersymmetry with bilinear breaking of R parity leads to a weak-scale seesaw mechanism for the atmospheric neutrino scale and a radiative mechanism for the solar neutrino scale. The model has striking implications for collider searches of supersymmetric particles. Assuming that the lightest SUSY particle is the lightest neutralino we demonstrate that (i) the neutralino decays inside the detector even for tiny neutrino masses and (ii) measurements of the neutrino mixing angles lead to predictions for the ratios of various neutralino decay branching ratios implying an independent test of neutrino physics at future colliders, such as the CERN Large Hadron Collider or a Linear Collider. We study the lightest neutralino decay branching ratio predictions taking into account present supersymmetric particle mass limits as well as restrictions coming from neutrino physics, with emphasis on the solar and atmospheric neutrino anomalies.

A new approach to a global fit of the CKM matrix

We report on a global CKM matrix analysis taking into account most recent experimental and theoretical results. The statistical framework (Rfit) developed in this paper advocates formal frequentist statistics. Other approaches, such as Bayesian statistics or the 95% CL scan method are also discussed. We emphasize the distinction of a model testing and a model dependent, metrological phase in which the various parameters of the theory are determined. Measurements and theoretical parameters entering the global fit are thoroughly discussed, in particular with respect to their theoretical uncertainties. Graphical results for confidence levels are drawn in various one and two-dimensional parameter spaces. Numerical results are provided for all relevant CKM parameterizations, the CKM elements and theoretical input parameters. Predictions for branching ratios of rare K and B meson decays are obtained. A simple, predictive SUSY extension of the Standard Model is discussed.

Charmless decays $B \to{\mathrm{PP}}, {\mathrm{PV}}$ , and the effects of new strong and electroweak penguins in topcolor-assisted technicolor model

Based on the low energy effective Hamiltonian with generalized factorization, we calculate the new physics contributions to the branching ratios and CP-violating asymmetries of the two-body charmless hadronic decays $B \to PP, PV$ from the new strong and electroweak penguin diagrams in the TC2 model. The top-pion penguins dominate the new physics corrections, and both new gluonic and electroweak penguins contribute effectively to most decay modes. For tree-dominated decay modes $B \to \pi \pi, \rho \pi, etc,$ the new physics corrections are less than 10%. For decays $B \to K^{(*)} \pi$, $K^{(*)} \eta$, $etc$, the new physics enhancements can be rather large (from $- 70%$ to $\sim 200%$) and are insensitive to the variations of $N_c^{eff}$, $k^2$, $\eta$ and $m_{\tilde{\pi}}$ within the reasonable ranges. For decays $B^0 \to \phi \pi$, $\phi \eta^{(')}$, $K^* \bar{K}^0$ and $\rho^+ K^0$, $\delta {\cal B}$ is strongly $N_c^{eff}-$dependent: varying from -90% to $\sim 1680%$ in the range of $N_c^{eff}=2-\infty$. The new physics corrections to the CP-violating asymmetries ${\cal A}_{CP}$ vary greatly for different B decay channels. For five measured CP asymmetries of $B \to K \pi, K \eta', \omega \pi$ decays, $\delta {\cal A}_{CP}$ is only about 20% and will be masked by large theoretical uncertainties. The new physics enhancements to interesting $B \to K \eta'$ decays are significant in size ($\sim 50%$), insensitive to the variations of input parameters and hence lead to a plausible interpretation for the unexpectedly large $B \to K \eta'$ decay rates. The TC2 model predictions for branching ratios and CP-violating asymmteries of all fifty seven $B \to PP, PV$ decay modes are consistent with the available data within one or two standard deviations.

Final-state interaction andB→KKdecays in perturbative QCD

We predict branching ratios and CP asymmetries of the $B\to KK$ decays using perturbative QCD factorization theorem, in which tree, penguin, and annihilation contributions, including both factorizable and nonfactorizable ones, are expressed as convolutions of hard six-quark amplitudes with universal meson wave functions. The unitarity angle $\phi_3= 90^o$ and the $B$ and $K$ meson wave functions extracted from experimental data of the $B\to K\pi$ and $\pi\pi$ decays are employed. Since the $B\to KK$ decays are sensitive to final-state-interaction effects, the comparision of our predictions with future data can test the neglect of these effects in the above formalism. The CP asymmetry in the $B^\pm\to K^\pm K^0$ modes and the $B_d^0\to K^\pm K^\mp$ branching ratios depend on annihilation and nonfactorizable amplitudes. The $B\to KK$ data can also verify the evaluation of these contributions.

NLL corrections for B-meson radiative exclusive decays

We calculate the next-to-leading corrections to the branching ratio of exclusive B→K ∗γ decay. The renormalization scale dependence is reduced compared to the leading logarithmic result but there remains a dependence on a cutoff parameter of the hadronic model. The calculated corrections increase the predicted branching ratio by about 10%, but it remains in agreement with the experimental value.

U(1)textures and lepton flavor violation

U(1) family symmetries have led to successful predictions of the fermion mass spectrum and the mixing angles of the hadronic sector. In the context of the supersymmetric unified theories, they further imply a non-trivial mass structure for the scalar partners, giving rise to new sources of flavor violation. In the present work, lepton flavor non-conserving processes are examined in the context of the minimal supersymmetric standard model augmented by a U(1)-family symmetry. We calculate the mixing effects on the \mu-> e\gamma and \tau -> \mu\gamma rare decays. All supersymmetric scalar masses involved in the processes are determined at low energies using two loop renormalization group analysis and threshold corrections. Further, various novel effects are considered and found to have important impact on the branching ratios. Thus, a rather interesting result is that when the see-saw mechanism is applied in the (12 X 12)-sneutrino mass matrix, the mixing effects of the Dirac matrix in the effective light sneutrino sector are canceled at first order. In this class of models and for the case that soft term mixing is already present at the GUT scale, tau -> \mu \gamma decays are mostly expected to arise at rates significantly smaller than the current experimental limits. On the other hand, the $\mu \ra e \gamma$ rare decays impose important bounds on the model parameters, particularly on the supersymmetric scalar mass spectrum. In the absence of soft term mixing at high energies, the predicted branching ratios for rare decays are, as expected, well below the experimental bounds.

Exclusive charmless Bs hadronic decays into η′ and η

Using the next-to-leading order QCD-corrected effective Hamiltonian, charmless exclusive nonleptonic decays of the B s meson into η or η′ are calculated within the generalized factorization approach. Nonfactorizable contributions, which can be parameterized in terms of the effective number of colors N c eff for PP and VP decay modes, are studied in two different schemes: (i) the one with the “homogeneous” structure in which ( N c eff) 1≈( N c eff) 2≈⋯≈( N c eff) 10 are assumed, and (ii) the “heterogeneous” one in which the possibility of N c eff( V+ A)≠ N c eff( V− A) is considered, where N c eff( V+ A) denotes the effective value of colors for the ( V− A)( V+ A) penguin operators while N c eff( V− A) for the ( V− A)( V− A) ones. For processes depending on the N c eff-stable a i such as B s →(π,ρ)(η ′,η) , the predicted branching ratios are not sensitive to the factorization approach we choose. While for the processes depending on the N c eff-sensitive a i such as B s →ωη (′) , there is a wide range for the branching ratios depending on the choice of the N c eff involved. We have included the QCD anomaly effect in our calculations and found that it is important for B s →η (′)η (′) . The effect of the (c c ̄ )→η′ mechanism is found to be tiny due to a possible CKM-suppression and the suppression in the decay constants except for the B s →φη decay within the “naive” factorization approach, where the internal W diagram is CKM-suppressed and the penguin contributions compensate.

Non-perturbative chiral approach to K−p → γ Y reactions

A recently developed non-perturbative chiral approach to describe the S = −1 meson-baryon reactions has been extended to investigate the near threshold K − p → γΛ,γΣ 0 reactions. With the parameters governed by chiral SU(3) symmetry, we show that the predicted branching ratios Γ K − p→γΛ /Γ K − p→ all and Γ K − p→γΣ 0 /Γ K − p→ all are close to the experimental values. The coupling with the η channels, which was shown to be important in the S = −1 meson-baryon reactions, is also found to be significant here. Our results are consistent with the interpretation of the Λ(1405) as a quasi-bound meson-baryon state as found in other similar chiral approaches.

On some rare weak decays of vector mesons

Some semileptonic weak decays of vector mesons are considered in the framework of the most popular quark models. The predicted branching ratios are unfortunately too small to make a study of these decays realistic at meson factories under construction.

Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4

The measurement of branching ratios, cross sections and radiative lifetimes for rare earth ions in solids is considered. The methods are applied to Tm and Ho in YLF as a test case. De-activation rates for electric dipole and magnetic dipole emission are calculated for many of the lower lying manifolds in Tm:YLF and Ho:YLF in the context of the Judd-Ofelt theory to determine radiative lifetimes. Measured values for the branching ratios as well as the absorption and emission cross sections are also presented for many of the excited state manifolds. From these measurements, a methodology is developed to extract measured values for the radiative lifetimes. These results are compared with the Judd-Ofelt theory as a guide for consistency and for determining the accuracy of the Judd-Ofelt theory in predicting branching ratios and radiative lifetimes. The parameters generated by the methods covered here have potential applications for more accurate modeling of Tm:Ho laser systems.

Charmless B decays to η′ and η

Exclusive charmless B decays to $\eta'$ and $\eta$ are studied in the standard effective Hamiltonian approach. The effective coefficients that take into account nonfactorizable effects in external and internal W-emission amplitudes are fixed by experiment. Factorization is applied to the matrix elements of QCD, electroweak penguin operators and next-to-leading corrections to penguin Wilson coefficients, which are renormalization-scheme dependent, are included, but the resultant amplitude is renormalization-scheme and -scale independent. We show that the unexpectedly large branching ratio of $B^\pm\to \eta' K^\pm$ measured by CLEO can be explained by the Cabibbo-allowed internal W-emission process $b\to c\bar cs$ followed by a conversion of the $c\bar c$ pair into the $\eta'$ via gluon exchanges characterized by a decay constant of order -50 MeV. Implications are discussed. The mechanism of the transition $c\bar c\to\eta'$, if correct, will enhance the decay rates of $B\to \eta' K^{*}$ by more than an order of magnitude. However, it plays only a minor role to the rare decays $B\to \eta'(\eta)\pi(\rho)$. The predicted branching ratio of $B^\pm\to \eta\pi^\pm$ for positive $\rho$ is marginally ruled out by experiment, indicating that the favored Wolfenstein parameter $\rho$ is negative.

QCD corrections toB→J/ψ+anything

We calculate the branching ratio for B -> J/psi + anything, within the color-singlet approximation for J/psi production, but including perturbative QCD corrections beyond the leading logarithm approximation. Such higher order corrections are necessary, in order to obtain a result that is not strongly dependent on the renormalization scale. As in the earlier work of Bergstrom and Ernstrom, we use a double expansion in alpha_s and in the small ratio of Wilson coefficients L_0/L_2, to identify the dominant terms in the decay amplitude. We complete their work by calculating all the leading order terms in this double expansion. The predicted branching ratio is then BR(B -> J/psi + anything) = 0.09 (+1.1)(-0.3) %, which is well below the experimental value BR(experimental) = 0.80 (+-0.08) %. This confirms the suspicion that non-perturbative corrections to the color-singlet approximation for J/psi production in B decays are important.

Some two body non-leptonicB decays and estimation off D in the heavy quark effective theory

We have studied some of the two body nonleptonic decays ofB meson in the context of heavy quark effective theory using factorization hypothesis. Treatinga1 as a free parameter, we have obtained its value asa1=0.822±0.045, by correlating the experimental and predicted branching ratio for\(\bar B^0 \to D^ + \pi ^ - \) process. With this value ofa1 the branching ratios obtained for other decay channels are in good agreement with the experiment. The decay constant ofD meson is extracted to be 280.82 MeV. Heavy quark spin symmetry has also been tested.

Measurement of thel-forbidden Gamow-Teller branch of37K

The {beta} decay of {sup 37}K is studied in detail. Several new {beta} decay branches and {gamma}-ray transitions are assigned to this nucleus. The l-forbidden 0d{sub 3/2}{r_arrow}1s{sub 1/2} Gamow-Teller branch to the first excited state in {sup 37}Ar is observed for the first time and its branching ratio measured to be (42.2{plus_minus}7.5){times}10{sup {minus}6}. Such l-forbidden branches are very sensitive to extranucleonic effects such as meson-exchange currents and {Delta}-isobar excitations. A calculation of these as well as core-polarization and relativistic effects, predict branching ratios of 8{times}10{sup {minus}6} with universal s-d wave functions and 52{times}10{sup {minus}6} with Chung-Wildenthal wave functions. {copyright} {ital 1997} {ital The American Physical Society}

Optical spectra, energy levels and branching ratios of trivalent dysprosium-doped yttrium scandium gallium garnet

Absorption spectra of trivalent dysprosium ions in yttrium scandium gallium garnet are reported between 2.9 and 0.4 μn at 4K. Laser-excited fluorescence was observed at 4 K for transitions between the 4 F 9 2 manifold and several of the lower-lying 6 H J and 6 F J manifolds. A crystal-field splitting calculation was carried out in which a parametrized Hamiltonian (including Coulombic, spin-orbit, and crystal field terms in D 2 symmetry) was diagonalized for selected manifolds of the Dy 3+ (4 f 9 ) configuration. The RMS deviation between 69 experimental and calculated Stark levels was 8 cm −1 . Calculations were carried out to predict branching ratios for emission from the 4 F 9 2 manifold.

Nonleptonic two-body decays of D mesons in broken SU(3).

Decays of the D mesons to two pseudoscalars, to two vectors, and to pseudoscalar plus vector are discussed in the context of broken flavor SU(3). A few assumptions are used to reduce the number of parameters. Amplitudes are fit to the available data, and predictions of branching ratios for unmeasured modes are made.