Cabibbo-favored Decay Research Articles

The doubly Cabibbo-suppressed decay D+ → K+ π − π +

We report the observation of the doubly Cabibbo-suppressed decay D + → K + π − π + in data from Fermilab charm hadroproduction experiment E791. With a signal of 59 ± 13 events we measured the ratio of the branching fraction for this mode to that of the Cabibbo-favored decay D + → K − π + π + to be B(D + → K + π − π +) / B( D + → K − π + π +) = (7.7 ± 1.7 ± 0.8) × 10 −3. A Dalitz plot analysis was performed to search for resonant structures.

Two body weak hadronic decays of charmed baryons and b- baryons

The two body Cabibbo favored hadronic decays of charmed baryons into an octet baryon and a pseudoscalar meson are examined in the SU(3) symmetry scheme and those of b-baryons in pole model. The numerical estimates for decay widths and branching ratios of some of the modes are obtained and are in good agreement with experiment. We also study b- conserving strangeness changing mode of b- baryon decays.

Cabibbo favored hadronic decays of charmed baryons in flavor SU(3).

The two body Cabibbo favored hadronic decays of charmed baryons $\Lambda^{+}_{c}$, $\Xi^{+}_{c}$ and $\Xi_{c}^{0}$ into an octet or decuplet baryon and a pseudoscalar meson are examined in the SU(3) symmetry scheme. The numerical estimates for decay widths and branching ratios of some of the modes are obtained and are in good agreement with experiment.

Nonfactorization in hadronic two-body Cabibbo-favored decays of D0 and D+

With the inclusion of nonfactorized amplitudes in a scheme with $N_c=3$, we have studied Cabibbo-favored decays of $D^0$ and $D^+$ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.

An analysis of Cabibbo-favored two-body decays of charmed mesons withη orη′ in the final state

We have carried out a study of Cabbibbo-favored two-body decays ofD 0 andD + involving η and η′ in the final state, $$D^0 \to (\eta ,\eta ')\bar K^0 , D^0 \to (\eta ,\eta ')\bar K*^0 $$ andD s + →(η,η′)π +,D s + →(η,η′)ρ +. We have introduced an annihilation term wherever admissible, and investigated its size if it were to bridge the gap between theory and experiment in each case. We have also related the semileptonic rates forD s + →(η,η′)e + v to those of the hadronic rates forD s + →(η,η′)π + and unveiled a puzzle. We offer a possible solution.

Test of factorization in Cabibbo-favored two-body hadronic decays of D mesons.

We propose a method that involves quantities independent of strong interaction phases to test the factorization model in Cabibbo-favored two-body decays of [ital D] mesons. The method tests if the factorization model correctly predicts the magnitudes of the isospin amplitudes. We have applied this method to the Cabibbo-favored decays [ital D][r arrow][ital [bar K]][pi], [ital [bar K]][rho], and [ital [bar K]][sup *][pi]. The test, used as a diagnostic tool, allows us to pinpoint the isospin amplitudes for which the factorization model fails. We discuss the roles of annihilation terms and inelastic final state interactions in resolving the differences between the factorization model predictions and experiments.

Nonleptonic charmed-baryon decays: Bc-->B(3/2(+), decuplet)+P(0(-)) or V(1(-)).

In contrast to the nonleptonic decays of charmed baryons ${B}_{c}\ensuremath{\rightarrow}B({\frac{1}{2}}^{+})+P({0}^{\ensuremath{-}})$, where the decay amplitude receives contributions both from the $s$-channel and $u$-channel ${J}^{P}={\frac{1}{2}}^{\ifmmode\pm\else\textpm\fi{}}$ poles and from the factorization term, the Cabibbo-favored decays ${B}_{c}\ensuremath{\rightarrow}B({\frac{3}{2}}^{+},\mathrm{decuplet})+P({0}^{\ensuremath{-}}) or V({1}^{\ensuremath{-}})$ are much simpler to describe. In general, one finds that either the pole term (we confine ourselves to ${\mathrm{\textonehalf{}}}^{\ifmmode\pm\else\textpm\fi{}}$ poles only) or the factorization term contributes, but not both. In this paper we have considered the Cabibbo-favored decays of ${\ensuremath{\Lambda}}_{c}^{+}$, ${\ensuremath{\Xi}}_{c}^{0A}$, ${\ensuremath{\Xi}}_{c}^{+A}$, and ${\ensuremath{\Omega}}_{c}^{0}$. In the model where only ${\mathrm{\textonehalf{}}}^{\ifmmode\pm\else\textpm\fi{}}$ poles are kept, we find that ${\ensuremath{\Lambda}}_{c}^{+}$ and ${\ensuremath{\Xi}}_{c}^{0A}$ decays receive contributions from $s$-channel poles only and that ${\ensuremath{\Omega}}_{c}^{0}$ decays into $B({\frac{3}{2}}^{+},\mathrm{decuplet})+P({0}^{\ensuremath{-}}) or V({1}^{\ensuremath{-}})$ through the factorization process only. ${\ensuremath{\Xi}}_{c}^{+A}$ decays are forbidden. We make numerical estimates of decay rates and the asymmetry parameters. We emphasize that the decays ${B}_{c}\ensuremath{\rightarrow}B({\frac{3}{2}}^{+},\mathrm{decuplet})+P({0}^{\ensuremath{-}}) or V({1}^{\ensuremath{-}})$ are theoretically "clean" and simple to describe and that data in these decay modes will be very desirable.

Semileptonic decays of the charmed baryon [formula omitted] in the phenomenological chiral lagrangian method

The phenomelogical chiral larangian method is applied for describing the semileptonic decays of the charmed baryon ∧ + c . The partial widths are calculated for three- and four-body decays. It is shown that the Cabibbo-favored decay ∧ + c → ∧ ev dominates; the branching ratio for this decay is close to the experimental result for the inclusive decay ∧ + c → ∧ eX .

Observation of a narrow state at 2.46 GeV/ c2 — a candidate for the charmed strange Baryon A +

A narrow state has been observed in the reaction Σ − + Be → ( ΛK − π + π +) + X in an experiment at the CERN SPS hyperon beam. At 2.46 GeV/ c 2 the effective ( ΛK − π + π +) mass distribution shows an excess of 82 events above a background estimated to be 147, corresponding to a statistical significance of more than 6 standard deviations. The positive charge of the observed final state, which has strangeness −2, suggests the interpretation as a Cabibbo favoured decay of the charmed strange baryon, A + [quark content (csu)]. The cross section times branching ratio is measured to be σ · B = (5.3 ± 2.0) μb/ (Be nucleus) for x > 0.6. The invariant production cross section is described by E d 3 σ/d p 3 ∞ (1 - x) (1.7±0.7) exp[−(1.1 −0.4 +0.7) p T 2].

Nonleptonic Decays of Charmed Mesons under the W-Exchange Dominance Hypothesis

Two- and three-body decays of charmed mesons are studied under the “W-exchange” dominance hypothesis. As for the two-body decays, the branching ratios for them are calculated in the scalar meson pole approximation. It is seen through a phenomenological analysis that the contribution of the annihilation diagram is much smaller than that of the W-exchange. This predicts that the F+→π+η decay is considerably suppressed although it is a Cabibbo favored decay. It is also seen that the new Cabibbo angle θc′ which is defined in the charm changing currents is nearly equal to the old one θc. The soft meson technique combined with a linear approximation is applied to the three-body decays. The calculated value of B(D+→π+π+K-) reproduces considerably well the experimental value, but this method is not successful in the other three-body decays of D mesons. The branching ratios for these decays calculated by assuming that quasi tow-body decays contribute dominantly to these decays are almost consistent with the known data.