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Register a new userSemileptonic weak decays of anti-triplet charmed baryons in the light-front formalism
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We systematically study the semileptonic decays of ${bf B_c} to {bf B_n}ell^+ u_{ell}$ in the light-front constituent quark model, where ${bf B_c}$ represent the anti-triplet charmed baryons of $(Xi_c^0,Xi_c^+,Lambda_c^+)$ and ${bf B_n}$ correspond to the octet ones. We determine the spin-flavor structures of the constituents in the baryons with the Fermi statistics and calculate the decay branching ratios (${cal B}$s) and averaged asymmetry parameters ($alpha$s) with the helicity formalism. In particular, we find that ${cal B}( Lambda_c^+ to Lambda e^+ u_{e}, ne^+ u_{e})=(3.55pm1.04, 0.36pm0.15)%$, ${cal B}( Xi_c^+ to Xi^0 e^+ u_{e},Sigma^0 e^+ u_{e},Lambda e^+ u_{e})=(11.3pm3.35), 0.33pm0.09,0.12pm0.04%$ and ${cal B}( Xi_c^0 to Xi^- e^+ u_{e},Sigma^- e^+ u_{e})=(3.49pm0.95,0.22pm0.06)%$. Our results agree with the current experimental data. Our prediction for ${cal B}( Lambda_c^+ to n e^+ u_{e})$ is consistent with those in the literature, which can be measured by the charm-facilities, such as BESIII and BELLE. Some of our results for the $Xi_c^{+(0)}$ semileptonic channels can be tested by the experiments at BELLE as well as the ongoing ones at LHCb and BELLEII.
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We analyze the decay processes of ${bf B}_c to {bf B}_n M$ with the $SU(3)_F$ flavor symmetry and spin-dependent amplitudes, where ${bf B}_c({bf B}_n)$ and $M$ are the anti-triplet charmed (octet) baryon and nonet meson states, respectively. In the $SU(3)_F$ approach, it is the first time that the decay rates and up-down asymmetries are fully and systematically studied without neglecting the ${cal O}(overline{15})$ contributions of the color anti-symmetric parts in the effective Hamiltonian. Our results of the up-down asymmetries based on $SU(3)_F$ are quite different from the previous theoretical values in the literature. In particular, we find that the up-down symmetry of $ alpha(Lambda_c^+to Xi^0 K^+)_{SU(3)} = 0.94^{+0.06}_{-0.11}$, which is consistent with the recent experimental data of $0.77pm0.78$ by the BESIII Collaboration, but predicted to be zero in the literature. We also examine the $K_S^0-K_L^0$ asymmetries between the decays of ${bf B}_c to {bf B}_n K_S^0$ and ${bf B}_c to {bf B}_n K_L^0$ with both Cabibbo-allowed and doubly Cabibbo-suppressed transitions.
The hadronic two-body weak decays of the doubly charmed baryons $Xi_{cc}^{++}, Xi_{cc}^+$ and $Omega_{cc}^+$ are studied in this work. To estimate the nonfactorizable contributions, we work in the pole model for the $P$-wave amplitudes and current algebra for $S$-wave ones. For the $Xi_{cc}^{++}to Xi_c^+pi^+$ mode, we find a large destructive interference between factorizable and nonfactorizable contributions for both $S$- and $P$-wave amplitudes. Our prediction of $sim 0.70%$ for its branching fraction is smaller than the earlier estimates in which nonfactorizable effects were not considered, but agrees nicely with the result based on an entirely different approach, namely, the covariant confined quark model. On the contrary, a large constructive interference was found in the $P$-wave amplitude by Dhir and Sharma, leading to a branching fraction of order $(7-16)%$. Using the current results for the absolute branching fractions of $(Lambda_c^+,Xi_c^+)to p K^-pi^+$ and the LHCb measurement of $Xi_{cc}^{++}toXi_c^+pi^+$ relative to $Xi_{cc}^{++}toLambda_c^+ K^- pi^+pi^+$, we obtain $B(Xi_{cc}^{++}toXi_c^+pi^+)_{rm expt}approx (1.83pm1.01)%$ after employing the latest prediction of $B(Xi_{cc}^{++}toSigma_c^{++}overline{K}^{*0})$. Our prediction of $mathcal{B}(Xi_{cc}^{++}toXi_c^+pi^+)approx 0.7%$ is thus consistent with the experimental value but in the lower end. It is important to pin down the branching fraction of this mode in future study. Factorizable and nonfactorizable $S$-wave amplitudes interfere constructively in $Xi_{cc}^+toXi_c^0pi^+$. Its large branching fraction of order 4% may enable experimentalists to search for the $Xi_{cc}^+$ through this mode. That is, the $Xi_{cc}^+$ is reconstructed through the $Xi_{cc}^+toXi_c^0pi^+$ followed by the decay chain $Xi_c^0to Xi^-pi^+to ppi^-pi^-pi^+$.
There has been important experimental progress in the sector of heavy baryons in the past several years. We study the strong decays of the S-wave, P-wave, D-wave and radially excited charmed baryons using the $^3P_0$ model. After comparing the calcul
ated decay pattern and total width with the available data, we discuss the possible internal structure and quantum numbers of those charmed baryons observed recently.
Doubly Cabibbo-suppressed (DCS) nonleptonic weak decays of antitriplet charmed baryons are studied systematically in this work. The factorizable and nonfactorizable contributions can be classified explicitly in the topological-diagram approach and treated separately. In particular, the evaluation of nonfactorizable terms is based on the pole model in conjunction with current algebra. All three types of relevant non-perturbative parameters contributing factorizable and nonfactorizable terms are estimated in the MIT bag model. Branching fractions of all the DCS decays are predicted to be of order $10^{-4}sim 10^{-6}$. In particular, we find that the three modes $Xi_c^+to Sigma^+ K^0, Sigma^0 K^+$ and $Xi_c^0to Sigma^- K^+$ are as large as $(1sim 2)times 10^{-4}$, which are the most promising DCS channels to be measured. We also point out that the two DCS modes $Xi_c^+to Sigma^+ K^0$ and $Xi_c^0to Sigma^0 K^0$ are possible to be distinguished from $Xi_c^+to Sigma^+ K_S$ and $Xi_c^0to Sigma^0 K_S$. The decay asymmetries for all the channels with a kaon in their final states are found to be large in magnitude and negative in sign.
Without contamination from the final state interactions, the calculation of the branching ratios of semileptonic decays $Xi^{()}_{c}toXi+e^+ u_e$ may provide us more information about the inner structure of charmed baryons. Moreover, by studying those processes, one can better determine the form factors of $Xi_ctoXi$ which can be further applied to relevant estimates. In this work, we use the light-front quark model to carry out the computations where the three-body vertex functions for $Xi_c$ and $Xi$ are employed. To fit the new data of the Belle II, we re-adjust the model parameters and obtain $beta_{s[sq]}=1.07$ GeV which is 2.9 times larger than $beta_{sbar s}=0.366$ GeV. This value may imply that the $ss$ pair in $Xi$ constitutes a more compact subsystem. Furthermore, we also investigate the non-leptonic decays of $Xi^{()}_cto Xi$ which will be experimentally measured soon, so our model would be tested by consistency with the new data.
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