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Register a new userStudying Radiative Baryon Decays with the SU(3) Flavor Symmetry
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The weak and electromagnetic radiative baryon decays of octet $T_{8}$, decuplet $T_{10}$, single charmed anti-triplet $T_{c3}$ and sextet $T_{c6}$, single heavy bottomed anti-triplet $T_{b3}$ and sextet $T_{b6}$ are investigated by using SU(3) flavor symmetry irreducible representation approach. We analyze the contributions from a single quark transition $q_1to q_2gamma$ and $W$ exchange transitions, and find that the amplitudes could be easily related by SU(3) flavor symmetry in the $T_{b3,b6}$ weak radiative decays, $T_{c3,c6}$ weak radiative decays, $T_{10}to T_{8}gamma $ weak decays, $T_{10}to T_{10}gamma $ weak decays and $T_{10}to T_{8}gamma $ electromagnetic decays. Nevertheless, the amplitude relations are a little complex in the $T_{8}to T_{8}gamma$ and $T_{8}to T_{10}gamma$ weak decays due to quark antisymmetry in $T_{8}$ and $W$ exchange contributions. Predictions for branching ratios of $Lambda^{0}_bto ngamma$, $Xi^{-}_bto Xi^-gamma$, $Xi^{-}_bto Sigma^-gamma$, $Xi^{0}_bto Sigma^0gamma$, $Xi^{0}_bto Lambda^0gamma$, $Xi^{0}_bto Xi^0gamma$, $Xi^{*}to Xigamma$, $Sigma^{*0}to Sigma^{0}gamma$, $Delta^0to ngamma$ and $Delta^+to pgamma$ are given. The results in this work can be used to test SU(3) flavor symmetry approach in the radiative baryon decays by the future experiments at BESIII, LHCb and Belle-II.
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We study the three-body anti-triplet ${bf B_c}to {bf B_n}MM$ decays with the $SU(3)$ flavor ($SU(3)_f$) symmetry, where ${bf B_c}$ denotes the charmed baryon anti-triplet of $(Xi_c^0,-Xi_c^+,Lambda_c^+)$, and ${bf B_n}$ and $M(M)$ represent baryon and meson octets, respectively. By considering only the S-wave $MM$-pair contributions without resonance effects, the decays of ${bf B_c}to {bf B_n}MM$ can be decomposed into irreducible forms with 11 parameters under $SU(3)_f$, which are fitted by the 14 existing data, resulting in a reasonable value of $chi^2/d.o.f=2.8$ for the fit. Consequently, we find that the triangle sum rule of ${cal A}(Lambda_c^+to nbar K^0 pi^+)-{cal A}(Lambda_c^+to pK^- pi^+)-sqrt 2 {cal A}(Lambda_c^+to pbar K^0 pi^0)=0$ given by the isospin symmetry holds under $SU(3)_f$, where ${cal A}$ stands for the decay amplitude. In addition, we predict that ${cal B}(Lambda_c^+to n pi^{+} bar{K}^{0})=(0.9pm 0.8)times 10^{-2}$, which is $3-4$ times smaller than the BESIII observation, indicating the existence of the resonant states. For the to-be-observed ${bf B_c}to {bf B_n}MM$ decays, we compute the branching fractions with the $SU(3)_f$ amplitudes to be compared to the BESIII and LHCb measurements in the future.
In this paper, we calculate the decay rates of $D^+ to D^0 e^+ u$, $D^+_S to D^0 e^+ u$, $B^0_S to B^+ e^- bar{ u}$, $D^+_S to D^+ e^- e^+$ and $B^0_S to B^0 e^-e^+$ semileptonic decay processes, in which only the light quarks decay, while the heavy flavors remain unchanged. The branching ratios of these decay processes are calculated with the flavor SU(3) symmetry. The uncertainties are estimated by considering the SU(3) breaking effect. We find that the decay rates are very tiny in the framework of the Standard Model. We also estimate the sensitivities of the measurements of these rare decays at the future experiments, such as BES-III, super-$B$ and LHC-$b$.
The charmonium-like exotic states $Y(4230)$ and the less known $Y(4320)$, produced in $e^+e^-$ collisions, are sources of positive parity exotic hadrons in association with photons or pseudoscalar mesons. We analyze the radiative and pion decay channels in the compact tetraquark scheme, with a method that proves to work equally well in the most studied $D^*to gamma/pi+D$ decays. The decay of the vector $Y$ into a pion and a $Z_c$ state requires a flip of charge conjugation and isospin that is described appropriately in the formalism used. Rates however are found to depend on the fifth power of pion momentum which would make the final states $pi Z_c(4020)$ strongly suppressed with respect to $pi Z_c(3900)$. The agreement with BES III data would be improved considering the $pi Z_c(4020)$ events to be fed by the tail of the $Y(4320)$ resonance under the $Y(4230)$. These results should renovate the interest in further clarifying the emerging experimental picture in this mass region.
The axial-vector form factors and axial-vector constants of the baryon decuplet are investigated within a pion mean-field approach, which is also known as the chiral quark-soliton model. Given an axial-vector current with a specified flavor, there are four different form factors of a decuplet baryon. When we consider the singlet, triplet, and octet axial-vector currents, we have twelve different form factors for each member of the baryon decuplet. We compute all these axial-vector form factors of the baryon decuplet, taking into account the rotational $1/N_c$ corrections and effects of flavor SU(3) symmetry breaking. We find that, for a given flavor, two of the form factors for a decuplet baryon are only independent within the present approach. We first examine properties of the axial-vector form factors of the $Delta^+$ isobar and $Omega^-$ hyperon. We also compare the results of the triplet axial-vector form factors of $Delta^+$ with those from lattice QCD and those of the present work for the axial-vector constants of the baryon decuplet with the lattice data. All the results for other members of the baryon decuplet are then presented. The results of the axial charges are compared with those of other works. The axial masses and axial radii are also discussed.
Motivated by recent anomalies in FCNC $bto sell^+ell^-$, we study $B_1to B_2ell^+ell^-(ell=e,mu,tau)$ semi-leptonic weak decays with the SU(3) flavor symmetry, where $B_{1,2}$ are the spin-1/2 baryons of single bottomed anti-triplet $T_{b3}$, single charmed anti-triplet $T_{c3}$ or light baryon octet $T_{8}$. Using the SU(3) irreducible representation approach, we first obtain the amplitude relations among different decays, and then predict the relevant not-yet measured observables of these decays. (a) We calculate the branching ratios of the $T_{b3}to T_8 mu^+mu^-$ and $T_{b3}to T_8 tau^+tau^-$ in the whole $q^2$ region and in the different $q^2$ bins by the measurement of $Lambda^0_bto Lambda^0 mu^+mu^-$. Many of them are obtained for the first time. In addition, the longitudinal polarization fractions and the leptonic forward-backward asymmetries of all $T_{b3}to T_{8}ell^+ell^-$ decays are very similar to each other in certain $q^2$ bin due to the SU(3) flavor symmetry. (b) We analyze the upper limits of $B(T_{c3}to T_{8}ell^+ell^-)$ by using the experimental upper limits of $B(Lambda^+_cto pmu^+mu^-)$ and $B(Lambda^+_cto pe^+e^-)$, and find the experimental upper limit of $B(Lambda^+_cto pmu^+mu^-)$ giving effective bounds on the relevant SU(3) flavor symmetry parameters. The predictions of $B(Xi^0_c to Xi^0e^+e^-)$ and $B(Xi^0_c to Xi^0mu^+mu^-)$ will be different between the single-quark transition dominant contributions and the W-exchange dominant ones. (c) As for $T_{8}to T_8 ell^+ell^-$ decays, we analyze the single-quark transition contributions and the W-exchange contributions by using two measurements of $ B(Xi^0to Lambda^0 e^+e^-)$ and $ B(Sigma^+to pmu^+mu^-)$, and give the branching ratio predictions by assuming either single-quark transition dominant contributions or the W-exchange dominant ones.
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