No Arabic abstract
The strong and radiative decays of the low-lying $lambda$-mode $D$-wave $Lambda_{c(b)}$, $Sigma_{c(b)}$, $Xi_{c(b)}$, $Xi_{c(b)}$, and $Omega_{c(b)}$ baryons are studied in a constituent quark model. Our calculation shows the following: (i) The missing $lambda$-mode $D$-wave $Omega_{c(b)}$, $Lambda_{b}$, and $Xi_{b}$ baryons have a relatively narrow decay width of a few MeV or a few tens of MeV and their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiments. (ii) The $lambda$-mode $1D$-wave excitations in the $Sigma_{c(b)}$ and $Xi_{c(b)}$ families appear to have a relatively broad width of $sim 50-200$ MeV.Most of the $1D$-wave states have large decay rates into the $1P$-wave heavy baryons via the pionic or kaonic strong decay processes, which should be taken seriously in future observations. (iii) Both $Lambda_c(2860)$ and $Xi_c(3050)$ seem to favor the $J^P=3/2^+$ excitation $|^2D_{lambdalambda} frac{3}{2}^+ rangle$ of $bar{mathbf{3}}_F$, while both $Lambda_c(2880)$ and $Xi_c(3080)$ may be assigned as the $J^P=5/2^+$ excitation $|^2D_{lambdalambda} frac{5}{2}^+ rangle$ of $bar{mathbf{3}}_F$. The nature of $Xi_c(3050)$ and $Xi_c(3080)$ could be tested by the radiative transitions $Xi_c(3055)^0to Xi_c(2790)^0 gamma$ and $Xi_c(3080)^0 to Xi_c(2815)^0 gamma$, respectively.
The radiative decays of the p-wave charmed heavy baryons to the ground state baryon states are studied in the framework of the light cone QCD sum rules method. Firstly, the transition form factors that describe these transitions are estimated, and then using these form factors the corresponding decay widths are calculated. A comparison of our results on the decay widths with those predicted by the other approaches existing in literature is performed.
We study the isospin mass differences of singly heavy baryons, based on a pion mean-field approach. We consider both the electromagnetic interactions and the hadronic contributions that arise from the mass difference of the up and down quarks. The relevant parameters have been already fixed by the baryon octet. In addition, we introduce the strong hyperfine interactions between the light quarks inside a chiral soliton and the Coulomb interactions between the chiral soliton and a heavy quark. The numerical results are in good agreement with the experimental data. In particular, the results for the neutral mass relations, which contain only the electromagnetic contributions, are in remarkable agreement with the data, which implies that the pion mean field approach provides a good description of the singly heavy baryons.
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
A U-spin relation among four ratios of amplitudes for $D^0 to pi^+K^-$, $K^+pi^-$, $K^+K^-, pi^+pi^-$, including first, second and third order U-spin breaking, has been derived recently with a precision of $10^{-3}$. We study effects of new $|Delta C|=1$ operators on this relation. We find that it is not affected by U-spin scalar operators, including QCD penguin and chromomagnetic dipole operators occurring in supersymmetric and extra-dimensional models. The relation is modified by new $U=1$ operators with a sensitivity of a few percent characteristic of second order U-spin breaking. Combining this relation with CP asymmetries in $D^0to K^+K^-, pi^+pi^-$ leads to a more solid constraint on $U=1$ operators than from asymmetries alone.
The mass spectra of singly charmed and bottom baryons, $Lambda_{c/b}(1/2^pm,3/2^-)$ and $Xi_{c/b}(1/2^pm,3/2^-)$, are investigated using a nonrelativistic potential model with a heavy quark and a light diquark. The masses of the scalar and pseudoscalar diquarks are taken from a chiral effective theory. The effect of $U_A(1)$ anomaly induces an inverse hierarchy between the masses of strange and non-strange pseudoscalar diquarks, which leads to a similar inverse mass ordering in $rho$-mode excitations of singly heavy baryons.