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Register a new userElectromagnetic structure of charmed baryons in Lattice QCD
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As a continuation of our recent work on the electromagnetic properties of the doubly charmed $Xi_{cc}$ baryon, we compute the charge radii and the magnetic moments of the singly charmed $Sigma_c$, $Omega_c$ and the doubly charmed $Omega_{cc}$ baryons in 2+1 flavor Lattice QCD. In general, the charmed baryons are found to be compact as compared to the proton. The charm quark acts to decrease the size of the baryons to smaller values. We discuss the mechanism behind the dependence of the charge radii on the light valence- and sea-quark masses. The magnetic moments are found to be almost stable with respect to changing quark mass. We investigate the individual quark sector contributions to the charge radii and the magnetic moments. The magnetic moments of the singly charmed baryons are found to be dominantly determined by the light quark and the role of the charm quark is significantly enhanced for the doubly charmed baryons.
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We compute the electromagnetic properties of Xi_cc baryons in 2+1 flavor Lattice QCD. By measuring the electric charge and magnetic form factors of Xi_cc baryons, we extract the magnetic moments, charge and magnetic radii as well as the Xi_cc Xi_cc rho coupling constant, which provide important information to understand the size, shape and couplings of the doubly charmed baryons. We find that the two heavy charm quarks drive the charge radii and the magnetic moment of Xi_cc to smaller values as compared to those of, e.g., the proton.
We present the ground and excited state spectra of singly, doubly and triply charmed baryons by using dynamical lattice QCD. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to 7/2 and the low lying states remarkably resemble the expectations of quantum numbers from SU(6) $otimes$ O(3) symmetry. Various energy splittings between the extracted states, including splittings due to hyperfine as well as spin-orbit coupling, are considered and those are also compared against similar energy splittings at other quark masses.
We evaluate the spin-$3/2 to$ spin-$1/2$ electromagnetic transitions of the doubly charmed baryons on 2+1 flavor, $32^3 times 64$ PACS-CS lattices with a pion mass of $156(9)$ MeV/c$^2$. A relativistic heavy quark action is employed to minimize the associated systematic errors on charm-quark observables. We extract the magnetic dipole, $M1$, and the electric quadrupole, $E2$, transition form factors. In order to make a reliable estimate of the $M1$ form factor, we carry out an analysis by including the effect of excited-state contributions. We find that the $M1$ transition is dominant and light degrees of freedom ($u/d$- or $s$-quark) play the leading role. $E2$ form factors, on the other hand, are found to be negligibly small, which in turn, have minimal effect on the helicity and transition amplitudes. We predict the decay widths and lifetimes of $Xi_{cc}^{ast +,++}$ and $Omega_{cc}^{ast +}$ based on our results. Finite size effects on these ensembles are expected to be around 1%. Differences in kinematical and dynamical factors with respect to the $NgammatoDelta$ transition are discussed and compared to non-lattice determinations as well keeping possible systematic artifacts in mind. A comparison to $Omega_c gamma rightarrow Omega_c^ast$ transition and a discussion on systematic errors related to the choice of heavy quark action are also given. Results we present here are particularly suggestive for experimental facilities such as LHCb, PANDA, Belle II and BESIII to search for further states.
The spectrum of excitations of triply-charmed baryons is computed using lattice QCD including dynamical light quark fields. Calculations are performed on anisotropic lattices with temporal and spatial spacings a_t = 0.0351(2) and a_s ~ 0.12 fm respectively and with pion mass of about 390 MeV. The spectrum obtained has baryonic states with well-defined total spin up to 7/2 and the low-lying states closely resemble the expectation from models with an SU(6)X O(3) symmetry. Energy splittings between extracted states, including those due to spin-orbit coupling in the heavy quark limit are computed and compared against data at other quark masses.
We present the ground and excited state spectra of doubly charmed baryons from lattice QCD with dynamical quark fields. Calculations are performed on anisotropic lattices of size 16^3 X 128, with inverse spacing in temporal direction 1/a_t = 5.67(4) GeV and with a pion mass of about 390 MeV. A large set of baryonic operators that respect the symmetries of the lattice yet which retain a memory of their continuum analogues are used. These operators transform as irreducible representations of SU(3) symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) for spatial symmetry. The distillation method is utilized to generate baryon correlation functions which are analysed using the variational fitting method to extract excited states. The lattice spectra obtained have baryonic states with well-defined total spins up to 7/2 and the pattern of low lying states does not support the diquark picture for doubly charmed baryons. On the contrary the calculated spectra are remarkably similar to the expectations from models with an SU(6)X O(3) symmetry. Various spin dependent energy splittings between the extracted states are also evaluated.
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