相关论文: Status of isospin splittings in mesons and baryons
Isospin splittings in baryons with two heavy quarks and a $u$ or $d$ quark are calculated using simple methods proposed previously by the authors. The results are $M(\Xi_{cc}^{++})-M(\Xi_{cc}^+) = 1.41 \pm 0.12^{+0.76}$ MeV, $M(\Xi_{bb}^0)…
Lattice QCD simulations are now reaching a precision where isospin breaking effects become important. Previously, we have developed a program to systematically investigate the pattern of flavor symmetry beaking within QCD and successfully…
A recent general analysis of light-baryon isospin splittings is updated and extended to charmed baryons. The measured $\Sigma_c$ and $\Xi_c$ splittings stand out as being difficult to understand in terms of two-body forces alone. We also…
Masses and decay constants of mesons containing a single $c$ or $b$ quark are described within the framework of heavy-quark symmetry. The $B_s^* - B_s$ and $\bar B^{*0} - \bar B^0$ mass splittings are found equal to within a fraction of an…
We discuss the isospin-breaking mass differences among baryons, with particular attention in the charm sector to the $\Sigma_c^{+}-\Sigma_c^0$, $\Sigma_c^{++}-\Sigma_c^0$, and $\Xi_c^+-\Xi_c^0$ splittings. Simple potential models cannot…
We discuss the isospin-breaking mass differences among baryons, with particular attention in the charm sector to the $\Sigma_c^{+}-\Sigma_c^0$, $\Sigma_c^{++}-\Sigma_c^0$, and $\Xi_c^+-\Xi_c^0$ splittings. Simple potential models cannot…
We study the isospin symmetry breaking and mass splittings of the eight lowest-lying baryons. We consider three kinds of baryon mass terms, including the bare mass term, the electromagnetic terms and the spontaneous chiral symmetry breaking…
Baryon mass splittings are analyzed in terms of a simple model with general pairwise interactions. At present, the $\Delta$ masses are poorly known from experiments. Improvement of these data would provide an opportunity to make a…
We estimate the isospin breaking contributions to the baryon masses which we analyzed recently using a loop expansion in the heavy baryon approximation to chiral effective field theory. To one loop, the isospin breaking corrections come…
Decay constants of $D$ and $B$ mesons are estimated within the framework of a heavy-quark approach using measured isospin mass splittings in the $D$, $D^*$, and $B$ states to isolate the electromagnetic hyperfine interaction between quarks.…
We present a new method to evaluate with high precision isospin breaking effects due to the small mass difference between the up and down quarks using lattice QCD. Our proposal is applicable in principle to any hadronic observable which can…
Electromagnetic splittings for mesons and baryons are calculated in a formalism where the constituent quarks are considered as dressed quasiparticles. The electromagnetic interaction, which contains coulomb, contact, and hyperfine terms, is…
The least well-known octet baryon mass is $M_{\Xi^0} = 1314.9 \pm 0.6$ MeV. The prospect of an improved measurement of its mass by the KTeV experimental program at Fermilab, and opportunities for improvements in charged and excited hyperon…
While electromagnetic and up-down quark mass difference effects on octet baryon masses are very small, they have important consequences. The stability of the hydrogen atom against beta decay is a prominent example. Here we include these…
Sum rules relating the masses of ground-state baryons and mesons are obtained in a constituent quark model. The interaction is assumed to be independent of quark spins except for a spin-dependent part that can be treated as a perturbation.…
Motivated by the precision measurements of heavy flavor baryon masses, we analyze the modification of quark charge by employing the screening effect inside the baryon. In addition, we calculate the isospin mass splitting up to charmed…
We give an update on an ongoing project in which we calculate the masses of octet and decuplet baryons including isospin-breaking effects. To this end, we employ single- and two-state-fits to effective masses up to leading order in the…
The SELEX Collaboration has reported a very large isospin splitting of doubly charmed baryons. We show that this effect would imply that the doubly charmed baryons are very compact. One intriguing possibility is that such baryons have a…
We report a new analysis of the isospin splittings within the decuplet baryon spectrum. Our numerical results are based upon five ensembles of dynamical QCD+QED lattices. The analysis is carried out within a flavour-breaking expansion which…
The masses of the low lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudo scalar masses in the range of about 270-500 MeV. The strange valence quark mass is tuned to reproduce the mass…