Chiaki Itoh

Bs and Bc meson masses

SummaryDiscussing the quark distances, we compute the masses ofs-wave heavy mesons in a semi-relativistic quark model. We reproduce the masses of the heavy mesons within ±4 MeV except for D*s. The new data of ARGUS imply a very different value of the B−−B0 mass difference, even in sign compared with the old data. The new data fit well in our model. We predict Bs=5344 MeV and B*s=5393 MeV, which are not so far from the B and B* masses and detectable in the γ(5S) decays.

Observed Λb and Σb > Ξb

SummaryMasses of the bottom baryons are calculated discussing quark distances in a semi-relativistic quark model. Our result of Λb mass is consistent with the recent UA1 result, Λb = (5640 ± 50 ± 30) MeV within the experimental error. The predicted mass difference Ξb′(b[su])-Σb(bdu) is negative, contrary to the expectation from the fact thatms> md. We show that the quark distances in a baryon are the same as those of perturbation theory up to the 2s state of the harmonic oscillator, if quarks in the baryon have the same flavour.

ηb, Bc and a Hybrid Potential

We propose a hybrid potential, which is a Coulomb plus harmonic oscillator potential at short distances and increases linearly at long distances, and compute the heavy meson masses of various quarkonia with common parameter values. We obtain good agreement with experimental data for the cu, cd, cs, bu, bd, bs, cc and bb meson masses: We find the first solution that fits both horizontal and vertical spectra of heavy mesons with common parameter values. In particular, we are able to account for a recent observation, which may be attributable to η b , with a mass of 9300 ± 20 ± 20 MeV, which is much smaller than values predicted by many models and is difficult to account for with a small value of α s for bottomonium. We attempt to determine the vertical spectrum of B c mesons as accurately as possible.

Perturbed energy eigenvalues of the Salpeter equation in the oscillator-representation method

SummaryOn the basis of the oscillator-representation method, we obtain the energy eigenvalue formulae upto the second order in the perturbation Hamiltonian for the 1S-6S, 1P, 2P, 1D and 2D states of the heavy quarkonia. The application of the formulae to the 1S-6S states in the linear confining potential suggests that we cannot neglect the effect of the relativistic kinetic terms on the energy eigenvalues in the excited states of the charmonia.

Heavy-quarkonium spectroscopy and leptonic decay widths

SummaryHeavy-quarkonium spectroscopy is discussed in the non-relativistic quark model for a hybrid potential which is Coulomb plus square-root (ur2−v)1/2 suggested by string theory at long distance and Coulomb plus harmonic at short distance. The predictons for the e+e− decay widths of the c

Doubly charmed baryon masses and quark wave functions in baryons

\overline c

Electromagnetic Mass Differences of Charmed Particles

and b