arXiv subjects
Publications and source records attributed to K. Terasaki.
A brief overview of charm scalar resonances is given. It is demonstrated that experimental data on the D_s^{*+}gamma and D_s^+pi^0 decays of D_{s0}^+(2317) favor its assignment to the I_3=0 component of iso-triplet four-quark mesons. The broad bump just below a large peak of the well-known D_2^* meson in the Dpi channel is also studied.
We propose that there coexist two scalar mesons of different structures (a conventional meson and a four-quark meson) in the recently observed broad bumps just below the large peak of the tensor meson in the D-pi mass distribution. We base this proposal on the interpretation of the charm-strange scalar meson of mass 2317 MeV as a four-quark meson. The strange counterparts of these scalar mesons are also studied.
We elaborate masses of open-charm mesons (c\bar{d} and c\bar{s}) with J^P=0^-,1^-,0^+,1^+ from a viewpoint of ordinary light-heavy systems in the analysis of standard Borel-transformed QCD sum rule. This analysis is implemented with the operator product expansion up to dimension 6, permitting corrections to the order alpha_s and to the order m_s, and without relying on 1/m_c-expansion. The obtained results following our stringent criteria for the continuum-threshold dependence, the Borel window and the Borel stability, indicate that the charmed-meson masses in the 0^+ channel are overestimated by 100 \sim 200 MeV in comparison with the experimental data, which were recently reported as the rather broad state of D^{*+}(2351) and the extremely narrow state of D_s^{*+}(2317), respectively. Such large mass-discrepancies from the data cannot be seen in other channels, where conversely our results of the c\bar{s}-meson masses are even underestimated somewhat in comparison with data, independent of the value of the strange-quark mass adopted in our calculations. From these results, it might be expected that the measured low mass of D_s^{*+}(2317) is a manifestation of an exotic state with the structures of a four-quark or a molecule, while at present the D^{*+} is not in conflict with the existing data due to its large width.
Charmed scalar mesons are studied. By assigning the newly observed charmed strange meson with a narrow width to one of the iso-triplet four-quark mesons, decays of the multiplet members are investigated and, as the consequence, existence of additional narrow scalar mesons is predicted. Decays of the ordinary charmed scalar mesons are also studied. In addition, it is demonstrated that four-quark mesons can play an important role in hadronic weak decays of charm mesons.
It is discussed that a newly observed broad bump around 2.3 GeV in the Dπmass distribution can include two scalar resonances, and is predicted that a broad scalar resonance can be observed around 2.45 GeV in the DK channels.
By assigning the narrow scalar resonance (which has been recently observed at the B-factories) to one of iso-triplet four-quark mesons containing a charm quark, two body decays of the four-quark mesons are studied. It is predicted that some of them can be observed as narrow resonances.
The new narrow resonance which has been observed at the B factories is assigned to the I_z=0 component of iso-triplet charmed four-quark mesons, and as its consequence, existence of additional narrow resonances in different channels is predicted.
Possible decays of four-quark mesons are studied by assigning the newly observed BABAR resonance to a four-quark meson with C=S=I=1. It is expected that some of them can be observed as narrow resonances. Implication of existence of four-quark mesons in hadronic weak interactions is also discussed.
In consistency with the b --> c type of (quasi) two body decays, recently observed two body decays of B mesons are studied in a hybrid perspective in which their amplitude is given by a sum of factorizable and non-factorizable ones, and a role of the latter in these decays are discussed.
The D^+ --> omega + pi^+ decay is studied by decomposing its amplitude into a sum of factorizable and non-factorizable ones. Its rate is predicted as a function of mass and width of a hypothetical hybrid meson.
Two-body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using the naive factorization while the latter is calculated by using a hard pion (or kaon) approximation in the infinite momentum frame. It is seen that the non-factorizable contribution is small but not negligible in color favored decays while it is more important in color mismatched decays.
The hypothesis of sigma meson pole dominance in the Delta I = 1/2 K -> pi pi amplitudes is tested by using the K_L-K_S mass difference.
Two body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states and is calculated by using a hard pion (or kaon) technique in the infinite momentum frame. Possible roles of the non-factorizable contributions are discussed by comparing the result with experiments.
Two pion decays of K mesons, K_L-K_S mass difference, two photon and the Dalitz decays of K_L are studied systematically by assuming that their amplitude is given by a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states.
Two body decays of charm mesons are studied by describing their amplitude in terms of a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is calculated by using a hard pseudo-scalar-meson approximation. The hard pseudo-scalar-meson amplitude is given by a sum of the so-called equal-time commutator term and surface term which contains all possible pole contributions of various mesons, not only the ordinary $\{q\bar q\}$ but also four-quark $\{qq\bar q\bar q\}$, hybrid $\{q\bar qg\}$ and glue-balls. Naively factorized amplitudes for the spectator decays which lead to too big rates can interfere destructively with exotic meson pole amplitudes and the total amplitudes can reproduce their observed rates. The non-factorizable contributions can supply sufficiently large contributions to the color suppressed decays which are strongly suppressed in the naive factorization. A possible solution to the long standing puzzle that the ratio of decay rates for $D^0\to K^+K^-$ to $D^0\to π^+π^-$ is around 2.5 is given by different contributions of exotic meson poles.
Two pion Decays of K mesons, K_L-K_S mass difference, two photon decay and the Dalitz decays of K_L are studied systematically by assuming that their amplitude can be described in terms of a sum of short distance and long distance contributions. Dominance of the short distance effect on the K_L-K_S mass difference will be checked by the Dalitz decays of K_L in a way consisten with the two pion decays of K mesons and the two photon decay of K_L.
$\bar B \to Dπ$, $D^*π$, $J/ψ\bar K$ and $J/ψπ$ decays are studied. Their amplitude is given by a sum of factorized and non-factorizable ones. The latter which is estimated by using a hard pion approximation is rather small in color favored $\bar B \to Dπ$ and $D^*π$ decays but still can efficiently interfere with the main amplitude given by the factorization. In the color suppressed $\bar B \to J/ψ\bar K$ and $J/ψπ$ decays, the non-factorizable contribution is very important. The sum of the factorized and non-factorizable amplitudes can reproduce well the existing experimental data on the branching ratios for the color favored $\bar B \to Dπ$ and $D^*π$ and the color suppressed $\bar B \to J/ψ\bar K$ and $J/ψπ$ decays by taking reasonable values of unknown parameters involved.