Yubing Dong

Strong two-body decays of the Lambda(c)(2940)(+) in a hadronic molecule picture

The Lambda c(2940)(+) baryon with possible quantum numbers J(P) = 1/2(+) and 1/2(-) is studied as a molecular state composed of a nucleon and D* meson. We give predictions for the strong two-body decay channels Lambda c(2940)(+) -> pD(0), Sigma(++)(c) pi(-) and Sigma(0)(c)pi(+), where the sum of partial widths is consistent with current data for the case of J(P) = 1/2(+). The case of J(P) = 1/2(-) is shown to be ruled out.

Charmed baryon Sigmac(2800) as a ND hadronic molecule

The isotriplet {Sigma}{sub c}(2800) baryon with possible quantum numbers J{sup P}=(1/2){sup {+-}}or (3/2){sup {+-}}is considered as a hadronic molecule composed of a nucleon and a D meson. We determine the strong two-body decay widths {Sigma}{sub c{yields}{Lambda}c{pi}} which are shown to be consistent with current data for the J{sup P}=(1/2){sup +} and J{sup P}=(3/2){sup -} assignments.

Electromagnetic form factors of pion and rho in the three forms of relativistic kinematics

The electromagnetic form factors of the pi and the rho are obtained using the three forms of relativistic kinematics, instant form, point form and (light) front form. Simple representations of the mass operator together with single quark currents are employed with all the forms. The Poincare covariant current operators are generated by the dynamics from single-quark currents that are covariant under the kinematic subgroup. Front and instant forms allow to reproduce the available data for the pion form factor. On the other hand point form is not able to reproduce qualitatively the experimental data with reasonable values for the wave function parameters. For the rho electromagnetic form factors, instant and front forms provide a consistent picture. The obtained results do not depend appreciably on the wave function used

Two-photon exchange contribution to proton form factors in the time-like region

We estimate the two-photon exchange contribution to the process e{sup +}+e{sup -}{yields}p+p . The two-photon exchange corrections to double spin polarization observables and form factors in the time-like region are calculated. The corrections are found to be small in magnitude but with a strong angular dependence at fixed momentum transfer. These two features are the same as those in the space-like region. In future experiments, the double spin polarization observable P{sub z} deserves to be considered.

Decay width of

The decay widths of four-body double-pion decays d* -> pn pi(0)pi(0), d* -> pn pi(+)pi(-), and isoscalar parts of d* -> pp pi(0)pi(-) and d* -> nn pi(+)pi(0) are explicitly calculated with the help of the d* wave function obtained in a chiral SU( 3) quark model calculation. The effect of the dynamical structure on d*s width is analyzed both in the single Delta Delta channel and the Delta Delta + CC coupled-channel approximations. It is found that in the latter case, the obtained partial decay widths of d* -> pn pi(0)pi(0), d* -> pn pi(+)pi(-), and those of d* to the isoscalar parts of pp pi(0)pi(-) and nn pi(+)pi(0) are about 9.6 MeV, 20.6 MeV, 3.5 MeV and 3.5 MeV, respectively. As a consequence, the total width is about 71.9 MeV. These widths are consistent with our previous estimation by using cross section data and observed width. Apparently, the resultant mass and width in the Delta Delta + CC coupled-channel calculation again support our assertion that the d* resonance is a six-quark dominated exotic state.

d^*(2380)\to NN \pi\pi

The decay widths of four-body double-pion decays d* -> pn pi(0)pi(0), d* -> pn pi(+)pi(-), and isoscalar parts of d* -> pp pi(0)pi(-) and d* -> nn pi(+)pi(0) are explicitly calculated with the help of the d* wave function obtained in a chiral SU( 3) quark model calculation. The effect of the dynamical structure on d*s width is analyzed both in the single Delta Delta channel and the Delta Delta + CC coupled-channel approximations. It is found that in the latter case, the obtained partial decay widths of d* -> pn pi(0)pi(0), d* -> pn pi(+)pi(-), and those of d* to the isoscalar parts of pp pi(0)pi(-) and nn pi(+)pi(0) are about 9.6 MeV, 20.6 MeV, 3.5 MeV and 3.5 MeV, respectively. As a consequence, the total width is about 71.9 MeV. These widths are consistent with our previous estimation by using cross section data and observed width. Apparently, the resultant mass and width in the Delta Delta + CC coupled-channel calculation again support our assertion that the d* resonance is a six-quark dominated exotic state.

processes

A phenomenological Lagrangian approach is employed to study the electromagnetic properties of the deuteron. The deuteron is regarded as a weakly bound state of the proton and neutron. We construct a general form for the electromagnetic one- and two-body transition operators formulated in terms of the nucleon fields, which are then used in the calculation of the electromagnetic deuteron form factors. One of the two-body operators is responsible for explaining the quadrupole moment form factor. We show that in our approach the data on the deuteron form factors as well as on the differential cross section of elastic electron-deuteron scattering are well explained.

Decay width ofd*(2380)→NNππprocesses

Abstract Careful observation of the experimental spectra of heavy-light mesons tells us that heavy-light mesons with the same angular momentum L are almost degenerate. The estimate is given how much this degeneracy is broken in our relativistic potential model, and it is analytically shown that expectation values of a commutator between the lowest order Hamiltonian and L → 2 are of the order of 1 / m Q with a heavy quark mass m Q . It turns out that nonrelativistic approximation of heavy quark system has a rotational symmetry and hence degeneracy among states with the same L. This feature can be tested by measuring higher orbitally and radially excited heavy-light meson spectra for D / D s / B / B s in LHCb and forthcoming BelleII.

Phenomenological Lagrangian approach to the electromagnetic deuteron form factors

The annihilation process p bar(p) -> p D0 bar(Lambda)_c(2286) is studied taking into account t-channel D0, D*0 meson exchange and the resonance contribution of Lambda_c(2286) and Lambda_c(2940) baryons. We assume that the Lambda_c(2940) baryon is a pD*0 molecular state with spin-parity (1/2)+ and (1/2)-. Our results show that near the threshold of p bar(p) -> Lambda_c(2286) bar(Lambda)_c(2286) the contribution from the intermediate state Lambda_c(2940) is also sizeable and can be observed at the PANDA experiment. Another conclusion is that the spin-parity assignment (1/2)- for Lambda_c(2940) gives enhancement for the cross section in comparison with a choice (1/2)+.

Approximate degeneracy of heavy-light mesons with the same L

The discrepancy between the PQCD calculation and the CLEO data for χc1→γV (V=ρ0, ω, φ) stimulates our interest in exploring other mechanisms of χc1 decay. In this work, we apply an important non-perturbative QCD effect, i.e., the hadronic loop mechanism, to study χc1→γV radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of χc1→γV are consistent with the corresponding CLEO data of χc1→γV. We expect further experimental measurement of χc1→γV, which will be helpful to test the hadronic loop effect on χc1 decay.