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Feng-Kun Guo

Publications and source records attributed to Feng-Kun Guo.

232 records · Page 13Linked to original sources
arXiv2009

Implications of heavy quark spin symmetry on heavy meson hadronic molecules

In recent years, many heavy mesons and charmonia were observed which do not fit in the conventional quark model expectations. Some of them are proposed to be hadronic molecules. Here we investigate the consequences of heavy quark spin symmetry on these heavy meson hadronic molecules. Heavy quark spin symmetry enables us to predict new heavy meson molecules and provides us with a method to test heavy meson molecule assumptions of some newly observed states. In particular, we predict an η_c'f_0(980) bound state as the spin-doublet partner of the Y(4660) proposed as a ψ'f_0(980) bound state with a mass of 4616^{+5}_{-6} MeV and the prominent decay mode η_c'ππ. The width is predicted to be Γ(η_c'ππ)=60\pm30 MeV. The pi^+π^- invariant mass spectrum and the line shape are calculated. We suggest to search for this state in B^{\pm}-->η_c'K^{\pm}π^+π^-, whose branching fraction is expected to be large.

hep-ph↗
arXiv2009

Interactions between heavy mesons and Goldstone bosons from chiral dynamics

We calculate the S-wave scattering lengths for charmed mesons scattering off Goldstone bosons and explore their quark mass dependence using chiral perturbation theory up to next-to-leading order as well as a unitarized version of it. The quark mass dependence of all scattering lengths determined in a recent lattice calculation can be reproduced by the unitarized version. We also discuss signals of possible bound states in these observables.

hep-ph↗
arXiv2009

Final state interactions in the decays J/psi->VPP

We investigate the interplay between crossed channel final state interactions and the constraints from two--particle unitarity for the reactions J/psi->V pi pi and VK\bar K, where V is either omega or phi. Using a model where the parameters are largely constrained by other sources, we find that, although small, crossed channel final state interaction can influence the amplitudes considerably, in special areas of phase space. These results cast doubt on the inapplicability of unitarity constraints on production amplitudes as recently claimed in the literature.

hep-ph↗
arXiv2008

Quark mass dependence of the pion vector form factor

We examine the quark mass dependence of the pion vector form factor, particularly the curvature (mean quartic radius). We focus our study on the consequences of assuming that the coupling constant of the rho to pions is largely independent of the quark mass while the quark mass dependence of the rho--mass is given by recent lattice data. By employing the Omnes representation we can provide a very clean estimate for a certain combination of the curvature and the square radius, whose quark mass dependence could be determined from lattice computations. This study provides an independent access to the quark mass dependence of the rho-pi-pi coupling and in this way a non-trivial check of the systematics of chiral extrapolations. We also provide an improved value for the curvature for physical values for the quark masses, namely = 0.73 +- 0.09 fm^4 or equivalently c_V=4.00\pm 0.50 GeV^{-4}.

hep-ph↗
arXiv2008

Mass splittings within heavy baryon isospin multiplets in chiral perturbation theory

We calculate the mass splittings within the heavy baryon isospin multiplets Σ_{c(b)} and Ξ_{c(b)}' in chiral perturbation theory to leading one-loop order. The pattern of the mass splittings in the Σ_c iso-triplet, which is different from that of any other known isospin multiplet, can be explained. We predict m_{Ξ_c'^+} - m_{Ξ_c'^0}=-0.2\pm0.6 MeV, m_{Ξ_b'^0} - m_{Ξ_b'^-}=-4.0\pm1.9 MeV and the mass of the Σ_b^0 to be 5810.3\pm1.9 MeV.

hep-ph↗
arXiv2008

Subleading contributions to the width of the D_{s0}*(2317)

We construct the effective chiral Lagrangian involving the D--mesons and Goldstone bosons at next-to-leading order taking into account strong as well as electromagnetic interactions. This allows us to disentangle -- to leading order in isospin violation -- the electromagnetic and the strong contribution to the D--meson mass differences. In addition, we also apply the interaction to the decay D_{s0}^*(2317)-> D_s pi0 under the assumption that the D_{s0}^*(2317) is a hadronic molecule. We find (180+-110) keV for the decay width $Γ(D_{s0}^*(2317)-> D_s pi0) -- consistent with currently existing experimental constraints as well as previous theoretical investigations. The result provides further evidence that this decay width can serve as a criterion for testing the nature of the D_{s0}^*(2317).

hep-ph↗
arXiv2008

Hadronic-loop induced mass shifts in scalar heavy-light mesons

We calculate the mass shifts of heavy-light scalar mesons due to hadronic loops under the assumption that these vanish for the groundstate heavy-light mesons. The results show that the masses calculated in quark models can be reduced significantly. We stress that the mass alone is not a signal for a molecular interpretation. Both the resulting mass and the width suggest the observed $D_0^*$ state could be a dressed $c\bar q$ state. We give further predictions for the bottom scalar mesons which can be used to test the dressing mechanism.

hep-ph↗
arXiv2007

On the structure of the pi pi invariant mass spectra of the Upsilon(4S)-->Upsilon(1S,2S) pi^+ pi^- decays

We perform a model-independent analysis for recently reported data of the $π^+π^-$ invariant mass spectra in the $Υ(4S)\toΥ(1S,2S)π^+π^-$ decays and point out that there does exist a broad peak below 0.6 GeV in the data of the $Υ(4S)\toΥ(1S)π^+π^-$ decay, which is analogous to that in the $Υ(3S)\toΥ(1S)π^+π^-$ decay. With the data of $Υ(4S)$ decays, we further test our model developed for studying the puzzle in the $Υ(3S)\toΥ(1S)π^+π^-$ decay. The result shows that with such a model, all the $π^+π^-$ invariant mass spectra of $Υ(4S)$ decays can be described. We also predict the $\cosθ_π^*$ distributions of $Υ(4S)\toΥ(1S,2S)π^+π^-$ decays, which can be used to justify our model prediction.

hep-ph↗
arXiv2007

Light vector hybrid states via QCD sum rules

Vector hybrid states with light quarks $u,d,s$ are investigated via QCD sum rules. The results show that the masses of the $q{\bar q}g$ $(q=u,d)$, $q{\bar s}g$, and $s{\bar s}g$ states with $J^{PC}=1^{--}$ are about 2.3-2.4, 2.3-2.5, and 2.5-2.6 GeV, respectively. It suggests that the recently discovered Y(2175) could not be a pure $s{\bar s}g$ vector hybrid state.

hep-ph↗
arXiv2007

Dynamically generated 1^+ heavy mesons

By using a heavy chiral unitary approach, we study the $S$ wave interactions between heavy vector meson and light pseudoscalar meson. By searching for poles of the unitary scattering amplitudes in the appropriate Riemann sheets, several $1^+$ heavy states are found. In particular, a $D^*K$ bound state with a mass of $2.462\pm0.010$ GeV which should be associated with the recently observed $D_{s1}(2460)$ state is obtained. In the same way, a $B^*{\bar K}$ bound state ($B_{s1}$) with mass of $5.778\pm0.007$ GeV in the bottom sector is predicted. The spectra of the dynamically generated $D_1$ and $B_1$ states in the $I=1/2$ channel are also calculated. One broad state and one narrow state are found in both the charmed and bottom sectors. The coupling constants and decay widths of the predicted states are further investigated.

hep-ph↗
arXiv2006

Isospin and a possible interpretation of the newly observed X(1576)

Recently, the BES collaboration observed a broad resonant structure X(1576) with a large width being around 800 MeV and assigned its $J^{PC}$ number to $1^{--}$. We show that the isospin of this resonant structure should be assigned to 1. This state might be a molecule state or a tetraquark state. We study the consequences of a possible $K^*(892)$-${\bar κ}$ molecular interpretation. In this scenario, the broad width can easily be understood. By using the data of $B(J/ψ\to Xπ^0)\cdot B(X\to K^+K^-)$, the branching ratios $B(J/ψ\to Xπ^0)\cdot B(X\to π^+π^-)$ and $B(J/ψ\to Xπ^0)\cdot B(X\to K^+K^-π^+π^-)$ are further estimated in this molecular state scenario. It is shown that the $X\to π^+π^-$ decay mode should have a much larger branching ratio than the $X\to K^+K^-$ decay mode has. As a consequence, this resonant structure should also be seen in the $J/ψ\to π^+π^-π^0$ and $J/ψ\to K^+K^-π^+π^-π^0$ processes, especially in the former process. Carefully searching this resonant structure in the $J/ψ\to π^+π^-π^0$ and $J/ψ\to K^+K^-π^+π^-π^0$ decays should be important for understanding the structure of X(1567).

hep-ph↗
arXiv2006

Dynamically generated 0^+ heavy mesons in a heavy chiral unitary approach

In terms of the heavy chiral Lagrangian and the unitarized coupled-channel scattering amplitude, interaction between the heavy meson and the light pseudoscalar meson is studied. By looking for the pole of scattering matrix on an appropriate Riemann sheet, a $DK$ bound state $D_{s0}^*$ with the mass of $2.312\pm0.041$ GeV is found. This state can be associated as the narrow $D_{sJ}^*(2317)$ state found recently. In the same way, a $B{\bar K}$ bound state $B_{s0}^*$ is found, and its mass of $5.725\pm0.039$ GeV is predicted. The spectra of $D_0^*$ and $B_0^*$ with $I=1/2$ are further investigated. One broad and one narrow states are predicted in both charm and bottom sectors. The coupling constants and decay widths of the predicted states are also calculated.

hep-ph↗
arXiv2006

Chromo-polarizability and pipi final state interaction

The chromo-polarizability of a quarkonium state is a measure of the amplitude of the $E1$-$E1$ chromo-electric interaction of the quarkonium with soft gluon fields and can be measured in the heavy quarkonium decays. Based on the chiral unitary approach, formulas with modification caused by the $S$ wave $ππ$ final state interaction (FSI) for measuring the chromo-polarizabilities are given. It is shown that the effect of the $S$ wave $ππ$ FSI is very important in extracting chromo-polarizabilities from the experimental data. The resultant values with the FSI are reduced to about 1/3 of those determined without the FSI. The consequences of the FSI correction in the $J/ψ$-nucleon scattering near the threshold are also discussed. The estimated lower bound of the total cross section is reduced from about 17 mb to 2.9 mb, which agrees with the experimental data point and is compatible with the previously estimated values in the literature. In order to understand the interaction of heavy quarkonia with light hadrons at low energies better and to obtain the chromo-polarizabilities of quarkonia accurately, more data should be accumulated. This can be done in the $J/ψ\to π^+π^-l^+l^-$ decay at BES-III and CLEO-c and in the $Υ\to π^+π^-l^+l^-$ decay at B factories.

hep-ph↗
arXiv2006

The pi pi Phase Shifts from psi' to J/psi pi^+ pi^- Decays

The $ψ'\to J/ψπ^+π^-$ decay process provides a new way to extract the $ππ$ $S$ wave phase shifts up to $0.59GeV$. In this paper we derive the formulae for extracting the $ππ$ $S$ wave phase shifts from the invariant mass spectrum of $ππ$ in the $ψ'\to J/ψπ^+π^-$ decay.

hep-ph↗
arXiv2006

S wave Kπscattering and effects of κin J/ψ\to {\bar K}^{*0}(892)K^+π^-

$Kπ$ $S$ wave scattering is studied using a chiral unitary approach (ChUT) taking into account coupled channels. With the amplitudes derived from the lowest order chiral Lagrangian as the kernel of a set of coupled channel Bathe-Salpeter equations, the $I=1/2$ $S$ wave $Kπ$ scattering phase shifts below 1.2 GeV can be fitted by one parameter, a subtraction constant, and a scalar resonance corresponding to the controversial $κ$ ($K^*_0(800)$) can be generated dynamically. A good description of the $I=3/2$ $S$ wave $Kπ$ scattering phase shifts below 1.2 GeV can also be obtained. An artificial singularity in the conventional cut-off method of the 2-meson loop integral of the ChUT is found. The formalism is applied to deal with the $S$ wave $Kπ$ final state interaction (FSI) in the decay $J/ψ\to {\bar K}^{*0}(892)K^+π^-$, and a qualitatively good fit to the data is achieved. The role of $κ$ in the decay is discussed.

hep-ph↗