arXiv subjects

Zhi-Feng Sun

Publications and source records attributed to Zhi-Feng Sun.

At least 37 records · Page 2Linked to original sources

arXiv2020

Study $B^{0}_{(s)}$ decays into $ϕ$ and a scalar or vector meson

In the present work, we investigate the decays of $B^{0}_{s} \rightarrow ϕπ^{+}π^{-}$ and $B^{0} \rightarrow ϕπ^{+}π^{-}$ with the final state interactions based on the chiral unitary approach. In the final state interactions of the $π^+π^-$ with its coupled channels, we study the effects of the $ηη$ channel in the two-body interactions for the reproduction of the $f_{0}(980)$ state. Our results for the $π^+π^-$ invariant mass distributions of the decay $B^{0}_{s} \rightarrow ϕπ^{+}π^{-}$ describe the experimental data up to 1 GeV well, with the resonance contributions from the $f_{0}(980)$ and $ρ$. For the predicted invariant mass distributions of the $B^{0} \rightarrow ϕπ^{+}π^{-}$ decay, we found that the contributions from the $f_{0}(500)$ are significant except for the ones from the $f_{0}(980)$ state. With some experimental branching ratios as input to determine the production vertex factors, we make some predictions for the branching ratios of the other final decay channels, including the vector mesons, in the $B^0_{(s)}$ decays, where some of them are consistent with the experimental ones within the uncertainties.

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arXiv2020

Explanation of the newly obseaved $Z_{cs}^-(3985)$ as a $D_s^{()-}D^{()0}$ molecular state

Inspired by the newly observed $Z_{cs}^-(3985)$ by BESIII collaboration, we study the structure of this particle in the picture of $D_s^{(*)-}D^{(*)0}$ molecular state. Firstly we systematically construct the Lagrangians which describing the interaction of charmed mesons, taking into account the chiral and hidden local symmetries. With the obtained effective potentials from the Lagrangians constructed, we solve the coupled channel Bethe-Salpeter equation with the on-shell approximation. On the third Reimann sheet, a pole position of around $3982.34-i0.53$ MeV is obtained, which can be associated to the $Z_{cs}^-(3985)$ and explained as a loose bound state of $D_s^*\bar{D}^*$.

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arXiv2020

$Ξ_{bb}$ and $Ω_{bbb}$ molecular states

Using the vector-exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangian, and has produced realistic results for $Ω_c, Ξ_c, Ξ_b$ and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the $Ξ_{bb}$ and $Ω_{bbb}$ excited states of the molecular type. We obtain seven states of the $Ξ_{bb}$ type with energies between $10408$ and $10869$ MeV and one $Ω_{bbb}$ state at $15212$ MeV.

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arXiv2019

$\bar{K}Λ$ molecular explanation to the newly observed $Ξ(1620)^0$

The newly observed $Ξ(1620)^0$ by the Belle Collaboration inspires our interest in performing a systematic study on the interaction of an anti-strange meson $(\bar{K}^{(*)})$ with a strange or doubly strange ground octet baryon $\mathcal{B}$ ($Λ$, $Σ$, and $Ξ$), where the spin-orbit force and the recoil correction are considered in the adopted one-boson-exchange model. Our results indicate that $Ξ(1620)^0$ can be explained as a $\bar{K}Λ$ molecular state with $I(J^P)=1/2(1/2^-)$ and the intermediate force from $σ$ exchange plays an important role. Additionally, we also predict several other possible molecular candidates, i.e., the $\bar{K}Σ$ molecular state with $I(J^P)=1/2(1/2^-)$ and the triply strange $\bar{K}Ξ$ molecular state with $I(J^P)=0(1/2^-)$.

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arXiv2019

Strong LHCb evidence supporting the existence of the hidden-charm molecular pentaquarks

On March 26th, 2019, at the Rencontres de Moriond QCD conference, the LHCb Collaboration reported the observation of three new pentaquarks, namely $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$, which are consistent with the loosely bound molecular hidden-charm pentaquark states composed of an S-wave charmed baryon $Σ_c$ and an S-wave anti-charmed meson ($\bar{D}, \bar{D}^*$). In this work, we present a direct calculation by the one-boson-exchange (OBE) model and demonstrate explicitly that the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ do correspond to the loosely bound $Σ_c\bar{D}$ with $(I=1/2,J^P=1/2^-)$, $Σ_c\bar{D}^*$ with $(I=1/2,J^P=1/2^-)$ and $Σ_c\bar{D}^*$ with $(I=1/2,J^P=3/2^-)$, respectively.

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arXiv2019

Possible bound states with hidden bottom from $\bar{K}^{()}B^{()}\bar{B}^{(*)}$ systems

We study the three-body systems of $\bar{K}^{(*)}B^{(*)}\bar{B}^{(*)}$ by solving the Faddeev equations in the fixed-center approximation, where the light particle $\bar{K}^{(*)}$ interacts with the heavy bound states of $B\bar{B}$ ($B^*\bar{B}^*$) forming the clusters. In terms of the very attractive $\bar{K}^*B$ and $\bar{K}^*B^*$ subsystems, which are constrained by the observed $B_{s1}(5830)$ and $B_{s2}^*(5840)$ states in experiment, we find two deep bound states, containing the hidden-bottom components, with masses $11002\pm 63$ MeV and $11078\pm 57$ MeV in the $\bar{K}^*B\bar{B}$ and $\bar{K}^*B^*\bar{B}^*$ systems, respectively. The two corresponding states with higher masses of the above systems are also predicted. In addition, using the constrained two-body amplitudes of $\bar{K}B^{(*)}$ and $\bar{K}\bar{B}^{(*)}$ via the hidden gauge symmetry in the heavy-quark sector, we also find two three-body $\bar{K}B\bar{B}$ and $\bar{K}B^{*}\bar{B}^*$ bound states.

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arXiv2018

Higher bottomonium zoo

In this work, we study higher bottomonia up to the $nL=8S$, $6P$, $5D$, $4F$, $3G$ multiplets using the modified Godfrey-Isgur (GI) model, which takes account of color screening effects. The calculated mass spectra of bottomonium states are in reasonable agreement with the present experimental data. Based on spectroscopy, partial widths of all allowed radiative transitions, annihilation decays, hadronic transitions, and open-bottom strong decays of each state are also evaluated by applying our numerical wave functions. Comparing our results with the former results, we point out difference among various models and derive new conclusions obtained in this paper. Notably, we find a significant difference between our model and the GI model when we study $D, F$, and $G$ and $n\ge 4$ states. Our theoretical results are valuable to search for more bottomonia in experiments, such as LHCb, and forthcoming Belle II.

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arXiv2018

Electromagnetic form factors of spin 1/2 doubly charmed baryons

We study the electromagnetic form factors of the doubly charmed baryons, using covariant chiral perturbation theory within the extended on-mass-shell (EOMS) scheme. Vector-meson contributions are also taken into account. We present results for the baryon magnetic moments, charge and magnetic radii. While some of the chiral Lagrangian parameters could be set to values determined in previous works, the available lattice results for $Ξ_{cc}^+$ and $Ω_{cc}^+$ only allow for robust constraints on the low-energy constant (LEC) combination, $c_{89}(=-\frac{1}{3}c_8+4c_9)$. The couplings of the doubly charmed baryons to the vector mesons have been estimated assuming the Okubo--Zweig--Iizuka (OZI) rule. We also give the expressions for the form factors of the double beauty baryons considering the masses predicted in the framework of quark models. A comparison of our results with those obtained in heavy baryon chiral perturbation theory (HBChPT) at the same chiral order is made.

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arXiv2018

The bottomed strange molecules with isospin 0

Using the local hidden gauge approach, we study the possibility of the existence of bottomed strange molecular states with isospin 0. We find three bound states with spin-parity $0^+$, $1^+$ and $2^+$ generated by the $\bar{K}^*B^*$ and $ωB_s^*$ interaction, among which the state with spin 2 can be identified as $B_{s2}^*(5840)$. In addition, we also study the $\bar{K}^*B$ and $ωB_s$ interaction and find a bound state which can be associated to $B_{s1}(5830)$. Besides, the $\bar{K}B^*$ and $ηB_s^*$ and $\bar{K}B$ and $ηB_s$ systems are studied, and two bound states are predicted. We expect that further experiments can confirm our predictions.

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arXiv2017

Constructing new pseudoscalar meson nonets with the observed $X(2100)$, $X(2500)$, and $η(2225)$

Stimulated by the BESIII observation of $X(2100)$, $X(2500)$, and $η(2225)$, we try to pin down new pseudoscalar meson nonets including these states. The analysis of mass spectra and the study of strong decays indicate that $X(2120)$ and $η(2225)$ associated with $π(2070)$ and the predicted kaon $K(2150)$ may form a new pseudoscalar meson nonet. In addition, more experimental data for $X(2100)$ are necessary to determine its structure of nonets. Then, $X(2500)$, $X(2370)$, $π(2360)$, and the predicted kaon $K(2414)$ can be grouped into another new nonet. These assignments to the discussed pseudoscalar states can be further tested in experiment.

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arXiv2016

Chiral corrections to the $1^{-+}$ exotic meson mass

We first construct the effective chiral Lagrangians for the $1^{-+}$ exotic mesons. With the infrared regularization scheme, we derive the one-loop infrared singular chiral corrections to the $π_1(1600)$ mass explicitly. We investigate the variation of the different chiral corrections with the pion mass under two schemes. Hopefully, the explicit non-analytical chiral structures will be helpful to the chiral extrapolation of the lattice data from the dynamical lattice QCD simulation of either the exotic light hybrid meson or tetraquark state.

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arXiv2016

$D_{s0}^{*}(2317)^+$ in the decay of $B_c$ into $J/ψDK$

In this paper we study the relationship between the $D_{s0}^{*}(2317)^+$ resonance and the decay of the $B_c$ meson into $J/ψDK$. In this process, the $B_c$ meson decays first into $J/ψ$ and the quark pair $c\bar{s}$, and then the quark pair hadronizes into $DK$ or $D_sη$ components, which undergo final state interaction. This final state interaction, generating the $D_{s0}^{*}(2317)^+$ resonance, is described by the chiral unitary approach. With the parameters which allow us to match the pole position of the $D_{s0}^{*}(2317)^+$, we obtain the $DK$ invariant mass distribution of the decay $B_c\to J/ψDK$, and also the rate for $B_c\to J/ψD_{s0}^{*}(2317)$. The ratio of these two magnitude is then predicted.

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arXiv2016

Can $X(5568)$ be described as a $B_sπ$, $B\bar{K}$ resonant state?

The D0 Collaboration has recently seen a resonant-like peak in the $B_sπ$ invariant mass spectrum, claimed to be a new state called $X(5568)$. Using a $B_sπ$--$B\bar{K}$ coupled channel analysis, implementing unitarity, and with the interaction derived from Heavy Meson Chiral Perturbation Theory, we are able to reproduce the reported spectrum, with a pole that can be associated to the claimed $X(5568)$ state, and with mass and width in agreement with the ones reported in the experimental analysis. However, if the $T$-matrix regularization is performed by means of a momentum cutoff, the value for the latter needed to reproduce the spectrum is $Λ= 2.80 \pm 0.04\ \text{GeV}$, much larger than a "natural" value $Λ\simeq 1\ \text{GeV}$. In view of this, it is difficult to interpret the nature of this new state. This state would not qualify as a resonance dynamically generated by the unitarity loops. Assuming the observed peak to correspond to a physical state, we make predictions for partners in the $D$, $D^\ast$, and $B^\ast$ sectors. Their observation (or lack thereof) would shed light into this issue.

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arXiv2016

Masses of doubly charmed baryons in the extended on-mass-shell renormalization scheme

In this work, we investigate the mass corrections of the doubly charmed baryons up to $N^2LO$ in the extended-on-mass-shell (EOMS) renormalization scheme, comparing with the results of heavy baryon chiral perturbation theory. We find that the terms from the heavy baryon approach are a subset of those obtained in the EOMS scheme. By fitting the lattice data, we can determine the parameters $\tilde{m}$, $α$, $c_1$ and $c_7$ from the Lagrangian, while in the heavy baryon approach no information on $c_1$ can be obtained from the baryons mass. Correspondingly, the masses of $m_{Ξ_{cc}}$ and $m_{Ω_{cc}}$ are predicted, in the EOMS scheme, extrapolating the results from different values of the charm quark and the pion masses of the lattice QCD calculations.

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arXiv2015

States of $ρB^* \bar{B}^*$ with $J=3$ within the Fixed Center Approximation to Faddeev equations

In this work we study the $ρB^*\bar{B}^*$ three-body system solving the Faddeev equations in the fixed center approximation. We assume the $B^*\bar{B}^*$ system forming a cluster, and in terms of the two-body $ρB^*$ unitarized scattering amplitudes in the local Hidden Gauge approach we find a new $I(J^{PC})=1(3^{--})$ state. The mass of the new state corresponds to a two particle invariant mass of the $ρB^\ast$ system close to the resonant energy of the $B^\ast_2(5747)$, indicating that the role of this $J=2$ resonance is important in the dynamical generation of the new state.

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arXiv2015

The $ρ(ω)B^*(B)$ interaction and states of $J=0,1,2$

In this work, we study systems composed of a $ρ/ω$ and $B^*$ meson pair. We find three bound states in isospin, spin-parity channels $(1/2, 0^+)$, $(1/2, 1^+)$ and $(1/2, 2^+)$. The state with $J=2$ can be a good candidate for the $B_2^*(5747)$. We also study the $ρB$ system, and a bound state with mass $5728$ MeV and width around $20$ MeV is obtained, which can be identified with the $B_1(5721)$ resonance. In the case of $I=3/2$, one obtains repulsion and thus, no exotic (molecular) mesons in this sector are generated in the approach.

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arXiv2015

The masses and axial currents of the doubly charmed baryons

The chiral dynamics of the doubly heavy baryons is solely governed by the light quark. In this work, We have derived the chiral corrections to the mass of the doubly heavy baryons up to N$^3$LO. The mass splitting of $Ξ_{cc}$ and $Ω_{cc}$ at the N$^2$LO depends on one unknown low energy constant $c_7$. With the experimental mass of $Ξ_{cc}(3520)$ as the input, we estimate the mass of $Ω_{cc}$ to be around 3.678 GeV. Moreover, we have also performed a systematical analysis of the chiral corrections to the axial currents and axial charges of the doubly heavy baryons. The chiral structure and analytical expressions will be very useful to the chiral extrapolations of the future lattice QCD simulations of the doubly heavy baryons.

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arXiv2014

Predicting exotic molecular states composed of nucleon and P-wave charmed meson

In this work, we study the interaction between a nucleon and a $P$-wave charmed meson in the $T$ doublet by exchanging a pion. Our calculations indicate that a nucleon and a $P$-wave charmed meson with $J^P=0^+$ or $J^P=1^+$ in the $T$ doublet can form bound states. We propose the experimental search for these exotic molecular states near the $D_1(2420)N$ and $D_2^*(2460)N$ thresholds, where Belle, LHCb and the forthcoming Belle II have the discovery potential for them.

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