Different Interaction Models in Strong Decays of Negative Parity N^＊ ResonancesUnder 2 GeV

In this paper, by using harmonic-oscillator wave functions of different interaction models, i.e. OPE (onepion-exchange model), OPsE (only pseudoscalar meson exchange model), the extended GBE (Goldstone-boson-exchange model including vector and scalar mesons), and OGE (one-gluon-exchange model), we calculate and compare the strong decays of negative parity N* resonances under 2 GeV. We find that the conventional mixing angles are correct, and GBE and OGE are obviously superior to OPE and OPsE.

Strong decays of P-wave mixing heavy-light 1^+ states

Many P-wave mixing heavy-light 1^＋ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1^＋ states D^0, D^±, D^±, B^0, B^±： and Bs are studied by the improved Bethe SMpeter （B-S） method with two conditions of mixing angle 0： one is 0 = 35.3°; the other is considering a correction to the mixing angle 0=35.3°＋θ1. Valuable predictions for the strong decay widths are obtained： F（D1^0）=232 MeV, r（D1^0）=21.5 MeV, F（D1^±）=232 MeV, F（D1^±）=21.5 MeV, F（Ds1^±）=0.0101 MeV,Г（Ds1^±l）=0.950 MeV, F（BГ^±＋）=263 MeV, F（B1^±=16.8 MeV, F（B′s1）=0.01987 MeV and F（B,1）=0.412 MeV. It is found that the decay widths of D~ and Bsl are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.

Strong decays of the P_(cs)(4459) as a Ξc D^(*) molecule

In this work,we study the strong decay of the newly observed P_(cs)(4459),assuming that it is a pureΞcD^(*)molecular state.Considering two possible spin-parity assignments J^(P)=1/2^(−)and J^(P)=3/2^(−),the partial decay widths of theΞcD^(*)molecular state into J/ψΛ,D^(−)_(s)Λ^(+)_(c),and DΞ^((′))_(c) final states through hadronic loops are evaluated with the help of the effective Lagrangians.In comparison with the LHCb data,the S-waveD^(*)Ξc molecular with J^(P)=1/2^(−)assignment for P_(cs)(4459)is supported by our study,while the P_(cs)(4459)in spin-parity J^(P)=3/2^(−)case may be explained as an S-wave coupled bound state with lagerΞcD^(*)component.In addition,the calculated partial decay widths with J^(P)=1/2^(−)ΞcD^(*)molecular state picture indicate that allowed decay mode,DΞ′c,may have the biggest branching ratio.The experimental measurements for this strong decay process could be a crucial test for the molecule interpretation of the P_(cs)(4459).

Mass spectrum and strong decays of strangeonium in a constituent quark model

In this work we calculate the mass spectrum of strangeonium up to the 3D multiplet within a nonrelativistic linear potential quark model.Furthermore,using the obtained wave functions,we also evaluate the strong decays of the strangeonium states with the ^3P_0 model.Based on our successful explanations of the well established states φ(1020) , φ(1680) , h_1(1415) , f'_2(1525) ,and φ_3(1850) ,we further discuss the possible assignments of strangeonium-like states from experiments by combining our theoretical results with observations.It is found that some resonances,such as f_2(2010) and f_2(2150) ,listed by the Particle Data Group,and X(2062) and X(2500) ,newly observed by BESIII,may be interpreted as strangeonium states.The possibility of φ(2170) as a candidate for φ(3S) or φ(2D) cannot be excluded.We expect our results to provide useful references for looking for the missing s\bar{s} states in future experiments.

Analysis of the charmonium-like states X~*(3860), X(3872), X(3915),X(3930) and X(3940) according to their strong decay behaviors

Inspired by the newly observed state X＊（3860）, we analyze the strong decay behaviors of some charmonium-like states, X＊（3860）, X（3872）, X（3915）, X（3930） and X（3940）, with the 3P0 model. We carry out our work based on the hypothesis that all of these states are charmonium systems. Our analysis indicates that, as a 0＋＋ charmonium state, X＊（3860） can reproduce the experimental data. As for X（3872）, it can tentatively be interpreted as the mixture of a m cc system and a D＊0D0 molecular state. If we consider X（3940） as a 31S0 state, its total width in the present work is much lower than the experimental result. Thus, the 31S0 charmonium state seems not to be a good candidate for X（3940）. Furthermore, our analysis implies that it is reasonable to assign X（3915） and X（3930） to be the same state, 2＋＋. However, combining our analysis with that in Refs.[14,71], we speculate that X（3915）/X（3930） might also be the mixture of a m cc system and a molecular state.

Strong decays of newly observed heavy flavor hadrons

In this talk, we briefly review the experimental status of newly observed charmed hadrons during the past years. Then we introduce the theoretical progresses on these charmed hadrons, especially our studies on the strong decays of new charmed hadrons during the past one year.

Chargino Production via Z^0-Boson Decay in a Strong Electromagnetic Field

In the framework of MSSM the probability of Z0-boson decay to chaxginos in a strong electromagnetic field, Z X＋X-, is analyzed. The method of calculations employs exact solutions of relativistic wave equations for charginos in a crossed electromagnetic field. Analytic expression for the decay width is obtained at an arbitrary value of the parameter which characterizes the external-field strength Fμv and Z%boson momentum qv. The process Z0→ X＋X- is forbidden in a vacuum for the case of relatively heavy charginos： Mx±mz/2. However, in an intense electromagnetic background this reaction could take place in the region of superstrong fields （x〉1）.

Towards the decays of X(1625) in the molecular picture

In this talk, we firstly overview the experimental status of Nx（1625）, which is an enhancement structure observed in K-3. invariant mass spectrum of J/ψ → pK-∧. process. Then we present the result of the decay of Nx（1625） under the two molecular assumptions, i.e. S-wave∧K- and S-wave ∑0K- molecular states. Several experimental suggestions for Nx （1625） are proposed.

Study of ψ(4415) in the QPC model

Some authors consider the ψ（4415） to be the 4S or 5S excited state of a cc pair. Starting from this assumption, we study the decays of the ψ（4415） to DD, D^＊D^＊, DsDs, Ds^＊Ds^＊, and get the corresponding branching ratios in terms of the Quark-Pair-Creation （QPC） model. Compared with the experimental data, we find that the results of 4S state agree much better than those of the 5S state. Therefore, it is more reasonable to assume the ψ（4415） to be a 4S state.

A note on ■_c(3055)^+ and ■_c(3123)^+

The Babar Collaboration announced two new excited charmed baryons c（3055）^＋ and c（3123）^＋. We study their strong decays assuming they are D-wave states. Some assignments are excluded by comparing our numerical results with the experimental values of the total widths of c（3055）^＋ and c（3123）^＋. We also suggest some possible decay modes, which will be helpful to determine the properties of c（3055）^＋ and c（3123）^＋.

Study on the possible molecular state composed of D^∗sD^¯s1 within the Bethe-Salpeter framework

Recently,a vector charmonium-like state Y(4626)was observed in the portal of D+sDs1(2536)−.This intrigues an active discussion on the structure of the resonance because it has obvious significance for gaining a better understanding on its hadronic structure that contains suitable inner constituents.Therefore,this observation concerns the general theoretical framework about possible structures of exotic states.Since the mass of Y(4626)is slightly above the production threshold of D+sDs1(2536)−,whereas it is below that of D^∗sD^¯s1(2536)with the same quark contents as that of D+sDs1(2536)−,it is natural to conjecture that Y(4626)is a molecular state of D^∗sD^¯s1(2536),as suggested in the literature.Confirming or negating this allegation would shed light on the goal we are concerned with.We calculate the mass spectrum of a system composed of a vector meson and an axial vector i.e.,D^∗sD^¯s1(2536)within the framework of the Bethe-Salpeter equations.Our numerical results show that the dimensionless parameterλin the form factor,which is phenomenologically introduced to every vertex,is far beyond the reasonable range for inducing even a very small binding energyΔE.It implies that the D^∗sD^¯s1(2536)system cannot exist in the nature as a hadronic molecule in this model.Therefore,we may not be able to assume the resonance Y(4626)to be a bound state of D^∗sD^¯s1(2536),and instead,it could be attributed to something else,such as a tetraquark.

Toward discovering low-lying P-wave excited∑_(c)baryon states

In this study,by combining the equal spacing rule with recent observations of Ω_(C)(X)and Ξ_(C)(X)baryons,we predict the spectrum of the low-lying λ-mode 1P-wave excited ∑_(c) states.Furthermore,their strong decay properties are predicted using the chiral quark model and the nature of∑_(c)(2800)is investigated by analyzing the invariant mass spectrum.The ∑_(c)(2800)structure observed in the Λ_(c)πmass spectrum was found to potentially arise from two overlapping P-wave resonances,∑_(c)(2813)3/2^(-)and ∑_(c)(2840)5/2^(-).These resonances have similar decay widths of Г〜40 MeV and predominantly decay into the Λ_(c)π channel.The ∑_(c)(2755)1/2^(-)state is likely to be a very narrow state with a width of Г〜15 MeV,with its decays almost saturated by the Λ_(c)π channel.Additionally,evidence of the Lc(2755)1/2^(-)resonance as a very narrow peak may be seen in the Λ_(c)π invariant mass spectrum.The other two P-wave states,∑_(c)(2746)1/2^(-)and ∑_(c)(2796)3/2^(-),are relatively narrow states with similar widths of「〜30 MeV and predominantly decay into ∑_(c)π and ∑^(*)_(c)π,respectively.This study can provide useful references for discovering these low-lying P-wave states in forthcoming experiments.

Hadron molecules

We discuss a possible interpretation of the open charm mesons D＊s0 （2317）,D s1 （2460） and the hidden charm mesons X（3872）,Y（3940） and Y（4140） as hadron molecules.Using a phenomenological Lagrangian approach we review the strong and radiative decays of the D＊ s0 （2317） and D s1 （2460） states.The X（3872） is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration.Determing the radiative （γJ/ψ and γψ（2s）） and strong （J/ψ2π and J/ψ3π） decay modes we show that the present experimental observation is consistent with the molecular structure assumption of the X（3872）.Finally,we give evidence for molecular interpretations of the Y（3940） and Y（4140） related to the observed strong decay modes J/ψ＋ω or J/ψ＋φ,respectively.