Analysis of the coupling constants g_(a_0ηπ~0) and g_(a_0η’ π~0) with light-cone QCD sum rules

In this article, we take the point of view that the light scalar meson a0(980) is a conventional qqstate, and calculate the coupling constants ga0ηπ0 and ga0ηπ0 with the light-cone QCD sum rules. The central value of the coupling constant ga0ηπ0 is consistent with that extracted from the radiative decay φ(1020) → a0(980)γ→ηπ0γ. The central value and lower bound of the decay width Γa0→ηπ0 =127+8448 MeV are compatible with the experimental data of the total decay width Γa0(980) = (50-100) MeV from the Particl...     

Analysis of the coupling constants g_(a_0ηπ~0 )and g_(a_0η'π~0) with light-cone QCD sum rules

Abstract In this article, we take the point of view that the light scalar meson a_0(980) is a conventional qq state, and calculate the coupling constants g_(a_0ηπ~0) and g_(a_0η'π~0) with the light-cone QCD sum rules. The central value of the coupling constant g_(a_0ηπ~0) is consistent with that extracted from the radiative decay φ(1020) → a_0(980)γ→ηπ~oγ. The central value and lower bound of the decay width Γ_(α_0→ηπ~0) = 127_(-48)~(+84) MeV are compatible with the experimental data of the total decay width Γ_(α_0(980))= (50-100) MeV from the Particle Data Group with a very model dependent estimation (the decay width can be much larger), while the upper bound is too large. We give a possible explanation for the discrepancy between the theoretical calculation and experimental data.     

Masses and Widths of Light Scalar Mesons in Chiral Perturbation Theory

Based on the diquark model, we assume that the light scalar mesons are q^2q^-2 states rather than qq^-. The chiral effective Lagrangian for the light scalar meson is constructed, and the mass relations are obtained： the isotriplet （a0） and the isosinglet （f0） are the heaviest and are degenerate, the isodoublets （κ） are heavier and the other isosinglet （σ） is the lightest; and 2Mκ^2 = Mα0^2＋ Mσ^2. Using experimental value for a0 and σ mass, we obtain Mκ=794 MeV, which is consistent with the experimental value. Then taking Г（a0^0 →ηπ^0） = 90 MeV and Г（f0→π^0π^0） = 20 MeV, we get the width of σ is： Г（σ0→π^＋π^-）= 150 MeV.     

Study on the Effects of the Light CP-odd Higgs via the Leptonic Decays of Pseudoscalar Mesons

To explain the anomalously large decay rate of Σ+→ p+μ+μ- , it was proposed that a new mechanism where a light CP-odd pseudoscalar boson of mA10 = 214.3 MeV makes a crucial contribution. Later, some authors have studied the transition π0→e+e- and Υ→γA10 in terms of the same mechanism and their result indicates that with the suggested mass one cannot fit the data. This discrepancy might be caused by experimental error of Σ+→p+μ+μ- because there were only a few events. Whether the mechanism is a reasonable one motivates us to investigate the transitions π0→e+e-; η(η′) →μ+μ- ; ηc→μ+μ- ;ηb→τ+τ- within the same framework. It is noted that for π0→e+e-, the standard model (SM) prediction is smaller than the data, whereas the experimental central value of η→μ+μ- is also above the SM prediction. It means that there should be extra contributions from other mechanisms and the contribution of A10 may be a possible one. Theoretically calculating the branching ratios of the concerned modes, we would check if we can obtain a universal mass for A10 which reconcile the theoretical predictions and data for all the modes. Unfortunately, we find that it is impossible to have such a mass with the same coupling |ge|. Therefore we conclude that the phenomenology does not favor such a light A10 , even though a small window is still open.     

Study ao（980）-f0（980） mixing in charmonium decays

In this proceeding, we propose to directly measure the a0^0（980）-f0 （980） mixing in J/ψ→φf0（980）→φa0^0（980） and Xc1→π^0a0^0（980） →π^0f0（980） with the upgraded Beijing Electron Positron Collider（BEPCII） with BESIII detector. We show that a narrow peak of about 8 MeV will be produced by the a0^0（980）-f0（980） mixing, and the predominant feature makes it standing out from the background contributions. The predicted branching ratios for these two reactions are both expected to be about O（10^-6）, which is unambiguously accessible with 10^9 J/ψ and 3 × 10^8 Xc1 at BESⅢ.     

Vector meson J/ψ,φ electro-production in QCD

We study the vector meson electro-production off the proton in a QCD inspired model.A calculation of the differential cross section is performed for the J/ψ,φ meson off the proton.The theoretical results are consistent with the experimental data,and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section.Since gluons interact among themselves via self-interaction,the gluons can form a glueball with quantum numbers IG,JPC =0+,2++,with a decay width Γt =100 MeV and mass of mG = 2.23 GeV.The three gluons can form a three gluon color bound state with charge conjugation quantum number C =-1.This study is quite important to verify the validity of QCD and to search for new particles(tensor glueball and Odderon) as well as quest for new physics.     

Probing new physics in B → J/ψπ~0 decay

We calculate the branching ratio of B → J/ψπ0 with a mixed formalism that combines the QCDimproved factorization and the perturbative QCD approaches.The result is consistent with experimental data.The quite small penguin contribution in B → J/ψπ0 decay can be calculated with this method.We suggest two methods to extract the weak phase β.One is through the dependence of the mixing induced CP asymmetry SJ/ψπ0 on the weak phase β,the other is from the relation of the total asymmetry ACP with the weak phase β.Our results show that the deviation ΔSJ/ψπ0 of the mixing induced CP asymmetry from sin（-2β） is of O（10-3） and has much less uncertainty.The above O（10-3） deviation can provide a good reference for identifying new physics.     

Analysis of the decay B^0→Xc1π^0 with light-cone QCD sum rules

In this article, we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay B^0→Xc1π^0 with the light-cone quantum chromo-dynamic （QCD） sum rules. The numerical results show that its contribution is rather large and should not be neglected. The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.     

Measurement of J/ψ→ηcγ at KEDR

We present a study of the inclusive photon spectra from 5.9 million J/ψ decays collected with the KEDR detector at the VEPP-4M e＋e collider. We measure the branching fraction of radiative decay J/ψ→ηcγ, ηc width and mass. Our preliminary results are： M（ηc） = 2979.4± 1.5 ± 1.9 MeV/c^2, Г（ηc） = 27.8±5.1 ±3.3 MeV, B（Jψ→ηcγ） = （2.34±0.15±0.40）%.     

Radial excitation states of η and η′ in the chiral quark model

A chiral quark model is applied to calculate the spectra of pseudoscalar mesons η and η . By analyzing the obtained spectra, we find that the mesons η (2 1 S 0 ), η(4 1 S 0 ), η (3 1 S 0 ) and η (4 1 S 0 ) are the possible candidates of η(1760), X(1835), X(2120) and X(2370). The strong decay widths of these pseudoscalars to all the possible two-body decay channels are calculated within the framework of the 3 P 0 model. Although the total width of η (21S0 ) is compatible with the BES Collaboration’s experimental value for η(1760), the partial decay width to ωω is too small, which is not consistent with the BES result. If X(1835) is interpreted as η(4 1 S 0 ), the total decay width is compatible with the experimental data, and the main decay modes will be πa 0 (980) and πa 0 (1450), which needs to be checked experimentally. The assignment of X(2120) and X(2370) to η (31S0 ) and η (41S0 ) is disfavored in the present calculation because of the incompatibility of the decay widths.     

Vector meson J/ψ, Ф electro-production in QCD

We study the vector meson electro-production off the proton in a QCD inspired model. A calculation of the differential cross section is performed for the J/ψ, Ф meson off the proton. The theoretical results are consistent with the experimental data, and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section. Since gluons interact among themselves via self-interaction, the gluons can form a glueball with quantum numbers I^G, J^PC = 0^＋, 2^＋＋ with a decay width Гt = 100 MeV and mass of mG = 2.23 GeV. The three gluons can form a three gluon color bound state with charge conjugation quantum number C = -1. This study is quite important to verify the validity of QCD and to search for new particles （tensor glueball and Odderon） as well as quest for new physics.     

X(2900) in a chiral quark model

Recently,the LHCb Collaboration reported their observation of the first two fully open-flavor tetraquark states named Xo(2900) and X_1(2900) with unknown parity.Inspired by the report,we consider all the possible fourquark candidates for X(2900),which include the molecular structure,diquark structure,and their coupling in a chiral quark model via the Gaussian expansion method.To identify the genuine resonances,the real-scaling method(stabilization method) was employed.Our results show that five possible resonances,R_0(2914) with Γ=42 MeV,R1(2906) with Γ=29 MeV,R_1(2912) with Γ=10 McV,Rj(2920) with Γ=9 MeV,and R_J(2842) with Γ=24 MeV,originate in the cs■ system.Compared with experimental data,R_0(2914) with Γ=42 MeV may be an optimal X_0(2900) candidate.However,none of the resonances have a similar width for X_1(2900).Hence,further study is required.     

pp final state interaction in J/ψ →γpp

The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ→γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G(p) with the form of 285500/(m 2 π + p 2 ) should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ→π 0 pp process is also discussed.     

Systematic Study on Alpha Decay Half-Lives of Superheavy Nuclei

The α-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have been determined in the quasi-molecular shape path within the Generalized Liquid Drop Model （GLDM） including the proximity effects between nucleons in a neck and the mass and charge asymmetry. The results are in reasonable agreement with the published experimental data for the alpha decay half-llves of isotopes of charge 112, 114, and 116, of the element 294118 and of some decay products. A comparison of present calculations with the results by the DDM3Y effective interaction and by the Viola-Seaborg-Sobiczewski （VSS） formulae is also made. The experimental a decay half lives all stand in between the GLDM calculations and VSS formula results. This demonstrates the possibility of these models to provide reasonable estimates for the half-lives of nuclear decays by a emissions for the domain of SHN. The half-lives of these new nuclei are thus well tested from the reasonable consistence of the macroscopic, the microscopic, the empirical formulae and the experimental data. This also shows that the present data of SHN themselves are consistent. It could suggest that the present experimental claims on the existence of new elements Z =110 - 118 are reliable. It is expected that greater deviations of a few SHN between the data and the model may be eliminated by further improvements on the precision of the measurements.     

Rare decays ^-Bs,d^0→e^＋e^- in a top quark two-Higgs-doublet model

In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of ^-Bs,d^0→e^＋e^-（e= e,μ） decays. Comparing the theoretical predictions with the experimental upper-limits, we found that （a） The data of Br（^-Bs,d^0→e^＋e^-） give the upper bound on tanβ： tanβ≤22, while Br（^-Bs^0→e^＋e^-） give tanβ≤12 for fixed δ = 0^0, mH＋ = 350 CeV, mH^0 = 160 GeV, mh^0 = 115 GeV and mA^0 = 120 GeV; （b） A light neutral Higgs boson mass mho （mA^0） less than 50 GeV （120 GeV） is excluded by the data of branching ratios for ^-Bs,d^0→e^＋e^-（e = μ） decays with tanβ= 10; （c） The bounds on mh^0 and tanβ, or mA^0 and tanβ are strongly correlated： a smaller （larger） tanβ means a lighter （heavier） neutral Higgs boson.     

Study on Bd → φKs Decay in EDQS Model

We study Bd → φKs decay in extra down-type quarks （EDQS） model with a non-universal Z boson associated with flavor changing neutral currents （FCNCs） at the tree level. With the up-to-date experimental data of Br（Bd → φKs）, SCKs, and ACKs, we derive the bounds on the Z-b-s coupling parameter ｜Ubs ｜ and the new weak phase φ, using the constrained parameter spaces, we finally give predictions for Bd → φφ decay, which could be tested at the Fermilab Tevatron and the LHC-b experiments.     

Hunting η-bound nuclei

The η meson can be bound to atomic nuclei.Experimental search is discussed in the form of final state interaction for the reactions dp → 3 Heη and dd → 4 Heη.For the latter case tensor polarized deuterons were used in order to extract the s-wave strength.For both reactions complex scattering lengths are deduced： a 3 Heη = ± 10.7±0.8 ＋0.1 -0.5 ＋i· 1.5±2.6 ＋1.0-0.9 fm and a 4 Heη = [±（3.1±0.5）＋i·（0±0.5）] fm.In a two-nucleon transfer reaction under quasi-free conditions,p^ 27 Al → ^3 HeX,was investigated.The system X can be the bound 25 Mg  η at rest.When a possible decay of an intermediate N  （1535） is required,a highly significant bump shows up in the missing mass spectrum.The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ=4.4±1.3 MeV.     

Pomeron-Quark Coupling from Charge Conjugation Invariance

Based on the charge conjugation invariance and the vacuum property of the Pomeron, we point out that the commonly used vector vertex of the Pomeron coupling to quark is incorrect since it contradicts with the Pomeron property. We also claim that the soft Pomeron could be a tensor glueball ξ(2230) with quantum numbers IG JPC = 0 2 and total decay width Γtot ≌ 100 MeV, which lies on the soft Pomeron trajectory αp = 1.08 0.20t. Therefore, the coupling vertex of the soft Pomeron to quark should be tensorial which is invariant under the charge conjugation and can explain why the inadequate vector coupling, γμ, of the soft Pomeron to quark is successful in dealing with Pomeron physics.     

QCD Approach to B →Dπ Decays and CP Violation

The branching ratios and CP violations of the B →Dπ decays, including both the color-allowed and the color-suppressed modes, are investigated in detail within QCD framework by considering all diagrams that lead to three effective currents of two quarks. An intrinsic mass scale as a dynamical gluon mass is introduced to treat the infrared divergence caused by the soft collinear approximation in the endpoint regions, and the Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators. When the dynamical gluon mass μg is regarded as a universal sca/e, it is extracted to be around μg = 440 MeV from one of the well-measured B →Dπ decay modes. The resulting predictions for all branching ratios are in agreement with the current experimental measurements. As these decays have no penguin contributions, there are no direct CP asymmetries. Due to interference between the Cabibbo-suppressed and the Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the B →D^±π^±↓ decays to be consistent with the experimental data at 1-σ level. More precise measurements will be helpful to extracting weak angle 2β＋γ.     

Analysis of Y（4660） and Related Bound States with QCD Sum Rules

In this article, we take the vector charmonium-like state Y（4660） as a φ＇ fo（980） bound state （irrespective of the hadro-charmonium and the molecular state） tentatively, and study its mass using the QCD sum rules. The numerical value My = 4.71 ±0.26 GeV is consistent with the experimental data. Considering the SU（3） symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states φ＇a（400-1200）, γ′″ fo（980）, and γ′″σ（400-1200） with the QCD sum rules, and make reasonable predictions for their masses.