Study on Production of Exotic 0 Meson D*sJ(2317) in Decays of ψ(4415)

The newly observed D*sJ family containing D*sJ(2317), DsJ(2460), and DsJ(2632) attracts great interests.Determining their structures may be an important task for both theorists and experimentalists. In this work we use a non-relativistic model (the harmonic oscillator model) to evaluate the production rate of D*sJ (2317) from the decays of ψ(4415). For a comparison, we also employ the widely adopted heavy quark effective theory to repeat the calculation.We find that the rate is sizable and may be observed at BES Ⅲ and CLEO, if it is a p-wave excited state of Ds (1968).Unfortunately, the other two members of the family cannot be observed through decays of charmonia, because of the constraints from the final state phase space.     

Search for the doubly heavy baryons Ω_(bc)~0 and Ξ_(bc)~0 decaying to Λ_c~+π~- and Ξ_c~+π~-

The first search for the doubly heavy Ω_(bc)~0 baryon and a search for the Ξ_(bc)~0 baryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.2 fb~(-1).The baryons are reconstructed via their decays to ∧_c~+π~-andΞ_c~+π~-.No significant excess is found for invariant masses between 6700 and 7300 MeV/c2,in a rapidity range from2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c.Upper limits are set on the ratio of the Ω_(bc)~0 andΞ_(bc)~0 production cross-section times the branching fraction to ∧_c~+π~-(Ξ_c~+π~-) relative to that of the ∧_b~0(Ξ_b~0) baryon,for different lifetime hypotheses,at 95% confidence level.The upper limits range from 0.5×10~(-4) to 2.5×10~(-4) for theΩ_(bc)~0→∧_c~+π~-(Ξ_(bc)~0→∧_c~+π~-) decay,and from 1.4×10~(-3) to 6.9×10~(-3) for the Ω_(bc)~0→Ξ_c~+π~-(Ξ_(bc)~0→Ξ_c~+π~-) decay,depending on the considered mass and lifetime of the Ω_(bc)~0(Ξ_(bc)~0) baryon.     

DOUBLY CHARMED BARYONS(C=+2)≡_(cc)~(++)=ucc,≡_(cc)~+=dcc,Ω_(cc)~+=scc

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Low-energy D~(*+)_1~0 scattering and the nature of resonance-like structure Z~+(4430)

Low-energy scattering of D *+ and  0 1 meson is studied using quenched lattice QCD with improved lattice actions on anisotropic lattices.The threshold scattering parameters,namely the scattering length a 0 and the effective range r 0,for the s-wave scattering in J P = 0 - channel are extracted: a 0 = 2.52(47) fm and r 0 = 0.7(1) fm.It is argued that,albeit the interaction between the two charmed mesons being attractive,it is unlikely that they can form a shallow bound state in this channel.Our calculation provides some useful information on the nature of the newly discovered resonance-like structure Z + (4430) by the Belle Collaboration.     

Thermonuclear ~(19)F(p,α_0)~(16)O reaction rate

The thermonuclear~(19)F(p,α_0)16O reaction rate in the temperature region 0.007–10 GK has been derived by re-evaluating the available experimental data, together with the low-energy theoretical R-matrix extrapolations.Our new rate deviates by up to about 30% compared to the previous results, although all rates are consistent within the uncertainties. At very low temperature(e.g. 0.01 GK) our reaction rate is about 20% lower than the most recently published rate, because of a difference in the low energy extrapolated S-factor and a more accurate estimate of the reduced mass used in the calculation of the reaction rate. At temperatures above ~1 GK, our rate is lower, for instance, by about 20% around 1.75 GK, because we have re-evaluated the previous data(Isoya et al., Nucl. Phys.7, 116(1958)) in a meticulous way. The present interpretation is supported by the direct experimental data. The uncertainties of the present evaluated rate are estimated to be about 20% in the temperature region below 0.2 GK,and are mainly caused by the lack of low-energy experimental data and the large uncertainties in the existing data.Asymptotic giant branch(AGB) stars evolve at temperatures below 0.2 GK, where the~(19)F(p,α)16O reaction may play a very important role. However, the current accuracy of the reaction rate is insufficient to help to describe, in a careful way, the fluorine over-abundances observed in AGB stars. Precise cross section(or S factor) data in the low energy region are therefore needed for astrophysical nucleosynthesis studies.     

Measurement of Ξ_(cc)~(++) production in pp collisions at s~(1/2)=13 TeV

The production of Ξ_(cc)~(++) baryons in proton-proton collisions at a centre-of-mass energy of s~(1/2)=13 TeV is measured in the transverse-momentum range 4 pT15 GeV/c and the rapidity range 2.0 y4.5.The data used in this measurement correspond to an integrated luminosity of 1.7 fb~(-1),recorded by the LHCb experiment during2016.The ratio of the Ξ_(cc)~(++) production cross-section times the branching fraction of the Ξ_(cc)~(++)→Λ_c~+K~-π~+π~+ decay relative to the prompt Λ_c~+production cross-section is found to be(2.22±0.27±0.29)×10~(-4),assuming the central value of the measured Ξ_(cc)~(++) lifetime,where the first uncertainty is statistical and the second systematic.     

G(1590)作为0~(++)胶子球候选者的一个直接的检验

本文用推广的矩分析法研究了在～1.7 GeV处J/φ辐射衰变产生的宽共振峰的结构,提供了一个检测是否此峰中可能同时存在θ/f_z(1720)和G(1590)态的方法.如果G(1590)确实存在,则是对G(1590)作为胶子球候选者的一个直接的检验.     

Experimental Study of f0 (975) in the J/ψ Decays

Based on 7.8×10⁶ J/ψ events collected by the BES at BEPC, through study of the hadronic decays J/ψ→φπ⁺π^－ and J/ψ→ωπ⁺π^－, the branching ratios of the processes and the mass positions and the widths of f0 are obtained. The angular distributions of J/ψ→φf₀,f₀→π⁺π^－, are fitted and the helicity amplitude ratio of this process is first given.     

The non-ordinary Regge behavior of the $$K^*_0(800)$$ or $$\kappa $$κ-meson versus the ordinary $$K^*_0(1430)$$K0∗(1430)

The Regge trajectory of an elastic resonance can be calculated from dispersion theory, instead of fitted phenomenologically, using only its pole parameters as input. This also provides a correct treatment of resonance widths in Regge trajectories, essential for very wide resonances. In this work we first calculate the \(K^*_0(1430)\) Regge trajectory, finding the ordinary almost real and linear behavior, typical of \(q \bar{q}\) resonances. In contrast, for the \(K^*_0(800)\) meson, the resulting Regge trajectory is non-linear and has a much smaller slope than ordinary resonances, being remarkably similar to that of the \(f_0(500)\) or \(\sigma \) meson. The slope of these unusual Regge trajectories seems to scale with the meson masses rather than with scales typical of quark degrees of freedom. We also calculate the range of the interaction responsible for the formation of these resonances. Our results strongly support a non-ordinary, predominantly meson–meson-like, interpretation for the lightest strange and non-strange resonances.     

Centrality Dependence of K~*(892)~0 and φ(1020) Production at LHC

We study the centrality dependence of the mid-rapidity(|y| 0.5) yields and transverse momentum distributions of K~*(892)~0 and φ(1020) resonances produced in Pb + Pb collisions at sNN~(1/2)= 2.76 TeV. The midrapidity density( dN/dy) and the shape of the transverse momentum spectra are well reproduced by an earlier proposed Unified Statistical Thermal Freeze-out Model(USTFM), which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow. The freeze-out properties in terms of kinetic freeze-out temperature and transverse flow velocity parameter are extracted from the model fits to the transverse momentum data provided by the ALICE experiment at the LHC. The kinetic freeze-out temperature is found to increase with decreasing event centrality while the transverse flow velocity parameter shows a mild decrease on moving towards peripheral collisions. Moreover the centrality dependence of the mid-rapidity system size at freeze-out has also been studied in terms of transverse radius parameter.     

Study of scalar meson f 0(980) from B→f 0(980)K * decays

We show how parton distributions unintegrated over the parton transverse momentum, k _t , may be generated, at NLO accuracy, from the known integrated (DGLAP-evolved) parton densities determined from global data analyses. A few numerical examples are given, which demonstrate that sufficient accuracy is obtained by keeping only the LO splitting functions together with the NLO integrated parton densities. However, it is important to keep the precise kinematics of the process, by taking the scale to be the virtuality rather than the transverse momentum, in order to be consistent with the calculation of the NLO splitting functions.     

~(14)N~(16)O分子X~2Π_(3/2)R(1.5)v=0→1及~(15)N~(16)O分子X~2Π_(3/2)Q(1.5)v=0→1跃迁的FLMR光谱

本文采用法拉弟效应的激光磁共振光谱技术，研究了－氧化氮分子１４Ｎ１６ＯＸ２Π３／２Ｒ（１．５）ｖ＝０→１和同位素分子１５Ｎ１６ＯＸ２Π３／２Ｑ（１．５）ｖ＝０→１跃迁的ＦＬＭＲ光谱，实验给出了样品浓度和信号强度之间的关系及调制磁场强度与ＦＬＭＲ信号强度之间的关系。     

Phenomenological studies on B~0 → [K~-π~+]_(S/V)[π~+π~-]_(V/S) → K~-π~+π~+π~- decay

Within the quasi-two-body decay model,we study the localized CP violation and branching fraction of the four-body decay B~0→[K~-π~+]_(s/V)[π~+π~-]_(V/)S→K-π~+π~-π~+ when the K~-π~+and π~-π~+ pair invariant masses are0.35 m(K~-π~+)2.04 GeV and 0 mπ~-π~+1.06 GeV,with the pairs being dominated by the K_0~*(700)~0,K~*(892)~0,K~*(1410)~0,K_0~*(1430) and K~*(1680)~0,and fo(500),ρ~0(770),ω(782) and fo(980) resonances,respectively.When dealing with the dynamical functions of these resonances,fo(500),ρ~0(770),fo(980) and K_0~*(1430) are modeled with the Bugg model,Gounaris-Sakurai function,Flatte formalism and LASS lineshape,respectively,while the others are described by the relativistic Breit-Wigner function.Adopting the end point divergence parameters ρA ∈[0,0.5] andΦ_A∈[0,2π],our predicted results are F_(CP)(B~0→K~-π~+π~+π~-)∈[-0.365,0.447] and B(B~0→K-π~+π~+π~-)∈[6.11,185.32] x 10~(-8),based on the hypothetical qq structures for the scalar mesons in the QCD factorization approach.Meanwhile,we calculate the CP violating asymmetries and branching fractions of the two-body decays B~0→SV(VS) and all the individual four-body decays B~0→SV(VS)→K~-π~+π~-π~+,respectively.Our theoretical results for the two-body decays B~0→K~*(892)~0 fo(980),B~0→K_0~*(1430)~0ω(782),B~0→K~*(892)~0 f~0(980),B~0→K_0~*(1430)~0ρ,and B~0→(1430)~0ω are consistent with the available experimental data,with the remaining predictions await testing in future high precision experiments.     

Measuring D~0-~0mixing in D→f_0(980)K~* and more

We investigate the D0-0 mixing through the doubly Cabibbo suppressed (DCS) channel D0 →f0(980)K0 and its charge conjugate channel, in which the K0 meson is reconstructed in both K π- and KSπ0 final state. Although the decay D0 →f0(980)K* has a small branching ratio, the final state mesons are relatively easy to identify. The f0(980) meson can be replaced by the S-wave π π- state, or a longitudinally polarized vector meson ρ0. All mixing parameters, including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

J/ψ→Σ~0 “非汉字符号”~0 衰变研究(英文)

利用北京正负电子对撞机 (BEPC)上的北京谱仪 (BES)收集的 7 8× 1 0 6 个J ψ事例 ,研究了J ψ→Σ0 Σ0 衰变 .其衰变分支比为BR(J ψ→Σ0 Σ0 ) =( 0 97±0 0 4± 0 2 4 )× 1 0 - 3,角分布具有 dNdcosθ=N0 ( 1 +αcos2 θ)的形式 ,α值等于 -0 2 1± 0 2 7± 0 1 3 .     

ThTiO_4~(-/0),Th_2TiO_6~(-/0)和ThTi_2O_6~(-/0)的电子结构和化学成键的密度泛函理论研究

本文采用B3LYP密度泛函理论方法,探究双核、三核掺杂钍氧簇体系ThTiO_4~(-/0)、Th_2TiO_6~(-/0)和ThTi_2O_6~(-/0)的几何构型、电子结构和化学成键等规律,并与等价电子体(TiO_2)-/0n(n=2,3)进行对比,研究掺杂效应对于掺杂体系的结构和成键等性质的影响.结果表明:掺杂钍氧簇与其等价电子体(TiO_2)-/0n(n=2,3)具有类似的键连方式.ThTiO_4~-中单电子占据的位置与Ti2O-4中单电子的所处位置类似,都是被两个金属原子共用,而Th_2 TiO_6~-,Th Ti_2O_6~-以及Ti_3O_6~-中的单电子均处于那个不含端氧的金属原子上.     

激光打靶发射的(3/2)ω_0和2ω_0谐波的能量测量

本文介绍了采用“神光”装置基频钕玻璃激光(λ=1.053μm)打平面靶和黑洞靶所发射的3/2ω_0和2ω_0谐波的能量测量原理和方法,给出了相应实验结果,并对所得结果进行了简要的分析和讨论。     

Search for B_c (ns) via the B_c (ns) → B_c (ms) π~+ π~- transition at LHCb and Z~0 factory

It is interesting to study the characteristics of the whole family of B c which contains two different heavy flavors.LHC and the proposed Z 0 factory provide an opportunity because a large database of the B c family will be achieved.B c and its excited states can be identified via their decay modes.As suggested by experimentalists,B-c (ns) → B c +γ is not easy to be clearly measured,instead,the trajectories of π + and π- occurring in the decay of B c (ns) → B c (ms) + π + π( n m ) can be unambiguously identified,thus the measurement seems easier and more reliable;therefore this mode is more favorable at the early running stage of LHCb and the proposed Z 0 factory.In this work,we calculate the rate of B c (ns) → B c (ms) + π + π-in terms of the QCD multipole-expansion and the numerical results indicate that the experimental measurements with the luminosity of LHC and Z 0 factory are feasible.     

Molecular Nature of X(3872) in B0→ K0X (3872) and B+→ K+X (3872) Decays

We investigate the decays of B⁰→ K⁰X(3872) and B⁺→ K⁺X(3872) based on the picture where the X(3872) resonance is strongly coupled to the ■+ c.c. channel. In addition to the decay mechanism where the X(3872) resonance is formed from the ■ pair hadronization with the short-distance interaction, we have also considered the ■ rescattering diagrams in the long-distance scale, where D and ■ are formed from c and ■ separately. Because of the difference of the...